675 results about "Leucines" patented technology

The invention discloses a high-performance carbonyl reductase mutant and application thereof in synthesis of a series of chiral alcohols. The high-performance carbonyl reductase mutant is obtained by performing the following mutations on an amino acid sequence as shown in SEQ ID NO.2: the 69th alanine mutates into any one of lysine, leucine, aspartic acid or asparagine, and the 69th alanine mutates into any one of lysine, leucine, aspartic acid or asparagine; and / or the 100th glycine is mutated into any one of glutamic acid, serine, lysine or asparagine. Compared with a wild type enzyme, the thermal stability and the catalytic activity of the obtained mutant are remarkably improved, particularly, single point mutants Mut-A69N, Mut-G100E and Mut-G100N and a combined mutant Mut-A69N-G100N show excellent relative enzyme activity, thermal stability and substrate tolerance. The mutant has high catalytic activity and stability to various chiral alcohols, and the contradiction that the traditional carbonyl reductase is easy to inactivate at high temperature and the catalytic efficiency is difficult to achieve at the same time is solved. The invention provides an efficient and stable enzyme catalysis tool for green biological preparation of chiral drug intermediates.

The invention relates to the technical field of biological catalysis, and discloses an L379A mutant enzyme for preparing rebaudioside I. The enzyme is obtained by the following mutations generated by UGT76G1: leucine of the 379th amino acid sequence is mutated into alanine; the enzyme can be applied to RA in-vitro conversion preparation of RI with higher utilization value, the conversion rate is higher than 50%, and the enzyme activity is remarkably improved by 7 times compared with the original enzyme catalytic conversion enzyme activity. The UGT76G1 mutant disclosed by the invention has the advantages that (1) the blank is filled, and a special enzyme catalyst capable of realizing efficient in-vitro synthesis of rebaudioside I (RI) is provided for the first time; 2) efficiency jump: the catalytic conversion rate is greatly increased from original about 7% to more than 50% (increase gt; and 3) stability and reliability: in the cross-scale reaction of 10mL to 5L, the catalyst has stable catalytic performance, shows excellent industrial application potential, and is suitable for popularization and application.

The present disclosure provides methods of treating a SYNGAP1-related disorder in a subject by administering a therapeutically effective amount of N-acetyl leucine.

The present disclosure provides methods of treating a neurodevelopmental disorder (NDD) in a subject by administering a therapeutically effective amount of N-acetyl leucine.

The invention discloses a p-nitrophenyl ethyl esterase mutant with high enantioselectivity as well as a construction method and application of the p-nitrophenyl ethyl esterase mutant. The p-nitrophenyl ethyl esterase mutant is obtained by mutating an amino acid sequence of wild p-nitrophenyl ethyl esterase pnbA as shown in SEQ ID NO.1 according to one or a combination of more of the following modes: leucine at the 273rd site is mutated into aspartic acid, phenylalanine at the 314th site is mutated into histidine, and leucine at the 362nd site is mutated into arginine. The mutant pnbA-L273D / F314H / L362R provided by the invention shows optimal catalytic performance (E = 47.16) for racemization-acetic acid pinyl hydrate, the enantiomeric excess value of the mutant is 95.13%, the conversion rate of 1S, 5R-acetic acid pinyl hydrate is 90.42%, the enantioselectivity of the mutant is obviously higher than that of a wild type, and the mutant has great application potential in biological catalytic synthesis of monocyclic monoterpenoid chiral alcohols.

The invention belongs to the technical field of genetic engineering and enzyme engineering, and particularly relates to a genetically engineered bacterium for stably and efficiently producing L-isoleucine as well as a construction method and application of the genetically engineered bacterium. The genetically engineered bacterium takes E. coliTHRD as a host and contains an RNA (Ribonucleic Acid) polymerase beta-subunit mutant coding gene rpoBM; compared with a parent RNA polymerase beta-subunit, the RNA polymerase beta-subunit mutant has the advantage that the amino acid residue at the 618th site of the amino acid sequence is sequentially replaced with leucine from the N terminal to the C terminal. The genetically engineered bacterium disclosed by the invention can tolerate L-isoleucine and accumulate less alpha-ketobutyric acid, and has a very good industrial application prospect.

