A compound or a salt thereof having an affinity substance for a soluble protein, a cleavable moiety, and a reactive group

Abstract

To develop a technique that enables the modification of soluble proteins, in particular the site-selective modification of soluble proteins. The present invention provides a compound of the following formula (I): ALBR (I) [During the ceremony, A is an affinity substance for soluble proteins, L is a cleavable linker, which is a divalent group that includes a cleavable moiety; B is (a) a divalent group containing a bioorthogonal functional group, or (b) a divalent group not containing a bioorthogonal functional group; and R is a group reactive to the soluble protein.] A compound or a salt thereof having an affinity substance for a soluble protein, a cleavable moiety, and a reactive group,

Description

Technical Field

[0001] The present invention relates to a compound having an affinity substance for a soluble protein, a cleavable moiety, and a reactive group, or a salt thereof, etc.

Background Art

[0002] In recent years, research and development of antibody-drug conjugates (ADCs) have been actively conducted. As the name suggests, ADC is a drug in which a drug (e.g., an anticancer agent) is conjugated to an antibody, and has direct cytotoxic activity against cancer cells and the like. A typical ADC is T-DM1 (trade name: Kadcyla (registered trademark)) jointly developed by Immunogene and Roche (Non-Patent Documents 1 to 3).

[0003] The non-uniformity of ADCs such as T-DM1 has been a problem since the beginning of their development. That is, since a low-molecular-weight drug is randomly reacted with about 70 to 80 Lys residues in the antibody, the drug-antibody ratio (DAR) and the conjugation position are not constant. Usually, in such a random conjugation method, the DAR is in the range of 0 to 8, and it has been found that a plurality of drugs with different drug-binding numbers are generated. In recent years, it has been reported that when the drug-binding number and binding position of ADC drugs are changed, the pharmacokinetics, drug release rate, and effects change. From these facts, it is required to control the number and position of drugs to be conjugated in next-generation ADCs. If the number and position are constant, it is considered that problems such as expected efficacy, variations in conjugated drugs, and lot differences, so-called regulation problems, will be solved (Non-Patent Document 4).

[0004] Site-selective modification methods of antibodies have been researched around the world, but most of these methods use genetic engineering techniques or enzymes. Although the site selectivity and number selectivity can be controlled with genetic engineering modification methods, problems such as a decrease in the expression efficiency of the antibody itself (a decrease in the total yield when preparing ADC) have been pointed out. Another problem is that it takes a long time to establish an antibody expression system (Non-Patent Documents 5 to 7).

[0005] Recently, a method for chemically modifying proteins in a contaminated environment such as inside a cell using a small molecule probe has been reported. This method is used for identifying receptors for imaging and repositioning of small molecule drugs. In the field of chemical biology, organic chemical protein modification methods using synthetic small molecule probes have attracted attention (Non-Patent Documents 8 to 10).

[0006] Recently, the C-CAP (Chemical Conjugation by Affinity Peptide) method has been developed. The method of reacting an antibody with a peptide reagent in which an NHS-activated ester and a drug are linked to a peptide (i.e., a method of producing an ADC via a linker containing a peptide portion) has succeeded in site-selective modification of an antibody. This method is the first in the world to successfully site-selectively modify an antibody Fc region with a drug by chemical synthesis, and has been confirmed to have good practical results (reaction time 30 minutes, yield 70% (in the case of DAR 1), site selectivity 100%). It has been demonstrated that the DAR can be controlled at 2 by adding about 5 equivalents of a peptide reagent, which is groundbreaking in that the modification site can also be controlled (Patent Document 1). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] International Publication No. 2016 / 186206 [Non-patent literature]

[0008] [Non-Patent Document 1] Reichert JM et al., Nat Biotechnol 2005;23:1073-8 [Non-Patent Document 2] Kubota T et al., Cancer Sci 2009;100:1566-72 [Non-Patent Document 3] Wu AM et al., Nat Biotechnol 2005;23:1137-46 [Non-Patent Document 4] Junutula JR et al., Nat Biotechnol 2008;26:925-32 [Non-Patent Document 5] Shen BQ et al., Nat Biotechnol 2012;30:184-9 [Non-Patent Document 6] Hofer T et al., Biochemistry 2009;48:12047-57 [Non-Patent Document 7] Liu W et al., Nat Methods 2007;4:239-44 [Non-Patent Document 8] S.T. Laughlin et al., Science 2008;320,664 [Non-Patent Document 9] A.E. Speers et al., ChemBioChem 2004;5,41 [Non-Patent Document 10] Y. Takaoka et al., Angew.Chem.Int.Ed. 2013;52,4088 [Summary of the Invention] [Problems to be Solved by the Invention]

[0009] An object of the present invention is to develop a technique that enables modification of a soluble protein, particularly site-selective modification of a soluble protein.

Means for Solving the Problems

[0010] As a result of intensive studies, the present inventors have found that a compound having (1) an affinity substance for a soluble protein, (2) a reactive group for an amino acid residue constituting the soluble protein, and (3) a cleavable moiety between the affinity substance and the reactive group, and (4) capable of generating a structural unit having a bioorthogonal functional group on the reactive group side by cleavage at the cleavable moiety (i.e., a structural unit containing a bioorthogonal functional group and a reactive group), which is developed based on a novel and original design concept, is useful for site-specific modification of soluble proteins (e.g., FIGS. 1-1, 1-2, 1-3, 2). The present inventors have also found that by using such a compound, a soluble protein having a functional substance (e.g., a drug) at a position-selective manner without containing a peptide moiety as a linker (e.g., an antibody-drug conjugate (ADC)) can be prepared. Avoiding the use of a linker containing a peptide moiety that has potential immunogenicity and is easily hydrolyzed in blood is desirable in the clinical application of ADCs. That is, it can be said that the method developed by the present inventors is the first in the world to succeed in site-selectively modifying the antibody Fc region with a drug by a chemical synthesis method without using a linker containing a peptide moiety. The present inventors have also succeeded in developing various compounds having the structural features (1) to (4) above (e.g., FIGS. 1-1, 1-2, 1-3, 2), and have completed the present invention.

[0011] That is, the present invention is as follows.

[0012] In a first embodiment, the present invention provides a compound or a salt thereof having an affinity substance for a soluble protein, a cleavable moiety and a reactive group, and a site-selective modification reagent for a soluble protein containing the compound or a salt thereof. [1] The following formula (I): A-L-B-R (I) [In the formula, A is an affinity substance for a soluble protein, L is a cleavable linker which is a divalent group containing a cleavable moiety, B is (a) a divalent group containing a bioorthogonal functional group or (b) a divalent group not containing a bioorthogonal functional group, R is a reactive group for the soluble protein. A compound having an affinity substance, a cleavable moiety and a reactive group for a soluble protein represented by 〕 or a salt thereof. 〔2〕The compound or a salt thereof according to 〔1〕, wherein L is (i) a cleavable linker which is a divalent group containing a cleavable moiety having the ability to generate a bioorthogonal functional group on the reactive group side by cleavage, or (ii) a cleavable linker which is a divalent group containing a cleavable moiety having no ability to generate a bioorthogonal functional group on the reactive group side by cleavage. 〔3〕The compound or a salt thereof according to 〔2〕, wherein L is the cleavable linker of (i) above. 〔4〕The compound or a salt thereof according to 〔2〕 or 〔3〕, wherein L is the cleavable linker of (i) above and B is the divalent group of (b) above. 〔5〕The compound or a salt thereof according to 〔2〕, wherein L is the cleavable linker of (ii) above and B is the divalent group of (a) above. 〔6〕The compound or a salt thereof according to any one of 〔1〕 to 〔5〕, wherein the affinity substance for the soluble protein is a peptide. 〔7〕The compound or a salt thereof according to 〔6〕, wherein the peptide is a binding peptide for the Fc region of a monoclonal antibody. 〔8〕The compound or a salt thereof according to 〔7〕, wherein the binding peptide is a binding peptide for the Fc region of IgG. 〔9〕The compound or a salt thereof according to any one of 〔1〕 to 〔8〕, wherein the affinity substance contains any one Fc region protein selected from the group consisting of the following (A) to (C) and is an affinity substance for an antibody having antigen-binding ability: (A) An Fc region protein containing the amino acid sequence of SEQ ID NO: 1; (B) An Fc region protein containing an amino acid sequence in which one or several amino acid residues are inserted, added, deleted or substituted in the amino acid sequence of SEQ ID NO: 1; or An Fc region protein comprising an amino acid sequence having 90% or more identity with the amino acid sequence of SEQ ID NO: 1.

[10] The binding peptide is represented by the following formula (i): (X 1-3 )-C-(X2)-H-(Xaa1)-G-(Xaa2)-L-V-W-C-(X 1-3 ) (SEQ ID NO: 94) (i) [In the formula, X is the same or different and is any amino acid residue other than cysteine, C is a cysteine residue, H is a histidine residue, Xaa1 is an arginine residue, leucine residue, lysine residue, aspartic acid residue, glutamic acid residue, 2-aminosuberic acid residue, or diaminopropionic acid residue, G is a glycine residue, Xaa2 is a lysine residue, glutamine residue, glutamic acid residue, asparagine residue, or aspartic acid residue, L is a leucine residue, V is a valine residue, and W is a tryptophan residue. ] A peptide or a salt thereof according to any one of [7] to [9], which comprises an amino acid sequence consisting of 13 to 17 amino acid residues represented by the above formula and is capable of binding to human IgG and / or rabbit IgG.

[11] The binding peptide is represented by the following formula (i-1): (X 1-3 )-C-(X2)-H-(Xaa1)-G-(Xaa2)-L-V-W-C-(X 1-3 ) (SEQ ID NO: 95) (i-1) [In the formula, X is the same or different and is any amino acid residue other than cysteine, C is a cysteine residue, H is a histidine residue, Xaa1 is a lysine residue, cysteine residue, aspartic acid residue, glutamic acid residue, 2-aminosuberic acid residue, or diaminopropionic acid residue, G is a glycine residue, Xaa2 is a glutamic acid residue or an asparagine residue, L is a leucine residue, V is a valine residue, and W is a tryptophan residue. ] A peptide or a salt thereof comprising an amino acid sequence consisting of 13 to 17 amino acid residues represented by the formula and capable of binding to human IgG and / or rabbit IgG, which is any one of the compounds of [7] to [9] or a salt thereof.

[12] The binding peptide is represented by the following formula (i-2): (X 1-3 )-C-(X2)-H-(Xaa1)-G-(Xaa2)-L-V-W-C-(X 1-3 ) (SEQ ID NO: 96) (i-2) [In the formula, X is the same or different and is any amino acid residue other than cysteine, C is a cysteine residue, H is a histidine residue, Xaa1 is an arginine residue or a leucine residue, G is a glycine residue, Xaa2 is a lysine residue, a glutamine residue, or an aspartic acid residue, L is a leucine residue, V is a valine residue, and, W is a tryptophan residue. ] A peptide or a salt thereof comprising an amino acid sequence consisting of 13 to 17 amino acid residues represented by the formula and capable of binding to human IgG and / or rabbit IgG, which is any one of the compounds of [7] to

[10] or a salt thereof.

[13] The binding peptide is represented by the following formula (v): (X 1-3 )-C-(Xaa3)-(xaa4)-H-(Xaa1)-G-(Xaa2)-L-V-W-C-(Xaa5)-(Xaa6)-(Xaa7) (SEQ ID NO: 102) (v) [In the formula, X is, independently or differently, any amino acid residue other than cysteine, C is a cysteine residue, Xaa3 is an alanine residue or a lysine residue, Xaa4 is a tryptophan residue or a tyrosine residue, H is a histidine residue, Xaa1 is an arginine residue, a leucine residue, a lysine residue, an aspartic acid residue, a glutamic acid residue, a 2-aminosuberic acid residue, or a diaminopropionic acid residue, G is a glycine residue, Xaa2 is a lysine residue, a glutamine residue, a glutamic acid residue, an asparagine residue, or an aspartic acid residue, L is a leucine residue, V is a valine residue, W is a tryptophan residue, Xaa5 is a threonine residue or a lysine residue, Xaa6 is a tyrosine residue, a lysine residue, or none, and Xaa7 is a histidine residue, a lysine residue, or none.〕, and includes an amino acid sequence consisting of 13 to 17 amino acid residues represented by the formula, and is a peptide or a salt thereof that can bind to human IgG and / or rabbit IgG, and is a compound according to any one of 〔7〕 to 〔12〕 or a salt thereof. 〔14〕The binding peptide has the following formula (vi): D-C-(Xaa3)-(Xaa4)-H-(Xaa1)-G-(Xaa2)-L-V-W-C-(Xaa5)-(Xaa6)-(Xaa7) (SEQ ID NO: 103) (vi) [In the formula, D is an aspartic acid residue, C is a cysteine residue, Xaa3 is an alanine residue or a lysine residue, Xaa4 is a tryptophan residue or a tyrosine residue, H is a histidine residue, Xaa1 is an arginine residue, a leucine residue, a lysine residue, an aspartic acid residue, a glutamic acid residue, a 2-aminosuberic acid residue, or a diaminopropionic acid residue, G is a glycine residue, Xaa2 is a lysine residue, a glutamine residue, a glutamic acid residue, an asparagine residue, or an aspartic acid residue, L is a leucine residue, V is a valine residue, W is a tryptophan residue, Xaa5 is a threonine residue, or a lysine residue, Xaa6 is a tyrosine residue, a lysine residue, or none, Xaa7 is a histidine residue, a lysine residue, or none. A peptide or a salt thereof, characterized by comprising an amino acid sequence consisting of 13 to 15 amino acid residues represented by the above formula and being capable of binding to human IgG and / or rabbit IgG. A compound according to any one of [7] to

[13] or a salt thereof.

[15] The binding peptide is represented by the following formula (vii): D-C-(Xaa3)-(Xaa4)-H-(Xaa1)-G-(Xaa2)-L-V-W-C-T (SEQ ID NO: 104) (vii) [In the formula, D is an aspartic acid residue, C is a cysteine residue, Xaa3 is an alanine residue, or a lysine residue, Xaa4 is a tryptophan residue, or a tyrosine residue, H is a histidine residue, Xaa1 is an arginine residue, a leucine residue, a lysine residue, an aspartic acid residue, a glutamic acid residue, a 2-aminosuberic acid residue, or a diaminopropionic acid residue, G is a glycine residue, Xaa2 is a lysine residue, a glutamine residue, a glutamic acid residue, an asparagine residue, or an aspartic acid residue, L is a leucine residue, V is a valine residue, W is a tryptophan residue, and T is a threonine residue] and contains an amino acid sequence consisting of 13 amino acid residues, and is a peptide or a salt thereof characterized by being capable of binding to human IgG and / or rabbit IgG, a compound according to any one of [7] to

[14] or a salt thereof.

[16] The binding peptide has the following formula (viii): R-G-N-C-(Xaa3)-(Xaa4)-H-(Xaa1)-G-(Xaa2)-L-V-W-C-(Xaa5)-(Xaa6)-(Xaa7) (SEQ ID NO: 105) (viii) [wherein, R is an arginine residue, G is a glycine residue, N is an asparagine residue, C is a cysteine residue, Xaa3 is an alanine residue or a lysine residue, Xaa4 is a tryptophan residue or a tyrosine residue, H is a histidine residue, Xaa1 is an arginine residue, a leucine residue, a lysine residue, an aspartic acid residue, a glutamic acid residue, a 2-aminosuberic acid residue, or a diaminopropionic acid residue, G is a glycine residue, Xaa2 is a lysine residue, a glutamine residue, a glutamic acid residue, an asparagine residue, or an aspartic acid residue, L is a leucine residue, V is a valine residue, W is a tryptophan residue, Xaa5 is a threonine residue or a lysine residue, Xaa6 is a tyrosine residue, a lysine residue, or none, and Xaa7 is a histidine residue, a lysine residue, or absent. A peptide or a salt thereof, which comprises an amino acid sequence consisting of 13 to 15 amino acid residues represented by 〕, and is capable of binding to human IgG and / or rabbit IgG, a compound according to any one of 〔7〕 to 〔13〕 or a salt thereof. 〔17〕 A compound according to any one of 〔7〕 to 〔16〕 or a salt thereof, wherein the binding peptide is capable of binding to human IgG. 〔18〕 The binding peptide is (a) in the amino acid sequence of FNMQCQRRFYEALHDPNLNEEQRNARIRSIRDDC (SEQ ID NO: 92), any amino acid residue is substituted by one amino acid residue selected from the group consisting of a lysine residue, an aspartic acid residue, a glutamic acid residue, a 2-aminosuberic acid residue, and a diaminopropionic acid residue, and (b) an affinity peptide or a salt thereof, which comprises an amino acid sequence having 90% or more identity to the amino acid sequence of SEQ ID NO: 92, a compound according to any one of 〔7〕 to 〔9〕 or a salt thereof. 〔19〕 A compound according to any one of 〔1〕 to 〔18〕 or a salt thereof, wherein the cleavable moiety is a moiety cleavable by any one of (a) treatment with one or more substances selected from the group consisting of an acidic substance, a basic substance, a reducing agent, an oxidizing agent, and an enzyme, (b) treatment with a physicochemical stimulus selected from the group consisting of light, or (c) leaving when using a cleavable linker containing a self-cleavable cleavable moiety. 〔20〕 The cleavable moiety is selected from the group consisting of a disulfide residue, an acetal residue, a ketal residue, an ester residue, a carbamoyl residue, an alkoxyalkyl residue, an imine residue, a tertiary alkyloxycarbamate residue, a silane residue, a hydrazone-containing residue, a phosphoramidate residue, an aconityl residue, a trityl residue, an azo residue, a vicinal diol residue, a selenium residue, an aromatic ring-containing residue having an electron-withdrawing group, a coumarin-containing residue, a sulfone-containing residue, an unsaturated bond-containing chain residue, and a glycosyl residue, a compound according to any one of 〔1〕 to 〔19〕 or a salt thereof. 〔21〕The cleavable moiety of (i) is any compound of [2] to

[20] or a salt thereof selected from the group consisting of a disulfide residue, an ester residue, an acetal residue, a ketal residue, an imine residue, and a vicinal diol residue. 〔22〕The cleavable moiety of (ii) is any compound of [2] to

[20] or a salt thereof selected from the group consisting of an ester residue, a carbamoyl residue, an alkoxyalkyl residue, an imine residue, a tertiary alkyloxycarbamate residue, a silane residue, a hydrazone-containing residue, a phosphoramidate residue, an aconityl residue, a trityl residue, an azo residue, a vicinal diol residue, a selenium residue, an aromatic ring-containing residue having an electron-withdrawing group, a coumarin-containing residue, a sulfone-containing residue, an unsaturated bond-containing chain residue, and a glycosyl residue. 〔23〕The cleavable moiety is as follows:

Chemical formula

[20] or a salt thereof corresponding to any one chemical structure selected from the group consisting of.

[24] The cleavable moiety of the above (i) is as follows: [Chemical formula] (Here, the wavy line perpendicular to the bond indicates the cleavage site, R 2a is the same as

[23] , ○ (white circle) indicates a bond to A, and ● (black circle) indicates a bond to B When the chemical structure is asymmetric around the cleavage site, ● may indicate a bond to A and ○ may indicate a bond to B. A compound of any one of [2] to

[19] ,

[21] ,

[23] or a salt thereof corresponding to any one chemical structure selected from the group consisting of.

[25] The cleavable moiety of the above (ii) is as follows: [Chemical formula] (Here, the wavy line perpendicular to the bond indicates the cleavage site, R 2b R 2c J, r are the same as

[23] , ○ (white circle) indicates a bond to A, and ● (black circle) indicates a bond to B When the chemical structure is asymmetric around the cleavage site, ● may represent a bond to A and ○ may represent a bond to B. A compound or a salt thereof according to any one of [2] to

[19] ,

[22] ,

[23] , corresponding to any one chemical structure selected from the group consisting of.

[26] L is represented by any one of the following formulas (L1) to (L3): La-C-Lb (L1) La-C (L2) C-Lb (L3) [In the formula, La and Lb are each a divalent group, C is a cleavable moiety. A compound or a salt thereof according to any one of [1] to

[25] , represented by any one of the above.

[27] The above La and Lb are respectively the following (La') and (Lb'): [Chemical formula] [In the formula, p and p' are the same or different and are any integer from 0 to 10, q and q' are the same or different and are any integer from 0 to 10, X and X' are the same or different and are a carbon atom, a nitrogen atom, or a single bond (where when X is a nitrogen atom, R 1b does not exist, and when X' is a nitrogen atom, R 1b’ does not exist. When X is a single bond, R 1a and R 1b do not exist, and when X' is a single bond, R 1a’ and R 1b’ do not exist), and R 1a , R 1b , R 1a’ and R 1b’ are the same or different and are an atom or a group selected from the group consisting of the above (i) to (vii). A compound or a salt thereof according to

[26] , represented by the above. The compound or its salt according to any one of [1] to

[27] , wherein the divalent group containing a bioorthogonal functional group is a divalent group containing a bioorthogonal functional group selected from the group consisting of an azide residue, an aldehyde residue, a thiol residue, an alkyne residue, an alkene residue, a tetrazine residue, a nitrone residue, a hydroxylamine residue, a nitrile residue, a hydrazine residue, a ketone residue, a boronic acid residue, a cyanobenzothiazole residue, an allyl residue, a phosphine residue, a maleimide residue, a disulfide residue, a thioester group, an α-halocarbonyl residue, an isonitrile residue, a sydnone residue, and a selenium residue in the main chain. The compound or its salt according to any one of [1] to

[27] , wherein the divalent group containing a bioorthogonal functional group is a divalent group containing a bioorthogonal functional group selected from the group consisting of an azide residue, an aldehyde residue, a thiol residue, an alkyne residue, an alkene residue, a halogen residue, a tetrazine residue, a nitrone residue, a hydroxylamine residue, a nitrile residue, a hydrazine residue, a ketone residue, a boronic acid residue, a cyanobenzothiazole residue, an allyl residue, a phosphine residue, a maleimide residue, a disulfide residue, an α-halocarbonyl residue, an isonitrile residue, a sydnone residue, and a selenium residue in the side chain. 〔30〕The bioorthogonal functional group is as follows:

Chemical formula

[29] , which is any one represented by the formula. 〔31〕The divalent group in the above (b) is optionally substituted alkylene, optionally substituted cycloalkylene, optionally substituted aryl, optionally substituted divalent heterocyclic group, -NR a -(R aa compound of any one of [1] to

[30] or a salt thereof, which is selected from the group consisting of a hydrogen atom, a substituent, -O-, or a combination of two or more thereof.

[32] B is represented by the following formula (B-1): [Chemical formula] [In the formula, Y is -NH-, -O-, -CH2-, or the following formula (B-2): [Chemical formula] (In the formula, V and V' are the same or different and are -NH-, -O-, -CH2-, or a single bond, V1 is a divalent group containing a bioorthogonal functional group, s is an arbitrary integer from 0 to 10, ○ and ● in formula (B-2) have the same orientation as ○ and ● in formula (B-1), respectively.) Z is an oxygen atom, a sulfur atom, or a hydrogen atom (when Z is a hydrogen atom, -C(=Z)- represents -CH2-).) ○ (white circle) in formula (B-1) represents a bond to the L-side moiety, and ● (black circle) represents a bond to the R-side moiety.〕 A compound of any one of [1] to

[31] or a salt thereof.

[33] A compound of any one of [1] to

[32] or a salt thereof, wherein the reactive group is a reactive group specific to the side chain of any one of a lysine residue, a tyrosine residue, or a tryptophan residue.

[34] A compound of

[33] or a salt thereof, wherein the reactive group is a reactive group specific to the side chain of a lysine residue.

[35] The reactive group is the following: [Chemical formula] [Here, R 5a and R 5c are an atom or a group selected from the group consisting of (i) to (vii) and R 5b is an electron-withdrawing group, j is any integer from 1 to 5, k is any integer from 1 to 4. A compound of any one selected from the group consisting of compounds represented by [1] to

[34] or a salt thereof corresponding to any one chemical structure.

[36] A compound of any one of [1] to

[35] or a salt thereof, wherein the number of atoms in the main chain connecting A and R is 4 to 20.

[37] A compound of any one of [1] to

[36] or a salt thereof, wherein the main chain connecting A and R does not contain a ring structure.

[38] A compound of any one of [1] to

[37] or a salt thereof, wherein the partial structure represented by L-B does not contain a peptide moiety.

[39] The compound represented by the formula (I) is the following (I'): A - B2 - L' - B1 - R (I') [wherein, A and R are the same as those in the formula (I) above L' is a cleavable linker which is a divalent group containing a cleavable moiety, B1 and B2 are the same or different and are (a) a divalent group containing a bioorthogonal functional group or (b) a divalent group not containing a bioorthogonal functional group, B1 and B2 may have a symmetric structure centered on L'. A compound represented by. A compound of any one of [1] to

[38] or a salt thereof.

[40] The compound represented by the formula (I') is the following (I''): [Chemical formula] [wherein, A and R are the same as those in the formula (I) described in [1], C is a cleavable moiety, p, p', q, q', X, X', R 1a 、R 1a’ 、R 1b 、and R 1b’ are the same as those in the formulas (La') and (Lb') described in

[27] , Y and Y', which may be the same or different, are the same as Y in formula (B-1) described in

[32] , Z and Z', which may be the same or different, are the same as Z in the above formula (B-1). A compound represented by

[39] or a salt thereof.

[41] The following formula (I): A-L-B-R (I) [In the formula, A is an affinity substance for a soluble protein, L is a cleavable linker which is a divalent group containing a cleavable moiety, B is (a) a divalent group containing a bioorthogonal functional group, or (b) a divalent group not containing a bioorthogonal functional group, R is a reactive group for the soluble protein. A compound having an affinity substance for a soluble protein, a cleavable moiety and a reactive group represented by

[16] or a salt thereof, and a site-selective modification reagent for a soluble protein.

[42] The following formula (I): A-L-B-R (I) [In the formula, A is an affinity substance for an antibody, L is a cleavable linker which is a divalent group containing a cleavable moiety, B is (a) a divalent group containing a bioorthogonal functional group, or (b) a divalent group not containing a bioorthogonal functional group, R is a reactive group specific for the side chain of a lysine residue. A compound having an affinity substance for an antibody, a cleavable moiety and a reactive group represented by

[30] or a salt thereof.

[43] The following formula (I): The following formula (I): A-L-B-R (I) [In the formula, A is an affinity substance for an antibody, L is a cleavable linker which is a divalent group containing a cleavable moiety, B is (a) a divalent group containing a bioorthogonal functional group, or (b) a divalent group not containing a bioorthogonal functional group, R is a reactive group specific for the side chain of a lysine residue. A site-selective modification reagent for an antibody, comprising a compound having an affinity substance for the antibody, a cleavable moiety, and a reactive group represented by the formula:

[0013] Second, the present invention provides an affinity substance for a soluble protein, a soluble protein having a cleavable moiety or a salt thereof, and a method for producing the same. (An affinity substance for a soluble protein, and a soluble protein having a cleavable moiety or a salt thereof)

[44] The following formula (II): A-L-B-R'-T (II) [In the formula, A is an affinity substance for a soluble protein, L is a cleavable linker which is a divalent group containing a cleavable moiety, B is (a) a divalent group containing a bioorthogonal functional group, or (b) a divalent group not containing a bioorthogonal functional group, R' is a moiety formed by the reaction between a soluble protein and a reactive group, T is a soluble protein. A soluble protein having an affinity substance for a soluble protein, and a cleavable moiety or a salt thereof, represented by the formula:

[45] The soluble protein or a salt thereof according to

[44] , wherein the soluble protein is a monoclonal antibody.

[46] The soluble protein or a salt thereof according to

[44] or

[45] , wherein the soluble protein is an IgG antibody.

[47] The soluble protein or a salt thereof according to any one of

[44] to

[46] , wherein the soluble protein is of human origin.

[48] The soluble protein or a salt thereof according to any one of

[44] to

[47] , wherein the soluble protein is an antibody containing any one Fc region protein selected from the group consisting of the following (A) to (C) and having antigen-binding ability: (A) An Fc region protein containing the amino acid sequence of SEQ ID NO: 1; (B) An Fc region protein comprising an amino acid sequence in which one or several amino acid residues are inserted, added, deleted or substituted in the amino acid sequence of SEQ ID NO: 1; or (C) An Fc region protein comprising an amino acid sequence having 90% or more identity with the amino acid sequence of SEQ ID NO: 1.

[49] A soluble protein contains one or more specific amino acid residues in a target region consisting of 1 to 50 consecutive amino acid residues, and contains five or more of the specific amino acid residues in a non-target region outside the target region. The structural unit represented by A-L-B-R' binds to one or more specific amino acid residues contained in the target region with a positional selectivity of 30% or more. A soluble protein according to any one of

[44] to

[48] or a salt thereof.

[50] The soluble protein according to

[49] or a salt thereof, wherein the target region is a region consisting of 1 to 10 consecutive amino acid residues.

[51] The soluble protein according to

[50] or a salt thereof, wherein the target region is a region consisting of 1 to 3 consecutive amino acid residues.

[52] The soluble protein according to

[51] or a salt thereof, wherein the target region is (a) a region consisting of amino acid residues at positions 246 to 248 in the human IgG Fc region, (b) a region consisting of amino acid residues at positions 288 to 290 in the human IgG Fc region, or (c) a region consisting of the amino acid residue at position 317 in the human IgG Fc region.

[53] The soluble protein according to any one of

[49] to

[52] or a salt thereof, wherein the positional selectivity is 50% or more.

[54] The soluble protein according to

[53] or a salt thereof, wherein the positional selectivity is 70% or more.

[55] The soluble protein according to

[54] or a salt thereof, wherein the positional selectivity is 90% or more. 〔56〕The soluble protein according to any one of 〔49〕to 〔55〕or a salt thereof, wherein the specific amino acid residue does not contain an amino acid residue of the same type as the specific amino acid residue, except for the specific amino acid residue present at the specific position, in the region up to a remote position of a amino acid residues (where a is an arbitrary integer of 1 to 10) on each of the N-terminal side and the C-terminal side with respect to the specific amino acid present at the specific position. 〔57〕The soluble protein is a multimeric protein containing a plurality of monomeric proteins, As a result of T having a structural unit represented by A-L-B-R’ in a plurality of corresponding target regions in a plurality of monomeric proteins, the multimeric protein has a plurality of structural units represented by A-L-B-R’. The soluble protein according to any one of 〔44〕to 〔56〕or a salt thereof. 〔58〕The soluble protein is an antibody containing a plurality of heavy chains, As a result of T having a structural unit represented by A-L-B-R’ in a plurality of corresponding target regions in a plurality of heavy chains, the antibody has a plurality of structural units represented by A-L-B-R’. The soluble protein according to any one of 〔44〕to 〔57〕or a salt thereof. 〔59〕The soluble protein according to 〔58〕or a salt thereof, wherein the number of heavy chains is 2. 〔60〕The soluble protein according to any one of 〔44〕to 〔59〕or a salt thereof, wherein the moiety generated by the reaction between the soluble protein and the reactive group is a moiety generated by the reaction of a reactive group specific to any one of the side chains of a lysine residue, a tyrosine residue, or a tryptophan residue with respect to a lysine residue, a tyrosine residue, or a tryptophan residue. 〔61〕The soluble protein according to any one of 〔44〕to 〔60〕or a salt thereof, wherein the moiety generated by the reaction between the soluble protein and the reactive group is a moiety generated by the reaction between a lysine residue and a reactive group specific to the side chain of the lysine residue. 〔62〕The moiety generated by the reaction is as follows:

Chemical formula

[44] to

[61] or a salt thereof corresponding to any one chemical structure selected from the group consisting of.

[63] A soluble protein of any one of

[44] to

[62] or a salt thereof, wherein the number of atoms in the main chain connecting A and R' is 4 to 20.

[64] A soluble protein of any one of

[44] to

[53] or a salt thereof, wherein the main chain connecting A and R does not contain a ring structure.

[65] A soluble protein of any one of

[44] to

[64] or a salt thereof, wherein the partial structure represented by L-B does not contain a peptide moiety.

[66] The compound represented by the formula (II) is the following (II'): A - B2 - L' - B1 - R' - T (II') [In the formula, A, R' and T are the same as those in the formula (II) above L' is a cleavable linker which is a divalent group containing a cleavable moiety, B1 and B2 are the same or different and are (a) a divalent group containing a bioorthogonal functional group, or (b) a divalent group not containing a bioorthogonal functional group, B1 and B2 may have a symmetric structure centered on L'.] A soluble protein of any one of

[44] to

[65] or a salt thereof which is a compound represented by.

[67] The compound represented by the formula (II') is the following (II''):

Chemical formula

[44] , C is a cleavable moiety, p and p' are the same or different and are arbitrary integers from 0 to 10, q and q' are the same or different and are arbitrary integers from 0 to 10, X and X' are the same or different and are a carbon atom, a nitrogen atom, or a single bond (wherein when X is a nitrogen atom, R 1b does not exist, and when X' is a nitrogen atom, R 1b’ does not exist. When X is a single bond, R 1a and R 1b do not exist, and when X' is a single bond, R 1a’ and R 1b’ do not exist), and R 1a , R 1b , R 1a’ and R 1b’ are the same or different and are (i) a hydrogen atom or a halogen atom; (ii) a monovalent hydrocarbon group; (iii) an aralkyl; (iv) a monovalent heterocyclic group; (v) R c -O-, R c -C(=O)-, R c -O-C(=O)-, or R c -C(=O)-O- (wherein R c represents a hydrogen atom or a monovalent hydrocarbon group); (vi) NR d R e -, NR d R e -C(=O)-, NR d R e -C(=O)-O-, or R d -C(=O)-NR e - (wherein R d and R e are the same or different and represent a hydrogen atom or a monovalent hydrocarbon group); or (vii) a nitro group, a sulfate group, a sulfonic acid group, a cyano group, or a carboxyl group selected from the group consisting of, Y and Y' are the same or different and are the same as Y in the formula (B-1) described in

[32] , Z and Z' are the same or different and are the same as Z in the formula (B-1).] represented by the soluble protein of

[66] or a salt thereof.

[68] The following formula (II): A-L-B-R’-T (II) [wherein A is an affinity substance for an antibody, L is a cleavable linker which is a divalent group containing a cleavable moiety, B is (a) a divalent group containing a bioorthogonal functional group, or (b) a divalent group not containing a bioorthogonal functional group, R’ is a moiety generated by the reaction between an antibody and a reactive group specific for the side chain of a lysine residue, T is an antibody.] An affinity substance for an antibody, and an antibody having a cleavable moiety or a salt thereof.

[0014] (Method for producing an affinity substance for a soluble protein, and a soluble protein having a cleavable moiety or a salt thereof)

[69] A method for producing an affinity substance for a soluble protein, and a soluble protein having a cleavable moiety or a salt thereof, comprising the following formula (I): A-L-B-R (I) [wherein A is an affinity substance for a soluble protein, L is a cleavable linker which is a divalent group containing a cleavable moiety, B is (a) a divalent group containing a bioorthogonal functional group, or (b) a divalent group not containing a bioorthogonal functional group, R is a reactive group for the soluble protein.] A compound having an affinity substance for a soluble protein, a cleavable moiety and a reactive group or a salt thereof represented by the formula (I) is reacted with a soluble protein to obtain the following formula (II): A-L-B-R’-T (II) [wherein A, L, and B are the same as those in the formula (I), R’ is a moiety generated by the reaction between a soluble protein and a reactive group, A method comprising producing an affinity substance for a soluble protein, and a soluble protein having a cleavable moiety or a salt thereof, represented by 〕T is a soluble protein. 〔70〕The method according to 〔69〕, wherein the soluble protein is an antibody and the reactive group is a reactive group specific for the side chain of a lysine residue.

[0015] Thirdly, the present invention provides a complex having an affinity substance for a soluble protein, a cleavable moiety, a functional substance and a soluble protein, or a salt thereof, and a method for producing the same. (A complex having an affinity substance for a soluble protein, a cleavable moiety, a functional substance and a soluble protein, or a salt thereof) 〔71〕The following formula (III): A-L-B’(-F)-R’-T (III) 〔In the formula, A is an affinity substance for a soluble protein, L is a cleavable linker which is a divalent group containing a cleavable moiety, B’ is a divalent group containing a moiety generated by the reaction between a functional substance and a bioorthogonal functional group, F is a functional substance, R’ is a moiety generated by the reaction between a soluble protein and a reactive group, T is a soluble protein.〕 A complex having an affinity substance for a soluble protein, a cleavable moiety, a functional substance and a soluble protein, or a salt thereof. 〔72〕The complex or a salt thereof according to 〔71〕, wherein the soluble protein is a monoclonal antibody. 〔73〕The complex or a salt thereof according to 〔71〕 or 〔72〕, wherein the soluble protein is an IgG antibody. 〔74〕The complex or a salt thereof according to any one of 〔71〕 to 〔73〕, wherein the soluble protein is of human origin. 〔75〕The complex or a salt thereof according to any one of 〔71〕 to 〔74〕, wherein the soluble protein is an antibody containing any one Fc region protein selected from the group consisting of the following (A) to (C) and having an antigen-binding ability: (A) An Fc region protein comprising the amino acid sequence of SEQ ID NO: 1; (B) An Fc region protein comprising an amino acid sequence in which one or several amino acid residues are inserted, added, deleted or substituted in the amino acid sequence of SEQ ID NO: 1; or (C) An Fc region protein comprising an amino acid sequence showing 90% or more identity with the amino acid sequence of SEQ ID NO: 1.

