IgG Fc Binding Polypeptide Stability Optimization
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Solution Overview
Problem
Current IgG Fc affinity ligands, such as Protein A and its variants, face limitations in stoichiometry and stability under acidic and alkaline conditions, necessitating the development of improved polypeptides for efficient antibody and Fc fusion protein purification in chromatography processes.
Innovation Solution
A novel IgG Fc-binding polypeptide with a specific amino acid sequence, designed to form a single three-helical bundle domain, is developed, offering enhanced binding capacity and stability through strategic amino acid substitutions and spacer sequences, allowing for optimized binding and cleavage properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Protein A or its variants are used as affinity ligands for IgG Fc purification, then binding capacity is achieved, but stability under acidic and alkaline conditions deteriorates
Solution Approach 1:
The invention divides the Protein A structure into five separate IgG Fc-binding domains (A, B, C, D, E) that can be independently expressed and combined. This segmentation allows optimization of each domain for specific conditions (acid/alkaline stability) while maintaining overall binding capacity through modular assembly into multimers.
Solution Approach 2:
The invention creates composite affinity ligands by combining multiple different Protein A domains (e.g., A2B2C2D2E2) into single multimeric structures. This composite approach enables the ligand to exhibit both high binding capacity (through multiple domains) and improved stability (through strategic domain selection and arrangement).
2Productivity
If multiple IgG Fc-binding domains are combined in a single ligand, then binding capacity increases, but structural complexity increases
Solution Approach 1:
The invention creates universal building blocks (the five Protein A domains) that can be independently expressed, stored, and recombined in various ratios (e.g., A2B2C2D2E2) to create different ligand variants. This modular universality simplifies production while enabling flexible optimization of binding capacity and stability profiles.
Solution Approach 2:
The invention systematically varies the composition parameters of the multimers (different ratios and combinations of domains A-E) to optimize performance. For example, certain domain combinations are selected for acid stability while others optimize for alkaline stability, allowing parameter tuning without increasing fundamental structural complexity.
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 polypeptide achieves improved binding affinity and stability under various pH conditions, enabling efficient separation and purification of IgG Fc-containing molecules with high specificity and stability, suitable for industrial-scale chromatography applications.
Implementation Method 1
the native affinity of Protein A for the Fc portion of IgG
Implementation Method 2
The amino acid sequence DP is susceptible to acid catalyzed hydrolysis, so the DP sequence may be used as a cleavage site for separation of subunits in the multimer from each other
Data Source
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AI summary
An immunoglobulin G Fc region binding polypeptide is provided, consisting of an amino acid sequence selected from i) and an amino acid sequence which has at least 95 % identity thereto. Also provided are methods for producing the polypeptide, compositions comprising the polypeptide, polynucleoties encoding the polypeptide, multimers of the polypeptide, and methods of using the polypeptide.