The invention belongs to the technical field of bioengineering, and relates to a transaminase mutant, a recombinant genetically engineered bacterium and application of the transaminase mutant in catalytic synthesis of (R)-1-Boc-3-aminopiperidine.The transaminase mutant is obtained by conducting single-point or combined mutation on the 131 site and / or the 197 site of an amino acid sequence shown in SEQ ID NO.2; the mutation sites comprise that the 131 phenylalanine is mutated into aspartic acid, threonine or tyrosine, and / or the 197 lysine is mutated into arginine or leucine. Experimental results show that compared with wild type transaminase, the catalytic activity, the thermal stability and the organic solvent tolerance of the obtained mutants, especially single-point mutants MyTA1-F131Y and MyTA1-K197R and a combined mutant MyTA1-F131Y-K197R, are all remarkably improved, and compared with the wild type transaminase, the catalytic activity, the thermal stability and the organic solvent tolerance of the obtained mutants are all remarkably improved. The mutant MyTA1-F131Y-K197R can be used for efficiently catalyzing asymmetric amination of N-Boc-3-piperidone to synthesize (R)-1-Boc-3-aminopiperidine, the conversion rate of the (R)-1-Boc-3-aminopiperidine after the (R)-1-Boc-3-aminopiperidine reacts for 24 hours under the condition that the substrate concentration is 100 g / L can reach 90% or above, and the mutant MyTA1-F131Y-K197R has a good industrial application prospect.

The invention relates to the technical field of biological catalysis, and discloses an L204A mutant enzyme for preparing rebaudioside I. The enzyme is obtained by the following mutations generated by UGT76G1: L204A: leucine of the 204 amino acid sequence of UGT76G1 mutates into alanine; the high-efficiency in-vitro enzymatic preparation of the rebaudioside I (RI) is realized for the first time, the catalytic efficiency of the rebaudioside I (RI) is improved by more than 7 times (from about 7% to more than or equal to 50%) compared with that of an original enzyme, the high-efficiency performance can be stably maintained under different scales of 10mL to 5L, a solid foundation is laid for industrial application of the RI, and the preparation method is simple, controllable in process condition and suitable for popularization and application.

The invention discloses a method for inhibiting production of vomitoxin from bacillus cereus, which is characterized in that isoleucine is added into a substance needing to inhibit production of vomitoxin from bacillus cereus, preferably 5-20mM of isoleucine is added. According to the present invention, the content of the toxin is detected through the liquid chromatography-mass spectrometry, and the cytotoxicity experiment verification results show that the isoleucine can significantly inhibit the synthesis of the vomitoxin of the bacillus cereus in the culture medium and the matrix, and can effectively reduce the toxic effect of the toxin on HeLa cells; the invention provides a safe and efficient biological control means which is suitable for various food systems such as starch food, dairy products, meat products and the like. Isoleucine can be used as a novel non-toxic and harmless food additive and is low in cost; the use method is simple, the output of vomitoxin can be reduced by directly adding a trace amount of isoleucine, and the food flavor is not affected.

The invention discloses a high-stability carbonyl reductase mutant and application of the high-stability carbonyl reductase mutant in chiral alcohol synthesis. An amino acid sequence as shown in SEQ ID NO.2 is mutated as follows: 20th leucine is replaced by any one of lysine, threonine, aspartic acid or isoleucine, and / or 55th leucine is replaced by any one of methionine, serine, lysine or isoleucine, and / or 55th leucine is replaced by any one of methionine, serine, lysine or isoleucine. Compared with a wild type enzyme, the stability of the obtained mutant is remarkably improved, particularly, single-point mutants Mut-L20I and Mut-L55I and a combined mutant Mut-L20I-L55I show excellent relative enzyme activity, thermal stability and substrate tolerance. The mutant has high catalytic activity and stability to various chiral alcohols, has the advantages of high catalytic efficiency, high thermal stability, strong substrate tolerance, easiness in fermentation production and the like, and is suitable for industrial application of enzymatic synthesis of chiral alcohols.

The invention discloses a yak bone collagen peptide for improving osteoporosis and preparation and application thereof, and relates to the field of biological medicine, the yak bone collagen peptide comprises collagen peptide with the molecular weight of 500-2000 Daltons, contains a glycine-proline-hydroxyproline tripeptide core structure, can promote osteoblast differentiation and inhibit osteoclast activity, and can be used for treating osteoporosis. The amino acid sequence of the collagen peptide is any one of the following sequences: glycine-proline-hydroxyproline-glycine-glutamic acid-arginine, and the amino acid sequence of the collagen peptide is any one of the following sequences: glycine-proline-hydroxyproline-glycine-glutamic acid-arginine; and the amino acid is glycine, proline, hydroxyproline, serine, leucine and alanine. The yak bone collagen peptide has a unique glycine-proline-hydroxyproline tripeptide structure, the molecular weight is controlled within the range of 500-2000 Daltons, the structure can promote osteoblast differentiation and inhibit osteoclast activity at the same time, and the problem that a traditional osteoporosis treatment medicine is single in function is solved.