[76] The soluble protein contains one or more specific amino acid residues in a target region consisting of 1 to 50 consecutive amino acid residues, and contains 5 or more of the specific amino acid residues in a non-target region other than the target region, A complex or a salt thereof according to any one of

[71] to

[75] , wherein the structural unit represented by A-L-B’(-F)-R’ binds to one or more specific amino acid residues contained in the target region with a positional selectivity of 30% or more.

[77] The complex or a salt thereof according to

[76] , wherein the specific amino acid residues do not contain amino acid residues of the same type as the specific amino acid residues present at the specific positions, except for amino acid residues at a remote position of a number of a (where a is an arbitrary integer from 1 to 10) amino acid residues on each of the N-terminal side and the C-terminal side with respect to the specific amino acids present at the specific positions.

[78] The soluble protein is a multimeric protein containing a plurality of monomeric proteins, As a result of T having the structural unit represented by A-L-B’(-F)-R’ in a plurality of corresponding target regions in a plurality of monomeric proteins, the multimeric protein has a plurality of structural units represented by A-L-B’(-F)-R’. A complex or a salt thereof according to any one of

[71] to

[77] .

[79] The soluble protein is an antibody containing a plurality of heavy chains, As a result of T having the structural unit represented by A-L-B’(-F)-R’ in a plurality of corresponding target regions in a plurality of heavy chains, the antibody has a plurality of structural units represented by A-L-B’(-F)-R’. A complex or a salt thereof according to any one of

[71] to

[78] . A complex of any one of

[71] to

[79] or a salt thereof, wherein the divalent group containing a moiety formed by the reaction between a functional substance and a bioorthogonal functional group is a divalent group containing a reactive moiety selected from the group consisting of a disulfide residue, an acetal residue, a ketal residue, an ester residue, a carbamoyl residue, an alkoxyalkyl residue, an imine residue, a tertiary alkyloxycarbamate residue, a silane residue, a hydrazone-containing residue, a phosphoramidate residue, an aconityl residue, a trityl residue, an azo residue, a vicinal diol residue, a selenium residue, an aromatic ring-containing residue having an electron-withdrawing group, a coumarin-containing residue, a sulfone-containing residue, an unsaturated bond-containing chain residue, and a glycosyl residue. 〔81〕The moiety formed by the reaction is as follows:

Chemical formula

[71] to

[80] or a salt thereof corresponding to any one chemical structure selected from the group consisting of.

[82] A part formed by the reaction between a soluble protein and a reactive group is a part formed by the reaction between a lysine residue, a tyrosine residue, or a tryptophan residue and a reactive group specific to any one side chain of a lysine residue, a tyrosine residue, or a tryptophan residue. A complex of any one of

[71] to

[81] or a salt thereof.

[83] A part formed by the reaction between a soluble protein and a reactive group is a part formed by the reaction between a lysine residue and a reactive group specific to the side chain of a lysine residue. A complex of any one of

[71] to

[82] or a salt thereof.

[84] The part formed by the above reaction is as follows:

Chemical Structure

[71] to

[83] or a salt thereof corresponding to any one chemical structure selected from the group consisting of.

[85] A complex of any one of

[71] to

[84] or a salt thereof, wherein the functional substance is a drug or a labeling substance.

[86] A complex of any one of

[71] to

[85] or a salt thereof, wherein the functional substance is a low molecular weight compound.

[87] A complex of

[85] or

[86] or a salt thereof, wherein the drug is an anticancer agent. A complex of any one of

[71] to

[87] or a salt thereof, wherein the number of atoms in the main chain connecting A and R' is 4 to 20. A complex of any one of

[71] to

[88] or a salt thereof, wherein the main chain connecting A and R does not contain a ring structure. A complex of any one of

[71] to

[89] or a salt thereof, wherein the partial structure represented by L-B does not contain a peptide moiety. 〔91〕The compound represented by the formula (III) is the following formula (III’): A - B2’(-F2) - L’ - B1’(-F1) - R’ - T (III’) 〔In the formula, A, R’ and T are the same as those in the formula (II) above, L’ is a cleavable linker which is a divalent group containing a cleavable moiety, B1’ and B2’ are the same or different and are divalent groups containing a moiety generated by the reaction between a functional substance and a bioorthogonal functional group, F1 and F2 are the same or different and are functional substances, B1’(-F1) and B2’(-F2) may have a symmetric structure centered on L’.〕 A complex of any one of

[71] to

[90] or a salt thereof. 〔92〕The compound represented by the formula (III’) is the following (III’’):

Chemical formula

[71] , C is a cleavable moiety, p and p’ are the same or different and are arbitrary integers from 0 to 10, q and q’ are the same or different and are arbitrary integers from 0 to 10, X and X’ are the same or different and are a carbon atom, a nitrogen atom, or a single bond (here, when X is a nitrogen atom, R 1b does not exist, and when X’ is a nitrogen atom, R 1b’ does not exist. When X is a single bond, R1a and R 1b is absent, and when X’ is a single bond, R 1a’ and R 1b’ is absent), and R 1a , R 1b , R 1a’ and R 1b’ are the same or different and are selected from the group consisting of the above (i) to (vii), Y and Y’ are the same or different and are residues obtained by removing one hydrogen atom from Y of the formula (B-1) described in

[32] , Z and Z’ are the same or different and are the same as Z in the above formula (B-1), F and F’ are the same or different and are functional substances. The complex of

[91] or a salt thereof represented by ].

[93] The following formula (III): A-L-B’(-F)-R’-T (III) [wherein, A is an affinity substance for an antibody, L is a cleavable linker which is a divalent group containing a cleavable moiety, B’ is a divalent group containing a moiety generated by the reaction between a functional substance and a bioorthogonal functional group, F is a functional substance, R’ is a moiety generated by the reaction between an antibody and a reactive group specific for the side chain of a lysine residue, T is an antibody. The complex having an affinity substance, a functional substance and an antibody or a salt thereof represented by ].

[0016] (Method for producing a complex having an affinity substance for a soluble protein, a cleavable moiety, a functional substance and a soluble protein or a salt thereof)

[94] A method for producing a complex having an affinity substance for a soluble protein, a cleavable moiety, a functional substance and a soluble protein or a salt thereof, comprising the following formula (II): A-L-B-R’-T (II) [wherein, A is an affinity substance for a soluble protein, L is a cleavable linker which is a divalent group containing a cleavable moiety, B is a divalent group (a) containing a bioorthogonal functional group, R’ is a moiety generated by the reaction between the soluble protein and a reactive group, T is a soluble protein. A method of reacting an affinity substance for a soluble protein, and a soluble protein or a salt thereof having a cleavable moiety, with a functional substance to obtain the following formula (III): A-L-B’(-F)-R’-T (III) wherein, A, L, R’ and T are the same as those in the formula (II), B’ is a divalent group containing a moiety generated by the reaction between the functional substance and the bioorthogonal functional group, F is a functional substance. A method comprising generating a complex or a salt thereof having an affinity substance for a soluble protein, a cleavable moiety, a functional substance and a soluble protein.

[95] The method of

[94] , wherein the soluble protein is an antibody and the reactive group is a reactive group specific for the side chain of a lysine residue.

[96] A method for producing a complex or a salt thereof having an affinity substance for a soluble protein, a cleavable moiety, a functional substance and a soluble protein, comprising (A) reacting a compound or a salt thereof represented by the following formula (I): A-L-B-R (I) wherein, A is an affinity substance for a soluble protein, L is a cleavable linker which is a divalent group containing a cleavable moiety, B is a divalent group (a) containing a bioorthogonal functional group, R is a reactive group for the soluble protein. with a soluble protein to obtain the following formula (II): A-L-B-R’-T (II) wherein, A, L, and B are the same as those in the formula (I), R' is a moiety formed by the reaction between a soluble protein and a reactive group, T is a soluble protein.], to produce an affinity substance for a soluble protein, and a soluble protein having a cleavable moiety or a salt thereof, and (B) reacting the affinity substance for the soluble protein, and the soluble protein having a cleavable moiety or a salt thereof with a functional substance, to produce the following formula (III): A-L-B'(-F)-R'-T (III) [wherein, A and L are the same as those in the formula (I), R' and T are the same as those in the formula (II), B' is a divalent group containing a moiety formed by the reaction between a functional substance and a bioorthogonal functional group, F is a functional substance.], to produce a complex having an affinity substance for a soluble protein, a cleavable moiety, a functional substance and a soluble protein or a salt thereof.

[0017] Fourthly, the present invention provides a method for producing a soluble protein having a bioorthogonal functional group.

[97] A method for producing a soluble protein having a bioorthogonal functional group or a salt thereof, comprising the following formula (II): A-L-B-R'-T (II) [wherein, A is an affinity substance for a soluble protein, L is a cleavable linker which is a divalent group containing a cleavable moiety, B is (a) a divalent group containing a bioorthogonal functional group or (a) a divalent group not containing a bioorthogonal functional group, R' is a moiety formed by the reaction between a soluble protein and a reactive group, T is a soluble protein. A method comprising cleaving a cleavable moiety of an affinity substance for a soluble protein represented by ], and a soluble protein having a cleavable moiety or a salt thereof, and the following formula (IV): L1-B-R’-T (IV) 〔In the formula, B, R’ and T are the same as those in the formula (II), L1 is (i’) a monovalent group containing a bioorthogonal functional group, or (ii’) a monovalent group not containing a bioorthogonal functional group.〕 A method comprising generating a soluble protein having a bioorthogonal functional group or a salt thereof represented by 〔98〕 The method according to

[97] , wherein L is (i) a cleavable linker which is a divalent group containing a cleavable moiety having the ability to generate a bioorthogonal functional group on the reactive group side upon cleavage, or (ii) a cleavable linker which is a divalent group containing a cleavable moiety not having the ability to generate a bioorthogonal functional group on the reactive group side upon cleavage. 〔99〕 The method according to

[98] , wherein L is the cleavable linker of (i) above, L1 is (i’) a monovalent group containing a bioorthogonal functional group, and B is the divalent group of (a) or (b) above. 〔100〕 The method according to

[98] , wherein L is the cleavable linker of (i) above, L1 is (i’) a monovalent group containing a bioorthogonal functional group, and B is the divalent group of (b) above. 〔101〕 The method according to

[98] , wherein L is the cleavable linker of (ii) above, L1 is (i’) a monovalent group not containing a bioorthogonal functional group, and B is the divalent group of (a) above. 〔102〕 The method according to any one of

[97] to

[101] , wherein the soluble protein is an antibody and the reactive group is a reactive group specific for the side chain of a lysine residue. 〔103〕 A method for producing a soluble protein having a bioorthogonal functional group or a salt thereof, comprising (A) the following formula (I): A-L-B-R (I) [wherein, A is an affinity substance for a soluble protein, L is a cleavable linker which is a divalent group containing a cleavable moiety, B is (a) a divalent group containing a bioorthogonal functional group, or (a) a divalent group not containing a bioorthogonal functional group, R is a reactive group for the soluble protein. ] A compound represented by the formula or a salt thereof is reacted with a soluble protein to the following formula (II): A-L-B-R'-T (II) [wherein, A, L, and B are the same as those in the formula (I) R' is a moiety generated by the reaction between the soluble protein and the reactive group, T is a soluble protein. ] To produce an affinity substance for a soluble protein, and a soluble protein having a cleavable moiety or a salt thereof, and (B) Cleaving the cleavable moiety of the affinity substance for the soluble protein, and the soluble protein having a cleavable moiety or a salt thereof to the following formula (IV): L1-B-R'-T (IV) [wherein, B, R' and T are the same as those in the formula (II), L1 is (i') a monovalent group containing a bioorthogonal functional group, or (ii') a monovalent group not containing a bioorthogonal functional group. ] To produce a soluble protein having a bioorthogonal functional group or a salt thereof, a method comprising.

[0018] Fifthly, the present invention provides a method for producing a soluble protein having a functional substance or a salt thereof.

[104] A method for producing a soluble protein having a functional substance or a salt thereof, the following formula (III): A-L-B'(-F)-R'-T (III) [wherein, A is an affinity substance for a soluble protein, L is a cleavable linker which is a divalent group containing a cleavable moiety, B’ is a divalent group containing a moiety generated by the reaction between a functional substance and a bioorthogonal functional group, F is a functional substance, R’ is a moiety generated by the reaction between a soluble protein and a reactive group, T is a soluble protein. A complex having an affinity substance, a cleavable moiety, a functional substance and a soluble protein represented by 〕, or a salt thereof, is cleaved at the cleavable moiety, or the following formula (IV): L1 - B - R’ - T (IV) 〔In the formula, L1 is a monovalent group (i’) containing a bioorthogonal functional group or (ii’) a monovalent group not containing a bioorthogonal functional group, B is a divalent group (a) containing a bioorthogonal functional group or (b) a divalent group not containing a bioorthogonal functional group, R’ is a moiety generated by the reaction between a soluble protein and a reactive group, T is a soluble protein. 〕 A soluble protein having a bioorthogonal functional group or a salt thereof represented by is reacted with a functional substance, the following formula (V): F - (L1 - B)’ - R’ - T (V) 〔In the formula, L1 is a monovalent group (i’) containing a bioorthogonal functional group or (ii’) a monovalent group not containing a bioorthogonal functional group, B is a divalent group (a) containing a bioorthogonal functional group or (b) a divalent group not containing a bioorthogonal functional group, The structural unit represented by (L1 - B)’ is a divalent structural unit containing a moiety generated by the reaction between a functional substance and one or both of the bioorthogonal functional groups in (i’) and (a), F is a functional substance, R’ is a moiety generated by the reaction between a soluble protein and a reactive group, A method comprising producing a soluble protein having a functional substance, or a salt thereof, represented by 〕T is a soluble protein.

[105] Cleaving an affinity substance for the soluble protein, a cleavable moiety, a functional substance, and a cleavable moiety of a complex having the soluble protein or a salt thereof to obtain the following formula (V1): L1-B’(-F)-R’-T (V1) [wherein, L1 is (i’) a monovalent group containing a bioorthogonal functional group, or (ii’) a monovalent group not containing a bioorthogonal functional group, B’, F, R’ and T are the same as those in the formula (III). ] A method according to

[104] , which is a method comprising producing a soluble protein having a functional substance, or a salt thereof, represented by

[106] Reacting a soluble protein having the bioorthogonal functional group or a salt thereof with one or two functional substances to obtain the following formula (V2): F-L1’-B-R’-T (V2) [wherein, B, R’ and T are the same as those in the formula (IV), L1’ is a divalent group containing a moiety generated by the reaction between a functional substance and (i’) a monovalent group containing a bioorthogonal functional group, F is a functional substance. ], or the following formula (V3): Fa-L1’-B’(-Fb)-R’-T (V3) [wherein, R’ and T are the same as those in the formula (IV), L1’ is the same as that in the formula (V2), B’ is a divalent group containing a moiety generated by the reaction between a functional substance and a bioorthogonal functional group, Fa and Fb are each the same or different functional substances. ] A method according to

[104] , which is a method comprising producing a soluble protein having a functional substance, or a salt thereof, represented by The method according to any one of

[104] to

[106] , wherein the soluble protein is an antibody and the reactive group is a reactive group specific to the side chain of a lysine residue. A method for producing a soluble protein having a functional substance or a salt thereof, comprising: (A) The following formula (II): A-L-B-R’-T (II) 〔In the formula, A is an affinity substance for a soluble protein, L is a cleavable linker which is a divalent group containing a cleavable moiety, B is (a) a divalent group containing a bioorthogonal functional group, R’ is a moiety generated by the reaction between the soluble protein and the reactive group, T is a soluble protein.〕Reacting an affinity substance for a soluble protein, and a soluble protein having a cleavable moiety or a salt thereof with a functional substance, to obtain the following formula (III): A-L-B’(-F)-R’-T (III) 〔In the formula, A, L, R’ and T are the same as those in the formula (II) above, B’ is a divalent group containing a moiety generated by the reaction between the functional substance and the bioorthogonal functional group, F is a functional substance.〕To produce a complex having an affinity substance for a soluble protein, a cleavable moiety, a functional substance and a soluble protein or a salt thereof, and (B) Cleaving the cleavable moiety of the complex having an affinity substance for the soluble protein, a cleavable moiety, a functional substance and a soluble protein or a salt thereof, to obtain the following formula (V1): L1-B’(-F)-R’-T (V1) 〔In the formula, L1 is (i’) a monovalent group containing a bioorthogonal functional group, or (ii’) a monovalent group not containing a bioorthogonal functional group, A method for producing a soluble protein having a functional substance or a salt thereof, represented by [wherein B', F, R' and T are the same as those in the formula (III)].

[109] A method for producing a soluble protein having a functional substance or a salt thereof, (A) A compound or a salt thereof having an affinity substance for a soluble protein, a cleavable moiety and a reactive group, represented by the following formula (I): A-L-B-R (I) [wherein, A is an affinity substance for a soluble protein, L is a cleavable linker which is a divalent group containing a cleavable moiety, B is (a) a divalent group containing a bioorthogonal functional group, R is a reactive group for the soluble protein.] is reacted with a soluble protein to produce a soluble protein having an affinity substance for a soluble protein, a cleavable moiety and a reactive group, or a salt thereof, represented by the following formula (II): A-L-B-R'-T (II) [wherein, A, L, and B are the same as those in the formula (I) R' is a moiety produced by the reaction between the soluble protein and the reactive group, T is a soluble protein.] to produce a soluble protein having an affinity substance for a soluble protein and a cleavable moiety, or a salt thereof, [wherein, (B) The soluble protein having an affinity substance for the soluble protein and a cleavable moiety, or a salt thereof, is reacted with a functional substance to produce a soluble protein having a functional substance or a salt thereof, represented by the following formula (III): A-L-B'(-F)-R'-T (III) [wherein, A and L are the same as those in the formula (I), R' and T are the same as those in the formula (II), B' is a divalent group containing a moiety produced by the reaction between the functional substance and the bioorthogonal functional group, F is a functional substance.〕 To produce a complex or a salt thereof having an affinity substance for a soluble protein, a cleavable moiety, a functional substance and a soluble protein, and (C) Cleaving the cleavable moiety of the complex or a salt thereof having an affinity substance for the soluble protein, a cleavable moiety, a functional substance and a soluble protein, The following formula (V1): L1-B’(-F)-R’-T (V1) [In the formula, L1 is (i’) a monovalent group containing a bioorthogonal functional group, or (ii’) a monovalent group not containing a bioorthogonal functional group, B’, F, R’ and T are the same as those in the formula (III).〕 To produce a soluble protein having a functional substance or a salt thereof. A method comprising.

[110] A method for producing a soluble protein having a functional substance or a salt thereof, (A) The following formula (II): A-L-B-R’-T (II) [In the formula, A is an affinity substance for a soluble protein, L is a cleavable linker which is a divalent group containing a cleavable moiety, B is (a) a divalent group containing a bioorthogonal functional group, or (a) a divalent group not containing a bioorthogonal functional group, R’ is a moiety formed by the reaction between a soluble protein and a reactive group, T is a soluble protein.〕 To cleave the affinity substance for a soluble protein and the cleavable moiety of the soluble protein or a salt thereof having a cleavable moiety, The following formula (IV): L1-B-R’-T (IV) [In the formula, B, R’ and T are the same as those in the formula (II), L1 is a monovalent group containing a bioorthogonal functional group (i') or a monovalent group not containing a bioorthogonal functional group (ii').], to produce a soluble protein having a bioorthogonal functional group represented thereby or a salt thereof, and (B) reacting the soluble protein having the bioorthogonal functional group or a salt thereof with one or more functional substances, the following formula (V2) F-L1'-B-R'-T (V2) [wherein, B, R' and T are the same as those in the formula (IV), L1' is a divalent group containing a moiety generated by the reaction between a functional substance and a monovalent group containing a bioorthogonal functional group (i'), F is a functional substance.], or the following formula (V3): Fa-L1'-B'(-Fb)-R'-T (V3) [wherein, R' and T are the same as those in the formula (IV), L1' is the same as that in the formula (V2), B' is a divalent group containing a moiety generated by the reaction between a functional substance and a bioorthogonal functional group, Fa and Fb are each the same or different functional substances.], to produce a soluble protein having a functional substance represented thereby or a salt thereof.

[111] A method for producing a soluble protein having a functional substance or a salt thereof, comprising: (A) The following formula (I): A-L-B-R (I) [wherein, A is an affinity substance for a soluble protein, L is a cleavable linker which is a divalent group containing a cleavable moiety, B is a divalent group (a) containing a bioorthogonal functional group or (a) a divalent group not containing a bioorthogonal functional group, R is a reactive group for the soluble protein.], to react a compound represented thereby or a salt thereof with a soluble protein, The following formula (II): A-L-B-R’-T (II) 〔In the formula, A, L, and B are the same as those in the formula (I), R’ is a moiety generated by the reaction between a soluble protein and a reactive group, T is a soluble protein.〕 To produce an affinity substance for a soluble protein and a soluble protein having a cleavable moiety or a salt thereof, (B) Cleaving the cleavable moiety of the affinity substance for the soluble protein and the soluble protein having a cleavable moiety or a salt thereof, The following formula (IV): L1-B-R’-T (IV) 〔In the formula, B, R’ and T are the same as those in the formula (II), L1 is (i’) a monovalent group containing a bioorthogonal functional group, or (ii’) a monovalent group not containing a bioorthogonal functional group.〕 To produce a soluble protein having a bioorthogonal functional group or a salt thereof, and (C) Reacting the soluble protein having a bioorthogonal functional group or a salt thereof with one or more functional substances, The following formula (V2) F-L1’-B-R’-T (V2) 〔In the formula, B, R’ and T are the same as those in the formula (IV), L1’ is a divalent group containing a moiety generated by the reaction between a functional substance and (i’) a monovalent group containing a bioorthogonal functional group, F is a functional substance.〕, or The following formula (V3): Fa-L1’-B’(-Fb)-R’-T (V3) 〔In the formula, R’ and T are the same as those in the formula (IV), L1’ is the same as that in the formula (V2), B’ is a divalent group containing a moiety generated by the reaction between a functional substance and a bioorthogonal functional group, Fa and Fb are each the same or different functional substances. A method comprising generating a soluble protein having a functional substance or a salt thereof represented by ].

[0019] Sixthly, the present invention provides a soluble protein or a salt thereof having a bioorthogonal functional group site-selectively, and a method for producing the same. (Soluble protein or salt thereof having a bioorthogonal functional group site-selectively) [1] A soluble protein or a salt thereof having a bioorthogonal functional group site-selectively, wherein the soluble protein contains one or more specific amino acid residues in a target region consisting of 1 to 50 consecutive amino acid residues, and contains five or more of the specific amino acid residues in a non-target region outside the target region, and the bioorthogonal functional group is bound to one or more specific amino acid residues contained in the target region with a site selectivity of 30% or more via a linker not containing a peptide moiety. A soluble protein or a salt thereof having a bioorthogonal functional group site-selectively. [2] The following formula (IV): L1-B-R’-T (IV) [wherein, L1 is (i’) a monovalent group containing a bioorthogonal functional group, or (ii’) a monovalent group not containing a bioorthogonal functional group, B is (a) a divalent group containing a bioorthogonal functional group, or (b) a divalent group not containing a bioorthogonal functional group, R’ is a moiety generated by the reaction between a soluble protein and a reactive group, T is a soluble protein, The soluble protein contains one or more specific amino acid residues in a target region consisting of 1 to 50 consecutive amino acid residues, and contains five or more of the specific amino acid residues in a non-target region outside the target region. A soluble protein having a bioorthogonal functional group that is regioselectively present, represented by 〕 and the structural unit represented by L1-B-R’ binds to one or more specific amino acid residues contained in the target region of the soluble protein with a regioselectivity of 30% or more, or a salt thereof. 〔3〕The soluble protein or a salt thereof according to 〔1〕 or 〔2〕, wherein the soluble protein is a monoclonal antibody. 〔4〕The soluble protein or a salt thereof according to 〔1〕 to 〔3〕, wherein the soluble protein is an IgG antibody. 〔5〕The soluble protein or a salt thereof according to any one of 〔1〕 to 〔4〕, wherein the soluble protein is of human origin. 〔6〕The soluble protein or a salt thereof according to any one of 〔1〕 to 〔5〕, wherein the soluble protein is an antibody that contains any one Fc region protein selected from the group consisting of the following (A) to (C) and has antigen-binding ability: (A) An Fc region protein containing the amino acid sequence of SEQ ID NO: 1; (B) An Fc region protein containing an amino acid sequence in which one or several amino acid residues are inserted, added, deleted or substituted in the amino acid sequence of SEQ ID NO: 1; or (C) An Fc region protein containing an amino acid sequence having 90% or more identity with the amino acid sequence of SEQ ID NO: 1. 〔7〕The soluble protein or a salt thereof according to any one of 〔1〕 to 〔6〕, wherein the target region is a region consisting of 1 to 10 consecutive amino acid residues. 〔8〕The soluble protein or a salt thereof according to any one of 〔1〕 to 〔7〕, wherein the target region is a region consisting of 1 to 3 consecutive amino acid residues. 〔9〕The soluble protein or a salt thereof according to 〔8〕, wherein the target region is (a) a region consisting of amino acid residues at positions 246 to 248 in the human IgG Fc region, (b) a region consisting of amino acid residues at positions 288 to 290 in the human IgG Fc region, or (c) a region consisting of the amino acid residue at position 317 in the human IgG Fc region. 〔10〕The soluble protein or a salt thereof according to any one of 〔1〕 to 〔9〕, wherein the site selectivity is 50% or more. 〔11〕The soluble protein or a salt thereof according to 〔10〕, wherein the site selectivity is 70% or more. 〔12〕The soluble protein or a salt thereof according to 〔11〕, wherein the site selectivity is 90% or more. 〔13〕The soluble protein or a salt thereof according to any one of 〔1〕 to 〔12〕, wherein, in the region up to a remote position of a amino acid residues (where a is an arbitrary integer of 1 to 10) on each of the N-terminal side and the C-terminal side with respect to the specific amino acid present at the specific position, the region other than the specific amino acid residue present at the specific position does not contain amino acid residues of the same type as the specific amino acid residue. 〔14〕The soluble protein is a multimeric protein containing a plurality of monomeric proteins, and as a result of having bioorthogonal functional groups at a plurality of specific amino acid residues present at the above positions in the plurality of monomeric proteins contained in the multimeric protein, the multimeric protein has a plurality of bioorthogonal functional groups. The soluble protein or a salt thereof according to any one of 〔1〕, 〔3〕 to 〔13〕. 〔15〕The soluble protein is an antibody containing a plurality of heavy chains, and as a result of having bioorthogonal functional groups at a plurality of specific amino acid residues present at the above positions in the plurality of heavy chains contained in the antibody, the antibody has a plurality of bioorthogonal functional groups. The soluble protein or a salt thereof according to any one of 〔1〕, 〔3〕 to 〔14〕. 〔16〕The soluble protein is a multimeric protein containing a plurality of monomeric proteins, As a result of T having a structural unit represented by A-L-B-R' in corresponding plural target regions in a plurality of monomeric proteins, a multimeric protein has a plurality of structural units represented by A-L-B-R', the soluble protein according to any one of [2] to

[13] or a salt thereof. 〔17〕The soluble protein is an antibody containing a plurality of heavy chains, As a result of T having a structural unit represented by A-L-B-R' in corresponding plural target regions in a plurality of heavy chains, the antibody has a plurality of structural units represented by A-L-B-R', the soluble protein according to any one of [2] to

[13] ,

[16] or a salt thereof. 〔18〕The soluble protein according to

[15] or

[17] or a salt thereof, wherein the number of heavy chains is two. 〔19〕L1 is represented by the following formula (L1-1) to (L1-2): C1-Lb (L1-1) C1 (L1-2) 〔In the formula, Lb is a divalent group, C1 is a bioorthogonal functional group or a group other than a bioorthogonal functional group.〕 The soluble protein according to any one of [2] to

[13] ,

[16] to

[18] or a salt thereof. 〔20〕The Lb is represented by the following formula (Lb'):

Chemical formula

Chemical formula

[13] ,

[16] to

[23] or a salt thereof. [(25)] B is the following formula (B-1): [Chemical formula] [In the formula, Y is -NH-, -O-, -CH2-, or the following formula (B-2): [Chemical formula] (In the formula, V and V' are the same or different and are -NH-, -O-, -CH2-, or a single bond, V1 is a divalent group containing a bioorthogonal functional group, s is an arbitrary integer from 0 to 10, ○ and ● in formula (B-2) have the same orientation as ○ and ● in formula (B-1), respectively.). Z is an oxygen atom, a sulfur atom, or a hydrogen atom (when Z is a hydrogen atom, -C(=Z)- represents -CH2-), ○ (white circle) in formula (B-1) represents a bond to the L-side portion, and ● (black circle) represents a bond to the R-side portion.], and is a soluble protein of any one of [2] to

[13] ,

[16] to

[24] or a salt thereof. [(26)] The bioorthogonal functional group is bonded to the soluble protein via the side chain of any one of a lysine residue, a tyrosine residue, or a tryptophan residue, and is a soluble protein of any one of [1] to

[25] or a salt thereof. [(27)] The bioorthogonal functional group is bonded to the soluble protein via the side chain of a lysine residue, and is the soluble protein of

[26] or a salt thereof. The soluble protein or a salt thereof according to any one of [2] to

[13] ,

[16] to

[26] , wherein the reactive group is a reactive group specific to the side chain of any one of a lysine residue, a tyrosine residue, or a tryptophan residue. The soluble protein or a salt thereof according to any one of [2] to

[13] ,

[16] to

[28] , wherein the reactive group is a reactive group specific to the side chain of a lysine residue. 〔30〕The reactive group is as follows:

Chemical formula

[13] ,

[16] to

[29] , corresponding to any one chemical structure selected from the group consisting of. 〔31〕The soluble protein or a salt thereof according to any one of [1] to

[30] , wherein the bioorthogonal functional group is bound to the soluble protein via a linker having 2 to 10 atoms in the main chain connecting the bioorthogonal functional group and the side chain of a specific amino acid residue. 〔32〕The soluble protein or a salt thereof according to any one of [1] to

[31] , wherein the bioorthogonal functional group is bound to the soluble protein via a linker whose main chain connecting the bioorthogonal functional group and the side chain of a specific amino acid residue does not contain a ring structure. 〔33〕The soluble protein or a salt thereof according to any one of [2] to

[13] ,

[16] to

[32] , wherein the number of atoms in the main chain connecting the L1 terminal portion and R' is 2 to 10. 〔34〕The soluble protein or a salt thereof according to any one of [2] to

[13] ,

[16] to

[33] , wherein the main chain connecting A and R does not contain a ring structure. A soluble protein or a salt thereof according to any one of [2] to

[13] ,

[16] to

[34] , wherein the partial structure represented by L1-B does not contain a peptide moiety. 〔36〕The soluble protein represented by the formula (IV) is the following (IV’):

Chemical formula

[13] ,

[16] to

[35] . 〔37〕A soluble protein or a salt thereof having a bioorthogonal functional group in a site-selective manner, wherein , the soluble protein contains one or more specific amino acid residues in a target region consisting of 1 to 50 consecutive amino acid residues, and contains five or more of the specific amino acid residues in a non-target region outside the target region, and the bioorthogonal functional group is bonded to one or more specific amino acid residues contained in the target region with a site selectivity of 30% or more via a linker that does not contain a peptide moiety, the bioorthogonal functional group is bonded to the soluble protein via the side chain of a lysine residue, the soluble protein is an antibody containing a plurality of heavy chains, as a result of having a bioorthogonal functional group at a plurality of specific amino acid residues present at the positions in the plurality of heavy chains contained in the antibody, the antibody has a plurality of bioorthogonal functional groups. A soluble protein or a salt thereof having a bioorthogonal functional group in a site-selective manner. 〔38〕The following formula (IV): L1-B-R’-T (IV) 〔In the formula, L1 is a monovalent group containing a bioorthogonal functional group or (ii') a monovalent group not containing a bioorthogonal functional group, B is a divalent group containing a bioorthogonal functional group or (b) a divalent group not containing a bioorthogonal functional group, R' is a moiety formed by the reaction between an antibody and a reactive group specific for the side chain of a lysine residue, T is a soluble protein, The soluble protein contains one or more specific amino acid residues in a target region consisting of 1 to 50 consecutive amino acid residues, and contains 5 or more of the specific amino acid residues in a non-target region outside the target region. It is represented by [ ] and the structural unit represented by L1-B-R' binds to one or more specific amino acid residues in the target region of the soluble protein with a positional selectivity of 30% or more. A soluble protein having a bioorthogonal functional group selectively or a salt thereof.

[0020] (Method for producing a soluble protein having a bioorthogonal functional group selectively or a salt thereof) The present invention also provides a method for producing a soluble protein having a bioorthogonal functional group selectively or a salt thereof, which requires identification by formula (IV) or a lower formula among the soluble proteins of the above [1] to

[38] . 〔39〕A method for producing a soluble protein having a bioorthogonal functional group selectively or a salt thereof, The following formula (II): A-L-B-R'-T (II) 〔In the formula, A is an affinity substance for the soluble protein, L is a cleavable linker which is a divalent group containing a cleavable moiety, B is a divalent group containing a bioorthogonal functional group or (a) a divalent group not containing a bioorthogonal functional group, R' is a moiety formed by the reaction between the soluble protein and a reactive group, T is a soluble protein, The soluble protein contains one or more specific amino acid residues in a target region consisting of 1 to 50 consecutive amino acid residues, and contains five or more of the specific amino acid residues in a non-target region outside the target region. ], and the structural unit represented by L1-B-R’ binds to one or more specific amino acid residues contained in the target region of the soluble protein with a positional selectivity of 30% or more, an affinity substance for the soluble protein, and a cleavable portion of the soluble protein or a salt thereof having a positional selectivity is cleaved, The following formula (IV): L1-B-R’-T (IV) [In the formula, B, R’ and T are the same as those in the formula (II), L1 is (i’) a monovalent group containing a bioorthogonal functional group, or (ii’) a monovalent group not containing a bioorthogonal functional group. ], and A method for producing a soluble protein or a salt thereof having a bioorthogonal functional group selectively, which comprises generating a soluble protein or a salt thereof in which the structural unit represented by L1-B-R’ binds to one or more specific amino acid residues contained in the target region of the soluble protein with a positional selectivity of 30% or more.

[0021] Preferably, the method of

[39] above may be as follows.

[40] The method of

[39] , wherein the soluble protein is an antibody and the reactive group is a reactive group specific to the side chain of a lysine residue.

[41] A method for producing a soluble protein or a salt thereof having a bioorthogonal functional group selectively, (A) The following formula (I): A-L-B-R (I) [In the formula, A is an affinity substance for the soluble protein, L is a cleavable linker which is a divalent group containing a cleavable portion, B is (a) a divalent group containing a bioorthogonal functional group, or (a) a divalent group not containing a bioorthogonal functional group, R is a reactive group towards the soluble protein. A compound represented by 〕 or a salt thereof is reacted with a soluble protein (wherein the soluble protein contains one or more specific amino acid residues in a target region consisting of 1 to 50 consecutive amino acid residues and contains five or more of the specific amino acid residues in a non-target region outside the target region). The following formula (II): A-L-B-R’-T (II) 〔In the formula, A, L, and B are the same as those in the formula (I) R’ is a moiety generated by the reaction between the soluble protein and the reactive group, T is a soluble protein. 〕 and is represented by A substance having an affinity for a soluble protein, in which the structural unit represented by L1-B-R’ binds to one or more specific amino acid residues contained in the target region of the soluble protein with a positional selectivity of 30% or more, and a soluble protein having a cleavable moiety or a salt thereof is generated, and (B) Cleaving the cleavable moiety of the substance having an affinity for the soluble protein and the soluble protein having a cleavable moiety or a salt thereof, The following formula (IV): L1-B-R’-T (IV) 〔In the formula, B, R’ and T are the same as those in the formula (II), L1 is (i’) a monovalent group containing a bioorthogonal functional group, or (ii’) a monovalent group not containing a bioorthogonal functional group. 〕 and is represented by A method comprising generating a soluble protein having a bioorthogonal functional group or a salt thereof, in which the structural unit represented by L1-B-R’ binds to one or more specific amino acid residues contained in the target region of the soluble protein with a positional selectivity of 30% or more.

