Engineered Ig-Binding Polypeptides for Higher-pH Antibody Elution
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Solution Overview
Problem
Existing Protein A ligands for affinity chromatography face limitations such as loss of binding capacity under alkaline conditions and incomplete elution of antibodies at higher pH values, necessitating the development of novel Ig binding proteins with improved properties for affinity purification of immunoglobulins, particularly those with an Fc domain.
Innovation Solution
Engineered Ig binding proteins with a specific structure comprising three domains and two linkers, allowing for stable binding to the Fc region of immunoglobulins and enabling elution at mild acidic conditions up to pH 5.5.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Protein A ligands are used for affinity chromatography, then high binding affinity and selectivity for immunoglobulins are achieved, but binding capacity is lost under alkaline conditions and elution is incomplete at higher pH values
Solution Approach 1:
The patent modifies the chemical structure of Protein A ligands by changing amino acid sequences and adding functional groups that alter pH-dependent binding characteristics. This enables the ligand to maintain binding capacity across a wider pH range while allowing controlled elution at higher pH values, resolving the contradiction between reliable binding and pH adaptability
Solution Approach 2:
The invention creates composite ligand structures combining multiple functional domains - including the original Protein A binding domain plus additional pH-responsive domains. This composite structure provides both high binding affinity and improved pH stability, enabling complete elution at higher pH while maintaining reliable binding under normal conditions
2Productivity
If Protein A ligands are used for affinity purification, then efficient capture of immunoglobulins is achieved, but elution requires harsh low pH conditions causing aggregate formation
Solution Approach 1:
The patent changes the elution pH parameter from harsh low pH (causing aggregates) to milder higher pH values (preventing aggregates). The modified ligand structure enables this parameter change while maintaining purification efficiency through controlled binding and elution kinetics
Solution Approach 2:
The invention converts the harmful effect of requiring low pH elution (which causes aggregate formation) into a beneficial feature by designing ligands that naturally elute at higher pH. This transforms a harmful constraint into a protective advantage, preventing aggregate formation while maintaining efficient purification
Data Source
AI summary
The present invention relates to novel engineered artificial immunoglobulin (Ig) binding polypeptides comprising three domains and two linkers. The invention further relates to affinity matrices comprising these artificial Ig binding molecules of the invention. The novel Ig binding proteins are particularly useful for the affinity purification of proteins requiring elution at a higher pH (in particular higher than pH 4.2). The invention also relates to a use of the novel Ig binding proteins or affinity matrices for affinity purification of immunoglobulins and to methods of affinity purification using the novel Ig binding proteins of the invention.