The present application relates to a pyridoxal kinase mutant, a recombinant expression vector and a microbial cell and their applications, and belongs to the technical field of biological catalysis. In order to solve the problem of low product concentration in existing enzyme catalysis, a pyridoxal kinase mutant is provided, the amino acid sequence is selected from the amino acid sequence shown in SEQ ID NO. 1, the lysine at position 229 is mutated to alanine, phenylalanine, methionine, arginine, threonine, histidine, serine, tyrosine, valine, leucine, isoleucine, proline, asparagine, aspartic acid or glutamic acid; the pyridoxal kinase mutant is used for catalyzing pyridoxal to synthesize pyridoxal phosphate, and a recombinant expression vector and a microbial cell can be further formed. The present application has good enzyme activity, high product conversion rate, high concentration of pyridoxal phosphate obtained, and the concentration of the product catalyzed by the wild-type pyridoxal kinase to phosphorylate pyridoxal is obviously improved.

The invention belongs to the field of plant genetic engineering, and discloses a key gene OsHPCA1 for positively regulating salt stress and oxidative stress tolerance of rice. The gene (with the login number of Os05g40770) encodes a receptor protein capable of specifically sensing hydrogen peroxide, and belongs to a leucine repeat receptor-like protein kinase (LRR-RLKs) family, wherein the family is the largest subfamily in the receptor-like protein kinase (RLKs). The OsHPCA1 responds to salt and oxidative stress signals, and the salt tolerance and oxidative stress resistance of the rice are positively regulated and responded. The OsHPCA1 overexpression rice strain shows very strong salt tolerance; and the OsHPCA1 knockout strain oshpca1 is more sensitive to salt stress. The OsHPCA1 protein encoded by the OsHPCA1 gene and rich in leucine repeat receptor-like protein kinase can positively regulate and control the activity of catalase C (CatC) in rice and enhance the removal efficiency of H2O2 under salt stress, so that the salt tolerance of rice is improved. When the OsHPCA1 is overexpressed, the activity of CatC in the overexpressed strain OsHPCA1 is obviously increased, the H2O2 removal capability is enhanced, and the salt tolerance and oxidative stress tolerance of the rice are improved.

The invention belongs to the technical field of gestational diabetes diagnosis marker screening, and particularly relates to a biomarker for predicting or diagnosing gestational diabetes and application of the biomarker. The invention discloses a biomarker for predicting or diagnosing gestational diabetes mellitus, the biomarker is selected from one or more of hypoxanthine, cortisol, dihydrotachysterol and cycloleucine, and more preferably, the biomarker comprises hypoxanthine, cortisol, dihydrotachysterol, (3R, 4R)-D-ketolactone, creatine, cycloleucine and L-hydroorotic acid. The seven biomarkers disclosed by the invention can predict or diagnose gestational diabetes mellitus independently or jointly through plasma detection at the early pregnancy stage, effectively improve the early diagnosis rate of gestational diabetes mellitus and improve disease prognosis, and have clinical use and popularization values.

The invention discloses a chitosanase mutant which is derived from bacillus subtilis and has the capacity of hydrolyzing chitosan to produce chitosan disaccharide per unit and belongs to a GH46 family, and application of the chitosanase mutant in hydrolyzing chitosan to produce chitosan oligosaccharide. Compared with wild type chitosanase capable of producing chitodisaccharide and chitotriose, the chitosanase mutant has the advantage that the chitodisaccharide can be produced per unit when the chitodisaccharide is hydrolyzed by the chitosanase mutant. The invention provides eight kinds of chitosanase mutants, and the mutants are obtained by carrying out site-specific mutagenesis on 21st-site glycine on the basis of wild type chitosanase and respectively mutating the 21st-site glycine into lysine, arginine, leucine, histidine, methionine, tyrosine, proline and glutamine. The mutant can hydrolyze chitosan under mild conditions to produce chitosan oligosaccharide with single polymerization degree, and can greatly relieve the difficulty in separation and purification in chitosan oligosaccharide production.

