Alkali-Stable IgG-Binding Peptide via Disulfide Cross-Linking
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Solution Overview
Problem
Protein A columns used for IgG purification are contaminated with protein A, which is immunogenic and costly to purify, and existing peptide ligands have affinity issues with alkaline solutions.
Innovation Solution
A solid-phase support with an IgG-binding peptide, specifically the amino acid sequence GPDCAYHRGELVWCTFH, where sulfide groups in cysteine residues are cross-linked using a specific linker, enhancing stability and resistance to alkaline conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If protein A is used as an affinity ligand for IgG purification, then IgG binding capacity is improved, but contamination with immunogenic protein A and endotoxin occurs, increasing cost and safety concerns
Solution Approach 1:
The invention extracts only the essential IgG-binding functional domain from the full protein A molecule, using a specifically designed peptide sequence (GPDCAYHRGELVWCTFH) that captures IgG without requiring the complete protein A structure. This extraction eliminates the immunogenic and endotoxin-containing portions of protein A while retaining the affinity binding function.
Solution Approach 2:
The invention creates a simplified peptide copy of the IgG-binding function found in protein A. Instead of using the complex, multi-domain protein A structure, a compact peptide sequence is designed and synthesized that replicates the essential binding interface, providing the same functional outcome with reduced complexity and eliminated harmful components.
2Reliability
If a peptide ligand with disulfide bond cross-linking is used for IgG purification, then initial IgG binding capacity is achieved, but affinity decreases after repeated washing with alkaline solution
Solution Approach 1:
The invention changes the chemical parameter of the cross-linking bond from a disulfide bond (S-S) to a carbon-based cross-linkage. This parameter change transforms the bond's chemical stability characteristics, making it resistant to alkaline hydrolysis while maintaining the structural integrity needed for IgG binding. The cross-linked peptide structure remains stable during repeated alkaline washing cycles.
3Object-generated harmful factors
If protein A is highly purified to prevent contamination, then safety and cost issues are improved, but the purification process becomes more complex and expensive
Solution Approach 1:
The invention extracts only the essential IgG-binding functional domain from the full protein A molecule, using a specifically designed peptide sequence (GPDCAYHRGELVWCTFH) that captures IgG without requiring the complete protein A structure. This extraction eliminates the immunogenic and endotoxin-containing portions of protein A while retaining the affinity binding function.
Solution Approach 2:
The invention creates a simplified peptide copy of the IgG-binding function found in protein A. Instead of using the complex, multi-domain protein A structure, a compact peptide sequence is designed and synthesized that replicates the essential binding interface, providing the same functional outcome with reduced complexity and eliminated harmful components.
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 peptide maintains high IgG binding capacity even after alkaline washing, enabling efficient and cost-effective IgG purification without protein A contamination.
Implementation Method 1
cross-linking sulfide groups in cysteine residues in a peptide by a linker having a specific structure
Implementation Method 2
the peptide being capable of binding to human IgG
Data Source
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AI summary
The present invention provides an IgG-binding peptide which can be used for the purification of IgG and has excellent stability, e.g., alkali stability. The present invention also provides a method for purifying IgG using the IgG-binding peptide. Specifically, the present invention relates to a solid-phase support including an IgG-binding peptide, an IgG separation column including the solid-phase support, a kit including the solid-phase support or the column, and a method for purifying IgG using the solid-phase support or the column.