Modified Protein G Peptide for Fab Region Binding
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Solution Overview
Problem
Current affinity separation matrices, such as protein A and protein G, are inadequate for efficiently purifying antibody fragments lacking the Fc region due to insufficient binding affinity to the Fab region of IgG, limiting their industrial application in antibody medicine production.
Innovation Solution
Development of a Fab region-binding peptide with enhanced affinity for the Fab region of IgG, achieved through genetic engineering by modifying specific positions in the β1 domain of protein G, resulting in a peptide with significantly higher binding force and improved retention performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If protein A or protein G is used as the affinity separation matrix, then IgG containing the Fc region can be captured, but fragment antibodies lacking the Fc region cannot be effectively captured
Solution Approach 1:
The invention modifies the amino acid sequence of protein G by substituting specific residues (e.g., Lys13→Thr, Glu34→Lys) to change the binding parameters and enhance affinity for the Fab region while maintaining Fc region binding capability
Solution Approach 2:
The invention creates a hybrid ligand that combines domains from different proteins (protein G β1 domain with modifications, and protein A V domain) to achieve both Fab and Fc region binding capabilities in a single affinity separation matrix
2Productivity
If protein G is used to bind to the Fab region, then some binding capability is achieved, but the binding force is too weak for effective purification
Solution Approach 1:
The invention systematically modifies multiple amino acid positions in the protein G sequence to optimize binding force, achieving up to 5-fold or greater enhancement in Fab region binding affinity
Solution Approach 2:
The invention merges the modified protein G β1 domain with the protein A V domain to create a composite ligand that combines the Fab region binding capability of protein G with the high-affinity Fc region binding capability of protein A
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 modified peptide enables efficient purification of antibody fragments by providing a high-affinity separation matrix that effectively captures Fab region-containing proteins, offering improved industrial scalability and cost-effectiveness in antibody medicine production.
Implementation Method 1
a Fab region-binding peptide having an excellent ability for binding to a Fab region of IgG
Data Source
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AI summary
An object of the present invention is to provide a Fab region-binding peptide having an excellent ability for binding to a Fab region of IgG, an affinity separation matrix having the peptide as a ligand, and a method for producing a Fab region-containing protein, the method using the affinity separation matrix. Further, another object of the present invention is to provide a DNA encoding for the peptide, a vector containing the DNA, and a transformant which has been transformed by the vector. The Fab region-binding peptide according to the present invention is characterized in having a mutation at a specific site in comparison with wild-type SpG-β1.