The invention provides a strain for producing L-isoleucine as well as a construction method and application thereof. The strain is obtained by modifying a chassis strain escherichia coli XX12 by utilizing a metabolic engineering modification method, ldhA, adhE and pflB genes are deleted, the transcriptional levels of aspC, pykF, pntAB, ppK, ppc, ilvAfbr, ilvIHfbr and ygaZH genes are up-regulated, the transcriptional level of a leuA gene is down-regulated, a bcd gene derived from B.subtilis 168 and ppnK and cysK genes derived from Cornebacterium glutamicum ATCC 13032 are heterologously expressed, and the strain has the advantages that the strain can be used for producing L-isoleucine; the method has the advantages of no need of adding resistant substances, good L-isoleucine synthesis capability, short fermentation period by using glucose as a carbon source, and good economic benefit and industrial application value.

In the first aspect, the present disclosure provides a Lactoferrin polypeptide fragment, where the Lactoferrin polypeptide fragment has an amino acid sequence shown in SEQ ID NO: 1. In the second aspect, the present disclosure provides a preparation method of the Lactoferrin polypeptide fragment, including: protecting amino acids using a 9-fluorenylmethoxycarbonyl (Fmoc) protecting group, coupling the amino acids with a P-hydroxymethylphenoxymethyl polyethylene resin (HMP resin) in an order of cysteine, alanine, leucine, cysteine, glutamate, threonine, asparagine, aspartate, asparagine, phenylalanine, leucine, leucine, asparagine, and lysine, and separating the HMP resin to obtain a target Lactoferrin polypeptide fragment. In the third aspect, the present disclosure further provides an anti-Lactoferrin antibody prepared using the Lactoferrin polypeptide fragment, and use of the Lactoferrin polypeptide fragment in preparation of an anti-Lactoferrin flow cytometric antibody and in preparation of a Lactoferrin detection product.

The invention discloses an amino acid composition for treating alopecia and application of the amino acid composition in preparation of a medicine for treating alopecia, and belongs to the field of medicine configuration products, the amino acid composition is composed of a targeting core intervention component and an auxiliary strengthening synergistic component, the targeting core intervention component is prepared from 30-50 parts of arginine, 50-155 parts of lysine and 50-120 parts of glutamic acid, and the auxiliary strengthening synergistic component is prepared from an auxiliary strengthening synergistic component and an auxiliary strengthening synergistic component. 10 to 40 parts of cysteine and 20 to 60 parts of leucine; the auxiliary strengthening synergistic component is prepared from 15 to 45 parts of tyrosine, 15 to 40 parts of glycine, 10 to 40 parts of glutamine, 20 to 35 parts of serine, 5 to 25 parts of alanine, 2 to 20 parts of aspartic acid and 15 to 35 parts of phenylalanine; the composition can be used as an active ingredient to be prepared into different dosage forms such as a pigmentum, a spray, an ointment and a liniment, is applied to prevention of alopecia and promotion of hair growth, and has a remarkable treatment effect.

The invention discloses an engineered glycosyl transferase and application thereof in efficient preparation of triterpenoid saponin. The engineered glycosyl transferase is obtained by mutating serine at the 15th site of UGT74AC1 enzyme into alanine, mutating histidine at the 47th site into aspartic acid, mutating leucine at the 48th site into valine, mutating alanine at the 180th site into serine, mutating histidine at the 180th site into aspartic acid, mutating histidine at the 180th site into aspartic acid, mutating histidine at the 180th site into aspartic acid, mutating histidine at the 180th site into aspartic acid The mutant is obtained by mutating serine at the 332 site into proline, phenylalanine at the 367 site into tryptophan and lysine at the 420 site into arginine. According to the invention, the glycosyl transferase with high catalytic activity is obtained by modifying an enzyme engineering technology, and good application of the glycosyl transferase in synthesis of triterpenoid saponin is realized. The glycosyl transferase disclosed by the invention can also be coupled with sucrose synthase, or coupled with N-acetylhexosamine kinase and N-acetylglucosamine-1-uridine phosphate transferase, and acetylglucosamine is used as a glycosyl donor, so that cascade production of triterpenoid saponin with lower cost and higher efficiency is realized.

The present disclosure is directed to HLA class II molecules having a higher affinity for CD4 than naturally occurring HLA class II molecules. In certain aspects, the HLA class II molecule comprises a DQ beta chain having (i) an amino acid other than leucine at a position corresponding to amino acid residue 114 of SEQ ID NO: 1, (ii) an amino acid other than valine at a position corresponding to amino acid residue 143 of SEQ ID NO: 1, (iii) or both (i) and (ii). Certain aspects of the present disclosure are directed to nucleic acid molecules encoding the HLA class II molecules, vectors comprising the nucleic acid molecule, cells comprising the same, and methods of use thereof.