[0022] Seventhly, the present invention provides a soluble protein having a functional substance or a salt thereof, and a method for producing the same. (Soluble protein having a functional substance in a site-selective manner or a salt thereof) [1] A soluble protein having a functional substance in a site-selective manner or a salt thereof, wherein the soluble protein contains one or more specific amino acid residues in a target region consisting of 1 to 50 consecutive amino acid residues, and contains five or more of the specific amino acid residues in a non-target region outside the target region, and the functional substance is bound to one or more specific amino acid residues contained in the target region with a site selectivity of 30% or more via a linker not containing a peptide moiety. A soluble protein having a functional substance in a site-selective manner or a salt thereof. [2] The following formula (V): F-(L1-B)’-R’-T (V) [In the formula, L1 is (i’) a monovalent group containing a bioorthogonal functional group, or (ii’) a monovalent group not containing a bioorthogonal functional group, B is (a) a divalent group containing a bioorthogonal functional group, or (b) a divalent group not containing a bioorthogonal functional group, the structural unit represented by (L1-B)’ is a divalent structural unit containing a part generated by the reaction between the functional substance and one or both of the bioorthogonal functional groups in (i’) and (a), F is a functional substance, R’ is a part generated by the reaction between the soluble protein and a reactive group, T is a soluble protein, the soluble protein contains one or more specific amino acid residues in a target region consisting of 1 to 50 consecutive amino acid residues, and contains five or more of the specific amino acid residues in a non-target region outside the target region.], and the structural unit represented by F-(L1-B)’ is bound to one or more specific amino acid residues contained in the target region of the soluble protein with a site selectivity of 30% or more. A soluble protein having a functional substance in a site-selective manner or a salt thereof. [3] The soluble protein or a salt thereof is represented by the following formula (V1): L1-B’(-F)-R’-T (V1) 〔wherein, L1, F, R’ and T are the same as those in the formula (V), B’ is a divalent group containing a moiety generated by the reaction between a functional substance and a bioorthogonal functional group.〕 represented by the formula, and the structural unit represented by L1-B’(-F)-R’ binds to one or more specific amino acid residues contained in the target region of the soluble protein with a positional selectivity of 30% or more, a soluble protein having a functional substance with positional selectivity or a salt thereof, which is the soluble protein or a salt thereof according to [2]. 〔4〕The soluble protein or a salt thereof is represented by the following formula (V2): F-L1’-B-R’-T (V2) 〔wherein, F, B, R’ and T are the same as those in the formula (V), L1’ is a divalent group containing a moiety generated by the reaction between a functional substance and a monovalent group containing (i’) a bioorthogonal functional group.〕 represented by the formula, and the structural unit represented by F-L1’-B-R’ binds to one or more specific amino acid residues contained in the target region of the soluble protein with a positional selectivity of 30% or more, a soluble protein having a functional substance with positional selectivity or a salt thereof, or the following formula (V3): Fa-L1’-B’(-Fb)-R’-T (V3) 〔wherein, R’ and T are the same as those in the formula (V), L1’ is the same as that in the formula (V2), B’ is a divalent group containing a moiety generated by the reaction between a functional substance and a bioorthogonal functional group, Fa and Fb are each the same or different functional substances.], and a structural unit represented by Fa-L1'-B'(-Fb)-R' binds to one or more specific amino acid residues contained in the target region of the soluble protein with a positional selectivity of 30% or more, A soluble protein having a functionally selective functional substance or a salt thereof, which is the soluble protein or a salt thereof of [2]. The soluble protein of [5] is a monoclonal antibody, and the soluble protein or a salt thereof according to any one of [1] to [4]. The soluble protein of [6] is an IgG antibody, and the soluble protein or a salt thereof according to any one of [1] to [5]. The soluble protein of [7] is of human origin, and the soluble protein or a salt thereof according to any one of [1] to [6]. The soluble protein of [8] is an antibody containing any one Fc region protein selected from the group consisting of the following (A) to (C) and having an antigen-binding ability, and the soluble protein or a salt thereof according to any one of [1] to [7]: (A) An Fc region protein containing the amino acid sequence of SEQ ID NO: 1; (B) An Fc region protein containing an amino acid sequence in which one or several amino acid residues are inserted, added, deleted or substituted in the amino acid sequence of SEQ ID NO: 1; or (C) An Fc region protein containing an amino acid sequence having 90% or more identity with the amino acid sequence of SEQ ID NO: 1. The soluble protein of [9], or a salt thereof, wherein the target region is a region consisting of 1 to 10 consecutive amino acid residues, and the soluble protein or a salt thereof according to any one of [1] to [8]. The soluble protein of

[10] , or a salt thereof, wherein the target region is a region consisting of 1 to 3 consecutive amino acid residues, and the soluble protein or a salt thereof according to [9]. The soluble protein of

[11] , or a salt thereof, wherein the target region is (a) a region consisting of amino acid residues at positions 246 to 248 in the human IgG Fc region, (b) a region consisting of amino acid residues at positions 288 to 290 in the human IgG Fc region, or (c) an amino acid residue at position 317 in the human IgG Fc region, and the soluble protein or a salt thereof according to

[10] . 〔12〕The soluble protein according to any one of 〔1〕to 〔11〕or a salt thereof, wherein the site selectivity is 50% or more. 〔13〕The soluble protein according to 〔12〕or a salt thereof, wherein the site selectivity is 70% or more. 〔14〕The soluble protein according to 〔13〕or a salt thereof, wherein the site selectivity is 90% or more. 〔15〕The soluble protein according to any one of 〔1〕to 〔14〕or a salt thereof, wherein the specific amino acid residue is in a region extending up to a remote position of a amino acid residues (where a is an arbitrary integer of 1 to 10) on each of the N-terminal side and the C-terminal side with respect to the specific amino acid present at a specific position, and does not contain an amino acid residue of the same type as the specific amino acid residue other than the specific amino acid residue present at the specific position. 〔16〕The soluble protein according to any one of 〔1〕, 〔5〕to 〔15〕or a salt thereof, wherein the soluble protein is a multimeric protein containing a plurality of monomeric proteins, and as a result of having a functional substance in the plurality of specific amino acid residues present at the position in the plurality of monomeric proteins contained in the multimeric protein, the multimeric protein has a plurality of functional substances. 〔17〕The soluble protein according to any one of 〔1〕, 〔5〕to 〔16〕or a salt thereof, wherein the soluble protein is an antibody containing a plurality of heavy chains, and as a result of having a functional substance in the plurality of specific amino acid residues present at the position in the plurality of heavy chains contained in the antibody, the antibody has a plurality of functional substances. 〔18〕The soluble protein according to any one of 〔2〕to 〔15〕or a salt thereof, wherein the soluble protein is a multimeric protein containing a plurality of monomeric proteins, and as a result of T having a structural unit represented by A-L-B-R’in corresponding plurality of target regions in the plurality of monomeric proteins, the multimeric protein has a plurality of structural units represented by A-L-B-R’. 〔19〕The soluble protein according to any one of 〔2〕to 〔15〕or a salt thereof, wherein the soluble protein is an antibody containing a plurality of heavy chains, As a result of T having a structural unit represented by A-L-B-R' in a plurality of corresponding target regions in a plurality of heavy chains, the antibody has a plurality of structural units represented by A-L-B-R', and is a soluble protein according to any one of [2] to

[15] ,

[18] or a salt thereof.

[20] A soluble protein according to

[17] or

[19] or a salt thereof, wherein the number of heavy chains is two.

[21] L1 is represented by the following formula (L1-1) to (L1-2): C1-Lb (L1-1) C1 (L1-2) (In the formula, Lb is a divalent group, C1 is a bioorthogonal functional group or a group other than a bioorthogonal functional group. ) and is a soluble protein according to any one of [2] to

[15] ,

[18] to

[20] or a salt thereof.

[22] The Lb is represented by the following formula (Lb'):

Chemical formula

[21] or a salt thereof. The soluble protein or a salt thereof according to any one of [1] to

[22] , wherein the divalent group containing a bioorthogonal functional group is a divalent group containing a bioorthogonal functional group selected from the group consisting of an azide residue, an aldehyde residue, a thiol residue, an alkyne residue, an alkene residue, a tetrazine residue, a nitrone residue, a hydroxylamine residue, a nitrile residue, a hydrazine residue, a ketone residue, a boronic acid residue, a cyanobenzothiazole residue, an allyl residue, a phosphine residue, a maleimide residue, a disulfide residue, a thioester group, an α-halocarbonyl residue, an isonitrile residue, a sydnone residue, and a selenium residue in the main chain. 〔24〕The soluble protein or a salt thereof according to any one of [1] to

[22] , wherein the divalent group containing a bioorthogonal functional group is a divalent group containing a bioorthogonal functional group selected from the group consisting of an azide residue, an aldehyde residue, a thiol residue, an alkyne residue, an alkene residue, a halogen residue, a tetrazine residue, a nitrone residue, a hydroxylamine residue, a nitrile residue, a hydrazine residue, a ketone residue, a boronic acid residue, a cyanobenzothiazole residue, an allyl residue, a phosphine residue, a maleimide residue, a disulfide residue, an α-halocarbonyl residue, an isonitrile residue, a sydnone residue, and a selenium residue in the side chain. 〔25〕The bioorthogonal functional group is as follows:

Chemical formula

[24] . 〔26〕The divalent group of (b) is an optionally substituted alkylene, an optionally substituted cycloalkylene, an optionally substituted aryl, an optionally substituted divalent heterocyclic group, -NR a -(R arepresents a hydrogen atom or a substituent), -O-, or a combination of two or more thereof, and is a soluble protein of any one of [1] to

[25] or a salt thereof.

[27] B is represented by the following formula (B-1): [Chemical formula] [In the formula, Y is -NH-, -O-, -CH2-, or the following formula (B-2): [Chemical formula] (In the formula, V and V' are the same or different and are -NH-, -O-, -CH2-, or a single bond, V1 is a divalent group containing a bioorthogonal functional group, s is an arbitrary integer from 0 to 10, ○ and ● in formula (B-2) have the same orientation as ○ and ● in formula (B-1), respectively.) and is a soluble protein of any one of [2] to

[15] ,

[18] to

[26] or a salt thereof. Z is an oxygen atom, a sulfur atom, or a hydrogen atom (when Z is a hydrogen atom, -C(=Z)- represents -CH2-.), ○ (white circle) in formula (B-1) represents a bond to the L-side part, and ● (black circle) represents a bond to the R-side part.].) and is a soluble protein of any one of [2] to

[15] ,

[18] to

[26] or a salt thereof.

[28] The reactive group is a reactive group specific to the side chain of any one of a lysine residue, a tyrosine residue, or a tryptophan residue, and is a soluble protein of any one of [2] to

[15] ,

[18] to

[27] or a salt thereof.

[29] The reactive group is a reactive group specific to the side chain of a lysine residue, and is a soluble protein of any one of [2] to

[15] ,

[18] to

[28] or a salt thereof.

[30] The reactive group is the following: [Chemical formula] [Here, R 5a and R 5cis an atom or group selected from the group consisting of the above (i) to (vii), R 5b is an electron-withdrawing group, j is any integer from 1 to 5, k is any integer from 1 to 4.], a soluble protein of any one of [2] to

[15] ,

[18] to

[29] or a salt thereof corresponding to any one chemical structure.

[31] A soluble protein of any one of [1] to

[30] or a salt thereof, wherein a bioorthogonal functional group is bound to the soluble protein via a linker having 2 to 10 atoms in the main chain connecting the functional substance and the side chain of a specific amino acid residue.

[32] A soluble protein of any one of [1] to

[31] or a salt thereof, wherein a bioorthogonal functional group is bound to the soluble protein via a linker having a main chain connecting the functional substance and the side chain of a specific amino acid residue and not containing a ring structure.

[33] A soluble protein of any one of [2] to

[15] ,

[18] to

[32] or a salt thereof, wherein the number of atoms in the main chain connecting the L1 terminal portion and R' is 2 to 10.

[34] A soluble protein of any one of [2] to

[15] ,

[18] to

[33] or a salt thereof, wherein the main chain connecting A and R does not contain a ring structure.

[35] A soluble protein of any one of [2] to

[15] ,

[18] to

[34] or a salt thereof, wherein the partial structure represented by L1-B does not contain a peptide portion.

[36] Soluble proteins or salts thereof having a functional substance selectively at a position, represented by the above formulas (V1), (V2) and (V3), are respectively the following (V1'), (V2') and (V3):

Chemical formula

Chemical formula

Chemical formula

[15] ,

[18] to

[35] . 〔37〕A soluble protein having a functional substance selectively located or a salt thereof, wherein the soluble protein contains one or more specific amino acid residues in a target region consisting of 1 to 50 consecutive amino acid residues, and contains five or more of the specific amino acid residues in a non-target region outside the target region, and The functional substance binds to one or more specific amino acid residues contained in the target region with a regioselectivity of 30% or more via a linker that does not contain a peptide moiety. The functional substance binds to the soluble protein via the side chain of a lysine residue. The soluble protein is an antibody containing a plurality of heavy chains. As a result of having the functional substance at a plurality of specific amino acid residues present at the positions in the plurality of heavy chains contained in the antibody, the antibody has a plurality of functional substances, a soluble protein having a functional substance regioselectively or a salt thereof.

[38] The following formula (V): F-(L1-B)’-R’-T (V) [In the formula, L1 is (i’) a monovalent group containing a bioorthogonal functional group, or (ii’) a monovalent group not containing a bioorthogonal functional group. B is (a) a divalent group containing a bioorthogonal functional group, or (b) a divalent group not containing a bioorthogonal functional group. The structural unit represented by (L1-B)’ is a divalent structural unit containing a moiety generated by the reaction between the functional substance and one or both of the bioorthogonal functional groups in (i’) and (a). F is a functional substance. R’ is a moiety generated by the reaction between a lysine residue of the antibody and a reactive group specific to the side chain of the lysine residue. T is an antibody. The antibody contains one or more specific amino acid residues in a target region consisting of 1 to 50 consecutive amino acid residues, and contains 5 or more of the specific amino acid residues in a non-target region outside the target region. ], and the structural unit represented by F-(L1-B)’ binds to one or more specific amino acid residues contained in the target region of the soluble protein with a regioselectivity of 30% or more, a soluble protein having a functional substance regioselectively or a salt thereof.

[39] The soluble protein or a salt thereof is represented by the following formula (V1): L1-B’(-F)-R’-T (V1) [In the formula, L1, F, R’ and T are the same as those in the formula (V), B’ is a divalent group containing a moiety formed by the reaction between a functional substance and a bioorthogonal functional group. The soluble protein having a site-selectively functional substance, or a salt thereof, is represented by

[38] , in which the structural unit represented by L1-B’(-F)-R’ binds to one or more specific amino acid residues contained in the target region of the soluble protein with a site selectivity of 30% or more.

[40] The soluble protein or a salt thereof is represented by the following formula (V2): F-L1’-B-R’-T (V2) [wherein, F, B, R’ and T are the same as those in the formula (V), L1’ is a divalent group containing a moiety formed by the reaction between a functional substance and a monovalent group containing (i’) a bioorthogonal functional group. The soluble protein having a site-selectively functional substance, or a salt thereof, is represented by

[38] , in which the structural unit represented by F-L1’-B-R’ binds to one or more specific amino acid residues contained in the target region of the soluble protein with a site selectivity of 30% or more, or the following formula (V3): Fa-L1’-B’(-Fb)-R’-T (V3) [wherein, R’ and T are the same as those in the formula (V), L1’ is the same as that in the formula (V2), B’ is a divalent group containing a moiety formed by the reaction between a functional substance and a bioorthogonal functional group, Fa and Fb are the same or different functional substances, respectively. The soluble protein having a site-selectively functional substance, or a salt thereof, is represented by

[38] , in which the structural unit represented by Fa-L1’-B’(-Fb)-R’ binds to one or more specific amino acid residues contained in the target region of the soluble protein with a site selectivity of 30% or more.

[0023] (Method for Producing Soluble Protein Having Functionality Substance at Positional Selectivity or Salt Thereof) The present invention also provides a method for producing a soluble protein having a functionality substance at positional selectivity or a salt thereof, which requires specification by formula (V) or a lower formula among the soluble proteins of the above [1] to

[40] .

[41] A method for producing a soluble protein having a functionality substance at positional selectivity or a salt thereof, comprising the following formula (III): A-L-B’(-F)-R’-T (III) [wherein, A is an affinity substance for the soluble protein, L is a cleavable linker which is a divalent group containing a cleavable moiety, B’ is a divalent group containing a moiety generated by the reaction between the functionality substance and the bioorthogonal functional group, F is a functionality substance, R’ is a moiety generated by the reaction between the soluble protein and the reactive group, T is a soluble protein, the soluble protein contains one or more specific amino acid residues in a target region consisting of 1 to 50 consecutive amino acid residues, and contains five or more of the specific amino acid residues in a non-target region outside the target region.], and the structural unit represented by A-L-B’(-F)-R’ binds to one or more specific amino acid residues contained in the target region of the soluble protein with a positional selectivity of 30% or more. Cleaving the cleavable moiety of the complex or its salt having an affinity substance for the soluble protein, a cleavable moiety, a functionality substance, and a soluble protein at positional selectivity, or the following formula (IV): L1-B-R’-T (IV) [wherein, L1 is (i’) a monovalent group containing a bioorthogonal functional group, or (ii’) a monovalent group not containing a bioorthogonal functional group, B is (a) a divalent group containing a bioorthogonal functional group, or (b) a divalent group not containing a bioorthogonal functional group, R’ is a moiety generated by the reaction between a soluble protein and a reactive group, T is a soluble protein that contains one or more specific amino acid residues in a target region consisting of 1 to 50 consecutive amino acid residues, and contains five or more of the specific amino acid residues in a non-target region outside the target region.], and the structural unit represented by A-L-B’(-F)-R’ binds to one or more specific amino acid residues contained in the target region of the soluble protein with a positional selectivity of 30% or more. Reacting a soluble protein having a bioorthogonal functional group with a positional selectivity or a salt thereof with a functional substance, The following formula (V): F-(L1-B)’-R’-T (V) [In the formula, L1 is (i’) a monovalent group containing a bioorthogonal functional group, or (ii’) a monovalent group not containing a bioorthogonal functional group, B is (a) a divalent group containing a bioorthogonal functional group, or (b) a divalent group not containing a bioorthogonal functional group, The structural unit represented by (L1-B)’ is a divalent structural unit containing a moiety generated by the reaction between a functional substance and one or both of the bioorthogonal functional groups in (i’) and (a) of the structural unit, F is a functional substance, R’ and T are the same as those in the above formula (III) or (IV).], and the structural unit represented by F-(L1-B)’-R’ binds to one or more specific amino acid residues contained in the target region of the soluble protein with a positional selectivity of 30% or more. A method comprising producing a soluble protein having a functional substance with a positional selectivity or a salt thereof.

[0024] Preferably, the method of

[41] above may be as follows.

[42] Cleaving the affinity substance, the cleavable moiety, the functional substance, and the cleavable moiety of the complex or its salt having a positional selectivity for the soluble protein with respect to the soluble protein, The following formula (V1): L1-B’(-F)-R’-T (V1) [In the formula, L1 is a monovalent group containing a (i’) bioorthogonal functional group or a (ii’) monovalent group not containing a bioorthogonal functional group, B’, F, R’ and T are the same as those in the formula (III).], and the structural unit represented by L1-B’(-F)-R’ binds to one or more specific amino acid residues contained in the target region of the soluble protein with a positional selectivity of 30% or more, A method according to

[41] comprising producing a soluble protein having a functional substance selectively positioned or a salt thereof.

[43] Reacting the soluble protein having the bioorthogonal functional group selectively positioned or a salt thereof with one or two functional substances, The following formula (V2): F-L1’-B-R’-T (V2) [In the formula, B, R’ and T are the same as those in the formula (IV), L1’ is a divalent group containing a moiety generated by the reaction between a functional substance and a (i’) monovalent group containing a bioorthogonal functional group, F is a functional substance.], and the structural unit represented by F-L1’-B-R’ binds to one or more specific amino acid residues contained in the target region of the soluble protein with a positional selectivity of 30% or more, A soluble protein having a functional substance selectively positioned, or The following formula (V3): Fa-L1’-B’(-Fb)-R’-T (V3) [In the formula, R’ and T are the same as those in the formula (IV), L1’ is the same as that in the formula (V2), B’ is a divalent group containing a moiety generated by the reaction between a functional substance and a bioorthogonal functional group, Fa and Fb are each the same or different functional substances. A method according to

[41] , which comprises producing a soluble protein having a functional substance with positional selectivity or a salt thereof, wherein a structural unit represented by [ ] and represented by Fa-L1'-B'(-Fb)-R' binds to one or more specific amino acid residues contained in the target region of the soluble protein with a positional selectivity of 30% or more. The method according to any one of

[41] to

[43] , wherein the soluble protein is an antibody and the reactive group is a reactive group specific to the side chain of a lysine residue. A method for producing a soluble protein having a functional substance with positional selectivity or a salt thereof, comprising: (A) The following formula (II): A-L-B-R'-T (II) 〔In the formula, A is an affinity substance for a soluble protein, L is a cleavable linker which is a divalent group containing a cleavable moiety, B is (a) a divalent group containing a bioorthogonal functional group, R' is a moiety formed by the reaction between a soluble protein and a reactive group, T is a soluble protein, The soluble protein contains one or more specific amino acid residues in a target region consisting of 1 to 50 consecutive amino acid residues, and contains 5 or more of the specific amino acid residues in a non-target region outside the target region. A soluble protein having an affinity substance for a soluble protein, and a soluble protein or a salt thereof having a cleavable moiety with positional selectivity, wherein a structural unit represented by [ ] and represented by A-L-B-R' binds to one or more specific amino acid residues contained in the target region of the soluble protein with a positional selectivity of 30% or more, are reacted with a functional substance to obtain The following formula (III): A-L-B'(-F)-R'-T (III) 〔In the formula, A, L, R' and T are the same as those in the formula (II), B’ is a divalent group containing a moiety generated by the reaction between a functional substance and a bioorthogonal functional group, F is a functional substance.], and a structural unit represented by A-L-B’(-F)-R’ binds to one or more specific amino acid residues contained in the target region of the soluble protein with a positional selectivity of 30% or more, producing a complex or a salt thereof having a positional selectivity for a soluble protein, an affinity substance for the soluble protein, a cleavable moiety, a functional substance, and a soluble protein, and (B) Cleaving the cleavable moiety of a complex or a salt thereof having a positional selectivity for a soluble protein, an affinity substance for the soluble protein, a cleavable moiety, a functional substance, and a soluble protein, to give the following formula (V1): L1-B’(-F)-R’-T (V1) [wherein, L1 is (i’) a monovalent group containing a bioorthogonal functional group, or (ii’) a monovalent group not containing a bioorthogonal functional group, B’, F, R’ and T are the same as those in the above formula (III).], and a structural unit represented by L1-B’(-F)-R’ binds to one or more specific amino acid residues contained in the target region of the soluble protein with a positional selectivity of 30% or more, producing a soluble protein having a positional selectivity for a functional substance or a salt thereof. The method includes

[46] A method for producing a soluble protein having a positional selectivity for a functional substance or a salt thereof, comprising (A) The following formula (I): A-L-B-R (I) [wherein, A is an affinity substance for a soluble protein, L is a cleavable linker which is a divalent group containing a cleavable moiety, B is (a) a divalent group containing a bioorthogonal functional group, R is a reactive group for the soluble protein. A compound or a salt thereof having, in a regioselective manner, an affinity substance for a soluble protein, a cleavable moiety, and a reactive group represented by the following formula: reacting with a soluble protein (wherein the soluble protein contains one or more specific amino acid residues in a target region consisting of 1 to 50 consecutive amino acid residues and contains five or more of the specific amino acid residues in a non-target region outside the target region). and the following formula (II): A-L-B-R’-T (II) 〔In the formula, A, L, and B are the same as those in the formula (I), R’ is a moiety formed by the reaction between the soluble protein and the reactive group, T is a soluble protein.〕 represented by and having a structural unit represented by A-L-B-R’ bonded to one or more specific amino acid residues contained in the target region of the soluble protein with a regioselectivity of 30% or more to produce an affinity substance for the soluble protein and a soluble protein or a salt thereof having a cleavable moiety in a regioselective manner, (B) Reacting a soluble protein or a salt thereof having, in a regioselective manner, an affinity substance for the soluble protein and a cleavable moiety with a functional substance to obtain the following formula (III): A-L-B’(-F)-R’-T (III) 〔In the formula, A and L are the same as those in the formula (I), R’ and T are the same as those in the formula (II), B’ is a divalent group containing a moiety formed by the reaction between the functional substance and a bioorthogonal functional group, F is a functional substance.], and a structural unit represented by A-L-B’(-F)-R’ binds to one or more specific amino acid residues contained in the target region of the soluble protein with a positional selectivity of 30% or more, producing a complex or a salt thereof having a positional selectivity for an affinity substance, a cleavable moiety, a functional substance, and a soluble protein with respect to the soluble protein, and (C) Cleaving the cleavable moiety of a complex or a salt thereof having a positional selectivity for an affinity substance, a cleavable moiety, a functional substance, and a soluble protein with respect to the soluble protein, the following formula (V1): L1-B’(-F)-R’-T (V1) [wherein, L1 is (i’) a monovalent group containing a bioorthogonal functional group, or (ii’) a monovalent group not containing a bioorthogonal functional group, B’, F, R’ and T are the same as those in the formula (III).], and a structural unit represented by L1-B’(-F)-R’ binds to one or more specific amino acid residues contained in the target region of the soluble protein with a positional selectivity of 30% or more, producing a soluble protein having a positional selectivity for a functional substance or a salt thereof.

[47] A method for producing a soluble protein having a positional selectivity for a functional substance or a salt thereof, (A) The following formula (II): A-L-B-R’-T (II) [wherein, A is an affinity substance for a soluble protein, L is a cleavable linker which is a divalent group containing a cleavable moiety, B is (a) a divalent group containing a bioorthogonal functional group, or (a) a divalent group not containing a bioorthogonal functional group, R’ is a moiety generated by a reaction between a soluble protein and a reactive group, T is a soluble protein, The soluble protein contains one or more specific amino acid residues in a target region consisting of 1 to 50 consecutive amino acid residues, and contains five or more of the specific amino acid residues in a non-target region outside the target region. It is represented by 〕 and is represented by A-L-B-R’ A structural unit represented by binds to one or more specific amino acid residues contained in the target region of the soluble protein with a positional selectivity of 30% or more, an affinity substance for the soluble protein, and a cleavable moiety of the soluble protein having a cleavable moiety or a salt thereof is cleaved to the following formula (IV): L1-B-R’-T (IV) [wherein, B, R’ and T are the same as those in the formula (II), L1 is (i’) a monovalent group containing a bioorthogonal functional group, or (ii’) a monovalent group not containing a bioorthogonal functional group. It is represented by 〕 and a structural unit represented by L1-B-R’ binds to one or more specific amino acid residues contained in the target region of the soluble protein with a positional selectivity of 30% or more, to produce a soluble protein having a bioorthogonal functional group or a salt thereof, and (B) reacting the soluble protein having a bioorthogonal functional group or a salt thereof with one or more functional substances to the following formula (V2) F-L1’-B-R’-T (V2) [wherein, B, R’ and T are the same as those in the formula (IV), L1’ is a divalent group containing a moiety generated by the reaction between a functional substance and (i’) a monovalent group containing a bioorthogonal functional group, F is a functional substance. It is represented by 〕 and a structural unit represented by F-L1’-B-R’ binds to one or more specific amino acid residues contained in the target region of the soluble protein with a positional selectivity of 30% or more, a soluble protein having a functional substance or a salt thereof, or the following formula (V3): Fa-L1’-B’(-Fb)-R’-T (V3) [In the formula, R’ and T are the same as those in the formula (IV), L1’ is the same as that in the formula (V2), B’ is a divalent group containing a part generated by the reaction between a functional substance and a bioorthogonal functional group, Fa and Fb are each the same or different functional substances.], and the structural unit represented by Fa-L1’-B’(-Fb)-R’ binds to one or more specific amino acid residues contained in the target region of the soluble protein with a positional selectivity of 30% or more, A method comprising producing a soluble protein having a functional substance that is positionally selective or a salt thereof.

[48] A method for producing a soluble protein having a functional substance that is positionally selective or a salt thereof, (A) The following formula (I): A-L-B-R (I) [In the formula, A is an affinity substance for a soluble protein, L is a cleavable linker which is a divalent group containing a cleavable part, B is (a) a divalent group containing a bioorthogonal functional group, or (a) a divalent group not containing a bioorthogonal functional group.], and a compound represented by the formula or a salt thereof is reacted with a soluble protein (here, the soluble protein contains one or more specific amino acid residues in a target region consisting of 1 to 50 consecutive amino acid residues, and contains 5 or more of the specific amino acid residues in a non-target region outside the target region.) to , the following formula (II): A-L-B-R’-T (II) [In the formula, A, L, and B are the same as those in the formula (I) R’ is a part generated by the reaction between a soluble protein and a reactive group, T is a soluble protein. A substance having an affinity for a soluble protein, which is represented by [ ] and in which a structural unit represented by A-L-B-R’ binds to one or more specific amino acid residues contained in the target region of the soluble protein with a positional selectivity of 30% or more, and a soluble protein having a cleavable moiety with positional selectivity or a salt thereof are produced. (B) Cleaving the cleavable moiety of the substance having an affinity for the soluble protein and the soluble protein having a cleavable moiety with positional selectivity or a salt thereof. The following formula (IV): L1-B-R’-T (IV) [In the formula, B, R’ and T are the same as those in the formula (II), L1 is (i’) a monovalent group containing a bioorthogonal functional group or (ii’) a monovalent group not containing a bioorthogonal functional group. A soluble protein having a bioorthogonal functional group with positional selectivity or a salt thereof, which is represented by [ ] and in which a structural unit represented by L1-B-R’ binds to one or more specific amino acid residues contained in the target region of the soluble protein with a positional selectivity of 30% or more, is produced, and (C) Reacting the soluble protein having a bioorthogonal functional group with positional selectivity or a salt thereof with one or more functional substances. The following formula (V2): F-L1’-B-R’-T (V2) [In the formula, B, R’ and T are the same as those in the formula (IV), L1’ is a divalent group containing a moiety generated by a reaction between a functional substance and (i’) a monovalent group containing a bioorthogonal functional group, F is a functional substance. A soluble protein having a functional substance with positional selectivity or a salt thereof, which is represented by [ ] and in which a structural unit represented by F-L1’-B-R’ binds to one or more specific amino acid residues contained in the target region of the soluble protein with a positional selectivity of 30% or more, or The following formula (V3): Fa-L1’-B’(-Fb)-R’-T (V3) [In the formula, R’ and T are the same as those in the formula (IV), L1’ is the same as that in the formula (V2), B’ is a divalent group containing a moiety generated by the reaction between a functional substance and a bioorthogonal functional group, Fa and Fb are each the same or different functional substances.], and a structural unit represented by Fa-L1’-B’(-Fb)-R’ binds to one or more specific amino acid residues contained in the target region of the soluble protein with a positional selectivity of 30% or more, A method comprising producing a soluble protein having a functional substance or a salt thereof that is positionally selective. [Advantages of the Invention]

[0025] (I) The compound or a salt thereof of the present invention having an affinity substance, a cleavable moiety, and a reactive group for a soluble protein is useful, for example, for the site-selective modification of a soluble protein. (II) The soluble protein or a salt thereof of the present invention having an affinity substance for a soluble protein and a cleavable moiety (position-selectively), (III) the complex or a salt thereof of the present invention having an affinity substance for a soluble protein, a cleavable moiety, a functional substance, and a soluble protein (position-selectively), and (IV) the soluble protein or a salt thereof of the present invention having a bioorthogonal functional group (position-selectively) are useful as intermediates for the preparation of a soluble protein or a salt thereof having a functional substance (position-selectively), for example. (V) The soluble protein or a salt thereof of the present invention having a functional substance (position-selectively) is useful, for example, as a medicine or a reagent (e.g., a diagnostic agent, a research reagent). In particular, when the soluble protein is an antibody, the antibody or a salt thereof of the present invention having a functional substance (position-selectively) is suitable for these uses. [Brief Description of the Drawings]

[0026]

Figure 1-1

Figure 1-2

Figure 1-3

Figure 2

Figure 3

Figure 4

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MODE FOR CARRYING OUT THE INVENTION

[0027] 1. A compound or a salt thereof containing an affinity substance, a cleavable moiety, and a reactive group for a soluble protein 1-1. Overview The present invention provides a compound represented by formula (I) or a salt thereof, which contains an affinity substance for a soluble protein, a cleavable moiety, and a reactive group. A-L-B-R (I) [In the formula, A is an affinity substance for a soluble protein, L is a cleavable linker which is a divalent group containing a cleavable moiety, B is (a) a divalent group containing a bioorthogonal functional group, or (b) a divalent group not containing a bioorthogonal functional group, R is a reactive group for the soluble protein.]

[0028] In formula (I) and other formulas presented in connection with the present invention, -(hyphen) indicates that the two units present on both sides thereof are covalently bonded. Thus, in formula (I), A is covalently bonded to L, L is covalently bonded to A and B, B is covalently bonded to L and R, and R is covalently bonded to B.

[0029] 1-2. Affinity Substance (A) for Soluble Protein In formula (I), A is an affinity substance for a soluble protein. An affinity substance is a substance having the ability to bind to a target by non-covalent bonding.

[0030] The affinity substance used in the present invention targets a soluble protein, which is also referred to as a secreted protein. Examples of such soluble proteins include antibodies, soluble receptors, ligands, albumin, erythropoietin (EPO), vascular endothelial growth factor (Anti-VEGF), bone morphogenetic protein, follicle-stimulating hormone (FSH), glucagon, granulocyte colony-stimulating factor, granulocyte macrophage colony-stimulating factor, ciliary gonadotropin, insulin, interleukin, interferon, platelet-derived growth factor (PDGF), growth factors (TGF family, FGF family). The soluble protein may be a protein modified with a biomolecule (e.g., sugar) (e.g., glycoprotein) or a protein unmodified with a biomolecule.

[0031] The soluble protein that is the target of the affinity substance is also a naturally derived protein or an artificial protein.

[0032] Examples of the naturally derived proteins include proteins derived from organisms and viruses. Examples of the proteins derived from organisms include proteins derived from animals such as mammals, birds (e.g., chickens), insects, microorganisms, plants, fungi, and fish. Preferably, the naturally derived protein is a protein derived from a mammal. Examples of the mammals include primates (e.g., humans, monkeys, chimpanzees), rodents (e.g., mice, rats, guinea pigs, hamsters, rabbits), pet animals (e.g., dogs, cats), livestock (e.g., cows, pigs, goats), and draft animals (e.g., horses, sheep). More preferably, the naturally derived protein is a protein derived from a primate or a rodent, and even more preferably, from the perspective of the clinical application of the present invention, it is a protein derived from a human. Examples of the proteins derived from viruses include influenza viruses (e.g., avian influenza virus, swine influenza virus), AIDS virus, Ebola virus, and phage virus.

[0033] Examples of the artificial proteins include modified proteins of naturally derived proteins (e.g., proteins in which one or more amino acid residues selected from the group consisting of substitution, deletion, and insertion are introduced into the naturally derived protein), fusion proteins, and artificially designed monoclonal antibodies. Examples of the artificially designed monoclonal antibodies include chimeric antibodies, humanized antibodies, human antibodies, antibodies to which a predetermined sugar chain is added (e.g., antibodies modified to have a sugar chain binding consensus sequence such as an N-type sugar chain binding consensus sequence), bispecific antibodies, scFv antibodies, Fab antibodies, F(ab')2 antibodies, VHH antibodies, Fc region proteins, and Fc fusion proteins.

[0034] The soluble protein that is the target of the affinity substance may further be a monomeric protein or a multimeric (e.g., dimeric, trimeric, or tetrameric) protein. When the protein that is the target of the affinity substance is a multimeric protein, the multimeric protein may be a homomultimer or a heteromultimer. The multimeric protein may be a protein that forms a multimer via a covalent bond (e.g., a disulfide bond) (e.g., an antibody having a structure in which two units composed of a light chain and a heavy chain are linked via a disulfide bond), or a protein that forms a multimer via a non-covalent bond (i.e., association), but a protein that forms a multimer via a covalent bond is preferred. Examples of the multimeric protein that is the target of the affinity substance include divalent antibodies (e.g., IgG, IgD, IgE), tetravalent or higher antibodies (e.g., IgA antibody, IgM antibody), and albumin.

[0035] The soluble protein that is the target of the affinity substance may also be composed of any amino acid residues, but is preferably composed of the 20 natural L-α-amino acid residues that usually constitute a protein. Examples of such amino acid residues include L-alanine (A), L-asparagine (N), L-cysteine (C), L-glutamine (Q), L-isole Cysteine (C), L-leucine (L), L-methionine (M), L-phenylalanine (F), L-proline (P), L-serine (S), L-threonine (T), L-tryptophan (W), L-tyrosine (Y), L-valine (V), L-aspartic acid (D), L-glutamic acid (E), L-arginine (R), L-histidine (H), or L-lysine (K), and glycine (G) are mentioned (hereinafter, the notation of L is omitted). The soluble protein may be composed of, for example, 100 or more, preferably 120 or more, more preferably 150 or more, even more preferably 180 or more, and particularly preferably 200 or more amino acid residues. The soluble protein may also be, for example, 1000 or less, preferably 900 or less, more preferably 800 or less, even more preferably 700 or less, and particularly preferably 600 or less. More specifically, the soluble protein may be composed of, for example, 100 to 1000, preferably 120 to 900, more preferably 150 to 800, even more preferably 180 to 700 or more, and particularly preferably 200 to 600 amino acid residues. When the soluble protein is an antibody (e.g., an artificially designed monoclonal antibody as described above), the number of amino acid residues may correspond to the amino acid residues of the heavy chain of the antibody.

