Modified IgG Antibody with Peptide Linker for Radioactive Metal Labeling
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Solution Overview
Problem
Conventional methods for radioactive metal labeling of antibodies result in high accumulation in organs like the liver, leading to unnecessary radiation exposure and potential reduction in antibody function, with existing techniques failing to balance metabolism and function preservation.
Innovation Solution
A modified IgG antibody is developed by binding an IgG-binding peptide with a specific amino acid sequence and a modification linker to the IgG antibody, allowing for site-specific labeling and enhanced liver metabolism, reducing radioactive metal accumulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional chelate compound binding methods are used to label antibodies with radioactive metals, then the labeling can be performed, but the antibody activity is decreased and the number of bound compounds is difficult to control
Solution Approach 1:
The invention divides the labeling system into two separate components: an IgG-binding peptide that specifically binds to the Fc domain of IgG antibodies, and a chelate compound that binds to radioactive metals. This segmentation allows the peptide to handle antibody binding site-specifically while the chelate handles metal coordination, preventing interference with antibody activity and enabling controlled stoichiometry.
Solution Approach 2:
The IgG-binding peptide acts as an intermediary between the antibody and the chelate compound. It binds site-specifically to the Fc domain of the antibody and then recruits the chelate compound, thereby mediating the attachment of radioactive metals without direct interaction between the chelate and the antibody's antigen-binding sites, thus preserving antibody function.
2Manufacturing precision
If site-specific modification is performed by introducing unnatural amino acids or free cysteine through genetic engineering, then site-specific binding is achieved, but the development cost increases and antibody function may be reduced
Solution Approach 1:
Instead of modifying the antibody to enable binding, the invention inverts the approach by using a peptide that naturally binds to the antibody's Fc domain. This reverses the modification burden from the antibody to a separate, easily synthesized peptide, achieving site-specific binding without genetic engineering of the antibody itself.
Solution Approach 2:
The invention uses a peptide that copies or mimics the binding capability of naturally occurring Fc-binding proteins, achieving site-specific attachment to IgG antibodies through evolved peptide sequences rather than through modification of the antibody structure.
3Productivity
If low-molecular weight polypeptides are used for radioactive metal labeling, then the labeling is efficient, but radioactivity accumulates in the kidney causing radiation exposure and renal disorder
Solution Approach 1:
The invention creates a composite structure combining the IgG-binding peptide with a chelate compound. This composite maintains the efficient binding properties of peptide-chelate systems while the chelate component provides controlled radioactive metal coordination, reducing non-specific kidney accumulation through stable complex formation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The approach effectively promotes the excretion of radioactive metals from the body, improving pharmacokinetics and minimizing radiation exposure to normal organs while maintaining antibody function.
Implementation Method 1
linking a ligand to an IgG-binding peptide having a binding ability to a specific site of the Fc domain of an IgG antibody, and binding the IgG-binding peptide to the antibody
Implementation Method 2
a method has been used in which a chelate compound is bound to an antibody, and a radioactive metal element is supported on the chelate compound
Implementation Method 3
effectively promotes the excretion of radioactive metals from the body, improving pharmacokinetics and minimizing radiation exposure to normal organs
Data Source
AI summary
Described is a labeling technique which can facilitate the metabolism in the liver after administration to patients without the reduction in the antibody function, thereby reducing accumulation of radionuclides in an organ such as the liver, and a modified antibody containing an IgG antibody and an IgG-binding peptide bound to the IgG antibody. The IgG-binding peptide has an amino acid sequence consisting of 13 to 17 amino acid residues, such as GPDCAYH(Xaa1)GELVWCTFH (SEQ ID NO: 2) wherein Xaa1 represents a lysine residue, a cysteine residue, an aspartic acid residue, a glutamic acid residue, 2-aminosuberic acid, or diaminopropionic acid, and a compound represented by the following formula (II-1) is linked at a position of the lysine residue via a modification linker to the N terminus of the IgG-binding peptide.