The invention discloses a salicylic acid decarboxylase mutant and application of the salicylic acid decarboxylase mutant in degradation of salicylic acid. The mutant is obtained by carrying out site-specific modification on salicylic acid decarboxylase NahG, and specifically, valine at the 46th site, tyrosine at the 380th site and leucine at the 382nd site of an amino acid sequence shown in SEQ ID NO.2 are mutated into cysteine, phenylalanine and phenylalanine at the same time. The mutant shows remarkably improved catalytic efficiency, and salicylic acid can be efficiently and thoroughly decarboxylated and converted into catechol under mild conditions. The invention also provides a coding gene, a recombinant vector and an engineering bacterium of the mutant. The mutant not only can be used for efficient bioremediation of salicylic acid pollution, but also can effectively break through and accelerate a naphthalene catabolism pathway due to the characteristic of directionally generating catechol, and has important application value in the fields of environmental pollution abatement and biological catalysis.

The invention discloses a synthesis method of a chiral polyaniline nano material and application of the chiral polyaniline nano material in amino acid chiral crystallization. The preparation method comprises the following steps: ultrasonically dissolving unichiral tartaric acid, an aniline monomer and N-phenyl p-phenylenediamine in water, adding a certain volume of an ammonium persulfate aqueous solution to initiate polymerization, centrifuging after complete reaction to obtain a polyaniline-tartaric acid (PANI-TA) chiral nano material, and carrying out ammonia water dedoping and hydrochloric acid solution re-doping to obtain a polyaniline-hydrochloric acid (PANI-HCl) chiral nano material. And finally, respectively adding the polyaniline-hydrochloric acid chiral nano-material into a supersaturated leucine, alanine or tryptophan aqueous solution to induce chiral crystallization, wherein the result shows that the polyaniline-hydrochloric acid chiral nano-material can induce one configuration of amino acid to crystallize more quickly and the other configuration of amino acid with enantiomeric excess remains in the solution. The chiral polyaniline nano material prepared by the method avoids introduction of other chiral molecules in chiral crystallization, is beneficial to separation of products, has the advantages of simplicity in operation, low cost and the like, and has a wide application prospect in the field of chiral resolution.

The present invention discloses a cyclic lipopeptide carrier for encapsulating nucleic acid drugs, comprising a cyclic lactone structure formed by a heptapeptide R1R2R2R3R1R2R2 and a β-hydroxy fatty acid with a carbon chain length of 6 to 44, and its general structural formula is as follows: #imgabs0# wherein R1 is a basic amino acid, including one of histidine His, lysine Lys or arginine Arg, R2 is one of the hydrophobic amino acids leucine Leu, isoleucine Ile or valine Val, and R3 is one of any amino acid; n is an integer of 2 to 40; the positively charged basic amino acids in the cyclic lipopeptide bind to the negatively charged nucleic acid drug through electrostatic interaction to form cyclic lipopeptide-nucleic acid particles. The cyclic lipopeptide carrier for encapsulating nucleic acid drugs provided by the present invention has high safety, can effectively protect nucleic acid drugs, improves their stability, and has good transfection efficiency for a variety of cells, and has broad application prospects in the field of nucleic acid drug delivery.

The invention belongs to the technical field of enzyme mutants, and discloses a mutant of lycopene cyclase and application of the mutant, glutamic acid at the 321 site of wild type lycopene cyclase which is derived from arabidopsis and has an amino acid sequence as shown in SEQ ID NO.1 is mutated into lysine, phenylalanine at the 319 site of the wild type lycopene cyclase is mutated into leucine, cysteine at the 323 site of the wild type lycopene cyclase is mutated into alanine, and the mutant of the lycopene cyclase is obtained. 1, and the lycopene cyclase mutant with the amino acid sequence as shown in SEQ ID NO. 2 is obtained. BTS1, CrtB and CrtI are integrated into a saccharomyces cerevisiae BY4741 strain, and a chassis strain ZA1 for stably producing alpha-carotene precursor lycopene is constructed; mutant expression plasmids are constructed, positive clone strains are screened out, and the epsilon-cyclization ability of mutant enzymes is remarkably higher than the beta-cyclization ability; the method comprises the following steps: by taking lycopene as a substrate, constructing an expression vector lipid droplet surrounding protein PET10; gene PAH1, DGA1 and Cat2 related to TAG synthesis and perilipid droplet protein PET10 are constructed on an expression vector and converted into ZA1, and when lycopene is used as a substrate, the efficiency of catalytic production of alpha-carotene is improved.