[0036] The soluble protein that is the target of the affinity substance further has a side chain or a terminal (N-terminal and / or C-terminal), preferably a side chain, to which a reactive group as described later can react, at one position or a plurality of positions (preferably a plurality of positions), and is a protein containing specific amino acid residues. Examples of such specific amino acid residues include 14 amino acid residues as described later, but preferably amino acid residues selected from the group consisting of lysine residues, tyrosine residues, tryptophan residues, and cysteine residues. In view of the fact that the compound of the present invention can site-specifically modify a soluble protein, a soluble protein containing such specific amino acid residues at a plurality of positions is preferred. The plurality of positions is not particularly limited as long as it is two or more positions. For example, it may be three or more positions, preferably five or more positions, more preferably ten or more positions, even more preferably twenty or more positions, and particularly preferably thirty or more positions. The plurality of positions may also be, for example, 200 or less positions, preferably 180 or less positions, more preferably 150 or less positions, even more preferably 120 or less positions, and particularly preferably 100 or less positions. More specifically, the plurality of positions may be, for example, positions 3 to 200, preferably positions 5 to 180, more preferably positions 10 to 150, even more preferably positions 20 to 120, and particularly preferably positions 30 to 100. Even for a soluble protein containing such specific amino acid residues at a plurality of positions, the compound of the present invention can site-specifically modify a specific amino acid residue present at a specific single position. For example, the number of lysine residues in human IgG1 is generally said to be about 70 to 90, although it depends on the amino acid composition in the variable region. In the present invention, we have succeeded in site-specifically modifying the lysine residues present at specific positions in such human IgG1.

[0037] More specifically, in the present invention, from the viewpoint of modifying amino acid residues present at specific positions in a protein while maintaining the function of the protein such as an antibody (that is, while maintaining the native folding without denaturing the protein), site-selective modification of amino acid residues exposed on the surface of the protein is preferred. For example, in human IgG such as human IgG1, exposed lysine residues and exposed tyrosine residues are present at the following positions (according to EU numbering; see http: / / www.imgt.org / IMGTScientificChart / Numbering / Hu_IGHGnber.html). (1) Exposed lysine residues CH2 domain (positions 246, 248, 274, 288, 290, 317, 320, 322, 338) CH3 domain (positions 360, 414, 439) (2) Exposed tyrosine residues CH2 domain (positions 278, 296, 300) CH3 domain (position 436) Therefore, when human IgG such as human IgG1 is modified with a lysine residue or a tyrosine residue, modification at the above positions is preferred.

[0038] Preferably, when human IgG such as human IgG1 is modified with a lysine residue or a tyrosine residue, among the positions in the above (1) and (2), lysine residues or tyrosine residues present at the following positions with high surface exposure may be modified. (1’) Exposed lysine residues CH2 domain (positions 246, 248, 274, 288, 290, 317, 320, 322) CH3 domain (positions 360, 414, 439) (2’) Exposed tyrosine residues CH2 domain (positions 278, 296, 300) CH3 domain (position 436) Therefore, when human IgG such as human IgG1 is modified with a lysine residue or a tyrosine residue, modification at the above positions is more preferred.

[0039] More preferably, when a human IgG such as human IgG1 is modified with a lysine residue, among the positions of (1) above, lysine residues present at predetermined positions (e.g., positions 246, 248, 288, 290, 317) in the CH2 domain that can be efficiently modified in the present invention may be modified.

[0040] In a specific embodiment, when the soluble protein that is the target of the affinity substance contains a plurality of specific amino acid residues at a plurality of positions as described above, it may contain one or more specific amino acid residues in a target region consisting of 1 to 50 consecutive amino acid residues, and contain five or more specific amino acid residues in a non-target region outside the target region. The target region may preferably consist of 1 to 30, more preferably 1 to 20, even more preferably 1 to 10, 1 to 5, or 1 to 3 (i.e., 1, 2, or 3) amino acid residues. Particularly preferably, the target region may be a region consisting of specific amino acid residues present at specific positions. Such specific positions may vary depending on the types of the target protein and the affinity substance, etc., and may be, for example, specific positions in a specific region (e.g., CH1, CH2, CH3) in the constant region of the antibody, and preferably positions in the CH2 of the antibody. More specifically, the target region may be the following residues according to the Eu numbering in human IgG Fc: (1) The Lys248 residue (hereinafter, also simply referred to as "Lys248" in this specification, corresponding to the 18th residue of the human IgG CH2 region (SEQ ID NO: 1)) or the Lys246 residue (hereinafter, also simply referred to as "Lys246" in this specification, corresponding to the 16th residue of the human IgG CH2 region (SEQ ID NO: 1)) : (2) The Lys288 residue (hereinafter, also simply referred to as "Lys288" in this specification, corresponding to the 58th residue of the human IgG CH2 region (SEQ ID NO: 1)) or the Lys290 residue (hereinafter, also simply referred to as "Lys290" in this specification, corresponding to the 60th residue of the human IgG CH2 region (SEQ ID NO: 1)); (3)The Lys317 residue (hereinafter, also simply referred to as "Lys317" in this specification, corresponding to the 87th residue of the human IgG CH2 region (SEQ ID NO: 1)).

[0041] According to the present invention, specific amino acid residues in the above target region can be highly regioselectively modified. Such regioselectivity is, for example, 30% or more, preferably 40% or more, more preferably 50% or more, even more preferably 60% or more, particularly preferably 70% or more, 80% or more, 90% or more, 95% or more, 96% or more, 97% or more, 98% or more, 99% or more, or even 100% or more.

[0042] The target region may also be such that specific amino acid residues present at specific positions do not contain amino acid residues of the same type as the specific amino acid residues present at the specific positions, in regions up to a remote position of a amino acid residues (where a is an arbitrary integer from 1 to 10) on the N-terminal side and the C-terminal side with respect to each of the specific positions. a is preferably an integer from 1 to 5, more preferably an integer from 1 to 3, even more preferably 1 or 2, and particularly preferably 1.

[0043] In a preferred embodiment, the affinity substance for the soluble protein is an affinity substance for an antibody. The antibody is a polyclonal antibody or a monoclonal antibody. Examples of antibody isotypes include IgG (e.g., IgG1, IgG2, IgG3, IgG4), IgM, IgA, IgD, IgE, and IgY. The antibody is a full-length antibody or an antibody fragment (e.g., F(ab’)2, Fab’, Fab, Fv, single-chain antibody), but a full-length antibody is preferred.

[0044] The antibody is an antibody against any antigen. For example, such an antigen may be a component found in an organism or virus as described above. Such antigens may also include, for example, proteins [including oligopeptides and polypeptides. It may be a protein modified with a biomolecule such as a sugar (e.g., glycoprotein)], sugar chains, nucleic acids, and low-molecular-weight compounds.

[0045] Preferably, the antibody may be an antibody against a protein as an antigen. Examples of the protein include cell membrane receptors, cell membrane proteins other than cell membrane receptors (e.g., extracellular matrix proteins), ligands, and soluble receptors.

[0046] More specifically, the protein that is the antigen of the antibody may be a disease target protein. Examples of the disease target protein include the following.

[0047] (1) Cancer region PD-L1, GD2, PDGFRα (platelet-derived growth factor receptor), CD22, HER2, phosphatidylserine (PS), EpCAM, fibronectin, PD-1, VEGFR-2, CD33, HGF, gpNMB, CD27, DEC-205, folate receptor, CD37, CD19, Trop2, CEACAM5, S1P, HER3, IGF-1R, DLL4, TNT-1 / B, CPAAs, PSMA, CD20, CD105 (endoglin), ICAM-1, CD30, CD16A, CD38, MUC1, EGFR, KIR2DL1,2,, NKG2A, tenascin-C, IGF (Insulin-like growth factor), CTLA-4, mesothelin, CD138, c-Met, Ang2, VEGF-A, CD79b, ENPD3, folate receptor α, TEM-1, GM2, glypican 3, macrophage inhibitory factor, CD74, Notch1, Notch2, Notch3, CD37, TLR-2, CD3, CSF-1R, FGFR2b, HLA-DR, GM-CSF, EphA3, B7-H3, CD123, gpA33, Frizzled7 receptor, DLL4, VEGF, RSPO, LIV-1, SLITRK6, Nectin-4, CD70, CD40, CD19, SEMA4D (CD100), CD25, MET, Tissue Factor, IL-8, EGFR, cMet, KIR3DL2, Bst1 (CD157), P-cadherin, CEA, GITR, TAM (tumor associated macrophage), CEA, DLL4, Ang2, CD73, FGFR2, CXCR4, LAG-3, GITR, Fucosyl GM1, IGF-1, Angiopoietin 2, CS F-1R, FGFR3, OX40, BCMA, ErbB3, CD137 (4-1BB), PTK7, EFNA4, FAP, DR5, CEA, Ly6E, CA6, CEACAM5, LAMP1, tissue factor, EPHA2, DR5, B7-H3, FGFR4, FGFR2, α2-PI, A33, GDF15, CAIX, CD166, ROR1, GITR, BCMA, TBA, LAG-3, EphA2, TIM-3, CD-200, EGFRvIII, CD16A, CD32B, PIGF, Axl, MICA / B, Thomsen-Friedenreich, CD39, CD37, CD73, CLEC12A, Lgr3, transferrin receptor, TGFβ, IL-17, 5T4, RTK, Immune Suppressor Protein, NaPi2b, Lewis blood group B antigen, A34, Lysil-Oxidase, DLK-1, TROP-2, α9 integrin, TAG-72 (CA72-4), CD70

[0048] (2) Autoimmune diseases · Inflammatory diseases IL-17, IL-6R, IL-17R, INF-α, IL-5R, IL-13, IL-23, IL-6, ActRIIB, β7-Integrin, IL-4αR, HAS, Eotaxin-1, CD3, CD19, TNF-α, IL-15, CD3ε, Fibronectin, IL-1β, IL-1α, IL-17, TSLP (Thymic Stromal Lymphopoietin), LAMP (Alpha4 Beta 7 Integrin), IL-23, GM-CSFR, TSLP, CD28, CD40, TLR-3, BAFF-R, MAdCAM, IL-31R, IL-33, CD74, CD32B, CD79B, IgE (immunoglobulin E), IL-17A, IL-17F, C5, FcRn, CD28, TLR4, MCAM, B7RP1, CXCR1,2 Ligands, IL-21, Cadherin-11, CX3CL1, CCL20, IL-36R, IL-10R, CD86, TNF-α, IL-7R, Kv1.3, α9 integrin, LIFHT

[0049] (3) Neurological diseases CGRP, CD20, β-amyloid, β-amyloid protofibril, Calcitonin Gene-Related Peptide Receptor, LINGO (Ig Domain Containing1), α-synuclein, extracellular tau, CD52, insulin receptor, tau protein, TDP-43, SOD1, TauC3, JC virus

[0050] (4) Infectious diseases Clostridium Difficile toxin B, cytomegalovirus, RS virus, LPS, S.Aureus Alpha-toxin, M2e protein, Psl, PcrV, S.Aureus toxin, influenza A, Alginate, Staphylococcus aureus, PD-L1, influenza B, Acinetobacter, F-protein, Env, CD3, pathogenic Escherichia coli, Klebsiella, Streptococcus pneumoniae

[0051] (5) Hereditary and rare diseases Amyloid AL, SEM A4D (CD100), insulin receptor, ANGPTL3, IL4, IL13, FGF23, adrenocorticotropic hormone, transthyretin, huntingtin

[0052] (6) Eye diseases Factor D, IGF-1R, PGDFR, Ang2, VEGF-A, CD-105 (Endoglin), IGF-1R, β-amyloid

[0053] (7) Orthopedic field Sclerostin, Myostatin, Dickkopf-1, GDF8, RNAKL, HAS, Siglec-15

[0054] (8) Blood diseases vWF, Factor IXa, Factor X, IFNγ, C5, BMP-6, Ferroportin, TFPI

[0055] (9) Other diseases BAFF (B cell activating factor), IL-1β, PCSK9, NGF, CD45, TLR-2, GLP-1, TNFR1, C5, CD40, LPA, prolactin receptor, VEGFR-1, CB1, Endoglin, PTH1R, CXCL1, CXCL8, IL-1β, AT2-R, IAPP

[0056] In a more preferred embodiment, the affinity substance for the soluble protein is an affinity substance for a monoclonal antibody. The isotype of the monoclonal antibody is the same as those described above for the antibody, but IgG (e.g., IgG1, IgG2, IgG3, IgG4) is preferred. Preferably, the monoclonal antibody is a full-length monoclonal antibody.

[0057] In an even more preferred embodiment, the affinity substance for the soluble protein is an affinity substance for a chimeric antibody, a humanized antibody, or a human antibody (e.g., IgG such as IgG1, IgG2, IgG3, IgG4) that is a full-length monoclonal antibody.

[0058] In a particularly preferred embodiment, the affinity substance for the soluble protein is an affinity substance for an antibody that contains any one Fc region protein selected from the group consisting of the following (A) to (C) and has antigen-binding ability: (A) An Fc region protein containing the amino acid sequence of SEQ ID NO: 1; (B) An Fc region protein containing an amino acid sequence in which one or several amino acid residues are inserted, added, deleted, or substituted in the amino acid sequence of SEQ ID NO: 1; or (C) An Fc region protein containing an amino acid sequence showing 90% or more identity with the amino acid sequence of SEQ ID NO: 1.

[0059] The amino acid sequence of SEQ ID NO: 1 is an Fc region protein. Such an Fc region protein is known to have the ability to be secreted. Therefore, the Fc region proteins of (A) to (C) above can have the ability to be secreted. In addition, an antibody containing such an Fc region protein can have antigen-binding ability. The amino acid residue at position 18 in SEQ ID NO: 1 is an arbitrary amino acid residue, preferably a neutral amino acid residue, more preferably an amino acid residue having a nonpolar side chain as described below, even more preferably leucine, isoleucine or alanine, and particularly preferably leucine or alanine. The amino acid residue at position 19 in SEQ ID NO: 1 is an arbitrary amino acid residue, preferably a neutral amino acid residue or an acidic amino acid residue, more preferably an amino acid residue having a nonpolar side chain or an acidic amino acid residue, even more preferably leucine or glutamic acid. The amino acid residue at position 21 in SEQ ID NO: 1 is an arbitrary amino acid residue, preferably a neutral amino acid residue, more preferably an amino acid residue having a nonpolar side chain, even more preferably glycine or alanine. The amino acid residue at position 140 in SEQ ID NO: 1 is an arbitrary amino acid residue, preferably an acidic amino acid residue, more preferably glutamic acid or aspartic acid. The amino acid residue at position 142 in SEQ ID NO: 1 is an arbitrary amino acid residue, preferably a neutral amino acid residue, more preferably an amino acid residue having a nonpolar side chain, even more preferably methionine, leucine or isoleucine, and particularly preferably methionine or leucine. The amino acid residue at position 177 in SEQ ID NO: 1 is an arbitrary amino acid residue is preferably a neutral amino acid residue, more preferably an amino acid residue having an uncharged polar side chain or a nonpolar side chain as described below, even more preferably threonine, alanine or glycine, and particularly preferably threonine or alanine.

[0060] In a preferred embodiment, the amino acid sequence of SEQ ID NO: 1 may be an amino acid sequence consisting of amino acid residues at positions 220 to 449 in the amino acid sequence of SEQ ID NO: 2 or SEQ ID NO: 41.

[0061] In another preferred embodiment, the amino acid sequence of SEQ ID NO: 1 may be an amino acid sequence consisting of amino acid residues at positions 7 to 236 in the amino acid sequence of SEQ ID NO: 3.

[0062] In a specific embodiment, an antibody comprising an Fc region protein containing an amino acid sequence as described above may be an antibody comprising an Fc region protein containing an amino acid sequence as described above and a constant region of the antibody. The constant region of such an antibody may be a constant region of a chimeric antibody, a humanized antibody, or a human antibody (e.g., IgG such as IgG1, IgG2, IgG3, IgG4, etc.).

[0063] In the Fc region protein (B), one or several amino acid residues may be modified by 1, 2, 3, or 4 types of mutations selected from the group consisting of deletion, substitution, addition, and insertion of amino acid residues. The mutation of amino acid residues may be introduced into one region in the amino acid sequence, or may be introduced into a plurality of different regions. The term "one or several" indicates the number that does not significantly impair the activity of the protein. The number indicated by the term "one or several" is, for example, 1 to 100, preferably 1 to 80, more preferably 1 to 50, 1 to 30, 1 to 20, 1 to 10, or 1 to 5 (e.g., 1, 2, 3, 4, or 5).

[0064] In the Fc region protein (C), the identity percentage with the amino acid sequence of SEQ ID NO: 1 may be 70% or more, 75% or more, 80% or more, 85% or more, 90% or more, 91% or more, 92% or more, 93% or more, 94% or more, 95% or more, 96% or more, 97% or more, 98% or more, or 99% or more. In the present invention, the calculation of the identity percentage of a peptide or polypeptide (protein) can be performed by the algorithm blastp. More specifically, the calculation of the percentage of polypeptide identity can be performed using the default Scoring Parameters (Matrix: BLOSUM62; Gap Costs: Existence = 11 Extension = 1; Compositional Adjustments: Conditional compositional score matrix adjustment) in the algorithm blastp provided by the National Center for Biotechnology Information (NCBI). Also, the calculation of the identity percentage of a polynucleotide (gene) can be performed by the algorithm blastn. More specifically, the calculation of the percentage of polynucleotide identity can be performed using the default Scoring Parameters (Match / Mismatch Scores = 1, -2; Gap Costs = Linear) in the algorithm blastn provided by NCBI.

[0065] Secretion in terms of secretory ability has the same meaning as the secretion of a secreted protein (so-called solubility). Therefore, "having secretory ability" means functioning as a soluble protein, similar to a normal antibody.

[0066] The antibody containing the above Fc region protein may have a mutation introduced at a specific site as long as it retains the desired properties (e.g., secretory ability, antigen-binding ability). A mutation that can retain the desired properties The positions of amino acid residues into which mutations may be introduced will be apparent to those skilled in the art. Specifically, those skilled in the art can 1) compare the amino acid sequences of a plurality of proteins having the same kind of characteristics, 2) identify relatively conserved regions and relatively non-conserved regions, and then 3) predict regions that can play an important role in function and regions that cannot play an important role in function from the relatively conserved regions and relatively non-conserved regions, respectively, so that the structure-function correlation can be recognized. Therefore, those skilled in the art can identify the positions of amino acid residues into which mutations may be introduced in the amino acid sequence of an antibody containing the above Fc region protein.

[0067] When an amino acid residue is mutated by substitution, the substitution of the amino acid residue may be a conservative substitution. As used herein, the term "conservative substitution" refers to substituting a given amino acid residue with an amino acid residue having a similar side chain. Families of amino acid residues having similar side chains are well known in the art. For example, such families include amino acids having basic side chains (e.g., lysine, arginine, histidine), amino acids having acidic side chains (e.g., aspartic acid, glutamic acid), amino acids having uncharged polar side chains (e.g., asparagine, glutamine, serine, threonine, tyrosine, cysteine), amino acids having nonpolar side chains (e.g., glycine, alanine, valine, leucine, isoleucine, proline, phenylalanine, methionine, tryptophan), amino acids having β-branched side chains (e.g., threonine, valine, isoleucine), amino acids having aromatic side chains (e.g., tyrosine, phenylalanine, tryptophan, histidine), amino acids having side chains containing a hydroxyl group (e.g., alcoholic, phenolic) (e.g., serine, threonine, tyrosine), and amino acids having sulfur-containing side chains (e.g., cysteine, methionine). Preferably, conservative substitutions of amino acids may be substitutions between aspartic acid and glutamic acid, substitutions between arginine, lysine, and histidine, substitutions between tryptophan and phenylalanine, substitutions between phenylalanine and valine, substitutions between leucine, isoleucine, and alanine, and substitutions between glycine and alanine.

[0068] Examples of the antibody containing any one Fc region selected from the group consisting of the above (A) to (C) include chimeric antibodies (e.g., rituximab, basiliximab, infliximab, cetuximab, sirukumab, dinutuximab, ortatoxumab), humanized antibodies (e.g., daclizumab, palivizumab, trastuzumab, alemtuzumab, omalizumab, efalizumab, bevacizumab, natalizumab (IgG4), tocilizumab, eculizumab (IgG2), mogamulizumab, pertuzumab, obinutuzumab, vedolizumab, pemrolizumab (IgG4), mepolizumab, elotuzumab, daratumumab, ikesekiizumab (IgG4), reslizumab (IgG4), atezolizumab), and human antibodies (e.g., adalimumab, panitumumab, golimumab, ustekinumab, canakinumab, ofatumumab, denosumab (IgG2), ipilimumab, belimumab, lirilumab, ramucirumab, nivolumab (IgG4), secukinumab, evolocumab (IgG2), alirocumab, nesvacumab, brodalumab (IgG2), olaratumab). (When not referring to the IgG subtype, it indicates IgG1).

[0069] Examples of the affinity substance for the soluble protein as described above include peptides (including oligopeptides, polypeptides, and proteins), low molecular weight compounds, nucleic acids, nucleic acid-peptide complexes, peptide-low molecular weight compound complexes, and nucleic acid-low molecular weight complexes.

[0070] In a specific embodiment, the affinity substance for the soluble protein as described above may be a peptide (including oligopeptides, polypeptides, proteins, and may be a glycoprotein). Examples of such peptides include the following: (1) IgG-binding peptides having an affinity for a specific region (CH2 region) of human IgG in general (i.e., human IgG1, IgG2, IgG3, and IgG4. The same applies hereinafter) (see, for example, International Publication No. 2016 / 186206, International Publication 2013 / 027796, International Publication No. 2008 / 054030); (2) ProteinA Mimetic (PAM) peptides that have an affinity for a specific region (CH2 region) of human IgG in general (see, for example, Fassina G et al., JOURNAL OF MOLECULAR RECOGNITION, 1996, VOL.6, 564-569); (3) EPIHRSTLTALL (SEQ ID NO: 9) that has an affinity for a specific region (CH2 region) of human IgG in general (see, for example, Ehrlich G.K et al., J.Biochem.Biophys.Methods, 2001, VOL.49, 443-454); (4) (NH2-Cys1-X1-X2-X3-X4)2-Lys-Gly-OH that has an affinity for a specific region (Fc region) of human IgG in general (see, for example, Ruvo M et al., ChemBioChem, 2005, VOL.6, 1242-1253); (5) FARLVSSIRY (SEQ ID NO: 10), FGRLVSSIRY (SEQ ID NO: 11), and TWKTSRISIF (SEQ ID NO: 12) that have an affinity for a specific region (Fc region) of human IgG in general (see, for example, Krook M et al., Journal of Immunological Methods, 1998, VOL.221, 151-157); (6) QSYP (SEQ ID NO: 13) that has an affinity for a specific region of human IgG in general (see, for example, Jacobs J.M. et al., Bio.Techniques, 2003, VOL.34, 132-141); (7) HWRGWV (SEQ ID NO: 14), HYFKFD (SEQ ID NO: 15), and HFRRHL (SEQ ID NO: 16) that have an affinity for a specific region (Fc region) of human IgG in general (see, for example, Carbonell R.G. et al., Journal of Chromatography A, 2009, VOL.1216, 910-918); (8) DAAG (SEQ ID NO: 17) that has an affinity for a specific region (Fc region) of human IgG in general (see, for example, Lund L.N. et al., Journal of Chromatography A, 2012, VOL.1225, 158-167); (9) Fc-I, Fc-II, and Fc-III having affinity for a specific region (Fc region) of human IgG in general (see, e.g., Warren L. Delano et al., Science, 2000, VOL. 287, 1279-1283; International Publication No. 2001 / 045746); and (10) NARKFYKG (SEQ ID NO: 18) and NKFRGKYK (SEQ ID NO: 19) having affinity for a specific region (Fc region) of human IgG in general (see, e.g., Biochemical Engineering Journal, 2013, VOL. 79, 33-40).

[0071] In another specific embodiment, the affinity substance for the soluble protein as described above may be a substance other than a peptide. As such a substance, for example, aptamers having affinity for a specific region (CH2 region, particularly the side chain of Lys340) of human IgG (e.g., human IgG1-4) [e.g., GGUGCU and GGUGAU and other GGUG(C / A)(U / T) motif-containing aptamers] have been reported (see, e.g., International Publication No. 2007 / 004748; Nomura Y et al., Nucleic Acids Res., 2010 Nov; 38(21):7822-9; Miyakawa S et al., RNA., 2008 Jun; 14(6):1154-63).

[0072] The affinity substance for the soluble protein as described above can be obtained by any known method in the art. For example, the whole soluble protein or a partial peptide in the soluble protein (e.g., when the protein surface-exposed region is known, present in the region An antibody can be prepared using a partial peptide (e.g., the hybridoma method), or an affinity substance can be obtained by screening an available library of affinity substances (e.g., peptide library, antibody library, antibody-producing cell library, aptamer library, phage library, mRNA library, cDNA library) (e.g., phage display method, SELEX method, mRNA display method, ribosome display method, cDNA display method, yeast display method). Further, when the affinity substance for the soluble protein is an affinity substance for the Fc region (soluble region) of the antibody, by using a partial peptide present in a specific region (e.g., CH1, CH2, CH3) of the Fc region of various antibodies (e.g., IgG, IgA, IgM, IgD, IgE), an affinity substance (e.g., antibody, aptamer) that can selectively bind to any part of the Fc region of the antibody can be efficiently obtained. Among the affinity substances thus obtained, those with relatively strong and weak affinity binding abilities are mixed. However, even an affinity substance with a weak affinity binding ability can reinforce its affinity binding ability by using an excessive amount.

[0073] The affinity substance for the soluble protein as described above may be an IgG-binding peptide represented by the following formula (i) or a salt thereof (e.g., Examples and International Publication No. 2016 / 186206). (X 1-3 )-C-(X2)-H-(Xaa1)-G-(Xaa2)-L-V-W-C-(X 1-3 ) (SEQ ID NO: 94) (i) 〔In the formula, X is the same or different and is any amino acid residue other than cysteine, C is a cysteine residue, H is a histidine residue, Xaa1 is an arginine residue, leucine residue, lysine residue, aspartic acid residue, glutamic acid residue, 2-aminosuberic acid residue, or diaminopropionic acid residue, G is a glycine residue, Xaa2 is a lysine residue, a glutamine residue, a glutamic acid residue, an asparagine residue, or an aspartic acid residue, and L is a leucine residue, V is a valine residue, and W is a tryptophan residue. ] A peptide or a salt thereof, which comprises an amino acid sequence consisting of 13 to 17 amino acid residues represented by the following formula and is capable of binding to human IgG and / or rabbit IgG. Preferably, Xaa1 and Xaa2 are different amino acid residues respectively.

[0074] In the present specification, the notation X at the N-terminus or C-terminus 1-3 means that 1 to 3 independent arbitrary amino acid residues X other than cysteine (C or Cys) are consecutive, and the amino acid residues constituting the same are the same or different residues, but preferably consist of a sequence in which not all 3 are the same residue. Similarly, X2 also means that 2 independent arbitrary amino acid residues X other than cysteine (C or Cys) are consecutive, and the amino acid residues constituting the same are the same or different residues, but preferably the 2 consecutive amino acid residues do not consist of the same residue. X1 described later also means that 1 independent arbitrary amino acid residue X other than cysteine (C or Cys) is present.

[0075] In addition, in the present specification, at least two cysteine residues separated in each amino acid sequence of the peptide can form a cyclic peptide by a disulfide bond. Usually, in the peptide of the formula such as the above formula (i), the two outer cysteine residues are disulfide-bonded. Alternatively, in the peptide of the formula such as the above formula (i), the sulfide groups in the two outer cysteine residues may be linked by a carbonyl group-containing linker represented by the following. It may be.

[0076]

Chemical formula

[0077] The dashed portion of the carbonyl group-containing linker represented above means the bonding portion with the sulfide group. This linker is more stable against reduction reactions and the like than ordinary disulfide bonds. This peptide can be prepared, for example, by the method described in International Publication No. 2016 / 186206.

[0078] In a specific embodiment, the affinity substance of the above formula (i) may be an IgG-binding peptide represented by the following formula (i-1) or a salt thereof (e.g., International Publication No. 2016 / 186206). (X 1-3 )-C-(X2)-H-(Xaa1)-G-(Xaa2)-L-V-W-C-(X 1-3 ) (SEQ ID NO: 95) (i-1) 〔In the formula, X is the same or different and is any amino acid residue other than cysteine, C is a cysteine residue, H is a histidine residue, Xaa1 is a lysine residue, a cysteine residue, an aspartic acid residue, a glutamic acid residue, a 2-aminosuberic acid residue, or a diaminopropionic acid residue, G is a glycine residue, Xaa2 is a glutamic acid residue or an asparagine residue, L is a leucine residue, V is a valine residue, and W is a tryptophan residue. 〕 A peptide or a salt thereof that comprises an amino acid sequence consisting of 13 to 17 amino acid residues represented by the above formula and is capable of binding to human IgG and / or rabbit IgG. It is preferable that Xaa1 and Xaa2 are different amino acid residues respectively.

[0079] In another specific embodiment, the affinity substance for the soluble protein as described above may be an IgG-binding peptide represented by the following formula (i-2) or a salt thereof (e.g., Examples). (X1-3 )-C-(X2)-H-(Xaa1)-G-(Xaa2)-L-V-W-C-(X 1-3 ) (SEQ ID NO: 96) (i-2) [In the formula, X is the same as or different from, and is any amino acid residue other than cysteine, C is a cysteine residue, H is a histidine residue, Xaa1 is an arginine residue or a leucine residue, G is a glycine residue, Xaa2 is a lysine residue, a glutamine residue, or an asparatic acid residue, L is a leucine residue, V is a valine residue, and W is a tryptophan residue.] and contains an amino acid sequence consisting of 13 to 17 amino acid residues, and is capable of binding to human IgG and / or rabbit IgG peptide or a salt thereof. An affinity substance having such a specific structure and not disclosed in WO 2016 / 186206 is useful for site-selective modification of the Lys248 residue or Lys246 residue according to the Eu numbering in human IgG Fc, or other amino acid residues other than the Lys248 residue or Lys246 residue (Examples).

[0080] Peptides represented by formula (i-1') and formula (i-1'') in which the amino acid residue X is further specified in the amino acid sequence of the peptide of formula (i-1) are shown below.

[0081] That is, the peptide represented by formula (i-1') is (X 1-3 )-C-(X1)-Y-H-(Xaa1)-G-N-L-V-W-C-(X 1-3 ) (SEQ ID NO: 97) (i-1') [In the formula, X is the same as or different from, and is any amino acid residue other than cysteine, C is a cysteine residue, Y is a tyrosine residue, H is a histidine residue, Xaa1 is a lysine residue, a cysteine residue, an aspartic acid residue, a glutamic acid residue, a 2-aminosuberic acid residue, or a diaminopropionic acid residue, G is a glycine residue, N is an asparagine residue, L is a leucine residue, V is a valine residue, and W is a tryptophan residue. ] It comprises an amino acid sequence consisting of 13 to 17 amino acid residues represented by the formula, and is characterized by being capable of binding to human IgG and / or rabbit IgG.

[0082] The peptide represented by formula (i-1'') is (X 1-3 )-C-A-(X1)-H-(Xaa1)-G-E-L-V-W-C-(X 1-3 ) (SEQ ID NO: 98) (i-1'') [Wherein, X is the same or different and is any amino acid residue other than cysteine, C is a cysteine residue, A is an alanine residue, H is a histidine residue, Xaa1 is a lysine residue, a cysteine residue, an aspartic acid residue, a glutamic acid residue, a 2-aminosuberic acid residue, or a diaminopropionic acid residue, G is a glycine residue, E is a glutamic acid residue, L is a leucine residue, V is a valine residue, and W is a tryptophan residue. ] It comprises an amino acid sequence consisting of 13 to 17 amino acid residues represented by the formula, and is characterized by being capable of binding to human IgG and / or rabbit IgG.

[0083] Also, peptides represented by formula (ii) in which the amino acid residue X in the amino acid sequence of the peptide of formula (i-1) is further specified are shown below.

[0084] That is, the peptide represented by formula (ii) is (X 1-3 )-C-(Xaa3)-(Xaa4)-H-(Xaa1)-G-(Xaa2) -L-V-W-C-(X 1-3 ) (SEQ ID NO: 99) (ii) 〔In the formula, X is the same or different and is any amino acid residue other than cysteine, C is a cysteine residue, H is a histidine residue, Xaa1 is a lysine residue, cysteine residue, aspartic acid residue, glutamic acid residue, 2-aminosuberic acid residue, or diaminopropionic acid residue, G is a glycine residue, Xaa2 is a glutamic acid residue or asparagine residue, L is a leucine residue, V is a valine residue, W is a tryptophan residue, Xaa3 is an alanine residue, serine residue, or threonine residue, and Xaa4 is a tyrosine residue or tryptophan residue.〕 It is characterized by comprising an amino acid sequence consisting of 13 to 17 amino acid residues represented by the formula and being capable of binding to human IgG and / or rabbit IgG.

[0085] In the amino acid sequence of the peptide of formula (i) or the like, when there are 17 amino acid residues, the first and second, and 16th and 17th amino acid residues X from the N-terminus may be deleted, and such a peptide consists of 13 amino acids in length.

[0086] As used herein, the term "when there are 17 amino acid residues" is a term used for convenience in numbering the 1st to 17th amino acid residues in order from the N-terminus of the longest amino acid length of the peptide such as the peptide of formula (i) when the amino acid residues of the peptide are referred to by amino acid numbers.

[0087] Further, the peptide represented by formula (iii) in which the amino acid residue X in the amino acid sequence of the peptide of formula (i-1) is further specified is shown below.

[0088] That is, the peptide represented by formula (iii) is (X 1-3 )-C-A-Y-H-(Xaa1)-G-E-L-V-W-C-(X 1-3 ) (SEQ ID NO: 100) (iii) [In the formula, X is the same or different and is any amino acid residue other than cysteine, C is a cysteine residue, A is an alanine residue, Y is a tyrosine residue, H is a histidine residue, Xaa1 is a lysine residue, a cysteine residue, an aspartic acid residue, a glutamic acid residue, a 2-aminosuberic acid residue, or a diaminopropionic acid residue, G is a glycine residue, E is a glutamic acid residue, L is a leucine residue, V is a valine residue, and W is a tryptophan residue. ] characterized by comprising an amino acid sequence consisting of 13 to 17 amino acid residues and being capable of binding to human IgG and / or rabbit IgG.

[0089] In the amino acid sequence of the peptide of formula (iii), when there are 17 amino acid residues, the 1st and 2nd, and 16th and 17th amino acid residues X from the N-terminus are deleted Alternatively, such a peptide may be 13 amino acids in length.

[0090] Furthermore, when the amino acid residues other than cysteine (C) in the amino acid sequence of the peptides of the above formulas are 17 amino acid residues, the 1st to 3rd, 5th, 6th, 15th to 17th amino acid residues from the N-terminus are preferably selected from the following. Here, each capital letter of the alphabet is the one-letter notation of an amino acid: 1st amino acid residue = S, G, F or none 2nd amino acid residue = D, G, A, S, P, homocysteine or none 3rd amino acid residue = S, D, T, N, E or R 15th amino acid residue = S, T or D 16th amino acid residue = H, G, Y, T, N, D, F, homocysteine or none 17th amino acid residue = Y, F, H, M or none 5th amino acid residue = A or T 6th amino acid residue = Y or W

[0091] Also, the peptide represented by formula (iv) in which the amino acid residue X in the amino acid sequence of the peptide of formula (i-1) is further specified is shown below.

[0092] That is, the peptide represented by formula (iv) is D-C-(Xaa3)-(Xaa4)-H-(Xaa1)-G-(Xaa2)-L-V-W-C-T (SEQ ID NO: 101) (iv) [In the formula, D is an aspartic acid residue, C is a cysteine residue, H is a histidine residue, Xaa1 is a lysine residue, cysteine residue, aspartic acid residue, glutamic acid residue, 2-aminosuberic acid residue, or diaminopropionic acid residue, G is a glycine residue, Xaa2 is a glutamic acid residue or asparagine residue L is a leucine residue, V is a valine residue, W is a tryptophan residue, T is a threonine residue, Xaa3 is an alanine residue or a threonine residue, and Xaa4 is a tyrosine residue or a tryptophan residue. It comprises an amino acid sequence consisting of 13 amino acid residues represented by the formula, and is characterized by being capable of binding to human IgG and / or rabbit IgG.

[0093] Some specific examples of the peptide of formula (i-1) are listed below in (1) to (19), but it goes without saying that it is not limited thereto: (1) DCAYH(Xaa1)GELVWCT (SEQ ID NO: 20); (2) GPDCAYH(Xaa1)GELVWCTFH (SEQ ID NO: 21); (3) RCAYH(Xaa1)GELVWCS (SEQ ID NO: 22); (4) GPRCAYH(Xaa1)GELVWCSFH (SEQ ID NO: 23); (5) SPDCAYH(Xaa1)GELVWCTFH (SEQ ID NO: 24); (6) GDDCAYH(Xaa1)GELVWCTFH (SEQ ID NO: 25); (7) GPSCAYH(Xaa1)GELVWCTFH (SEQ ID NO: 26); (8) GPDCAYH(Xaa1)GELVWCSFH (SEQ ID NO: 27); (9) GPDCAYH(Xaa1)GELVWCTHH (SEQ ID NO: 28); (10) GPDCAYH(Xaa1)GELVWCTFY (SEQ ID NO: 29); (11) SPDCAYH(Xaa1)GELVWCTFY (SEQ ID NO: 30); (12) SDDCAYH(Xaa1)GELVWCTFY (SEQ ID NO: 31); (13) RGNCAYH(Xaa1)GQLVWCTYH (SEQ ID NO: 32); (14)G(Xaa2)DCAYH(Xaa1)GELVWCT(Xaa2)H (SEQ ID NO: 33); (15)RRGPDCAYH(Xaa1)GELVWCTFH (SEQ ID NO: 34); (16)DCTYH(Xaa1)GNLVWCT (SEQ ID NO: 35); (17)DCAYH(Xaa1)GNLVWCT (SEQ ID NO: 36); (18)DCTYH(Xaa1)GELVWCT (SEQ ID NO: 37); and (19)DCAWH(Xaa1)GELVWCT (SEQ ID NO: 38). [In the formula, Xaa1 is a lysine residue, a cysteine residue, an aspartic acid residue, a glutamic acid residue, a 2-aminosuberic acid residue, or a diaminopropionic acid residue, Xaa2 is homocysteine, preferably, homocysteines form a disulfide bond with each other.].

