IgG Purification Peptide with Alkali-Resistant Cross-Linking
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Solution Overview
Problem
Existing methods for purifying IgG antibodies using protein A columns face challenges such as contamination with protein A, which is immunogenic and costly to purify, and peptides with low IgG-binding affinity and poor alkali resistance.
Innovation Solution
A solid-phase carrier is developed with an IgG-binding peptide that includes an amino acid sequence of 13 to 17 residues, specifically cross-linked by a linker to enhance alkali resistance and binding affinity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If protein A is used as an affinity ligand for IgG purification, then high IgG-binding affinity is achieved, 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 structure, using a minimal peptide sequence (13-17 amino acids) that retains binding capability while eliminating the harmful portions of the protein that cause contamination and immunogenicity
Solution Approach 2:
The peptide ligand is designed to be cost-effective and replaceable, providing a cheaper alternative to protein A columns while maintaining purification functionality, allowing for disposable or easily replaceable affinity media
2Reliability
If a peptide ligand with disulfide bond cross-linking is used, then IgG-binding affinity is achieved, but alkali resistance is poor due to disulfide bond cleavage during repeated washing
Solution Approach 1:
The invention changes the chemical nature of the cross-linking bond from a disulfide bond (which is alkali-labile) to a carbon-carbon single bond formed through reductive amination or other stable linkages, fundamentally altering the chemical stability parameter to resist alkaline conditions while preserving IgG-binding affinity
3Ease of manufacture
If peptide ligand structure is simplified to reduce cost, then manufacturing cost decreases, but IgG-binding affinity and alkali resistance are compromised
Solution Approach 1:
The peptide is designed with specific local quality features including particular amino acid residues at critical positions (e.g., aromatic residues for hydrophobic interactions, basic residues for electrostatic interactions) that locally provide high binding affinity, while the overall structure remains simplified and cost-effective to manufacture
Solution Approach 2:
The peptide ligand combines multiple functional elements within a short sequence: IgG-binding motifs, stable cross-linking chemistry, and appropriate length for optimal binding, creating a composite functional unit that achieves high performance at low cost
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 immobilized on the solid-phase carrier demonstrates improved alkali resistance and high IgG-binding affinity, enabling efficient IgG purification without the drawbacks of protein A columns.
Implementation Method 1
a cross-linked cyclic peptide having a specific amino acid sequence... capable of binding to IgG
Implementation Method 2
cross-linked via a disulfide bond... cross-linked by a linker having a specific structure
Data Source
AI summary
The purpose of the present invention is to provide a solid-phase carrier on which an IgG-binding peptide is immobilized, the peptide being usable for IgG purification, having resistance to repeated washing with an alkaline solution after IgG purification, and having a high binding affinity for IgG. Specifically, the present invention relates to a solid-phase carrier on which an IgG-binding peptide is immobilized, wherein the two cysteine residues on the outside of the peptide are linked as shown in the following formula:(in the formula, the upper cysteine residue is on the N-terminal side of the peptide, and the lower cysteine residue is on the C-terminal side of the peptide).