The invention relates to the technical field of graded screening, in particular to a graded screening system based on staggered stacked metal ring films and a preparation method and application. An organic ligand and two metal complexes are subjected to interface coordination assembly under the action of silver ions, an ordered staggered stacked metal ring film is constructed, the structure and performance of the metal ring film are precisely regulated and controlled, the metal ring film has a definite molecular sieve component difference, and then precise grading screening of different molecules is achieved. The film has an obvious lattice structure, has good crystalline orderliness, and can ensure the stability and reliability of the screening process. The graded screening system based on the staggered stacked metal ring membranes has excellent interception performance on target molecules, and effective separation of TAC from glucan and leucine can be achieved. The two-stage membrane classification screening strategy can also be popularized to separation and purification of other substances, and good universality and industrial application prospects are achieved.

The invention relates to aspartate kinase for relieving feedback inhibition of L-threonine and application of aspartate kinase, and belongs to the field of enzyme engineering and metabolic engineering. The mutant is obtained by carrying out E253K and / or K507E mutation on the basis of wild type aspartate kinase as shown in SEQ ID NO.1, the enzyme activity of the mutant is not obviously changed under the condition that the concentration of L-threonine is 0-12 mmol / L, and the feedback inhibition effect of L-threonine on the mutant is relieved. The method can be widely applied to synthesis of essential amino acids including L-threonine, L-tryptophan, L-isoleucine, L-lysine, L-leucine, L-valine, L-methionine, L-phenylalanine and the like.

The application relates to a buffer reagent, a kit, a branched-chain alpha-keto acid or a branched-chain amino acid detection method in the technical field of biological detection. The buffer reagent comprises 15-25 mM, pH 8.5-9.5 Tris-HCl buffer solution, 10-50 g / L trehalose, 0.1-1.5 g / L Proclin 300, 0.1-0.5 g / L Triton X-100, 0.1-1.5 g / L sodium salt of EDTA, 1-10 kU / L ascorbic acid oxidase and 0.5-3 g / L bovine serum albumin. The buffer reagent is suitable for preparation of a reagent containing leucine dehydrogenase, the reagent containing the buffer reagent and the leucine dehydrogenase and the kit prepared by using the reagent can effectively eliminate interference problems in the process of being used for branched-chain alpha-keto acid, branched-chain amino acid detection, and has good correlation with mass spectrometry.

This invention belongs to the field of diagnostic testing technology. Addressing the problem that existing gestational diabetes screening methods may miss the optimal time for early intervention, leading to the failure to promptly detect and manage some potentially hyperglycemic pregnant women, increasing the risk of adverse maternal and fetal outcomes, this invention proposes a plasma metabolic biomarker for the early diagnosis or prediction of gestational diabetes and its application. This plasma metabolic biomarker is at least one of L-lysine, propargylglycine, N6-acetyl-L-lysine, cyclic leucine, and glycine-deoxycholic acid. The five plasma metabolic biomarkers provided by this invention can be applied to the early diagnosis or prediction of gestational diabetes, and are of great significance for the prevention or treatment of gestational diabetes.

An Fc-binding polypeptide with improved alkaline stability comprising a mutant of the Fc-binding domain of Staphylococcus protein A (SpA), said mutant being defined by SEQ ID NO: 1, SEQ ID NO: 2, SEQ ID NO: 3, SEQ ID NO: 4, SEQ ID NO: 5, SEQ ID NO: 6, SEQ ID NO: 7, SEQ ID NO: 22, SEQ ID NO 51 or EQ ID NO 52, wherein at least the asparagine or serine residue at a position corresponding to position 11 in SEQ ID NO: 4-7 has been mutated to an amino acid selected from the group consisting of glutamic acid, lysine, tyrosine, threonine, phenylalanine, leucine, isoleucine, tryptophan, methionine, valine, alanine, histidine and arginine.

The present specification relates to a composition including a new amide-based compound derived from an amino acid structure such as valine, leucine, phenylalanine, proline, pipecolic acid, or the like, wherein the composition exhibits a skin anti-aging or skin reverse-aging effect by restoring the size and number of dendrites of aged melanin-producing cells to those of young cells. As a result, the composition may exhibit a skin brightening effect by inhibiting the amount of melanin produced in the melanin-producing cells.