[0094] Preferred specific examples of the peptide of formula (i-1) include the following: (1)DCAYH(Xaa1)GELVWCT (SEQ ID NO: 20); (2)GPDCAYH(Xaa1)GELVWCTFH (SEQ ID NO: 21); (13)RGNCAYH(Xaa1)GQLVWCTYH (SEQ ID NO: 22); (14)G(Xaa2)DCAYH(Xaa1)GELVWCT(Xaa2)H (SEQ ID NO: 33); and (15)RRGPDCAYH(Xaa1)GELVWCTFH (SEQ ID NO: 34). [In the formula, Xaa1 is a lysine residue, Xaa2 is homocysteine, preferably, cysteines and / or homocysteines form a disulfide bond with each other.]

[0095] The peptide of (13) above may be RGNCAYHKGQLVWCTYH (SEQ ID NO: 39).

[0096] In another specific embodiment, the affinity substance of the above formula (i) may be an IgG-binding peptide represented by the following formula (v) or a salt thereof (for example, see Examples). (X 1-3 )-C-(Xaa3)-(xaa4)-H-(Xaa1)-G-(Xaa2)-L-V-W-C-(Xaa5)-(Xaa6)-(Xaa7) (SEQ ID NO: 102) (v) 〔In the formula, X is the same or different and is any amino acid residue other than cysteine, C is a cysteine residue, Xaa3 is an alanine residue or a lysine residue, Xaa4 is a tryptophan residue or a tyrosine residue, H is a histidine residue, Xaa1 is an arginine residue, a leucine residue, a lysine residue, an aspartic acid residue, a glutamic acid residue, a 2-aminosuberic acid residue, or a diaminopropionic acid residue, G is a glycine residue, Xaa2 is a lysine residue, a glutamine residue, a glutamic acid residue, an asparagine residue, or an aspartic acid residue, L is a leucine residue, V is a valine residue, W is a tryptophan residue, Xaa5 is a threonine residue or a lysine residue, Xaa6 is a tyrosine residue, a lysine residue, or none, and Xaa7 is a histidine residue, a lysine residue, or none.〕 A peptide or a salt thereof, which comprises an amino acid sequence consisting of 13 to 17 amino acid residues and is capable of binding to human IgG.

[0097] An affinity substance not disclosed in International Publication No. 2016 / 186206 having such a specific structure is useful for site-selective modification of the Lys248 residue or Lys246 residue according to the Eu numbering in human IgG Fc, or other amino acid residues other than the Lys248 residue or Lys246 residue (Examples). Preferably, any one of Xaa3, Xaa1, Xaa2, Xaa5, Xaa6, and Xaa7 is a lysine residue. Xaa1 is preferably an arginine residue or a leucine residue. Alternatively, Xaa1 is preferably a lysine residue, an aspartic acid residue, a glutamic acid residue, a 2-aminosuberic acid residue, or a diaminopropionic acid residue, and more preferably a lysine residue, an aspartic acid residue, or a glutamic acid residue.

[0098] In the amino acid sequence of the peptide of formula (v), when there are 17 amino acid residues, the first and second, and the 16th and 17th amino acid residues X from the N-terminus may be deleted, and such a peptide consists of 13 amino acids in length.

[0099] Furthermore, amino acid residues other than cysteine (C) in the amino acid sequence of the peptide of formula (v), that is, when there are 17 amino acid residues, each of the first to third amino acid residues from the N-terminus is preferably selected from the following. Here, each capital letter of the alphabet is the one-letter notation of an amino acid: First amino acid residue = R, S, G, F or none (preferably R or none) Second amino acid residue = D, G, A, S, P, homocysteine or none (preferably G or none) Third amino acid residue = S, D, T, N, E or R (preferably N or D).

[0100] Some specific examples of the peptide of formula (v) are listed below in (16) to (34), but it goes without saying that they are not limited thereto: (16) RGNCAYH(Xaa1)GQLVWCTYH (SEQ ID NO: 73) (17)RGNCAWH(Xaa1)GQLVWCTYH (SEQ ID NO: 74) (18)RGNCAWH(Xaa1)GELVWCTYH (SEQ ID NO: 75) (19)RGNCKWH(Xaa1)GQLVWCTYH (SEQ ID NO: 76) (20)RGNCKYH(Xaa1)GELVWCTYH (SEQ ID NO: 77) (21)RGNCKYH(Xaa1)GQLVWCTYH (SEQ ID NO: 78) (22)DCKWH(Xaa1)GELVWCT (SEQ ID NO: 79) (23)DCKYH(Xaa1)GELVWCT (SEQ ID NO: 80) (24)DCKWH(Xaa1)GELVWCT (SEQ ID NO: 81) (25)DCKWH(Xaa1)GQLVWCT (SEQ ID NO: 82) (26)DCKYH(Xaa1)GELVWCT (SEQ ID NO: 83) (27)DCKYH(Xaa1)GQLVWCT (SEQ ID NO: 84) (28)DCKWH(Xaa1)GQLVWCT (SEQ ID NO: 85) (29)DCKYH(Xaa1)GQLVWCT (SEQ ID NO: 86) (30)RGNCAWH(Xaa1)GQLVWCKYH (SEQ ID NO: 87) (31)RGNCAWH(Xaa1)GELVWCKYH (SEQ ID NO: 88) (32)RGNCAYH(Xaa1)GQLVWCTKH (SEQ ID NO: 89) (33)RGNCAYH(Xaa1)GQLVWCTYK (SEQ ID NO: 90) (34)RGNCAYH(Xaa1)GQLVWCTKH (SEQ ID NO: 91). [Wherein, Xaa1 is an arginine residue, a leucine residue, a lysine residue, an aspartic acid residue, a glutamic acid residue, a 2-aminosuberic acid residue, or a diaminopropionic acid residue.]. Preferably, Xaa1 is an arginine residue, a leucine residue, or a lysine residue, and more preferably a lysine residue.

[0101] In addition, the IgG-binding peptide, as a primary structure in a broad sense, has the following formula (vi): D-C-(Xaa3)-(Xaa4)-H-(Xaa1)-G-(Xaa2)-L-V-W-C-(Xaa5)-(Xaa6)-(Xaa7) (SEQ ID NO: 103) (vi) [In the formula, D is an aspartic acid residue, C is a cysteine residue, Xaa3 is an alanine residue or a lysine residue, Xaa4 is a tryptophan residue or a tyrosine residue, H is a histidine residue, Xaa1 is an arginine residue, a leucine residue, a lysine residue, an aspartic acid residue, a glutamic acid residue, a 2-aminosuberic acid residue, or a diaminopropionic acid residue, G is a glycine residue, Xaa2 is a lysine residue, a glutamine residue, a glutamic acid residue, an asparagine residue, or an aspartic acid residue, L is a leucine residue, V is a valine residue, W is a tryptophan residue, Xaa5 is a threonine residue or a lysine residue, Xaa6 is a tyrosine residue, a lysine residue, or none, Xaa7 is a histidine residue, a lysine residue, or none.], and contains an amino acid sequence consisting of 13 to 15 amino acid residues, and is characterized by being capable of binding to human IgG and / or rabbit IgG (for example, Examples and International Publication No. 2016 / 186206). Preferably, any one of Xaa3, Xaa1, Xaa2, Xaa5, Xaa6, and Xaa7 is a lysine residue. Xaa1 is preferably a lysine residue, an arginine residue, or a leucine residue, and Xaa2 is preferably a lysine residue, a glutamine residue, or a glutamic acid residue..

[0102] In certain embodiments, the IgG-binding peptide has the following formula (vii): D-C-(Xaa3)-(Xaa4)-H-(Xaa1)-G-(Xaa2)-L-V-W-C-T (SEQ ID NO: 104) (vii) wherein D is an aspartic acid residue, C is a cysteine residue, Xaa3 is an alanine residue or a lysine residue, Xaa4 is a tryptophan residue or a tyrosine residue, H is a histidine residue, Xaa1 is an arginine residue, a leucine residue, a lysine residue, an aspartic acid residue, a glutamic acid residue, a 2-aminosuberic acid residue, or a diaminopropionic acid residue, G is a glycine residue, Xaa2 is a lysine residue, a glutamine residue, a glutamic acid residue, an asparagine residue, or an aspartic acid residue, L is a leucine residue, V is a valine residue, W is a tryptophan residue, and T is a threonine residue.〕 It is a peptide comprising an amino acid sequence consisting of 13 amino acid residues and capable of binding to human IgG and / or rabbit IgG (e.g., International Publication No. WO 2016 / 186206). Preferably, any one of Xaa3, Xaa1, and Xaa2 is a lysine residue. Xaa1 is preferably a lysine residue, an arginine residue, or a leucine residue, and Xaa2 is preferably a lysine residue, a glutamine residue, or a glutamic acid residue.

[0103] In another specific embodiment, the IgG-binding peptide has the following formula (viii): R-G-N-C-(Xaa3)-(Xaa4)-H-(Xaa1)-G-(Xaa2)-L-V-W-C-(Xaa5)-(Xaa6)-(Xaa7) (SEQ ID NO: 105) (viii) wherein R is an arginine residue, G is a glycine residue, N is an asparagine residue, C is a cysteine residue, Xaa3 is an alanine residue or a lysine residue, Xaa4 is a tryptophan residue or a tyrosine residue, H is a histidine residue, Xaa1 is an arginine residue, a leucine residue, a lysine residue, an aspartic acid residue, a glutamic acid residue, a 2-aminosuberic acid residue, or a diaminopropionic acid residue, G is a glycine residue, Xaa2 is a lysine residue, a glutamine residue, a glutamic acid residue, an asparagine residue, or an aspartic acid residue, L is a leucine residue, V is a valine residue, W is a tryptophan residue, Xaa5 is a threonine residue or a lysine residue, Xaa6 is a tyrosine residue, a lysine residue, or none, and Xaa7 is a histidine residue, a lysine residue, or none.〕 It contains an amino acid sequence consisting of 13 to 15 amino acid residues represented by the formula, and is characterized by being capable of binding to human IgG and / or rabbit IgG (Example). A compound not disclosed in International Publication No. 2016 / 186206 having such a specific structure is useful for site-selective modification of the Lys248 residue or Lys246 residue according to Eu numbering in human IgG Fc, or other amino acid residues other than the Lys248 residue or Lys246 residue (Example). Preferably, any one of Xaa3, Xaa1, Xaa2, Xaa5, Xaa6, and Xaa7 is a lysine residue. Xaa1 may preferably be an arginine residue or a leucine residue. Alternatively, Xaa1 is preferably a lysine residue, an arginine residue, or a leucine residue, and Xaa2 is preferably a lysine residue, a glutamine residue, or a glutamic acid residue.

[0104] The peptide has at least two cysteine (C) residues separated in each amino acid sequence that form a cyclic peptide by disulfide bonding, and may have one or two arbitrary amino acid residues other than cysteine on the N-terminal side and the C-terminal side of each cysteine residue. When having one or two amino acid residues on the N-terminal side and the C-terminal side of each cysteine residue, in the case of having 17 amino acid residues, the 1st to 2nd and 16th to 17th amino acid residues from the N-terminus are those exemplified above. Also, the amino acids constituting the above peptide may be either L-form or D-form, but the L-form is preferred (in the examples, all amino acid residues constituting the peptide are in the L-form). As described above, in the IgG-binding peptide, when the amino acid residue of Xaa is an amino acid residue that can be easily modified by a crosslinking agent (protein constituent amino acids such as lysine residue, cysteine residue, aspartic acid residue, or glutamic acid residue, or non-protein constituent amino acids such as diaminopropionic acid residue or 2-aminosuberic acid residue), among these amino acids, the lysine residue is preferred. Examples of such crosslinking agents include crosslinking agents preferably containing two or more succinimidyl groups such as DSG (disuccinimidyl glutarate), DSS (disuccinimidyl suberate), DMA (dimethyl adipimidate·2HCl), DMP (dimethyl pimelimidate·2 HCl), and DMS (dimethyl suberimidate·2

[0105] ​Crosslinking agents preferably containing two or more imidic acid moieties such as HCl and dimethyl 3,3’-dithiobispropionimidate dihydrochloride, and crosslinking agents having SS bonds such as DTBP (dimethyl 3,3’-dithiobispropionimidate·2HCl, dimethyl 3,3’-dithiobispropionimidate dihydrochloride) and DSP (dithiobis(succinimidyl propionate)) are exemplified (e.g., International Publication No. 2016 / 186206). In order to enhance site-specificity when modifying the IgG-binding peptide with a crosslinking agent, the IgG-binding peptide preferably has no or almost no (e.g., only one or two) residues the same as Xaa1 in its sequence. For example, when Xaa1 is a lysine residue, the IgG-binding peptide preferably has no or almost no lysine residues at positions other than Xaa1 in its sequence.

[0106] The IgG-binding peptide binds to the Fc domain of IgG. The IgG-binding peptide binds to a specific region of the IgG Fc, i.e., the Lys248 residue or the Lys246 residue according to Eu numbering in human IgG Fc, preferably in proximity to Lys248 (see Examples and International Publication No. 2016 / 186206). Alternatively, in the IgG-binding peptide, the amino acid residue of Xaa can be in proximity to an amino acid residue other than the Lys248 residue or the Lys246 residue according to Eu numbering in human IgG Fc.

[0107] More specifically, the peptides represented by the above formulas (i) to (viii) are as follows. (1’)RGNCAYHKGQLVWCTYH (SEQ ID NO: 39) (2’)RGNCKYHRGQLVWCTYH (SEQ ID NO: 42) (3’)RGNCAWHRGKLVWCTYH (SEQ ID NO: 43) (4’)RGNCKWHRGELVWCTYH (SEQ ID NO: 44) (5’)RGNCKWHRGQLVWCTYH (SEQ ID NO: 45) (6’)RGNCKYHLGELVWCTYH (SEQ ID NO: 46) (7’)RGNCKYHLGQLVWCTYH (SEQ ID NO: 47) (8’)DCKWHLGELVWCT (SEQ ID NO: 48) (9’)DCKYHLGELVWCT (SEQ ID NO: 49) (10’)DCKWHRGELVWCT (SEQ ID NO: 50) (11’)DCKWHLGQLVWCT (SEQ ID NO: 51) (12’)DCKYHRGELVWCT (SEQ ID NO: 52) (13’)DCKYHLGQLVWCT (SEQ ID NO: 53) (14’)DCKWHRGQLVWCT (SEQ ID NO: 54) (15’)DCKYHRGQLVWCT (SEQ ID NO: 55) (16’)RGNCAWHLGQLVWCKYH (SEQ ID NO: 56) (17’)RGNCAWHLGELVWCKYH (SEQ ID NO: 57) (18’)RGNCAYHLGQLVWCTKH (SEQ ID NO: 58) (19’)RGNCAYHLGQLVWCTYK (SEQ ID NO: 59) (20’)RGNCAYHRGQLVWCTKH (SEQ ID NO: 60)

[0108] In addition, the affinity substance for the soluble protein as described above is (a) In the amino acid sequence of FNMQCQRRFYEALHDPNLNEEQRNARIRSIRDDC (SEQ ID NO: 92), any amino acid residue is substituted by one amino acid residue selected from the group consisting of a lysine residue, an aspartic acid residue, a glutamic acid residue, a 2-aminosuberic acid residue, and a diaminopropionic acid residue (an amino acid residue that can be easily modified by a crosslinking agent) (preferably a lysine residue, an aspartic acid residue, or a glutamic acid residue, more preferably a lysine residue), and (b) It may also be an affinity peptide containing an amino acid sequence having 90% or more identity to the amino acid sequence of SEQ ID NO: 92.

[0109] Preferably, the amino acid sequence having the characteristics of (a) and (b) can bind to human IgG as described herein.

[0110] The peptide consisting of the amino acid sequence of SEQ ID NO: 92 is a modification of two K (lysine) residues at positions 26 and 28 counted from the N-terminus to R (arginine) in the affinity peptide known as Z34C due to the convenience of peptide reagent synthesis. Furthermore, the N-terminus can be acetylated and the C-terminus can be amidated for use. More specifically, such an affinity peptide includes Ac-FNMQCQRRFYEALHDPNLNEEQRNARIRSIRDDC-NH2 (SEQ ID NO: 92). Such an affinity substance having a specific structure is useful for site-selective modification of the Lys248 residue or Lys246 residue, Lys288 or Lys290, Lys317, or other amino acid residues according to the Eu numbering in human IgG Fc (Examples). Note that the amino acid sequence of Z34C above is FNMQCQRRFYEALHDPNLNEEQRNAKIKSIRDDC (SEQ ID NO: 93) (see, for example, Starovasnik, M. A. et al., Structural mimicry of a native protein by a minimized binding domain., Proc. Natl. Acad. Sci. USA., 94, 10080-10085 (1997)).

[0111] The affinity peptide can have an affinity for human IgG (e.g., human IgG as described above. Preferably human IgG1). The above affinity peptide may have a disulfide bond between the cysteine residues at positions 5 and 34 to form a cyclic peptide.

[0112] As the position where an amino acid residue that can be easily modified by a crosslinking agent is introduced, any position can be used as long as it has an affinity for human IgG such as human IgG1. Such positions can be easily identified by those skilled in the art. Preferably, the position where an amino acid residue that can be easily modified by a crosslinking agent is introduced is an amino acid residue other than the cysteine residues at positions 5 and 34, which may be disulfide-bonded. More preferably, examples of the position where an amino acid residue that can be easily modified by a crosslinking agent is introduced include amino acid residues at positions 1, 3, 6, 7, 13, 20, 24, 31, and 32.

[0113] Preferably, the amino acid sequence having the characteristics of (a) and (b) has one specific amino acid residue selected from the group consisting of a lysine residue, an aspartic acid residue, a glutamic acid residue, a 2-aminosuberic acid residue, and a diaminopropionic acid residue (an amino acid residue that can be easily modified by a crosslinking agent) at a predetermined position (preferably a lysine residue, an aspartic acid residue, or a glutamic acid residue, more preferably a lysine residue), and has mutations of the normal 20 types of amino acid residues constituting a natural protein (preferably 17 amino acid residues other than a lysine residue, an aspartic acid residue, and a glutamic acid residue, more preferably 19 amino acid residues other than a lysine residue) at positions other than the predetermined position. Such a predetermined position is not particularly limited, and examples thereof include the 1st, 3rd, 6th, 7th, 13th, 20th, 24th, 31st, and 32nd positions. The amino acid sequence having the characteristics of (a) and (b) maintains two cysteine residues at the 5th and 34th positions, and these two cysteine residues may be linked by a disulfide bond. An amino acid sequence having 90% or more identity to the amino acid sequence of SEQ ID NO: 92 may be one in which 1, 2, 3, or 4 mutations (preferably substitutions) selected from the group consisting of deletion, substitution, addition, and insertion of amino acid residues modify 1 to 3 (preferably 1 or 2, more preferably 1) amino acid residues. The mutation of the amino acid residue may be introduced into one region in the amino acid sequence, or may be introduced into a plurality of different regions.

[0114] More preferably, the amino acid sequence having the characteristics of (a) and (b) may be the following (c) or (d). (c) An amino acid sequence selected from the group consisting of the following amino acid sequences (1) to (9): (1) KNMQCQRRFYEALHDPNLNEEQRNARIRSIRDDC (SEQ ID NO: 61); (2) FNMQCQKRFYEALHDPNLNEEQRNARIRSIRDDC (SEQ ID NO: 62); (3) FNMQCQRRFYEAKHDPNLNEEQRNARIRSIRDDC (SEQ ID NO: 63); (4) FNMQCQRRFYEALHDPNLNEEQRKARIRSIRDDC (SEQ ID NO: 64); (5) FNMQCQRRFYEALHDPNLNKEQRNARIRSIRDDC (SEQ ID NO: 65); (6) FNMQCQRRFYEALHDPNLNEEQRNARIRSIKDDC (SEQ ID NO: 68); (7) FNKQCQRRFYEALHDPNLNEEQRNARIRSIRDDC (SEQ ID NO: 70); (8) FNMQCKRRFYEALHDPNLNEEQRNARIRSIRDDC (SEQ ID NO: 71); and (9) FNMQCQRRFYEALHDPNLNEEQRNARIRSIRKDC (SEQ ID NO: 72); or (d) An amino acid sequence having 90% or more identity (which may be a modification of the number of amino acid residues as described above) to any one of the amino acid sequences of (1) to (9) above, wherein at positions other than one lysine residue and two cysteine residues (e.g., positions 1, 3, 6, 7, 13, 20, 24, 31, and 32), there are mutations of 19 amino acid residues other than the lysine residue. The amino acid sequence of (d) preferably maintains two cysteine residues at positions 5 and 34, and these two cysteine residues may be linked by a disulfide bond. The affinity peptide having the amino acid sequence of (d) is preferably capable of binding to human IgG as described herein.

[0115] As long as the above-mentioned affinity peptide has an identity of 90% or more with the amino acid sequence of SEQ ID NO: 92 or the amino acid sequences of (1) to (9) above, in addition to the introduction of one amino acid residue that can be easily modified by a cross-linking agent, it may also have further amino acid residue mutations. Those skilled in the art can easily identify the positions where further amino acid mutations can be introduced. As such positions, for example, positions other than the cysteine residues at positions 5 and 34 can be utilized. For example, the phenylalanine residue at position 1, the arginine residue at position 6, the leucine residue at position 13, the glutamic acid residue at position 20, the asparagine residue at position 24, or the arginine residue at position 31 (excluding the positions where amino acid residues that can be easily modified by a cross-linking agent have already been introduced) can also be utilized. Examples of amino acids that can be introduced by further amino acid mutations include alanine (A), asparagine (N), cysteine (C), glutamine (Q), glycine (G), isoleucine (I), leucine (L), methionine (M), phenylalanine (F), proline (P), serine (S), threonine (T), tryptophan (W), tyrosine (Y), valine (V), aspartic acid (D), glutamic acid (E), arginine (R), histidine (H), and lysine (L). Preferably, these 19 amino acids other than lysine may be utilized. The amino acid may be either the L-form or the D-form, but the L-form is preferred (in the examples, all amino acid residues constituting the peptide are in the L-form).

[0116] The degree of identity % to the amino acid sequence of SEQ ID NO: 92 or the amino acid sequences of (1) to (9) can be determined as described above. The degree of identity % is preferably 92% or more, more preferably 94% or more, even more preferably 95% or more, and particularly preferably 97% or more (that is, having only a mutation of one amino acid residue selected from the group consisting of a lysine residue, an aspartic acid residue, a glutamic acid residue, a 2-aminosuberic acid residue, and a diaminopropionic acid residue with respect to the amino acid sequence of SEQ ID NO: 92).

[0117] When the affinity substance is a peptide, the amino group and carboxy group at the ends of the peptide may be protected. Examples of the protecting group for the N-terminal amino group include an alkylcarbonyl group (acyl group) (e.g., an acetyl group, a propoxy group, a butoxycarbonyl group such as a tert-butoxycarbonyl group), an alkyloxycarbonyl group (e.g., a fluorenylmethoxycarbonyl group), an aryloxycarbonyl group, and an arylalkyl (aralkyl)oxycarbonyl group (e.g., a benzyloxycarbonyl group). As the protecting group for the N-terminal amino group, an acetyl group is preferred. Examples of the protecting group for the C-terminal carboxy group include a group capable of forming an ester or an amide. Examples of the group capable of forming an ester or an amide include an alkyloxy group (e.g., methyloxy, ethyloxy, propyloxy, butyloxy, pentyloxy, hexyloxy), an aryloxy group (e.g., phenyloxy, naphthyloxy), an aralkyloxy group (e.g., benzyloxy), and an amino group. As the protecting group for the C-terminal carboxy group, an amino group is preferred. When the affinity substance is a peptide containing two or more cysteine residues, a disulfide bond may be formed via the thiol group in the side chain of the cysteine residue.

[0118] 1-3. Linker (L) In formula (I), L is a cleavable linker which is a divalent group containing a cleavable moiety.

[0119] The cleavable linker represented by L is a divalent group containing a cleavable moiety. The cleavable moiety is a site cleavable by a specific treatment under conditions (mild conditions) that cannot cause denaturation or decomposition of the protein (e.g., cleavage of an amide bond). Therefore, it can be said that the cleavable moiety is a site (bond other than an amide bond) cleavable by a specific cleavage treatment under mild conditions. Such specific treatments include, for example, (a) an acidic substance, a basic substance, a reducing Treatment with one or more substances selected from the group consisting of an agent, an oxidizing agent, and an enzyme, (b) treatment with a physicochemical stimulus selected from the group consisting of light, or (c) leaving when using a cleavable linker containing a self-degradable cleavable moiety. Such cleavable linkers and their cleavage conditions are common general knowledge in the art (e.g., G. Leriche, L. Chisholm, A. Wagner, Bioorganic & Medicinal Chemistry. 20, 571 (2012); Feng P. et al., Jounal of American Chemical Society. 132, 1500 (2010).; Bessodes M. et al., Journal of Controlled Release, 99, 423 (2004).; DeSimone, J.M., Journal of American Chemical Society. 132, 17928 (2010); Thompson, D.H., Journal of Controlled Release, 91, 187 (2003); Schoenmarks, R.G., Journal of Controlled Release, 95, 291 (2004)). Examples of such cleavable moieties include a disulfide residue, an acetal residue, a ketal residue, an ester residue, a carbamoyl residue, an alkoxyalkyl residue, an imine residue, a tertiary alkyloxycarbamate residue (e.g., tert-butyloxycarbamate residue), a silane residue, a hydrazone-containing residue (e.g., a hydrazone residue, an acylhydrazone residue, a bisarylhydrazone residue), a phosphoramidate residue, an aconityl residue, a trityl residue, an azo residue, a vicinal diol residue, a selenium residue, an aromatic ring-containing residue having an electron-withdrawing group, a coumarin-containing residue, a sulfone-containing residue, an unsaturated bond-containing chain residue, and a glycosyl residue.

[0120] The aromatic ring group having an electron-withdrawing group preferably has an aromatic ring group selected from the group consisting of aryl, aralkyl, aromatic heterocyclic group, and alkyl having an aromatic heterocyclic group, and more preferably aralkyl and alkyl having an aromatic heterocyclic group. The electron-withdrawing group is preferably bonded to the 2-position of the ring. Even more preferably, the aromatic ring-containing residue having an electron-withdrawing group is, for example, an aralkyl having an electron-withdrawing group at the 2-position (e.g., benzyl). Examples of the electron-withdrawing group include a halogen atom, an alkyl substituted with a halogen atom (e.g., trifluoromethyl), a boronic acid residue, mesyl, tosyl, triflate, nitro, cyano, a phenyl group, and a keto group (e.g., acyl).

[0121] Definitions, examples, and preferred examples of groups such as alkyl, acyl (i.e., alkylcarbonyl), alkoxy (i.e., alkyloxy), aryl, and aralkyl, which are found as terms such as prefixes and suffixes in relation to the name of the residue as the cleavable moiety, are the same as those described later.

[0122] Examples of the ester residue include ordinary ester residues composed of a carbon atom and an oxygen atom [e.g., alkyl ester (e.g., tertiary alkyloxycarbonyl such as tert-butyloxycarbonyl), aryl ester (e.g., phenacyl ester, 2-(diphenylphosphino)benzoate), glycosyl ester residue, orthoester residue, ester residue containing a sulfur atom and an oxygen atom (e.g., thioester residue such as α-thiophenyl ester residue and alkylthioester residue), ester residue containing a phosphorus atom and an oxygen atom (e.g., phosphodiester residue, phosphotriester residue), and activated ester residue (e.g., N-hydroxysuccinimide residue)].

[0123] Examples of the sulfone-containing residue include a sulfone residue and a quinolinylbenzenesulfonate residue.

[0124] The silane residue is preferably a silane residue having a group selected from the group consisting of alkyl, aryl, aralkyl, and alkoxy. Examples of such silane residues include dialkyldialkoxysilane residues (e.g., dimethyldialkoxysilane, diethyldialkoxysilane), or diaryldialkoxysilane residues (e.g., diphenyldialkoxysilane).

[0125] The alkoxyalkyl (i.e., alkyloxyalkyl) residue is a group formed by combining an alkyloxy and an alkyl described below (the definitions, examples, and preferred examples of alkyloxy and alkyl are the same as those described below). Examples include, but are not limited to, methoxymethyl residue, ethoxymethyl residue, methoxyethyl residue, and ethoxyethyl residue.

[0126] The unsaturated bond-containing chain residue is a residue containing an unsaturated bond portion consisting of only carbon atoms (e.g., vinyl (ethenyl), which is the smallest unit having a double bond between carbon atoms, or ethynyl, which is the smallest unit having a triple bond between carbon atoms), or a residue containing an unsaturated bond portion consisting of carbon atoms and heteroatoms (e.g., nitrogen atom, sulfur atom, oxygen atom) (e.g., aldehyde, cyano). Examples of the unsaturated bond-containing chain residue include vinyl ether residue, cyanoethyl residue, ethylene residue, and malondialdehyde residue.

[0127] Examples of acidic substances (also referred to as electrophilic reagents) include inorganic acidic substances such as hydrochloric acid, sulfuric acid, and nitric acid, and organic acidic substances such as formic acid, acetic acid, 4-(2-hydroxyethyl)-1-piperazinepropanesulfonic acid, 3-morpholinopropanesulfonic acid, sodium dihydrogen phosphate, citric acid, dodecyl sulfate, N-dodecanoylsarcosine, and trifluoroacetic acid. Examples of sites cleavable by acidic substances include alkyloxyarylalkyl residues, tertiary alkyloxycarbamate residues, acetal residues, silane residues, imine residues, vinyl ether residues, β-thiopropionate residues, trityl residues, hydrazone residues, aconityl residues, orthoester residues, carbamoyl residues, and 2-(diphenylphosphino)benzoate residues.

[0128] Examples of basic substances (also referred to as nucleophilic reagents) include inorganic basic substances such as sodium hydroxide, potassium hydroxide, sodium acetate, potassium acetate, and ammonium acetate, and organic basic substances such as triethylamine and N,N'-diisopropylamine. Examples of sites cleavable by basic substances include silane residues, cyanoethyl residues, sulfone residues, ethylene residues, glycosyldisuccinate residues, α-thiophenyl ester residues, unsaturated vinyl sulfide residues, malondialdehyde residues, acylhydrazone residues, and alkylthioester residues.

[0129] Examples of reducing agents include cysteine, dithiothreitol, reduced glutathione, hydroxylamine, and β-mercaptoethanol. Examples of sites cleavable by reducing agents include disulfide residues, alkoxyalkyl residues, and azo residues.

[0130] Examples of oxidizing agents include sodium periodate and oxidized glutathione. Examples of sites cleavable by oxidizing agents include vicinal diol residues and selenium residues.

[0131] Examples of the enzyme include trypsin, papain, TEV, thrombin, cathepsin B, cathepsin D, cathepsin K, caspase, protease, matrix metalloprotease, lipase, endoglycosidase, and PNGase F. Examples of the site cleavable by the enzyme include an ester residue, a phosphodiester residue, and a glycosyl residue.

[0132] Examples of the site cleavable by light include a 2-nitrobenzyl residue, a phenacyl ester residue, an 8-quinolinebenzenesulfonate residue, a coumarin residue, a phosphotriester residue, a bisarylhydrazone residue, and a biman dithiopropionate residue.

[0133] Examples of the self-degradable cleavable moiety include an activated ester residue (e.g., N-hydroxysuccinimide residue).

[0134] More specifically, the cleavable moiety may correspond to any one chemical structure selected from the group consisting of the following.

Chemical formula

[0135] J is -CH2-, -O-, or -S-. j is preferably -CH2- or -O-, more preferably -CH2-.

[0136] r is any integer from 1 to 4, preferably any integer from 1 to 3, more preferably 1 or 2.

[0137] In one embodiment, the cleavable linker may be a cleavable linker which is a divalent group containing a cleavable moiety having the ability to generate a bioorthogonal functional group on the reactive group side upon cleavage, or (ii) a cleavable linker which is a divalent group containing a cleavable moiety having no ability to generate a bioorthogonal functional group on the reactive group side upon cleavage.

[0138] Examples of the cleavable moiety of (i) include a disulfide residue, an ester residue, an acetal residue, a ketal residue, an imine residue, and a vicinal diol residue.

[0139] More specifically, the cleavable moiety of (i) is, for example, as follows:

Chemical Structure

[0140] Examples of the cleavable moiety in (ii) include an ester residue, a carbamoyl residue, an alkoxyalkyl residue, an imine residue, a tertiary alkyloxycarbamate residue, a silane residue, a hydrazone-containing residue, a phosphoramidate residue, an aconityl residue, a trityl residue, an azo residue, a vicinal diol residue, a selenium residue, an aromatic ring-containing residue having an electron-withdrawing group, a coumarin-containing residue, a sulfone-containing residue, an unsaturated bond-containing chain residue, and a glycosyl residue.

[0141] More specifically, the cleavable moiety in (ii) is, for example, the following: [Chemical formula] [Here, the wavy line orthogonal to the bond indicates the cleavage site, a plurality of Rs 2b a plurality of Rs 2c J, and r are each selected from the group consisting of a hydrogen atom and the substituents described below, ○ (white circle) indicates a bond to A (or La described below), and ● (black circle) indicates a bond to B (or Lb described below). When the chemical structure is asymmetric around the cleavage site, ● may indicate a bond to A (or La described below), and ○ may indicate a bond to B (or Lb described below).] It may correspond to any one chemical structure selected from the group consisting of.

[0142] In a specific embodiment, the cleavable linker (L) may be represented by any one of the following formulas (L1) to (L3): La-C-Lb (L1) La-C (L2) C-Lb (L3) [In the formula, La and Lb are each a divalent group, C is a cleavable moiety.]

[0143] Examples of the divalent group include a divalent hydrocarbon group which may have a substituent, a divalent heterocyclic group which may have a substituent, -C(=O)-, -NR a -(R arepresents a hydrogen atom or a substituent), -O-, -S-, -C(=S)-, and a group consisting of a combination of two or more (for example, 2 to 8, preferably 2 to 6, more preferably 2 to 4) of these.

[0144] The divalent hydrocarbon group is a linear, branched, or cyclic divalent hydrocarbon group, preferably a linear or branched divalent hydrocarbon group. Examples of the divalent hydrocarbon group include alkylene, alkenylene, alkynylene, and arylene.

[0145] As the alkylene, alkylene having 1 to 12 carbon atoms is preferable, alkylene having 1 to 6 carbon atoms is more preferable, and alkylene having 1 to 4 carbon atoms is particularly preferable. The carbon atoms of the substituent are not included in the above carbon atom numbers. The alkylene may be linear, branched, or cyclic, but linear alkylene is preferable. Examples of such alkylene include methylene, ethylene, propylene, butylene, pentylene, and hexylene.

[0146] As the alkenylene, alkenylene having 2 to 12 carbon atoms is preferable, alkenylene having 2 to 6 carbon atoms is more preferable, and alkenylene having 2 to 4 carbon atoms is particularly preferable. The carbon atoms of the substituent are not included in the above carbon atom numbers. The alkenylene may be linear, branched, or cyclic, but linear alkenylene is preferable. Examples of such alkenylene include ethylenylene, propynylene, butenylene, pentenylene, and hexenylene.

[0147] As the alkynylene, alkynylene having 2 to 12 carbon atoms is preferable, alkynylene having 2 to 6 carbon atoms is more preferable, and alkynylene having 2 to 4 carbon atoms is particularly preferable. The carbon atoms of the substituent are not included in the above carbon atom numbers. The alkynylene may be linear, branched, or cyclic, but linear alkynylene is preferable. Examples of such alkynylene include ethynylene, propynylene, butynylene, pentynylene, and hexynylene.

[0148] As the arylene, an arylene having 6 to 24 carbon atoms is preferable, an arylene having 6 to 18 carbon atoms is more preferable, an arylene having 6 to 14 carbon atoms is still more preferable, and an arylene having 6 to 10 carbon atoms is even more preferable. The carbon atom number of the substituent is not included in the above carbon atom number. Examples of the arylene include phenylene, naphthylene, and anthracenylene.

[0149] The divalent heterocyclic group is a divalent aromatic heterocyclic group or a divalent non-aromatic heterocyclic group. It preferably contains at least one selected from the group consisting of an oxygen atom, a sulfur atom, a nitrogen atom, a phosphorus atom, a boron atom, and a silicon atom as the hetero atom constituting the heterocyclic ring, and more preferably contains at least one selected from the group consisting of an oxygen atom, a sulfur atom, and a nitrogen atom.

[0150] As the divalent aromatic heterocyclic group, a divalent aromatic heterocyclic group having 3 to 21 carbon atoms is preferable, a divalent aromatic heterocyclic group having 3 to 15 carbon atoms is more preferable, a divalent aromatic heterocyclic group having 3 to 9 carbon atoms is still more preferable, and a divalent aromatic heterocyclic group having 3 to 6 carbon atoms is even more preferable. The carbon atom number of the substituent is not included in the above carbon atom number. More specifically, examples of the divalent aromatic heterocyclic group include pyrenediyl, pyrrolediyl, furandiyl, thiophenediyl, pyridinediyl, pyridazinediyl, pyrimidinediyl, pyrazinediyl, triazinediyl, pyrrolinediyl, piperidinediyl, triazolediyl, purinediyl, anthraquinonediyl, carbazolediyl, fluorenediyl, quinolinediyl, and isoquinolinediyl.

[0151] The divalent non-aromatic heterocyclic group is preferably a non-aromatic heterocyclic group having 3 to 21 carbon atoms, more preferably a non-aromatic heterocyclic group having 3 to 15 carbon atoms, still more preferably a non-aromatic heterocyclic group having 3 to 9 carbon atoms, and even more preferably a non-aromatic heterocyclic group having 3 to 6 carbon atoms. The number of carbon atoms of the substituent is not included in the above number of carbon atoms. More specifically, examples of the divalent non-aromatic heterocyclic group include pyrrolidione diyl, pyrrolinedione diyl, oxirane diyl, aziridine diyl, azetidine diyl, oxetane diyl, thietane diyl, pyrrolidine diyl, dihydrofuran diyl, tetrahydrofuran diyl, dioxolane diyl, tetrahydrothiophene diyl, imidazolidine diyl, oxazolidine diyl, piperidine diyl, dihydropyran diyl, tetrahydropyran diyl, tetrahydrothiopyran diyl, morpholine diyl, thiomorpholine diyl, piperazine diyl, dihydrooxazine diyl, tetrahydrooxazine diyl, dihydropyrimidine diyl, and tetrahydropyrimidine diyl.

[0152] The divalent groups represented by La and Lb may have, for example, 1 to 5, preferably 1 to 3, more preferably 1 or 2 substituents. Such substituents are the same as the substituents represented by the above R a and R b . Examples of such substituents include the following: (i) A halogen atom; (ii) A monovalent hydrocarbon group; (iii) An aralkyl; (iv) A monovalent heterocyclic group; (v) R c -O-, R c -C(=O)-, R c -O-C(=O)-, or R c -C(=O)-O-(wherein R c represents a hydrogen atom or a monovalent hydrocarbon group); or (vi) NR d R e -, NR d R e -C(=O)-, NRd R e -C(=O)-O-, or R d -C(=O)-NR e -(R d and R e are the same or different and each represents a hydrogen atom or a monovalent hydrocarbon group.); (vii) nitro group, sulfate group, sulfonic acid group, cyano group, and carboxyl group.

[0153] Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0154] Examples of the monovalent hydrocarbon group include a monovalent chain hydrocarbon group, a monovalent alicyclic hydrocarbon group, and a monovalent aromatic hydrocarbon group.

[0155] The monovalent chain hydrocarbon group means a hydrocarbon group composed only of a chain structure and does not include a cyclic structure in the main chain. However, the chain structure may be linear or branched. Examples of the monovalent chain hydrocarbon group include alkyl, alkenyl, and alkynyl. Alkyl, alkenyl, and alkynyl may be linear or branched.

[0156] As the alkyl, an alkyl having 1 to 12 carbon atoms is preferable, an alkyl having 1 to 6 carbon atoms is more preferable, and an alkyl having 1 to 4 carbon atoms is even more preferable. The number of carbon atoms of the substituent is not included in the number of carbon atoms. Examples of the alkyl having 1 to 12 carbon atoms include methyl, ethyl, n-propyl, i-propyl, n-butyl, s-butyl, isobutyl, t-butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, and dodecyl.

[0157] As the alkenyl, an alkenyl having 2 to 12 carbon atoms is preferred, an alkenyl having 2 to 6 carbon atoms is more preferred, and an alkenyl having 2 to 4 carbon atoms is even more preferred. The carbon atoms of the substituents are not included in the above carbon atom numbers. Examples of the alkenyl having 2 to 12 carbon atoms include vinyl, propenyl, and n-butenyl.

[0158] As the alkynyl, an alkynyl having 2 to 12 carbon atoms is preferred, an alkynyl having 2 to 6 carbon atoms is more preferred, and an alkynyl having 2 to 4 carbon atoms is even more preferred. The carbon atoms of the substituents are not included in the above carbon atom numbers. The alkynyl having 2 to 12 carbon atoms includes, for example, ethynyl, propynyl, and n-butynyl.

[0159] As the monovalent chain hydrocarbon group, alkyl is preferred.

[0160] The monovalent alicyclic hydrocarbon group means a hydrocarbon group containing only an alicyclic hydrocarbon as a ring structure and not containing an aromatic ring, and the alicyclic hydrocarbon may be either a monocyclic or polycyclic one. However, it does not necessarily have to be composed only of alicyclic hydrocarbons, and a part thereof may contain a chain structure. Examples of the monovalent alicyclic hydrocarbon group include cycloalkyl, cycloalkenyl, and cycloalkynyl, and these may be either monocyclic or polycyclic.

[0161] As the cycloalkyl, a cycloalkyl having 3 to 12 carbon atoms is preferred, a cycloalkyl having 3 to 6 carbon atoms is more preferred, and a cycloalkyl having 5 to 6 carbon atoms is even more preferred. The carbon atoms of the substituents are not included in the above carbon atom numbers. Examples of the cycloalkyl having 3 to 12 carbon atoms include cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl.

[0162] As the cycloalkenyl group, a cycloalkenyl group having 3 to 12 carbon atoms is preferred, a cycloalkenyl group having 3 to 6 carbon atoms is more preferred, and a cycloalkenyl group having 5 to 6 carbon atoms is even more preferred. The carbon atom number of the substituent is not included in the above carbon atom number. Examples of the cycloalkenyl group having 3 to 12 carbon atoms include cyclopropenyl, cyclobutenyl, cyclopentenyl, and cyclohexenyl.

[0163] As the cycloalkynyl group, a cycloalkynyl group having 3 to 12 carbon atoms is preferred, a cycloalkynyl group having 3 to 6 carbon atoms is more preferred, and a cycloalkynyl group having 5 to 6 carbon atoms is even more preferred. The carbon atom number of the substituent is not included in the above carbon atom number. Examples of the cycloalkynyl group having 3 to 12 carbon atoms include cyclopropynyl, cyclobutinyl, cyclopentynyl, and cyclohexynyl.

[0164] As the monovalent alicyclic hydrocarbon group, cycloalkyl is preferred.

[0165] The monovalent aromatic hydrocarbon group means a hydrocarbon group containing an aromatic ring structure. However, it is not necessary to be composed only of an aromatic ring, and a chain structure or an alicyclic hydrocarbon may be included in a part thereof, and the aromatic ring may be either a monocyclic or polycyclic ring. As the monovalent aromatic hydrocarbon group, aryl having 6 to 12 carbon atoms is preferred, aryl having 6 to 10 carbon atoms is more preferred, and aryl having 6 carbon atoms is even more preferred. The carbon atom number of the substituent is not included in the above carbon atom number. Examples of the aryl having 6 to 12 carbon atoms include phenyl and naphthyl.

[0166] As the monovalent aromatic hydrocarbon group, phenyl is preferred.

[0167] Among these, as the monovalent hydrocarbon group, alkyl, cycloalkyl, and aryl are preferred, and alkyl is more preferred.

[0168] An aralkyl group refers to an arylalkyl group. The definitions, examples, and preferred examples of aryl and alkyl in an arylalkyl group are as described above. As the aralkyl group, an aralkyl group having 3 to 15 carbon atoms is preferred. Examples of such an aralkyl group include benzoyl, phenethyl, naphthylmethyl, and naphthylethyl.

[0169] The monovalent heterocyclic group refers to a group obtained by removing one hydrogen atom from a heterocyclic ring of a heterocyclic compound. The monovalent heterocyclic group is a monovalent aromatic heterocyclic group or a monovalent non-aromatic heterocyclic group. As the heteroatom constituting the heterocyclic group, it preferably contains one or more selected from the group consisting of an oxygen atom, a sulfur atom, a nitrogen atom, a phosphorus atom, a boron atom, and a silicon atom, and more preferably contains one or more selected from the group consisting of an oxygen atom, a sulfur atom, and a nitrogen atom.

[0170] As the monovalent aromatic heterocyclic group, a monovalent aromatic heterocyclic group having 3 to 15 carbon atoms is preferred, a monovalent aromatic heterocyclic group having 3 to 9 carbon atoms is more preferred, and a monovalent aromatic heterocyclic group having 3 to 6 carbon atoms is even more preferred. The carbon atoms of the substituents are not included in the above carbon atom numbers. Examples of the monovalent aromatic heterocyclic group include pyrenyl, pyrrolyl, furanyl, thiophenyl, pyridinyl, pyridazinyl, pyrimidinyl, pyrazinyl, triazinyl, pyrrolinyl, piperidinyl, triazonyl, purinyl, carbazonyl, fluorenyl, quinolinyl, and isoquinolinyl.

[0171] The monovalent non-aromatic heterocyclic group is preferably a non-aromatic heterocyclic group having 3 to 15 carbon atoms, more preferably a non-aromatic heterocyclic group having 3 to 9 carbon atoms, and even more preferably a non-aromatic heterocyclic group having 3 to 6 carbon atoms. The carbon atoms of the substituent are not included in the number of carbon atoms. Examples of the monovalent non-aromatic heterocyclic group include oxiranyl, aziridinyl, azetidinyl, oxetanyl, thietanyl, pyrrolidinyl, dihydrofuranyl, tetrahydrofuranyl, dioxolanyl, tetrahydrothiophenyl, imidazolidinyl, oxazolidinyl, piperidinyl, dihydropyranyl, tetrahydropyranyl, tetrahydrothiopyranyl, morpholinyl, thiomorpholinyl, piperazinyl, dihydrooxazinyl, tetrahydrooxazinyl, dihydropyrimidinyl, and tetrahydropyrimidinyl.

[0172] Among these, as the monovalent heterocyclic group, a 5- or 6-membered heterocyclic group is preferred.

[0173] Preferably, the substituent may be any of the following: (i’) a halogen atom; (ii’) an alkyl, phenyl, or naphthyl having 1 to 12 carbon atoms; (iii’) an aralkyl having 3 to 15 carbon atoms; (iv’) a 5- or 6-membered heterocycle; (v’) R c -O-, R c -C(=O)-, R c -O-C(=O)-, or R c -C(=O)-O-(R c represents a hydrogen atom or an alkyl having 1 to 12 carbon atoms); or (vi’) NR d R e -, NR d R e -C(=O)-, NR d R e -C(=O)-O-, or R d -C(=O)-NR e -(R d and R eis the same as or different from, a hydrogen atom, or an alkyl group having 1 to 12 carbon atoms.); (vii’) The same group as those listed in the above (vii).

[0174] More preferably, the substituent may be as follows: (i’’) A halogen atom; (ii’’) An alkyl group having 1 to 12 carbon atoms; (iii’’) R c -O-, R c -C(=O)-, R c -O-C(=O)-, or R c -C(=O)-O-(R c represents a hydrogen atom, or an alkyl group having 1 to 12 carbon atoms.); or (iv’’) NR d R e -, NR d R e -C(=O)-, NR d R e -C(=O)-O-, or R d -C(=O)-NR e -(R d and R e are the same as or different from, a hydrogen atom, or an alkyl group having 1 to 12 carbon atoms.); (v’’) The same group as those listed in the above (vii).

[0175] Even more preferably, the substituent may be as follows: (i’’’) A halogen atom; (ii’’’) An alkyl group having 1 to 6 carbon atoms; (iii’’’) R c -O-, R c -C(=O)-, R c -O-C(=O)-, or R c -C(=O)-O-(R c represents a hydrogen atom, or an alkyl group having 1 to 6 carbon atoms.); or (iv’’’) NR d R e -, NR d Re -C(=O)-, NR d R e -C(=O)-O-, or R d -C(=O)-NR e -(R d and R e are the same or different and each represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.); (v’’’) The same groups as those listed in (vii) above.

[0176] Particularly preferably, the substituent may be as follows: (i’’’’) A halogen atom; (ii’’’’) An alkyl group having 1 to 4 carbon atoms; (iii’’’’) R c -O-, R c -C(=O)-, R c -O-C(=O)-, or R c -C(=O)-O-(R c represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.); or (iv’’ ’’) NR d R e -, NR d R e -C(=O)-, NR d R e -C(=O)-O-, or R d -C(=O)-NR e -(R d and R e are the same or different and each represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.); (v’’’’) The same groups as those listed in (vii) above.

[0177] In certain embodiments, La and Lb are, respectively, the following (La’) and (Lb’):

Chemical formula

[0178] p and p' are the same or different and are any integer from 0 to 10, preferably an integer from 0 to 8, more preferably an integer from 0 to 6, even more preferably an integer from 0 to 4, and particularly preferably 0, 1, or 2. Preferably, p and p' are the same.

[0179] q and q' are the same or different and are any integer from 0 to 10, preferably an integer from 0 to 8, more preferably an integer from 0 to 6, even more preferably an integer from 0 to 4, and particularly preferably 0, 1, or 2. Preferably, q and q' are the same.

[0180] X and X' are the same or different and are a carbon atom, a nitrogen atom, or a single bond, preferably a carbon atom or a single bond. Preferably, X and X' are the same.

[0181] R 1a 、R 1b 、R 1a’ and R 1b’ are the same or different and are a hydrogen atom or are selected from the group consisting of the substituents described below. The definition, examples, and preferred examples of the substituents are as described above. Preferably, R 1a, R 1b , R 1a’ and R 1b’ are hydrogen atoms.

[0182] 1-4. (a) A divalent group containing a bioorthogonal functional group, or (b) A divalent group (B) not containing a bioorthogonal functional group In formula (I), B is (a) a divalent group containing a bioorthogonal functional group, or (b) a divalent group not containing a bioorthogonal functional group.

[0183] A bioorthogonal functional group refers to a group that does not react with biological components (e.g., amino acids, nucleic acids, lipids, sugars, phosphates), or reacts with biological components at a slow rate, but selectively reacts with components other than biological components. Bioorthogonal functional groups are well-known in the art (see, for example, Sharpless K.B. et al., Angew. Chem. Int. Ed. 40, 2004 (2015); Bertozzi C.R. et al., Science 291, 2357 (2001); Bertozzi C.R. et al., Nature Chemical Biology 1, 13 (2005)).

[0184] When the target of the affinity substance is a soluble protein, the bioorthogonal functional group is a bioorthogonal functional group for the protein. A bioorthogonal functional group for a protein is a group that reacts with a predetermined functional group without reacting with the side chains of the 20 natural amino acid residues that make up the protein. The 20 natural amino acids that make up a protein are alanine (A), asparagine (N), cysteine (C), glutamine (Q), glycine (G), isoleucine (I), leucine (L), methionine (M), phenylalanine (F), proline (P), serine (S), threonine (T), tryptophan (W), tyrosine (Y), valine (V), aspartic acid (D), glutamic acid (E), arginine (R), histidine (H), and lysine (L). Among these 20 natural amino acids, glycine with no side chain (i.e., a hydrogen atom), and alanine, isoleucine, leucine, phenylalanine, and valine whose side chains are hydrocarbon groups (i.e., do not contain a heteroatom selected from the group consisting of a sulfur atom, a nitrogen atom, and an oxygen atom in the side chain) are inert to normal reactions. Therefore, the bioorthogonal functional group for a protein is a functional group that cannot react with the side chains of these amino acids having side chains that are inert to normal reactions, in addition to the side chains of asparagine, glutamine, methionine, proline, serine, threonine, tryptophan, tyrosine, aspartic acid, glutamic acid, arginine, histidine, and lysine.

[0185] Examples of such bioorthogonal functional groups that cannot react with proteins include, for example, azide residues, aldehyde residues, thiol residues, alkene residues (in other words, it suffices to have a vinylene (ethenylene) moiety which is the smallest unit having a double bond between carbon atoms. The same applies hereinafter), alkyne residues (in other words, it suffices to have an ethynylene moiety which is the smallest unit having a triple bond between carbon atoms. The same applies hereinafter), halogen residues, tetrazine residues, nitrone residues, hydroxylamine residues, nitrile residues, hydrazine residues, ketone residues, boronic acid residues, cyanobenzothiazole residues, allyl residues, phosphine residues, maleimide residues, disulfide residues, thioester groups, α-halocarbonyl residues (e.g., a carbonyl residue having a fluorine atom, chlorine atom, bromine atom or iodine atom at the α-position. The same applies hereinafter), isonitrile residues, sydnone residues, selenium residues. As proteins, there are proteins that may contain free thiol (cysteine) (e.g., proteins other than antibodies), and proteins that cannot contain free thiol (e.g., antibodies). In proteins that cannot contain free thiol , thiol functions as a bioorthogonal functional group. Therefore, when the soluble protein that is the target of the affinity substance is a protein that cannot contain free thiol (e.g., an antibody), it is preferable that the bioorthogonal functional group contains thiol. Also, when the soluble protein is a protein that may contain free thiol (e.g., a protein other than an antibody), it is preferable that the bioorthogonal functional group does not contain thiol. One or more (e.g., 2, 3, 4) bioorthogonal functional groups may be included in a divalent group, but preferably, one bioorthogonal functional group may be included in a divalent group.

[0186] In one embodiment, the divalent group containing a bioorthogonal functional group may be a divalent group containing a bioorthogonal functional group selected from the group consisting of an azide residue, an aldehyde group, a thiol residue, an alkyne residue, an alkene residue, a tetrazine residue, a nitrone residue, a hydroxylamine residue, a nitrile residue, a hydrazine residue, a ketone residue, a boronic acid residue, a cyanobenzothiazole residue, an allyl residue, a phosphine residue, a maleimide residue, a disulfide residue, a thioester group, an α-halocarbonyl residue, an isonitrile residue, a sydnone residue, and a selenium residue in the main chain.

[0187] In another embodiment, the divalent group containing a bioorthogonal functional group may be a divalent group containing a bioorthogonal functional group selected from the group consisting of an azide residue, an aldehyde residue, a thiol residue, an alkyne residue, an alkene residue, a halogen residue, a tetrazine residue, a nitrone residue, a hydroxylamine residue, a nitrile residue, a hydrazine residue, a ketone residue, a boronic acid residue, a cyanobenzothiazole residue, an allyl residue, a phosphine residue, a maleimide residue, a disulfide residue, an α-halocarbonyl residue, an isonitrile residue, a sydnone residue, and a selenium residue in the side chain.

[0188] More specifically, the bioorthogonal functional group may correspond to any one chemical structure selected from the group consisting of the following.

Chemical formula

[0189] Examples of the electron-withdrawing group include those described above, and a halogen atom, a boronic acid residue, mesyl, tosyl, and triflate are preferable.

[0190] In one embodiment, B may be a divalent group containing a bioorthogonal functional group. The number of bioorthogonal functional groups contained in the divalent group may be single or plural, for example, 1 to 5, preferably 1 to 3, more preferably 1 or 2, and even more preferably 1. When the number of bioorthogonal functional groups contained in the divalent group is plural, the plural bioorthogonal functional groups may be of the same kind or different kinds, but from the viewpoint of adopting a simple structure, etc., it is preferable that they are of the same kind.

[0191] In a specific embodiment, B may be a divalent group containing a bioorthogonal functional group in the main chain. The divalent group containing a bioorthogonal functional group in the main chain is a group in which the bioorthogonal functional group itself selected from the group consisting of an azide residue, an aldehyde group, a thiol residue, an alkyne residue, an alkene residue, a tetrazine residue, a nitrone residue, a hydroxylamine residue, a nitrile residue, a hydrazine residue, a ketone residue, a boronic acid residue, a cyanobenzothiazole residue, an allyl residue, a phosphine residue, a maleimide residue, a disulfide residue, a thioester group, an α-halocarbonyl residue, an isonitrile residue, a sydnone residue, a selenium residue is used as the divalent group, or a group in which the above-mentioned divalent group is linked to one or both ends of any one of such divalent bioorthogonal functional groups. The definition, examples and preferred examples of the divalent group to be linked are the same as those of the above-mentioned divalent group.

[0192] In another specific embodiment, B may be a divalent group containing a bioorthogonal functional group in the side chain. The divalent group containing a bioorthogonal functional group in the side chain is a bioorthogonal functional group selected from the group consisting of an azide residue, an aldehyde residue, a thiol residue, an alkyne residue, an alkene residue, a halogen residue, a tetrazine residue, a nitrone residue, a hydroxylamine residue, a nitrile residue, a hydrazine residue, a ketone residue, a boronic acid residue, a cyanobenzothiazole residue, an allyl residue, a phosphine residue, a maleimide residue, a disulfide residue, an α-halocarbonyl residue, an isonitrile residue, a sydnone residue, a selenium residue or a divalent group substituted with a group containing the same. The definition, examples and preferred examples of the divalent group to be substituted are the same as those of the above-mentioned divalent group.

[0193] In another embodiment, B may be a divalent group that does not contain a bioorthogonal functional group. Such a divalent group may be an optionally substituted alkylene, an optionally substituted cycloalkylene, an optionally substituted aryl, an optionally substituted divalent heterocyclic group, -NR a -(R a represents a hydrogen atom or a substituent), -O-, and a group consisting of a combination of two or more of these (for example, 2 to 8, preferably 2 to 6, more preferably 2 to 4). The substituents in the case of being optionally substituted, and the substituents of R a are substituents other than bioorthogonal functional groups. Such substituents include, for example, alkyl, cycloalkyl, aralkyl, monovalent heterocyclic group, hydroxyl, amino, alkyloxy (alkoxy), cycloalkyloxy, aralkyloxy. The number of such substituents is, for example, 1 to 5, preferably 1 to 3, more preferably 1 or 2, and even more preferably 1.

[0194] Regarding the substituents other than bioorthogonal functional groups, the definitions, examples and preferred examples of alkyl, cycloalkyl, aralkyl, and monovalent heterocyclic groups are as described above.

[0195] Regarding the substituents other than bioorthogonal functional groups, the definitions, examples and preferred examples of alkyl in alkyloxy (alkoxy), cycloalkyl in cycloalkyloxy, and aralkyl in aralkyloxy are as described above. More specifically, examples of alkyloxy include, for example, methyloxy, ethyloxy, propyloxy (e.g., n -propyloxy, iso-propyloxy), butyloxy (e.g., n-butyloxy, iso-butyloxy, sec-butyloxy, tert-butyloxy), pentyloxy (e.g., n-pentyloxy), hexyloxy (e.g., n-hexyloxy). Examples of cycloalkyloxy include cyclopropyloxy, cyclobutyloxy, cyclopentyloxy, cyclohexyloxy. Examples of aralkyloxy include benzyloxy, phenethyloxy, naphthylmethyloxy, naphthylethyloxy.

[0196] The divalent group that does not contain a bioorthogonal functional group may also be a group that is highly inert to the reaction. Thus, such a divalent group may be a group composed of only carbon atoms and hydrogen atoms. Such a divalent group is alkylene, cycloalkylene, or aryl, and combinations of two or more thereof (e.g., 2 or 3). When the divalent group that does not contain a bioorthogonal functional group is a group that is highly inert to the reaction, such a divalent group may have a substituent selected from the group consisting of alkylene, cycloalkylene, and aryl as a substituent that is highly inert to the reaction. The number of substituents that are highly inert to the reaction is, for example, 1 to 5, preferably 1 to 3, more preferably 1 or 2.

[0197] In a particular embodiment, B is of the following formula (B-1):

Chemical formula

Chemical formula

[0198] Y is -NH-, -O-, -CH2-, or a group represented by the above formula (B-2). From the perspective of simplifying the structure, etc., Y may be -NH-, -O-, or -CH2-. Alternatively, from the perspective of designing a structure based on carbon atoms, etc., Y may be -CH2- or a group represented by the above formula (B-2).

[0199] Z is an oxygen atom, a sulfur atom, or a hydrogen atom, preferably an oxygen atom or a sulfur atom.

[0200] V and V’ are -NH-, -O-, -CH2-, or a single bond, preferably -CH2- or a single bond.

[0201] V1 is (a) a divalent group containing a bioorthogonal functional group or (b) a divalent group not containing a bioorthogonal functional group. Such divalent groups are the same as those described above.

[0202] Preferably, the divalent group in V1 is an optionally substituted divalent hydrocarbon group or an optionally substituted divalent heterocyclic group. The definitions, examples and preferred examples of the divalent hydrocarbon group are the same as those described above. However, in the case of V1, alkylene, alkenylene, alkynylene, cycloalkylene, cycloalkenylene, cycloalkynylene, arylene are preferred. For example, when not substituted with a moiety containing a bioorthogonal functional group, alkenylene, alkynylene, cycloalkenylene, cycloalkynylene are preferred. On the other hand, when substituted with a moiety containing a bioorthogonal functional group, alkylene, cycloalkylene, arylene are preferred. Examples and preferred examples of these groups are as described above. The definitions, examples and preferred examples of the divalent heterocyclic group are the same as those described above. However, in the case of V1, a 5- or 6-membered heterocyclic group is preferred. Examples and preferred examples of the 5- or 6-membered heterocyclic group are the same as those described above. The definitions, examples and preferred examples of the substituent are as described above. V1 may (a) optionally have 1 to 5, preferably 1 to 3, more preferably 1 or 2, even more preferably 1 bioorthogonal functional group. When the number of bioorthogonal functional groups contained in the divalent group is plural, the plural bioorthogonal functional groups may be of the same kind or different kinds. From the viewpoints of adopting a simple structure and improving reactivity, etc., it is preferably of the same kind. From the viewpoints of ensuring a differentiated reaction, etc., it is preferably of different kinds. V1 may also (b) optionally have 1 to 5, preferably 1 to 3, more preferably 1 or 2 substituents.

[0203] s is an arbitrary integer from 0 to 10, preferably an integer from 0 to 8, more preferably an integer from 0 to 6, even more preferably an integer from 0 to 4, and particularly preferably 0, 1 or 2.

[0204] In a further specific embodiment, V1 is represented by the following formula (B-3):

Chemical formula

[0205] G and G' are the same or different and are -NH-, -O-, -CH2-, a single bond, or a group represented by the above formula (B-4). From the viewpoint of simplifying the structure, etc., G and G' may be -NH-, -O-, -CH2-, or a single bond. Alternatively, from the viewpoint of designing a structure based on carbon atoms, etc., G and G' may be -CH2-, a single bond, or a group represented by the above formula (B-4).

[0206] H is -CH2-, -C=O-, -C=S-, -NH-, or a single bond. Preferably, H is -CH2- or a single bond.

[0207] I is a divalent hydrocarbon group, a divalent heterocycle, or a single bond. The divalent hydrocarbon group and the divalent heterocycle may or may not be substituted with substituents. The definitions, examples, and preferred examples of the divalent hydrocarbon group, the divalent heterocycle, and the substituents are the same as those described above for V1.

[0208] W and W' are the same or different and are -NH-, -O-, -CH2-, or a single bond, preferably -CH2- or a single bond.

[0209] W1 is a divalent group containing a bioorthogonal functional group or (b) a divalent group not containing a bioorthogonal functional group. Such divalent groups are the same as those described above.

[0210] t is an arbitrary integer from 0 to 10, preferably an integer from 0 to 8, more preferably an integer from 0 to 6, even more preferably an integer from 0 to 4, and particularly preferably 0, 1 or 2.

[0211] 1-5. Reactive group (R) In formula (I), R is a reactive group with respect to a soluble protein. Such reactive groups are common general knowledge in the art.

[0212] The reactive group is a group of the same or different type as the bioorthogonal functional group.

[0213] For example, when B is a divalent group containing a bioorthogonal functional group, the reactive group may be a group different from the bioorthogonal functional group. This is because if the reactive group is a group of the same type as the bioorthogonal functional group, the reaction specificity of the reactive group with respect to the soluble protein cannot be ensured. Also, fundamentally, the bioorthogonal functional group is a group that cannot react with the side chains of the 20 natural amino acid residues constituting the soluble protein.

[0214] More specifically, among the above-described 20 natural amino acids that constitute proteins, glycine without a side chain, and alanine, isoleucine, leucine, phenylalanine, and valine whose side chains are hydrocarbon groups are inert to normal reactions. Therefore, the reactive group for the protein is a group capable of reacting with any one or two or more (e.g., 2, 3, 4) side chains of 14 amino acids consisting of asparagine, glutamine, methionine, proline, serine, threonine, tryptophan, tyrosine, aspartic acid, glutamic acid, arginine, histidine, and lysine. Depending on conditions such as the amino acid composition of the protein, one or two or more (e.g., 2, 3, 4) reactive groups may be included in the compound represented by formula (I), but preferably, one reactive group may be included in the compound represented by formula (I).

[0215] Preferably, the reactive group is a group capable of reacting with the side chain of any one of the 14 amino acids as described above that constitute the protein.

[0216] More preferably, the reactive group may be a reactive group specific to the side chain of any one of lysine, tyrosine, tryptophan, or cysteine.

[0217] Even more preferably, the reactive group may be a reactive group specific to the side chain of any one of lysine, tyrosine, or tryptophan.

[0218] When the protein is human IgG such as human IgG1, the reactive group is preferably a reactive group specific to the side chain of lysine or tyrosine.

[0219] The reactive group specific to the side chain of a lysine residue is a group that can specifically react with the amino group (NH2) present in the side chain of the lysine residue. For example, an activated ester residue (e.g., N-hydroxysuccinimide residue), vinyl sulfone residue, sulfonyl chloride residue, isocyanate residue, isothiocyanate residue, aldehyde residue, 1,4,7,10-tetra Examples include azacyclododecane-1,4,7,10-tetraacetic acid residue, 2-imino-2-methoxyethyl residue, diazonium terephthalic acid residue.

[0220] Examples of the linking moiety formed by the reaction between the above-described reactive group specific to the side chain of a lysine residue and the amino group (NH2) present in the side chain of the lysine residue include an amide residue, urea residue, pyridine residue, carbamate residue, sulfonamide residue.

[0221] More specifically, the reactive group specific to the side chain of a lysine residue may correspond to any one chemical structure selected from the group consisting of the following. [Chemical formula] [Here, R 5a and R 5c are a hydrogen atom or the above-described substituent, R 5b is an electron-withdrawing group, j is an arbitrary integer from 1 to 5, k is an arbitrary integer from 1 to 4. ]

[0222] R 5a and R 5c are a hydrogen atom or the above-described substituent. The definitions, examples, and preferred examples of the substituent are the same as those described above.

[0223] R 5b is an electron-withdrawing group. Examples of such electron-withdrawing groups include those described above, but a halogen atom, boronic acid residue, mesyl, tosyl, triflate are preferred.

[0224] j is an arbitrary integer from 1 to 5, preferably an integer from 1 to 3, and more preferably 1 or 2.

[0225] k is an arbitrary integer from 1 to 4, preferably an integer from 1 to 3, and more preferably 1 or 2.

[0226] The linking moiety formed by the reaction between the above chemical structure, which is a reactive group specific to the side chain of the lysine residue, and the amino group (NH2) present in the side chain of the lysine residue may correspond to any one chemical structure selected from the group consisting of the following.

Chemical formula

[0227] The reactive group specific to the side chain of the tyrosine residue is a group that can specifically react with the atom at the ortho position of the phenolic hydroxyl group (OH) present in the side chain of the tyrosine residue, and examples thereof include a diazonium residue, a diazodicarboxylate residue, and a 2,3-dihydro-1H-pyrazin-6-one residue.

[0228] More specifically, the reactive group specific to the side chain of the tyrosine residue may correspond to any one chemical structure selected from the group consisting of the following.

Chemical formula

[0229] R 4a is a hydrogen atom or the above-described substituent. The definition, examples, and preferred examples of the substituent are the same as those described above.

[0230] The linking moiety formed by the reaction between the above chemical structure, which is a reactive group specific to the side chain of a tyrosine residue, and the atom at the ortho position of the phenolic hydroxyl group (OH) present in the side chain of the tyrosine residue may correspond to any one chemical structure selected from the group consisting of the following.

Chemical formula

[0231] R 4a is a hydrogen atom or the above-described substituent. The definition, examples, and preferred examples of the substituent are the same as those described above.

[0232] The reactive group specific to the side chain of a tryptophan residue is a group that can specifically react with the ring-constituting atom at the 3-position of the indole group present in the side chain of the tryptophan residue. Examples thereof include a 9-azabicyclo[3.3.1]nonan-3-one-N-oxyl residue. More specifically, the reactive group specific to the side chain of a tryptophan residue may correspond to any one chemical structure selected from the group consisting of the following.

[0233]

Chemical formula

Chemical formula

[0234] The linking moiety formed by the reaction between the above chemical structure, which is a reactive group specific to the side chain of a tryptophan residue, and the ring-constituting atom at the 3-position of the indole group present in the side chain of the tryptophan residue may correspond to any one chemical structure selected from the group consisting of the following.

Chemical formula

[0235] Particularly preferably, the reactive group may be a reactive group specific to the side chain of lysine.

[0236] 1-6. Substructural unit "L-B" 1-6-1. The length of the main chain in the substructural unit "L-B" connecting A and R In formula (I), the length of the main chain (the straight-chain portion in L-B) connecting A (affinity substance) and R (reactive group) can be appropriately designed according to various factors such as the types of the soluble protein and the affinity substance, the target site of the affinity substance in the soluble protein, and the relationship between the position and number of specific amino acid residues in the target region (e.g., a specific position) such as described above where R should react and bind. The compound represented by formula (I) can covalently bond to the soluble protein by the affinity substance associating with the soluble protein and then the reactive group covalently bonded to the affinity substance via L-B reacting with a group (e.g., the amino group in the side chain of a lysine residue) in the side chain of a specific amino acid residue present in the vicinity of the above target site. At this time, when there are no other specific amino acid residues in the vicinity region of the specific amino acid residue to which R should react and bind, the vicinity region of the above target site, and the region between the specific amino acid residue and the above target site, the reactive group can bind to the specific amino acid residue in a regioselective manner without strictly controlling the length of the main chain. Of course, even when there are other specific amino acid residues in such a region, by controlling the length of the main chain, the reactive group can bind to the specific amino acid residue in a regioselective manner.

[0237] The length of the main chain connecting A and R can vary depending on factors such as the types of the soluble protein and the affinity substance therefor, and the relationship between the position and number of specific amino acid residues in the target site in the soluble protein, but is about 5 Å or more, preferably about 7.5 Å, more preferably Alternatively, it may be about 10.5 Å or more. Such a main chain length may also be, for example, about 30 Å or less, preferably about 23 Å or less, more preferably about 16.5 Å or less. More specifically, such a main chain length may be, for example, about 5.0 to 30 Å, preferably about 7.5 to 23 Å, more preferably about 10.5 to 16.5 Å.

[0238] Incidentally, regarding the relationship of the length (distance) between atoms, it is common general knowledge in the art that it is as shown in the following table. Therefore, a person skilled in the art can appropriately design a main chain having the corresponding number of atoms for the main chain length (Å) as described above with reference to the atomic lengths in the following table.

[0239]

Table 1

[0240] More specifically, the length of the main chain connecting A and R can also be defined as the number of atoms constituting the main chain (excluding hydrogen atoms and substituents). The number of atoms constituting the main chain may be, for example, 4 or more (about 5.0 Å), preferably 6 (about 7.5 Å), more preferably 8 or more (about 10.5 Å). The number of atoms in the main chain may also be, for example, 20 or less (about 30 Å), preferably 16 or less (about 23 Å), more preferably 12 or less (about 16.5 Å). More specifically, the number of atoms in the main chain may be, for example, 4 to 20, preferably 6 to 16, more preferably 8 to 12.

[0241] When the main chain has a structure that does not include a ring structure, the number of atoms in the main chain can be determined by counting the number of atoms in the chain structure.

[0242] On the one hand, when the main chain has a structure including a ring structure, the number of atoms in the main chain does not necessarily correspond to the length described above, and the length that can be defined by the number of atoms in the main chain tends to be shorter than the length described above. Even in such a case, from the perspective of defining the length of the main chain, the number of atoms in the main chain can be counted for convenience. Specifically, in such a case, the number of atoms in the main chain can be determined by adding the number of atoms in the chain structure that does not contain a divalent ring structure in the main chain and counting the number of atoms in the shortest path connecting two bonds in the ring structure (for example, refer to the bold paths in (a) to (d) below). [Chemical formula] · represents a bond. In the case of (a), since the shortest path is the bold path, the number of atoms in the divalent ring structure that can be counted as the number of atoms in the main chain is 2. In the case of (b), since the shortest path is the bold path, the number of atoms in the divalent ring structure that can be counted as the number of atoms in the main chain is 3. In the case of (c), since any path is the shortest path (equal distance), the number of atoms in the divalent ring structure that can be counted as the number of atoms in the main chain is 4. In the case of (d), since the path at the condensation site is the shortest path, the number of atoms in the divalent ring structure that can be counted as the number of atoms in the main chain is 4.

[0243] Preferably, the connecting part (excluding the side chain) of A and R represented by L-B may be a chain structure that does not contain a divalent ring structure. In this case, L and B can be appropriately designed so that the divalent ring group is not included in the connecting chain part of A and R represented by L-B.

[0244] 1-6-2. Specific structure of the partial structure "L-B" In the above formula (I), L and B are structures that can be related to each other. Therefore, in the above formula (I), L and B can be defined as a partial structure represented by "L-B".

[0245] In one embodiment, the cleavable linker may be a cleavable linker which is a divalent group containing a cleavable moiety having the ability to generate a bioorthogonal functional group on the reactive group side upon cleavage, or (ii) a cleavable linker which is a divalent group containing a cleavable moiety having no ability to generate a bioorthogonal functional group on the reactive group side upon cleavage.

[0246] In a specific embodiment, when L is the cleavable linker of (i) above, B is (a) a divalent group containing a bioorthogonal functional group, or (b) a divalent group not containing a bioorthogonal functional group.

[0247] Preferably, when L is the cleavable linker of (i) above, B is (a) a divalent group containing a bioorthogonal functional group. In this case, the bioorthogonal functional group generated in (i) may be the same as or different from the bioorthogonal functional group in (a). From the viewpoint of adopting a simpler structure and / or improving the reactivity with a single functional substance, the bioorthogonal functional group generated in (i) may be the same as the bioorthogonal functional group in (a). On the other hand, from the viewpoints of ensuring differentiated reactivity with two or more functional substances and not using some of the bioorthogonal functional groups in the reaction, the bioorthogonal functional group generated in (i) may be different from the bioorthogonal functional group in (a).

[0248] Alternatively, when L is the cleavable linker of (i) above, B may be (b) a divalent group not containing a bioorthogonal functional group. In this case, the compound represented by formula (I) or a salt thereof will have a simpler structure, and thus the synthesis is easy.

[0249] In another specific embodiment, when L is the cleavable linker of (ii) above, B is (a ) a divalent group containing a bioorthogonal functional group.

[0250] In certain embodiments, the substructure represented by L-B preferably does not contain a peptide moiety. In this case, the soluble protein having the functional substance of the present invention obtained using the compound of the present invention (e.g., antibody-drug conjugate) has the advantage that it cannot contain a peptide moiety that may have immunogenicity as a linker.

[0251] In certain embodiments, the substructure represented by "L-B" may have a symmetric structure [e.g., cis type (i.e., Z), trans type (i.e., E)] with respect to an atom present at the central position of the main chain (the straight-chain portion in L-B) connecting A and R (e.g., when the number of atoms constituting the main chain is odd), or a bonding site present at the central position of the main chain (e.g., when the number of atoms constituting the main chain is even). For example, the bonding site present at the central position can also be designed as a cleavable moiety in the cleavage linker as described above. When the substructure represented by "L-B" has a symmetric structure, the substructure represented by "L-B" can be easily synthesized. For example, by reacting the same divalent group having a functional group capable of reacting to form a cleavable moiety at one end (e.g., a chain-like divalent group having an SH group at one end) with each other, a symmetric structure (chain-like divalent group -S-S- chain-like divalent group) containing a cleavable moiety at the central position of the main chain can be realized.

[0252] Therefore, the substructure represented by "L-B" may be a substructure represented by "B2-L'-B1" (i.e., L is a divalent group represented by B2-L', and B is B1). In this case, the compound represented by the above formula (I) can be defined as a compound represented by the following formula (I'). A - B2 - L' - B1 - R (I') [wherein, A and R are the same as those in the above formula (I) L' is a cleavable linker which is a divalent group containing a cleavable moiety, B1 and B2 are the same or different and are (a) a divalent group containing a bioorthogonal functional group, or (b) a divalent group not containing a bioorthogonal functional group, B1 and B2 may have a symmetric structure centered on L'.

[0253] B1 and B2 are the same as or different from each other and are the same as the definition, examples, and preferred examples of B.

[0254] In a specific embodiment, L' may be represented by any one of the following formulas (L1') to (L3'): La'-C'-Lb' (L1') La'-C' (L2') C'-Lb' (L3') 〔In the formula, La' and Lb' are each a divalent group, and C' is a cleavable moiety.〕

[0255] The divalent groups represented by La' and Lb' are the same as the definition, examples, and preferred examples of the divalent groups represented by La' and Lb', respectively.

[0256] The cleavable moiety represented by C' is the same as the definition, examples, and preferred examples of the cleavable moiety represented by C.

[0257] In another specific embodiment, the structural unit represented by L-B may be represented by the following formula (LB') as well.

Chemical formula

[0258] Therefore, the above formula (I) can be defined as the following formula (I'').

Chemical formula

[0259] In the above formulas (LB’) and (I’’), the length from the C (carbon atom) in C=Z to the C (carbon atom) in C=Z’ is the same as the length of the main chain connecting A and R. In these formulas, the length from the C in C=Z to the C in C=Z’ can also be defined as the number of atoms constituting the connecting chain (excluding hydrogen atoms and substituents) of the partial structure connecting the C in C=Z to the C in C=Z’. Such a number of atoms is the same as the number of atoms constituting the main chain connecting A and R. The connecting chain (excluding hydrogen atoms and substituents) of the partial structure connecting the C in C=Z to the C in C=Z’ may or may not contain a ring structure, but it is preferably free of a ring structure. The connecting chain (excluding hydrogen atoms and substituents) may preferably not contain a peptide moiety.

[0260] 1-8. Manufacturing method A compound or a salt thereof containing an affinity substance for a soluble protein, a cleavable moiety and a reactive group can be appropriately prepared. A compound containing an affinity substance for a soluble protein, a cleavable moiety and a reactive group is represented by formula (I), preferably formula (I’), more preferably formula (I’’).

[0261] As the affinity substance, those having any functional group can be appropriately selected. Therefore, by using a reactive group capable of reacting with the functional group, the affinity substance can be reacted with a structural unit represented by L-B-R or a structural unit represented by R-L-B-R (the two reactive groups are the same or different) to prepare a structural unit represented by A-L-B-R. For example, such a reaction can be carried out at an appropriate temperature (e.g., about 15 to 200 °C) in an appropriate reaction system, such as an organic solvent system or an aqueous solution system. The reaction system may contain an appropriate catalyst. The reaction time is, for example, 1 minute to 20 hours, preferably 10 minutes to 15 hours, more preferably 20 minutes to 10 hours, and even more preferably 30 minutes to 8 hours.

[0262] In the reaction system, the molar ratio (Y / X) of the structural unit represented by L-B-R or the structural unit represented by R-L-B-R (Y) to the affinity substance (X) varies depending on the types of the structural unit and the affinity substance, the number of sites in the affinity substance to be modified by the structural unit, etc., and is not particularly limited. For example, it is 0.1 to 50, preferably 0.5 to 40, more preferably 1 to 35, even more preferably 2 to 25, and particularly preferably 3 to 15.

[0263] The confirmation of the production of the affinity substance for the soluble protein and the soluble protein or its salt containing the cleavable moiety depends on the specific raw materials and the molecular weights of the products. For example, it can be carried out by electrophoresis, chromatography (e.g., gel filtration chromatography, ion exchange chromatography, reverse phase column chromatography, HPLC), or mass spectrometry, preferably by mass spectrometry. The affinity substance for the soluble protein and the soluble protein or its salt containing the cleavable moiety can be appropriately purified by any method such as chromatography (e.g., the above-mentioned chromatography and affinity chromatography).

[0264] 1-9. Others In the inventions described below [e.g., the inventions represented by formulas (II) to (v), their sub-concept formulas, and partial structural formulas (e.g., (L1) to (L3), (La’), (Lb’), (B-1) to (B-4))], any symbols (e.g., A, L, B, R), the terms represented by these symbols, and their details (e.g., definitions, examples, and preferred examples) are common to the invention of the compound represented by the above formula (I) or a salt thereof. Also, specific parts that can define the inventions described below (e.g., a cleavable part, a part having the ability to generate a bioorthogonal functional group on the reactive group side by cleavage), specific groups (e.g., bioorthogonal functional groups, divalent groups, alkyl groups, substituents, electron-withdrawing groups), and specific numerical values, as well as any technical elements such as salts (e.g., definitions, examples, and preferred examples) can also be made common to those described above. Therefore, these matters can be appropriately incorporated into the inventions described below without particular mention. Similarly, the technical elements of the specific inventions described in the inventions below can be appropriately incorporated as the technical elements of the present invention and other inventions.

[0265] 2. Affinity substance for soluble protein, and soluble protein or its salt containing a cleavable part 2-1. Outline The present invention provides an affinity substance for a soluble protein represented by formula (II), and a soluble protein or its salt containing a cleavable part. A-L-B-R’-T (II) 〔In the formula, A is an affinity substance for a soluble protein, L is a cleavable linker which is a divalent group containing a cleavable part, B is (a) a divalent group containing a bioorthogonal functional group, or (b) a divalent group not containing a bioorthogonal functional group, R’ is a part generated by the reaction between a soluble protein and a reactive group, T is a soluble protein.〕

[0266] 2-2. Part (R’) generated by the reaction between a soluble protein and a reactive group In the moiety formed by the reaction between the soluble protein and the reactive group, the definitions, examples and preferred examples of the soluble protein and the reactive group are as described above. The moiety formed by the reaction between the soluble protein and the reactive group is common general knowledge in the art and can be appropriately determined according to the types of the soluble protein and the reactive group.

[0267] Preferably, the moiety formed by the reaction between the soluble protein and the reactive group is a moiety formed by the reaction between the side chain of any one of the 14 amino acids (asparagine, glutamine, methionine, proline, serine, threonine, tryptophan, tyrosine, aspartic acid, glutamic acid, arginine, histidine, and lysine) that can be contained in the soluble protein and the reactive group corresponding thereto.

[0268] More preferably, the moiety formed by the reaction between the soluble protein and the reactive group may be a moiety formed by the reaction between the side chain of any one of lysine, tyrosine, tryptophan, or cysteine and the reactive group specific thereto.

[0269] Even more preferably, the moiety formed by the reaction between the soluble protein and the reactive group may be a moiety formed by the reaction between the side chain of any one of lysine, tyrosine, or tryptophan and the reactive group specific thereto. Examples of the moiety formed by the reaction between the side chain of any one of lysine, tyrosine, or tryptophan and the reactive group specific thereto include, for example, the linking moiety and / or chemical structure described in the above "1-5. Reactive group (R)".

[0270] Even more preferably, the moiety formed by the reaction between the soluble protein and the reactive group may be a moiety formed by the reaction between the side chain of lysine or tyrosine and a reactive group specific thereto (particularly when the soluble protein is a human IgG such as human IgG1). Examples of the moiety formed by the reaction between the side chain of lysine or tyrosine and a reactive group specific thereto include the linking moiety and / or chemical structure described in the above "1-5. Reactive group (R)".

[0271] Particularly preferably, the moiety formed by the reaction between the soluble protein and the reactive group may be a moiety formed by the reaction between the side chain of lysine and a reactive group specific thereto.

[0272] 2-3. Substructure "L-B" The details of the substructure "L-B" are as described in the above "1-6. Substructure 'L-B'".

[0273] In a specific embodiment, the substructure represented by "L-B" may be a substructure represented by "B2-L'-B1" (that is, L is a divalent group represented by B2-L', and B is B1). In this case, the affinity substance for the soluble protein and the soluble protein or its salt containing a cleavable moiety represented by the above formula (II) can be represented by the following formula (II'). A-B2-L'-B1-R'-T (II')[[]] [In the formula, A, R' and T are the same as those in the above formula (II) L' is a cleavable linker which is a divalent group containing a cleavable moiety, B1 and B2 are the same or different ...

Claims

1. The following formula (I): A-L-B-R (I) 〔In the formula,[[]] A is a binding peptide to the Fc region of a human IgG antibody, 〔Here, the binding peptide is a peptide or a salt thereof selected from the group consisting of the following (1) to (8): (1) The following formula (i): (X1-3)-C-(X2)-H-(Xaa1)-G-(Xaa2)-L-V-W-C-(X1-3) (SEQ ID NO: 94) (i) 〔In the formula,[[]] X is the same or different and is any amino acid residue other than cysteine, C is a cysteine residue, H is a histidine residue, Xaa1 is an arginine residue, leucine residue, lysine residue, aspartic acid residue, glutamic acid residue, 2-aminosuberic acid residue, or diaminopropionic acid residue, G is a glycine residue, Xaa2 is a lysine residue, glutamine residue, glutamic acid residue, asparagine residue, or aspartic acid residue, L is a leucine residue, V is a valine residue, and W is a tryptophan residue.〕 A peptide or a salt thereof that contains an amino acid sequence consisting of 13 to 17 amino acid residues represented by the formula and is capable of binding to human IgG; (2) The following formula (i-1): (X1-3)-C-(X2)-H-(Xaa1)-G-(Xaa2)-L-V-W-C-(X1-3) (SEQ ID NO: 95) (i-1) 〔In the formula,[[]] X is the same or different and is any amino acid residue other than cysteine, C is a cysteine residue, H is a histidine residue, Xaa1 is a lysine residue, cysteine residue, aspartic acid residue, glutamic acid residue, 2-aminosuberic acid residue, or diaminopropionic acid residue, G is a glycine residue, Xaa2 is a glutamic acid residue or asparagine residue, L is a leucine residue, V is a valine residue, and W is a tryptophan residue.〕 A peptide or a salt thereof that contains an amino acid sequence consisting of 13 to 17 amino acid residues represented by the formula and is capable of binding to human IgG; (3) The following formula (i-2): (X1-3)-C-(X2)-H-(Xaa1)-G-(Xaa2)-L-V-W-C-(X1-3) (SEQ ID NO: 96) (i-2) 〔In the formula,[[]] X is the same or different and is any amino acid residue other than cysteine, C is a cysteine residue, H is a histidine residue, Xaa1 is an arginine residue or a leucine residue, G is a glycine residue, Xaa2 is a lysine residue, a glutamine residue or an aspartic acid residue, L is a leucine residue, V is a valine residue, and W is a tryptophan residue.], a peptide consisting of 13 to 17 amino acid residues and capable of binding to human IgG, or a salt thereof; (4) The following formula (v): (X1-3)-C-(Xaa3)-(xaa4)-H-(Xaa1)-G-(Xaa2)-L-V-W-C-(Xaa5)-(Xaa6)-(Xaa7) (SEQ ID NO: 102) (v) [In the formula, X is the same or different and is any amino acid residue other than cysteine, C is a cysteine residue, Xaa3 is an alanine residue or a lysine residue, Xaa4 is a tryptophan residue or a tyrosine residue, H is a histidine residue, Xaa1 is an arginine residue, a leucine residue, a lysine residue, an aspartic acid residue, a glutamic acid residue, a 2-aminosuberic acid residue or a diaminopropionic acid residue, G is a glycine residue, Xaa2 is a lysine residue, a glutamine residue, a glutamic acid residue, an asparagine residue or an aspartic acid residue, L is a leucine residue, V is a valine residue, W is a tryptophan residue, Xaa5 is a threonine residue or a lysine residue, Xaa6 is a tyrosine residue, a lysine residue or none, and Xaa7 is a histidine residue, a lysine residue or none.], a peptide consisting of 13 to 17 amino acid residues and capable of binding to human IgG, or a salt thereof; (5) The following formula (vi): D-C-(Xaa3)-(Xaa4)-H-(Xaa1)-G-(Xaa2)-L-V-W-C-(Xaa5)-(Xaa6)-(Xaa7) (SEQ ID NO: 103) (vi) [In the formula, D is an aspartic acid residue, C is a cysteine residue, Xaa3 is an alanine residue or a lysine residue, Xaa4 is a tryptophan residue or a tyrosine residue, H is a histidine residue, Xaa1 is an arginine residue, a leucine residue, a lysine residue, an aspartic acid residue, a glutamic acid residue, a 2-aminosuberic acid residue or a diaminopropionic acid residue, G is a glycine residue, Xaa2 is a lysine residue, a glutamine residue, a glutamic acid residue, an asparagine residue, or an aspartic acid residue, L is a leucine residue, V is a valine residue, W is a tryptophan residue, Xaa5 is a threonine residue, or a lysine residue, Xaa6 is a tyrosine residue, a lysine residue, or none, Xaa7 is a histidine residue, a lysine residue, or none.〕 It comprises an amino acid sequence consisting of 13 to 15 amino acid residues represented by, and is capable of binding to human IgG, characterized by a peptide or a salt thereof; (6) The following formula (vii): D-C-(Xaa3)-(Xaa4)-H-(Xaa1)-G-(Xaa2)-L-V-W-C-T (SEQ ID NO: 104) (vii) [In the formula, D is an aspartic acid residue, C is a cysteine residue, Xaa3 is an alanine residue, or a lysine residue, Xaa4 is a tryptophan residue, or a tyrosine residue, H is a histidine residue, Xaa1 is an arginine residue, a leucine residue, a lysine residue, an aspartic acid residue, a glutamic acid residue, 2-aminosuberic acid residue, or diaminopropionic acid residue, G is a glycine residue, Xaa2 is a lysine residue, a glutamine residue, a glutamic acid residue, an asparagine residue, or an aspartic acid residue, L is a leucine residue, V is a valine residue, W is a tryptophan residue, and T is a threonine residue] It comprises an amino acid sequence consisting of 13 amino acid residues represented by, and is capable of binding to human IgG, characterized by a peptide or a salt thereof; (7) The following formula (viii): R-G-N-C-(Xaa3)-(Xaa4)-H-(Xaa1)-G-(Xaa2)-L-V-W-C-(Xaa5)-(Xaa6)-(Xaa7) (SEQ ID NO: 105) (viii) [In the formula, R is an arginine residue, G is a glycine residue, N is an asparagine residue, C is a cysteine residue, Xaa3 is an alanine residue, or a lysine residue, Xaa4 is a tryptophan residue, or a tyrosine residue, H is a histidine residue, Xaa1 is an arginine residue, a leucine residue, a lysine residue, an aspartic acid residue, glu tamic acid residue, 2-aminosuberic acid residue, or diaminopropionic acid residue, G is a glycine residue, Xaa2 is a lysine residue, a glutamine residue, a glutamic acid residue, an asparagine residue, or an aspartic acid residue, L is a leucine residue, V is a valine residue, W is a tryptophan residue, Xaa5 is a threonine residue, or a lysine residue, Xaa6 is a tyrosine residue, a lysine residue, or none, and Xaa7 is a histidine residue, a lysine residue, or none.], a peptide or a salt thereof, comprising an amino acid sequence consisting of 13 to 15 amino acid residues and capable of binding to human IgG; (8) (a) In the amino acid sequence of FNMQCQRRFYEALHDPNLNEEQRNARIRSIIDD C (SEQ ID NO: 92), any amino acid residue is substituted with one amino acid residue selected from the group consisting of a lysine residue, an aspartic acid residue, a glutamic acid residue, a 2 - aminobutyric acid residue, and a diaminopropionic acid residue, and (b) an affinity peptide or a salt thereof, comprising an amino acid sequence having 90% or more identity to the amino acid sequence of SEQ ID NO: 92.], L is a cleavable linker which is a divalent group containing one cleavable moiety selected from the group consisting of a disulfide residue, an acetal residue, a ketal residue, an ester residue, a carbamoyl residue, an alkoxyalkyl residue, an imine residue, a tertiary alkyloxycarbamate residue, a silane residue, a hydrazone - containing residue, a phosphoramidate residue, an azo residue, a vicinal diol residue, an aromatic ring - containing residue having an electron - withdrawing group, a coumarin - containing residue, a sulfone - containing residue, an unsaturated - bond - containing chain residue, and a glycosyl residue, B is (a) a divalent group containing a bioorthogonal functional group, or (b) a divalent group not containing a bioorthogonal functional group, R is a reactive group specific to the side chain of a lysine residue, and is (1) one group selected from the group consisting of an activated ester residue, a vinyl sulfone residue, a sulfonyl chloride residue, an isocyanate residue, an isothiocyanate residue, an aldehyde residue, and a diazonium terephthalic acid residue, or (2) the following: 【Chemical 1】 [wherein, R ５ａ and R ５c is an atom or group selected from the group consisting of the following (i) to (vii), (i) a hydrogen atom, or a halogen atom; (ii) a monovalent hydrocarbon group; (iii) an aralkyl; (iv) a monovalent heterocyclic group; (v) Rc−O−, Rc−C(=O)−, Rc−O−C(=O)−, or Rc−C(=O)−O− (wherein Rc represents a hydrogen atom or a monovalent hydrocarbon group); (vi) NRdRe−, NRdRe−C(=O)−, NRdRe−C(=O)−O−, or Rd−C(=O)−NRe− (wherein Rd and Re are the same or different and each represents a hydrogen atom or a monovalent hydrocarbon group); or (vii) a nitro group, a sulfate group, a sulfonic acid group, a cyano group, or a carboxyl group, R ５ｂ is an electron-withdrawing group, j is an arbitrary integer of 1 to 5, k is an arbitrary integer of 1 to 4. ] A group corresponding to any one chemical structure selected from the group consisting of. ] A compound or a salt thereof having a binding peptide, a cleavable moiety, and a reactive group for the Fc region of a human IgG antibody, represented by

2. When L is a cleavable linker which is a divalent group containing a cleavable moiety having the ability to generate a bioorthogonal functional group on the reactive group side upon cleavage among the above-mentioned cleavable linkers, B is the divalent group of the above-mentioned (b), or when L is a cleavable linker which is a divalent group containing a cleavable moiety having no ability to generate a bioorthogonal functional group on the reactive group side upon cleavage among the above-mentioned cleavable linkers, B is the divalent group of the above-mentioned (a). The compound or a salt thereof according to claim 1.

3. The compound or a salt thereof according to any one of claims 1 or 2, wherein the binding peptide is a binding peptide for an antibody containing any one Fc region protein selected from the group consisting of the following (A) to (C) and having an antigen-binding ability: (A) An Fc region protein containing the amino acid sequence of SEQ ID NO: 1; (B) An Fc region protein containing an amino acid sequence in which one or several amino acid residues are inserted, added, deleted, or substituted in the amino acid sequence of SEQ ID NO: 1; or (C) An Fc region protein containing an amino acid sequence having 90% or more identity with the amino acid sequence of SEQ ID NO:

1.

4. The compound or a salt thereof according to any one of claims 1 to 3, wherein the cleavable moiety is the following (3): (3) The following: [Chemical 2] [Herein, the wavy line orthogonal to the bond indicates the cleavage site, A plurality of Rs ２ａ a plurality of Rs ２ｂ and a plurality of Rs ２ｃ are the same or different and (i) a hydrogen atom or a halogen atom; (ii) a monovalent hydrocarbon group; (iii) an aralkyl; (iv) a monovalent heterocyclic group; (v) R ｃ -O-, R ｃ -C(=O)-, R ｃ -O-C(=O)-, or R ｃ -C(=O)-O-(R ｃ represents a hydrogen atom or a monovalent hydrocarbon group.); (vi) NR ｄ R ｅ —, NR ｄ R ｅ —C(=O)—, NR ｄ R ｅ —C(=O)—O—, or R ｄ —C(=O)—NR ｅ —(R ｄ and R ｅ are the same or different and each represents a hydrogen atom or a monovalent hydrocarbon group.); or (vii) a nitro group, a sulfate group, a sulfonic acid group, a cyano group, or a carboxyl group selected from the group consisting of, J is -CH ２ -, -O-, or -S-, and r is an arbitrary integer from 1 to 4, ○ (white circle) indicates a bond to A, and ● (black circle) indicates a bond to B. When the chemical structure is asymmetric around the cleavage site, ● may indicate a bond to A and ○ may indicate a bond to B. A cleavable moiety corresponding to any one chemical structure selected from the group consisting of.

5. The cleavable moiety of (i) is selected from the group consisting of (1) a disulfide residue, an ester residue, an acetal residue, a ketal residue, an imine residue, a vicinal diol residue, or (2) the following: 【Chemical Formula 3】 〔Here, the wavy line orthogonal to the bond indicates the cleavage site, R ２ａ is the same as in claim 6, ○ (white circle) indicates a bond to A, and ● (black circle) indicates a bond to B. When the chemical structure is asymmetric around the cleavage site, ● may indicate a bond to A and ○ may indicate a bond to B. A compound or a salt thereof according to any one of claims 2 to 4 corresponding to any one chemical structure selected from the group consisting of.

6. The cleavable moiety of (ii) is the following: [Chemical Formula 4] 〔Here, the wavy line orthogonal to the bond indicates the cleavage site, R ２ｂ 、 R ２ｃ 、 identical or different, (i) a hydrogen atom or a halogen atom; (ii) a monovalent hydrocarbon group; (iii) an aralkyl; (iv) a monovalent heterocyclic group; (v) R ｃ -O-, R ｃ -C(=O)-, R ｃ -O-C(=O)-, or R ｃ -C(=O)-O-(R ｃ represents a hydrogen atom or a monovalent hydrocarbon group.). (vi) NR ｄ R ｅ —, NR ｄ R ｅ —C(=O)—, NR ｄ R ｅ —C(=O)—O—, or R ｄ —C(=O)—NR ｅ —(R ｄ and R ｅ are the same or different and each represents a hydrogen atom or a monovalent hydrocarbon group.); or (vii) a nitro group, a sulfate group, a sulfonic acid group, a cyano group, or a carboxyl group selected from the group consisting of, J is -CH ２ -, -O-, or -S-, and r is an arbitrary integer from 1 to 4, ○ (white circle) indicates a bond to A, and ● (black circle) indicates a bond to B. When the chemical structure is asymmetric around the cleavage site, ● may indicate a bond to A and ○ may indicate a bond to B. A compound or a salt thereof according to any one of claims 2 to 4 corresponding to any one chemical structure selected from the group consisting of.

7. The divalent group containing a bioorthogonal functional group is (1) a divalent group containing a bioorthogonal functional group selected from the group consisting of an azide residue, an aldehyde residue, a thiol residue, an alkyne residue, an alkene residue, a tetrazine residue, a nitrone residue, a hydroxylamine residue, a nitrile residue, a hydrazine residue, a ketone residue, a boronic acid residue, a cyanobenzothiazole residue, an allyl residue, a phosphine residue, a maleimide residue, a disulfide residue, a thioester group, an α-halocarbonyl residue, an isonitrile residue, a sydnone residue, and a selenium residue in the main chain, or (2) a divalent group containing a bioorthogonal functional group selected from the group consisting of an azide residue, an aldehyde residue, a thiol residue, an alkyne residue, an alkene residue, a halogen residue, a tetrazine residue, a nitrone residue, a hydroxylamine residue, a nitrile residue, a hydrazine residue, a ketone residue, a boronic acid residue, a cyanobenzothiazole residue, an allyl residue, a phosphine residue, a maleimide residue, a disulfide residue, an α-halocarbonyl residue, an isonitrile residue, a sydnone residue, and a selenium residue in the side chain. The compound or a salt thereof according to any one of claims 1 to 6.

8. The bioorthogonal functional group is the following: [Chemical Formula 5] 〔In the formula, R １ｆ , single or multiple R １ｇ and single or multiple R １ｈ are, identical or different, an atom or group selected from the group consisting of the above (i) to (vii), or an electron-withdrawing group, ・ represents a bond. ) Any one of the compounds or salts thereof according to any one of claims 1 to 6.

9. The divalent group of (b) is optionally substituted alkylene, optionally substituted cycloalkylene, optionally substituted aryl, optionally substituted divalent heterocyclic group, -NR ａ -(R ａ represents a hydrogen atom or a substituent), -O-, or a combination of two or more thereof, and the compound or a salt thereof according to any one of claims 1 to 8.

10. The number of atoms in the main chain connecting A and R is 4 to 20. The compound or a salt thereof according to any one of claims 1 to 9.

11. The main chain connecting A and R does not contain a ring structure. The compound or a salt thereof according to any one of claims 1 to 10.

12. The partial structure represented by L-B does not contain a peptide moiety. The compound or a salt thereof according to any one of claims 1 to 11.

13. The compound represented by the formula (I) is the following (I'): A - B2 - L' - B1 - R (I') 〔In the formula, A and R are the same as those in the formula (I) L' is a cleavable linker which is a divalent group containing one cleavable moiety selected from the group consisting of a disulfide residue, an acetal residue, a ketal residue, an ester residue, a carbamoyl residue, an alkoxyalkyl residue, an imine residue, a tertiary alkyloxycarbamate residue, a silane residue, a hydrazone-containing residue, a phosphoramidate residue, an azo residue, a vicinal diol residue, an aromatic ring-containing residue having an electron-withdrawing group, a coumarin-containing residue, a sulfone-containing residue, an unsaturated bond-containing chain residue, and a glycosyl residue, B1 and B2 are the same or different and are (a) a divalent group containing a bioorthogonal functional group or (b) a divalent group not containing a bioorthogonal functional group, B1 and B2 may have a symmetric structure centered on L'. A compound or a salt thereof according to any one of claims 1 to 12, which is a compound represented by.

14. The compound represented by the formula (I') is the following (I''): 【Chemical Formula 6】 [In the formula, A and R are the same as those in the formula (I) described in claim 1, C is one cleavable moiety selected from the group consisting of a disulfide residue, an acetal residue, a ketal residue, an ester residue, a carbamoyl residue, an alkoxyalkyl residue, an imine residue, a tertiary alkyloxycarbamate residue, a silane residue, a hydrazone-containing residue, a phosphoramidate residue, an azo residue, a vicinal diol residue, an aromatic ring-containing residue having an electron-withdrawing group, a coumarin-containing residue, a sulfone-containing residue, an unsaturated bond-containing chain residue, and a glycosyl residue, p and p' are the same or different and are arbitrary integers from 0 to 10, q and q' are the same or different and are arbitrary integers from 0 to 10, X and X' are the same or different and are a carbon atom, a nitrogen atom, or a single bond (where when X is a nitrogen atom, R １ｂ does not exist, and when X' is a nitrogen atom, R １ｂ’ does not exist. When X is a single bond, R １ａ and R １ｂ do not exist, and when X' is a single bond, R １ａ’ and R １ｂ’ do not exist), and R １ａ 、R １ｂ 、R １ａ’ and R １ｂ’ are the same or different and are atoms or groups selected from the group consisting of the above (i) to (vii). Y and Y' are the same or different and are -NH-, -O-, -CH ２ -, or the following formula (B-2): 【Chemical 7】 [In the formula, V and V' are the same or different and are —NH—, —O—, —CH ２ —, or a single bond, V1 is a divalent group containing a bioorthogonal functional group, s is an arbitrary integer from 0 to 10, The ○ and ● in the formula (B-2) have the same orientation as the ○ and ● in the formula (B-1), respectively.). Z and Z' are the same or different and are an oxygen atom, a sulfur atom, or a hydrogen atom (when Z is a hydrogen atom, -C(=Z)- represents -CH ２ -.). A compound according to claim 13 or a salt thereof, represented by 〕.

15. The following formula (I): A-L-B-R (I) [In the formula, A is a binding peptide to the Fc region of a human IgG antibody, [Here, the binding peptide is a peptide selected from the group consisting of the following (1) to (8) or a salt thereof: (1) The following formula (i): (X1-3)-C-(X2)-H-(Xaa1)-G-(Xaa2)-L-V-W-C-(X1-3) (SEQ ID NO: 94) (i) [In the formula, X is, independently or identically, any amino acid residue other than cysteine, C is a cysteine residue, H is a histidine residue, Xaa1 is an arginine residue, a leucine residue, a lysine residue, an aspartic acid residue, a glutamic acid residue, a 2-aminosuberic acid residue, or a diaminopropionic acid residue, G is a glycine residue, Xaa2 is a lysine residue, a glutamine residue, a glutamic acid residue, an asparagine residue, or an aspartic acid residue, L is a leucine residue, V is a valine residue, and W is a tryptophan residue. ] A peptide or a salt thereof, which comprises an amino acid sequence consisting of 13 to 17 amino acid residues represented by the above and is capable of binding to human IgG; (2) The following formula (i-1): (X1-3)-C-(X2)-H-(Xaa1)-G-(Xaa2)-L-V-W-C- (X1-3) (SEQ ID NO: 95) (i-1) [In the formula, X is, independently or identically, any amino acid residue other than cysteine, C is a cysteine residue, H is a histidine residue, Xaa1 is a lysine residue, a cysteine residue, an aspartic acid residue, a glutamic acid residue, a 2-aminosuberic acid residue, or a diaminopropionic acid residue, G is a glycine residue, Xaa2 is a glutamic acid residue or an asparagine residue, L is a leucine residue, V is a valine residue, and W is a tryptophan residue. ] A peptide or a salt thereof, which comprises an amino acid sequence consisting of 13 to 17 amino acid residues represented by the above and is capable of binding to human IgG; (3) The following formula (i-2): (X1-3)-C-(X2)-H-(Xaa1)-G-(Xaa2)-L-V-W-C-(X1-3) (SEQ ID NO: 96) (i-2) [In the formula, X is, independently or identically, any amino acid residue other than cysteine, C is a cysteine residue, H is a histidine residue, Xaa1 is an arginine residue or a leucine residue, G is a glycine residue, Xaa2 is a lysine residue, a glutamine residue, or an aspartic acid residue, L is a leucine residue, V is a valine residue, and, W is a tryptophan residue. ] A peptide or a salt thereof, which comprises an amino acid sequence consisting of 13 to 17 amino acid residues represented by the above and is capable of binding to human IgG; (4) The following formula (v): (X1-3)-C-(Xaa3)-(xaa4)-H-(Xaa1)-G-(Xaa2)-L-V-W-C-(Xaa5)-(Xaa6)-(Xaa7) (SEQ ID NO: 102) (v) [In the formula, X is the same or different and is any amino acid residue other than cysteine, C is a cysteine residue, Xaa3 is an alanine residue or a lysine residue, Xaa4 is a tryptophan residue or a tyrosine residue, H is a histidine residue, Xaa1 is an arginine residue, a leucine residue, a lysine residue, an aspartic acid residue, a glutamic acid residue, a 2-aminosuberic acid residue, or a diaminopropionic acid residue, G is a glycine residue, Xaa2 is a lysine residue, a glutamine residue, a glutamic acid residue, an asparagine residue, or an aspartic acid residue, L is a leucine residue, V is a valine residue, W is a tryptophan residue, Xaa5 is a threonine residue or a lysine residue, Xaa6 is a tyrosine residue, a lysine residue, or none, and Xaa7 is a histidine residue, a lysine residue, or none.], an amino acid sequence consisting of 13 to 17 amino acid residues, and capable of binding to human IgG peptide or a salt thereof; (5) The following formula (vi): D-C-(Xaa3)-(Xaa4)-H-(Xaa1)-G-(Xaa2)-L-V-W-C-(Xaa5)-(Xaa6)-(Xaa7) (SEQ ID NO: 103) (vi) [In the formula, D is an aspartic acid residue, C is a cysteine residue, Xaa3 is an alanine residue or a lysine residue, Xaa4 is a tryptophan residue or a tyrosine residue, H is a histidine residue, Xaa1 is an arginine residue, a leucine residue, a lysine residue, an aspartic acid residue, a glutamic acid residue, a 2-aminosuberic acid residue, or a diaminopropionic acid residue, G is a glycine residue, Xaa2 is a lysine residue, a glutamine residue, a glutamic acid residue, an asparagine residue, or an aspartic acid residue, L is a leucine residue, V is a valine residue, W is a tryptophan residue, Xaa5 is a threonine residue or a lysine residue, Xaa6 is a tyrosine residue, a lysine residue, or none, Xaa7 is a histidine residue, a lysine residue, or none. A peptide or a salt thereof, which comprises an amino acid sequence consisting of 13 to 15 amino acid residues represented by [ ], and is capable of binding to human IgG; (6) The following formula (vii): D-C-(Xaa3)-(Xaa4)-H-(Xaa1)-G-(Xaa2)-L-V-W-C-T (SEQ ID NO: 104) (vii) [In the formula, D is an aspartic acid residue, C is a cysteine residue, Xaa3 is an alanine residue or a lysine residue, Xaa4 is a tryptophan residue or a tyrosine residue, H is a histidine residue, Xaa1 is an arginine residue, a leucine residue, a lysine residue, an aspartic acid residue, a glutamic acid residue, a 2-aminosuberic acid residue, or a diaminopropionic acid residue, G is a glycine residue, Xaa2 is a lysine residue, a glutamine residue, a glutamic acid residue, an asparagine residue, or an aspartic acid residue, L is a leucine residue, V is a valine residue, W is a tryptophan residue, and T is a threonine residue] A peptide or a salt thereof, which comprises an amino acid sequence consisting of 13 amino acid residues represented by [ ], and is capable of binding to human IgG; (7) The following formula (viii): R-G-N-C-(Xaa3)-(Xaa4)-H-(Xaa1)-G-(Xaa2)-L-V-W-C-(Xaa5)-(Xaa6)-(Xaa7) (SEQ ID NO: 105) (viii) [In the formula, R is an arginine residue, G is a glycine residue, N is an asparagine residue, C is a cysteine residue, Xaa3 is an alanine residue or a lysine residue, Xaa4 is a tryptophan residue or a tyrosine residue, H is a histidine residue, Xaa1 is an arginine residue, a leucine residue, a lysine residue, an aspartic acid residue, a glutamic acid residue, a 2-aminosuberic acid residue, or a diaminopropionic acid residue, G is a glycine residue, Xaa2 is a lysine residue, a glutamine residue, a glutamic acid residue, an asparagine residue, or an aspartic acid residue, L is a leucine residue, V is a valine residue, W is a tryptophan residue, Xaa5 is a threonine residue or a lysine residue, Xaa6 is a tyrosine residue, a lysine residue, or none, and Xaa7 is a histidine residue, a lysine residue, or none. A peptide or a salt thereof, which comprises an amino acid sequence consisting of 13 to 15 amino acid residues represented by the formula: and is capable of binding to human IgG; (8) (a) In the amino acid sequence of FNMQCQRRFYEALHDPNLNEEQRNARIRSIrddc (SEQ ID NO: 92), any amino acid residue is substituted with one amino acid residue selected from the group consisting of a lysine residue, an aspartic acid residue, a glutamic acid residue, a 2-aminosuberic acid residue, and a diaminopropionic acid residue, and (b) An affinity peptide or a salt thereof, which comprises an amino acid sequence having 90% or more identity to the amino acid sequence of SEQ ID NO: 92.], L is a cleavable linker which is a divalent group containing one cleavable moiety selected from the group consisting of a disulfide residue, an acetal residue, a ketal residue, an ester residue, a carbamoyl residue, an alkoxyalkyl residue, an imine residue, a tertiary alkyloxycarbamate residue, a silane residue, a hydrazone-containing residue, a phosphoramidate residue, an azo residue, a vicinal diol residue, an aromatic ring-containing residue having an electron-withdrawing group, a coumarin-containing residue, a sulfone-containing residue, an unsaturated bond-containing chain residue, and a glycosyl residue; B is (a) a divalent group containing a bioorthogonal functional group, or (b) a divalent group not containing a bioorthogonal functional group; R is a reactive group specific to the side chain of a lysine residue, and is (1) one group selected from the group consisting of an activated ester residue, a vinylsulfone residue, a sulfonyl chloride residue, an isocyanate residue, an isothiocyanate residue, an aldehyde residue, and a diazonium terephthalic acid residue, or (2) The following: [Chemical 8] [wherein R ５ａ and R ５c is an atom or group selected from the group consisting of the following (i) to (vii), (i) a hydrogen atom or a halogen atom; (ii) a monovalent hydrocarbon group; (iii) an aralkyl; (iv) a monovalent heterocyclic group; (v) Rc-O-, Rc-C(=O)-, Rc-O-C(=O)-, or Rc-C(=O)-O- (Rc represents a hydrogen atom or a monovalent hydrocarbon group.); (vi) NRdRe-, NRdRe-C(=O)-, NRdRe-C(=O)-O-, or Rd-C(=O)-NRe- (Rd and Re are the same or different and each represents a hydrogen atom or a monovalent hydrocarbon group.); or (vii) a nitro group, a sulfuric acid group, a sulfonic acid group, a cyano group, or a carboxyl group, R ５ｂ is an electron-withdrawing group, j is an arbitrary integer from 1 to 5, k is an arbitrary integer from 1 to 4. ] A group corresponding to any one chemical structure selected from the group consisting of. ] A compound having a binding peptide, a cleavable moiety and a reactive group for the Fc region of a human IgG antibody represented by the formula: or a salt thereof, a reagent for site-selective modification of a human IgG antibody. **Claim 16** The following formula (II): A-L-B-R'-T (II) [In the formula, A is a binding peptide for the Fc region of a human IgG antibody, [Here, the binding peptide is a peptide selected from the group consisting of the following (1) to (8) or a salt thereof: (1) The following formula (i): (X1-3)-C-(X2)-H-(Xaa1)-G-(Xaa2)-L-V-W-C-(X1-3) (SEQ ID NO: 94) (i) [In the formula, X is the same or different and is any amino acid residue other than cysteine, C is a cysteine residue, H is a histidine residue, Xaa1 is an arginine residue, a leucine residue, a lysine residue, an aspartic acid residue, a glutamic acid residue, a 2-aminosuberic acid residue, or a diaminopropionic acid residue, G is a glycine residue, Xaa2 is a lysine residue, a glutamine residue, a glutamic acid residue, an asparagine residue, or an aspartic acid residue, L is a leucine residue, V is a valine residue, and W is a tryptophan residue. ] A peptide consisting of 13 to 17 amino acid residues represented by the formula: or a salt thereof, which contains an amino acid sequence and is capable of binding to human IgG; (2) The following formula (i-1): (X1-3)-C-(X2)-H-(Xaa1)-G-(Xaa2)-L-V-W-C-(X1-3) (SEQ ID NO: 95) (i-1) [In the formula, X is the same or different and is any amino acid residue other than cysteine, C is a cysteine residue, H is a histidine residue, Xaa1 is a lysine residue, a cysteine residue, an aspartic acid residue, a glutamic acid residue, a 2-aminosuberic acid residue, or a diaminopropionic acid residue, G is a glycine residue, Xaa2 is a glutamic acid residue or an asparagine residue, L is a leucine residue, V is a valine residue, and W is a tryptophan residue. ] A peptide or a salt thereof, which comprises an amino acid sequence consisting of 13 to 17 amino acid residues represented thereby and is capable of binding to human IgG; (3) The following formula (i-2): (X1-3)-C-(X2)-H-(Xaa1)-G-(Xaa2)-L-V-W-C-(X1-3) (SEQ ID NO: 96) (i-2) [In the formula, X is the same or different and is any amino acid residue other than cysteine, C is a cysteine residue, H is a histidine residue, Xaa1 is an arginine residue or a leucine residue, G is a glycine residue, Xaa2 is a lysine residue, a glutamine residue or an aspartic acid residue, L is a leucine residue, V is a valine residue, and W is a tryptophan residue. ] A peptide or a salt thereof, which comprises an amino acid sequence consisting of 13 to 17 amino acid residues represented thereby and is capable of binding to human IgG; (4) The following formula (v): (X1-3)-C-(Xaa3)-(xaa4)-H-(Xaa1)-G-(Xaa2)-L-V-W-C-(Xaa5)-(Xaa6)-(Xaa7) (SEQ ID NO: 102) (v) [In the formula, X is the same or different and is any amino acid residue other than cysteine, C is a cysteine residue, Xaa3 is an alanine residue or a lysine residue, Xaa4 is a tryptophan residue or a tyrosine residue, H is a histidine residue, Xaa1 is an arginine residue, a leucine residue, a lysine residue, an aspartic acid residue, a glutamic acid residue, a 2-aminosuberic acid residue or a diaminopropionic acid residue, G is a glycine residue, Xaa2 is a lysine residue, a glutamine residue, a glutamic acid residue, an asparagine residue or an aspartic acid residue, L is a leucine residue, V is a valine residue, W is a tryptophan residue, Xaa5 is a threonine residue or a lysine residue, Xaa6 is a tyrosine residue, a lysine residue or none, and Xaa7 is a histidine residue, a lysine residue or none. ] A peptide or a salt thereof, which comprises an amino acid sequence consisting of 13 to 17 amino acid residues represented thereby and is capable of binding to human IgG; (5) The following formula (vi): D-C-(Xaa3)-(Xaa4)-H-(Xaa1)-G-(Xaa2)-L-V-W-C-(Xaa5)-(Xaa6)-(Xaa7) (SEQ ID NO: 103) (vi) [In the formula, D is an aspartic acid residue, C is a cysteine residue, Xaa3 is an alanine residue or a lysine residue, Xaa4 is a tryptophan residue or a tyrosine residue, H is a histidine residue, Xaa1 is an arginine residue, a leucine residue, a lysine residue, an aspartic acid residue, a glutamic acid residue, a 2-aminosuberic acid residue, or a diaminopropionic acid residue, G is a glycine residue, Xaa2 is a lysine residue, a glutamine residue, a glutamic acid residue, an asparagine residue, or an aspartic acid residue, L is a leucine residue, V is a valine residue, W is a tryptophan residue, Xaa5 is a threonine residue or a lysine residue, Xaa6 is a tyrosine residue, a lysine residue, or none, Xaa7 is a histidine residue, a lysine residue, or none.] A peptide or a salt thereof, comprising an amino acid sequence consisting of 13 to 15 amino acid residues and being capable of binding to human IgG; (6) The following formula (vii): D-C-(Xaa3)-(Xaa4)-H-(Xaa1)-G-(Xaa2)-L-V-W-C-T (SEQ ID NO: 104) (vii) [In the formula, D is an aspartic acid residue, C is a cysteine residue, Xaa3 is an alanine residue or a lysine residue, Xaa4 is a tryptophan residue or a tyrosine residue, H is a histidine residue, Xaa1 is an arginine residue, a leucine residue, a lysine residue, an aspartic acid residue, a glutamic acid residue, a 2-aminosuberic acid residue, or a diaminopropionic acid residue, G is a glycine residue, Xaa2 is a lysine residue, a glutamine residue, a glutamic acid residue, an asparagine residue, or an aspartic acid residue, L is a leucine residue, V is a valine residue, W is a tryptophan residue, and T is a threonine residue] A peptide or a salt thereof, comprising an amino acid sequence consisting of 13 amino acid residues and being capable of binding to human IgG; (7) The following formula (viii): R-G-N-C-(Xaa3)-(Xaa4)-H-(Xaa1)-G-(Xaa2)-L-V-W-C-(Xaa5)-(Xaa6)-(Xaa7) (SEQ ID NO: 105) (viii) [In the formula, R is an arginine residue, G is a glycine residue, N is an asparagine residue, C is a cysteine residue, Xaa3 is an alanine residue or a lysine residue, Xaa4 is a tryptophan residue or a tyrosine residue, H is a histidine residue, Xaa1 is an arginine residue, a leucine residue, a lysine residue, an aspartic acid residue, a glutamic acid residue, a 2-aminosuberic acid residue, or a diaminopropionic acid residue, G is a glycine residue, Xaa2 is a lysine residue, a glutamine residue, a glutamic acid residue, an asparagine residue, or an aspartic acid residue, L is a leucine residue, V is a valine residue, W is a tryptophan residue, Xaa5 is a threonine residue or a lysine residue, Xaa6 is a tyrosine residue, a lysine residue, or none, and Xaa7 is a histidine residue, a lysine residue, or none.], a peptide or a salt thereof, which comprises an amino acid sequence consisting of 13 to 15 amino acid residues and is capable of binding to human IgG; (8) (a) In the amino acid sequence of FNMQCQRRFYEAHLDPNLNEEQRNARIRSIIDD C (SEQ ID NO: 92), any amino acid residue is substituted with one amino acid residue selected from the group consisting of a lysine residue, an aspartic acid residue, a glutamic acid residue, a 2-aminosuberic acid residue, and a diaminopropionic acid residue, and (b) an affinity peptide or a salt thereof, which comprises an amino acid sequence having 90% or more identity to the amino acid sequence of SEQ ID NO: 92.], L is a cleavable linker which is a divalent group containing one cleavable moiety selected from the group consisting of a disulfide residue, an acetal residue, a ketal residue, an ester residue, a carbamoyl residue, an alkoxyalkyl residue, an imine residue, a tertiary alkyloxycarbamate residue, a silane residue, a hydrazone-containing residue, a phosphoramidate residue, an azo residue, a vicinal diol residue, an aromatic ring-containing residue having an electron-withdrawing group, a coumarin-containing residue, a sulfone-containing residue, an unsaturated bond-containing chain residue, and a glycosyl residue, B is a divalent group containing a bioorthogonal functional group or a divalent group not containing a bioorthogonal functional group, R' is a reactive group specific to the side chain of a lysine residue and a human IgG antibody, and is (1) one group selected from the group consisting of an activated ester residue, a vinyl sulfone residue, a sulfonyl chloride residue, an isocyanate residue, an isothiocyanate residue, an aldehyde residue, and a diazonium terephthalic acid residue, or (2) the following: 【Chemical Formula 9】 [where R ５ａ and R ５c is an atom or group selected from the group consisting of the following (i) to (vii), (i) a hydrogen atom or a halogen atom; (ii) a monovalent hydrocarbon group; (iii) an aralkyl; (iv) a monovalent heterocyclic group; (v) Rc-O-, Rc-C(=O)-, Rc-O-C(=O)-, or Rc-C(=O)-O- (Rc represents a hydrogen atom or a monovalent hydrocarbon group.); (vi) NRdRe-, NRdRe-C(=O)-, NRdRe-C(=O)-O-, or Rd-C(=O)-NRe- (Rd and Re are the same or different and represent a hydrogen atom or a monovalent hydrocarbon group.); or (vii) a nitro group, a sulfate group, a sulfonic acid group, a cyano group, or a carboxyl group, R ５ｂ is an electron-withdrawing group, j is an arbitrary integer from 1 to 5, k is an arbitrary integer from 1 to 4. ] It is a part generated by the reaction with any one group corresponding to the chemical structure selected from the group consisting of, T is a human IgG antibody. ], a binding peptide to the Fc region of a human IgG antibody, and a human IgG antibody having a cleavable moiety or a salt thereof.

17. The human IgG antibody contains one or more specific amino acid residues in a target region consisting of 1 to 50 consecutive amino acid residues, the target region is the CH2 region of the human IgG antibody, and in a non-target region other than the target region, Contains 5 or more of the specific amino acid residues, The structural unit represented by A-L-B-R' binds to one or more specific amino acid residues contained in the target region with a positional selectivity of 30% or more. The human IgG antibody or a salt thereof according to claim 16.

18. The target region is (a) a region consisting of amino acid residues at positions 246 to 248 in the human IgG Fc region, (b) a region consisting of amino acid residues at positions 288 to 290 in the human IgG Fc region, or (c) the human IgG Fc region. The human IgG antibody or a salt thereof according to claim 17, which is a region consisting of the amino acid residue at position 317.

19. The human IgG antibody is a human IgG antibody containing a plurality of heavy chains, and as a result of T having a structural unit represented by A-L-B-R' in a plurality of corresponding CH2 regions among the plurality of heavy chains, the human IgG antibody has a plurality of structural units represented by A-L-B-R', the human IgG antibody or a salt thereof according to any one of claims 16 to 18.

20. The human IgG antibody or a salt thereof according to claim 19, wherein the number of heavy chains is two.

21. The portion generated by the reaction is as follows: 【Chemical formula 10】 〔Here, ● (black circle) indicates a bond to the T-side portion, and ○ (white circle) indicates a bond to the B-side portion. A straight line orthogonal to the bond indicates a bond generated by the reaction.〕 consisting of The human IgG antibody or a salt thereof according to any one of claims 16 to 20, corresponding to any one chemical structure selected from the group.

22. The compound represented by the formula (II) is the following (II'): A-B2-L'-B1-R'-T (II') 〔In the formula, A, R' and T are the same as those in the formula (II) L' is a cleavable linker which is a divalent group containing one cleavable moiety selected from the group consisting of a disulfide residue, an acetal residue, a ketal residue, an ester residue, a carbamoyl residue, an alkoxyalkyl residue, an imine residue, a tertiary alkyloxycarbamate residue, a silane residue, a hydrazone-containing residue, a phosphoramidate residue, an azo residue, a vicinal diol residue, an aromatic ring-containing residue having an electron-withdrawing group, a coumarin-containing residue, a sulfone-containing residue, an unsaturated bond-containing chain residue, and a glycosyl residue, B1 and B2 are the same or different and are (a) a divalent group containing a bioorthogonal functional group, or (b) a divalent group not containing a bioorthogonal functional group, B1 and B2 may have a symmetric structure centered on L'.〕 and is a compound represented by, the human IgG antibody or a salt thereof according to any one of claims 16 to 21.

23. The compound represented by the formula (II') is the following (II''): 【Chemical 11】 〔In the formula, A, R' and T are the same as those in the formula (II), C is one of the cleavable moieties selected from the group consisting of a disulfide residue, an acetal residue, a ketal residue, an ester residue, a carbamoyl residue, an alkoxyalkyl residue, an imine residue, a tertiary alkyloxycarbamate residue, a silane residue, a hydrazone-containing residue, a phosphoramidate residue, an azo residue, a vicinal diol residue, an aromatic ring-containing residue having an electron-withdrawing group, a coumarin-containing residue, a sulfone-containing residue, an unsaturated bond-containing chain residue, and a glycosyl residue, p and p' are the same or different and are any integer from 0 to 10, q and q' are the same or different and are any integer from 0 to 10, X and X' are the same or different and are a carbon atom, a nitrogen atom, or a single bond (wherein when X is a nitrogen atom, R １ｂ does not exist, and when X' is a nitrogen atom, R １ｂ’ does not exist. When X is a single bond, R １ａ and R １ｂ do not exist, and when X' is a single bond, R １ａ’ and R １ｂ’ do not exist), and R １ａ , R １ｂ , R １ａ’ and R １ｂ’ are the same or different, (i) a hydrogen atom or a halogen atom; (ii) a monovalent hydrocarbon group; (iii) an aralkyl; (iv) a monovalent heterocyclic group; (v) R ｃ -O-, R ｃ -C(=O)-, R ｃ -O-C(=O)-, or R ｃ -C(=O)-O-(R ｃ represents a hydrogen atom or a monovalent hydrocarbon group.); (vi) NR ｄ R ｅ —, NR ｄ R ｅ —C(=O)—, NR ｄ R ｅ —C(=O)—O—, or R ｄ —C(=O)—NR ｅ —(R ｄ and R ｅ are the same or different and each represents a hydrogen atom or a monovalent hydrocarbon group.); or (vii) a nitro group, a sulfate group, a sulfonic acid group, a cyano group, or a carboxyl group selected from the group consisting of, Y and Y' are the same or different and are —NH—, —O—, —CH ２ —, or the following formula (B-2): 【Chemical Formula 12】 (wherein, V and V' are the same or different and are —NH—, —O—, —CH ２ —, or a single bond, V1 is a divalent group containing a bioorthogonal functional group, s is any integer from 0 to 10, ○ and ● in formula (B-2) have the same orientation as ○ and ● in formula (B-1), respectively.) Z and Z' are the same or different and are an oxygen atom, a sulfur atom, or a hydrogen atom (when Z is a hydrogen atom, -C(=Z)- is -CH ２ -.).], the human IgG antibody or a salt thereof according to claim 22.

24. The following formula (III): A-L-B'(-F)-R'-T (III) [wherein, A is a binding peptide to the Fc region of a human IgG antibody, [where the binding peptide is a peptide or a salt thereof selected from the group consisting of the following (1) to (8): (1) The following formula (i): (X1-3)-C-(X2)-H-(Xaa1)-G-(Xaa2)-L-V-W-C-(X1-3) (SEQ ID NO: 94) (i) [wherein, Xs are the same or different and are any amino acid residues other than cysteine, C is a cysteine residue, H is a histidine residue, Xaa1 is an arginine residue, a leucine residue, a lysine residue, an aspartic acid residue, a glutamic acid residue, a 2-aminosuberic acid residue, or a diaminopropionic acid residue, G is a glycine residue, Xaa2 is a lysine residue, a glutamine residue, a glutamic acid residue, an asparagine residue, or an aspartic acid residue, L is a leucine residue, V is a valine residue, and W is a tryptophan residue.]] a peptide or a salt thereof containing an amino acid sequence consisting of 13 to 17 amino acid residues represented by the above and capable of binding to human IgG; (2) The following formula (i-1): (X1-3)-C-(X2)-H-(Xaa1)-G-(Xaa2)-L-V-W-C-(X1-3) (SEQ ID NO:95) (i-1) [In the formula, X is the same or different and is any amino acid residue other than cysteine, C is a cysteine residue, H is a histidine residue, Xaa1 is a lysine residue, a cysteine residue, an aspartic acid residue, a glutamic acid residue, a 2-aminosuberic acid residue, or a diaminopropionic acid residue, G is a glycine residue, Xaa2 is a glutamic acid residue or an asparagine residue, L is a leucine residue, V is a valine residue, and W is a tryptophan residue. ] A peptide or a salt thereof that comprises an amino acid sequence consisting of 13 to 17 amino acid residues represented by the formula and is capable of binding to human IgG; (3) The following formula (i-2): (X1-3)-C-(X2)-H-(Xaa1)-G-(Xaa2)-L-V-W-C-(X1-3) (SEQ ID NO:96) (i-2) [In the formula, X is the same or different and is any amino acid residue other than cysteine, C is a cysteine residue, H is a histidine residue, Xaa1 is an arginine residue or a leucine residue, G is a glycine residue, Xaa2 is a lysine residue, a glutamine residue, or an aspartic acid residue, L is a leucine residue, V is a valine residue, and W is a tryptophan residue. ] A peptide or a salt thereof that comprises an amino acid sequence consisting of 13 to 17 amino acid residues represented by the formula and is capable of binding to human IgG; (4) The following formula (v): (X1-3)-C-(Xaa3)-(xaa4)-H-(Xaa1)-G-(Xaa2)-L-V-W-C-(Xaa5)-(Xaa6)-(Xaa7) (SEQ ID NO:102) (v) [In the formula, X is the same or different and is any amino acid residue other than cysteine, C is a cysteine residue, Xaa3 is an alanine residue or a lysine residue, Xaa4 is a tryptophan residue or a tyrosine residue, H is a histidine residue, Xaa1 is an arginine residue, a leucine residue, a lysine residue, an aspartic acid residue, a glutamic acid residue, a 2-aminosuberic acid residue, or a diaminopropionic acid residue, G is a glycine residue, Xaa2 is a lysine residue, a glutamine residue, a glutamic acid residue, an asparagine residue, or an aspartic acid residue, L is a leucine residue, V is a valine residue, W is a tryptophan residue, Xaa5 is a threonine residue, or a lysine residue, Xaa6 is a tyrosine residue, a lysine residue, or none, and Xaa7 is a histidine residue, a lysine residue, or none.], comprising an amino acid sequence consisting of 13 to 17 amino acid residues and being capable of binding to human IgG; (5) The following formula (vi): D-C-(Xaa3)-(Xaa4)-H-(Xaa1)-G-(Xaa2)-L-V-W-C-(Xaa5)-(Xaa6)-(Xaa7) (SEQ ID NO: 103) (vi) [In the formula, D is an aspartic acid residue, C is a cysteine residue, Xaa3 is an alanine residue, or a lysine residue, Xaa4 is a tryptophan residue, or a tyrosine residue, H is a histidine residue, Xaa1 is an arginine residue, a leucine residue, a lysine residue, an aspartic acid residue, a glutamic acid residue, a 2-aminosuberic acid residue, or a diaminopropionic acid residue, G is a glycine residue, Xaa2 is a lysine residue, a glutamine residue, a glutamic acid residue, an asparagine residue, or an aspartic acid residue, L is a leucine residue, V is a valine residue, W is a tryptophan residue, Xaa5 is a threonine residue, or a lysine residue, Xaa6 is a tyrosine residue, a lysine residue, or none, Xaa7 is a histidine residue, a lysine residue, or none.], comprising an amino acid sequence consisting of 13 to 15 amino acid residues and being characterized by being capable of binding to human IgG; (6) The following formula (vii): D-C-(Xaa3)-(Xaa4)-H-(Xaa1)-G-(Xaa2)-L-V-W-C-T (SEQ ID NO: 104) (vii) [In the formula, D is an aspartic acid residue, C is a cysteine residue, Xaa3 is an alanine residue, or a lysine residue, Xaa4 is a tryptophan residue, or a tyrosine residue, H is a histidine residue, Xaa1 is an arginine residue, a leucine residue, a lysine residue, an aspartic acid residue, a glutamic acid residue, a 2-aminosuberic acid residue, or a diaminopropionic acid residue, G is a glycine residue, Xaa2 is a lysine residue, a glutamine residue, a glutamic acid residue, an asparagine residue, or an aspartic acid residue, L is a leucine residue, V is a valine residue, W is a tryptophan residue, and T is a threonine residue], and contains an amino acid sequence consisting of 13 amino acid residues, and is characterized by being capable of binding to human IgG; (7) The following formula (viii): R-G-N-C-(Xaa3)-(Xaa4)-H-(Xaa1)-G-(Xaa2)-L-V-W-C-(Xaa5)-(Xaa6)-(Xaa7) (SEQ ID NO: 105) (viii) [In the formula, R is an arginine residue, G is a glycine residue, N is an asparagine residue, C is a cysteine residue, Xaa3 is an alanine residue, or a lysine residue, Xaa4 is a tryptophan residue, or a tyrosine residue, H is a histidine residue, Xaa1 is an arginine residue, a leucine residue, a lysine residue, an aspartic acid residue, a glutamic acid residue, a 2-aminosuberic acid residue, or a diaminopropionic acid residue, G is a glycine residue, Xaa2 is a lysine residue, a glutamine residue, a glutamic acid residue, an asparagine residue, or an aspartic acid residue, L is a leucine residue, V is a valine residue, W is a tryptophan residue, Xaa5 is a threonine residue, or a lysine residue, Xaa6 is a tyrosine residue, a lysine residue, or none, and Xaa7 is a histidine residue, a lysine residue, or none.], and contains an amino acid sequence consisting of 13 to 15 amino acid residues, and is characterized by being capable of binding to human IgG; (8) (a) In the amino acid sequence of FNMQCQRRFYERALHDPNLNEEQRNARIRSIIDD C (SEQ ID NO: 92), any amino acid residue is replaced by one amino acid residue selected from the group consisting of a lysine residue, an aspartic acid residue, a glutamic acid residue, a 2-aminosuberic acid residue, and a diaminopropionic acid residue, and (b) An affinity peptide or a salt thereof, comprising an amino acid sequence having 90% or more identity to the amino acid sequence of SEQ ID NO:

92. ], L is a cleavable linker which is a divalent group containing one cleavable moiety selected from the group consisting of a disulfide residue, an acetal residue, a ketal residue, an ester residue, a carbamoyl residue, an alkoxyalkyl residue, an imine residue, a tertiary alkyloxycarbamate residue, a silane residue, a hydrazone-containing residue, a phosphoramidate residue, an azo residue, a vicinal diol residue, an aromatic ring-containing residue having an electron-withdrawing group, a coumarin-containing residue, a sulfone-containing residue, an unsaturated bond-containing chain residue, and a glycosyl residue, B' is a divalent group containing a moiety generated by the reaction between a functional substance and a bioorthogonal functional group, F is a functional substance, R' is a reactive group specific for the side chain of a lysine residue and a human IgG antibody, and is (1) one group selected from the group consisting of an activated ester residue, a vinyl sulfone residue, a sulfonyl chloride residue, an isocyanate residue, an isothiocyanate residue, an aldehyde residue, and a diazonium terephthalic acid residue, or (2) the following: 【Chemical Formula 13】 [wherein R ５ａ and R ５c is an atom or group selected from the group consisting of the following (i) to (vii), (i) a hydrogen atom or a halogen atom; (ii) a monovalent hydrocarbon group; (iii) an aralkyl; (iv) a monovalent heterocyclic group; (v) Rc-O-, Rc-C(=O)-, Rc-O-C(=O)-, or Rc-C(=O)-O- (Rc represents a hydrogen atom or a monovalent hydrocarbon group.); (vi) NRdRe-, NRdRe-C(=O)-, NRdRe-C(=O)-O-, or Rd-C(=O)-NRe- (Rd and Re are the same or different and represent a hydrogen atom or a monovalent hydrocarbon group.); or (vii) a nitro group, a sulfate group, a sulfonic acid group, a cyano group, or a carboxyl group, R ５ｂ is an electron-withdrawing group, j is an arbitrary integer from 1 to 5, k is an arbitrary integer from 1 to 4. ] and is a moiety generated by the reaction with a group corresponding to any one chemical structure selected from the group consisting of, T is a human IgG antibody. ], a conjugate or a salt thereof, having a binding peptide for the Fc region of a human IgG antibody, a cleavable moiety, a functional substance, and a human IgG antibody, wherein the functional substance is a drug or a labeling substance.

25. The human IgG antibody contains one or more specific amino acid residues in a target region consisting of 1 to 50 consecutive amino acid residues, the target region is the CH2 region of the human IgG antibody, and the non-target region other than the target region contains five or more of the specific amino acid residues. The complex or a salt thereof according to claim 24, wherein the structural unit represented by A-L-B'(-F)-R' binds to one or more specific amino acid residues contained in the target region with a positional selectivity of 30% or more.

26. The human IgG antibody is an antibody containing a plurality of heavy chains. The complex or a salt thereof according to claim 24 or 25, wherein T has a structural unit represented by A-L-B'(-F)-R' in the corresponding plurality of CH2 regions in the plurality of heavy chains, and as a result, the antibody has a plurality of structural units represented by A-L-B'(-F)-R'.

27. The complex or a salt thereof according to any one of claims 24 to 26, wherein the divalent group containing a moiety generated by the reaction between the functional substance and the bioorthogonal functional group is a divalent group containing a reaction moiety selected from the group consisting of a disulfide residue, an acetal residue, a ketal residue, an ester residue, a carbamoyl residue, an alkoxyalkyl residue, an imine residue, a tertiary alkyloxycarbamate residue, a silane residue, a hydrazone-containing residue, a phosphoramidate residue, an aconityl residue, a trityl residue, an azo residue, a vicinal diol residue, a selenium residue, an aromatic ring-containing residue having an electron-withdrawing group, a coumarin-containing residue, a sulfone-containing residue, an unsaturated bond-containing chain residue, and a glycosyl residue.

28. The moiety generated by the reaction is as follows: 【Chemical 14】 〔Here, the wavy line orthogonal to the bond indicates the bond generated by the reaction. A plurality of Rs ２ａ , a plurality of Rs ２ｂ , and a plurality of Rs ２ｃ are the same or different and (i) A hydrogen atom or a halogen atom; (ii) A monovalent hydrocarbon group; (iii) An aralkyl; (iv) A monovalent heterocyclic group; (v) R ｃ -O-, R ｃ -C(=O)-, R ｃ -O-C(=O)-, or R ｃ -C(=O)-O-(R ｃ represents a hydrogen atom or a monovalent hydrocarbon group.); (vi) NR ｄ R ｅ —, NR ｄ R ｅ —C(=O)—, NR ｄ R ｅ —C(=O)—O—, or R ｄ —C(=O)—NR ｅ —(R ｄ and R ｅ are the same or different and each represents a hydrogen atom or a monovalent hydrocarbon group.); or (vii) A nitro group, a sulfate group, a sulfonic acid group, a cyano group, or a carboxyl group selected from the group consisting of, J is -CH ２ -, -O-, or -S-, and r is an arbitrary integer from 1 to 4, ○ (white circle) indicates the bond to A, and ● (black circle) indicates the bond to B. When the chemical structure is asymmetric around the cleavage site, ● may indicate the bond to A and ○ may indicate the bond to B.〕 The complex or a salt thereof according to any one of claims 24 to 27, corresponding to any one of the chemical structures selected from the group consisting of.

29. The complex or a salt thereof according to claim 28, wherein the drug is an anticancer agent.

30. The compound represented by the formula (III) is the following formula (III'): A - B2'(-F2) - L' - B1'(-F1) - R' - T (III') [In the formula, A, R' and T are the same as those in the formula (II), L' is a cleavable linker which is a divalent group containing one cleavable moiety selected from the group consisting of a disulfide residue, an acetal residue, a ketal residue, an ester residue, a carbamoyl residue, an alkoxyalkyl residue, an imine residue, a tertiary alkyloxycarbamate residue, a silane residue, a hydrazone-containing residue, a phosphoramidate residue, an azo residue, a vicinal diol residue, an aromatic ring-containing residue having an electron-withdrawing group, a coumarin-containing residue, a sulfone-containing residue, an unsaturated bond-containing chain residue, and a glycosyl residue, B1' and B2' are the same or different and are divalent groups containing a moiety generated by the reaction between a functional substance and a bioorthogonal functional group, F1 and F2 are the same or different and are functional substances, B1'(-F1) and B2'(-F2) may have a symmetric structure centered on L'.] The complex or a salt thereof according to any one of claims 24 to 29.

31. The compound represented by the formula (III') is the following (III''): 【Chemical Formula 15】 [In the formula, A, R' and T are the same as those in the formula (III), C is one cleavable moiety selected from the group consisting of a disulfide residue, an acetal residue, a ketal residue, an ester residue, a carbamoyl residue, an alkoxyalkyl residue, an imine residue, a tertiary alkyloxycarbamate residue, a silane residue, a hydrazone-containing residue, a phosphoramidate residue, an azo residue, a vicinal diol residue, an aromatic ring-containing residue having an electron-withdrawing group, a coumarin-containing residue, a sulfone-containing residue, an unsaturated bond-containing chain residue, and a glycosyl residue, p and p' are the same or different and are arbitrary integers from 0 to 10, q and q' are the same or different and are arbitrary integers from 0 to 10, X and X' are the same or different and are a carbon atom, a nitrogen atom, or a single bond (wherein when X is a nitrogen atom, R １ｂ does not exist, and when X' is a nitrogen atom, R １ｂ’ does not exist. When X is a single bond, R １ａ and R １ｂ do not exist, and when X' is a single bond, R １ａ’ and R １ｂ’ do not exist), and R １ａ 、R １ｂ 、R １ａ’ and R １ｂ’ are the same or different and are selected from the group consisting of the above (i) to (vii), Y and Y' are the same or different and are -NH-, -O-, -CH ２ -, or the following formula (B-2): 【Chemical 16】 [In the formula, V and V' are the same or different and are —NH—, —O—, —CH ２ —, or a single bond, V1 is a divalent group containing a bioorthogonal functional group, s is an arbitrary integer from 0 to 10, ○ and ● in the formula (B - 2) have the same orientation as ○ and ● in the formula (B - 1), respectively.] Z and Z' are the same or different and are an oxygen atom, a sulfur atom, or a hydrogen atom (when Z is a hydrogen atom, —C(═Z)— is —CH ２ —). F and F' are the same or different and are functional substances. The complex or a salt thereof according to claim 30, represented by 〕.

32. The following formula (IV): L1 - B - R' - T (IV) 〔In the formula, L1 is (i') a monovalent group containing a bioorthogonal functional group, or (ii') a monovalent group not containing a bioorthogonal functional group, B is (a) a divalent group containing a bioorthogonal functional group, or (b) a divalent group not containing a bioorthogonal functional group, The partial structure represented by L1 - B is a group not containing a peptide moiety, R' is a reactive group specific for the side chain of a lysine residue with a human IgG antibody, and is (1) one group selected from the group consisting of an activated ester residue, a vinylsulfone residue, a sulfonyl chloride residue, an isocyanate residue, an isothiocyanate residue, an aldehyde residue, and a diazonium terephthalic acid residue, or (2) the following: 【Chemical 17】 〔Here, R ５ａ and R ５c is an atom or group selected from the group consisting of the following (i) to (vii): (i) a hydrogen atom or a halogen atom; (ii) a monovalent hydrocarbon group; (iii) an aralkyl; (iv) a monovalent heterocyclic group; (v) Rc - O -, Rc - C(=O) -, Rc - O - C(=O) -, or Rc - C(=O) - O - (Rc represents a hydrogen atom or a monovalent hydrocarbon group.); (vi) NRdRe -, NRdRe - C(=O) -, NRdRe - C(=O) - O -, or Rd - C(=O) - NRe - (Rd and Re are the same or different and represent a hydrogen atom or a monovalent hydrocarbon group.); or (vii) a nitro group, a sulfate group, a sulfonic acid group, a cyano group, or a carboxyl group, R ５ｂ is an electron-withdrawing group, j is an arbitrary integer from 1 to 5, k is an arbitrary integer from 1 to 4. 〕 is a part formed by the reaction with any one group selected from the group consisting of, T is a human IgG antibody, The human IgG antibody contains one or more lysine residues in a target region consisting of 1 to 50 consecutive amino acid residues, the target region is the CH2 region of the human IgG antibody, and contains 5 or more of the lysine residues in a non-target region other than the target region. 〕 and is represented by, and the structural unit represented by L1 - B - R' binds to one or more lysine residues contained in the target region of the antibody with a positional selectivity of 30% or more. A human IgG antibody having a bioorthogonal functional group with positional selectivity or a salt thereof.

33. The following formula (V): F - (L1 - B)' - R' - T (V) 〔In the formula, ​ L1 is a monovalent group containing a (i') bioorthogonal functional group or a (ii') monovalent group not containing a bioorthogonal functional group, B is a divalent group containing a (a) bioorthogonal functional group or a (b) divalent group not containing a bioorthogonal functional group, The structural unit represented by (L1-B)' is a divalent structural unit containing no peptide moiety and containing a moiety generated by the reaction between a functional substance and one or both of the bioorthogonal functional groups in (i') and (a), F is a functional substance, R' is a reactive group specific to the side chain of a lysine residue and a human IgG antibody, and is (1) a group selected from the group consisting of an activated ester residue, a vinyl sulfone residue, a sulfonyl chloride residue, an isocyanate residue, an isothiocyanate residue, an aldehyde residue, and a diazonium terephthalic acid residue, or (2) the following: 【Chemical 18】 [where R ５ａ and R ５c is an atom or group selected from the group consisting of the following (i) to (vii), (i) a hydrogen atom or a halogen atom; (ii) a monovalent hydrocarbon group; (iii) an aralkyl; (iv) a monovalent heterocyclic group; (v) Rc-O-, Rc-C(=O)-, Rc-O-C(=O)-, or Rc-C(=O)-O- (Rc represents a hydrogen atom or a monovalent hydrocarbon group.); (vi) NRdRe-, NRdRe-C(=O)-, NRdRe-C(=O)-O-, or Rd-C(=O)-NRe- (Rd and Re are the same or different and represent a hydrogen atom or a monovalent hydrocarbon group.); or (vii) a nitro group, a sulfate group, a sulfonic acid group, a cyano group, or a carboxyl group, R ５ｂ is an electron-withdrawing group, j is an arbitrary integer from 1 to 5, k is an arbitrary integer from 1 to 4. ] and is a moiety generated by the reaction with a group corresponding to any one chemical structure selected from the group consisting of, T is a human IgG antibody, The human IgG antibody contains one or more lysine residues in a target region consisting of 1 to 50 consecutive amino acid residues, the target region is the CH2 region of the human IgG antibody, and contains 5 or more lysine residues in a non-target region other than the target region. ], and A human IgG antibody or a salt thereof having a functional substance that selectively positions a functional substance represented by F-(L1-B)'-R' binds to one or more lysine residues contained in the target region of the antibody with a positional selectivity of 30% or more, and the functional substance is a drug or a labeling substance.

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