Modified Protein G Fab-Binding Regions for Antibody Purification

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Current immunoglobulin binding proteins (IBPs) like Protein-A and Protein-G have limitations due to their low affinity for the Fab domain of antibodies, which restricts their applications in purification and diagnostic assays.

Innovation Solution

Development of modified protein G Fab-binding regions with enhanced affinity for the Fab domain, achieved through specific amino acid modifications and engineering, allowing for improved binding properties and pH-dependent affinity modulation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If wild-type Protein-G is used, then it maintains natural binding properties, but it has low affinity for the Fab domain which limits its applications

Engineering Contradiction:

Improvebinding affinityVSAvoidapplication range

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent applies parameter changes by modifying specific amino acid residues in the Protein-G Fab-binding domain to alter binding affinity. Multiple variants are created with different amino acid substitutions (e.g., KTLKGETTTKAVDAATAEKVFKQYANDNG sequence modifications) to optimize Fab binding while maintaining Fc binding capability, thereby expanding application range without sacrificing reliability

Inventive Principle:

Principle #35Parameter changes

2Reliability

If Protein-A is used, then it has high affinity for Fc region, but it has limited capability for Fab domain binding

Engineering Contradiction:

ImproveFc binding affinityVSAvoiddual binding capability

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent creates multi-functional Protein-G variants that can bind both Fc and Fab domains simultaneously. The modified Protein-G maintains its natural Fc binding property while acquiring enhanced Fab binding capability through amino acid engineering, making it a universal reagent for both Fc and Fab purification and detection applications

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Reliability

If modified Protein-G variants are engineered, then affinity for Fab domain is improved, but protein structure complexity increases

Engineering Contradiction:

ImproveFab binding affinityVSAvoidprotein sequence complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies local quality by making targeted amino acid substitutions only in the Fab-binding region of Protein-G while leaving the rest of the protein structure unchanged. This localized modification approach improves Fab binding affinity without unnecessarily increasing overall protein complexity, maintaining simplicity in non-critical regions

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS10759834B2Methods and compositions involving protein G variants

Publication Date: 2020.09.01 UNIVERSITY OF CHICAGO

AI summary

Methods and compositions are provided concerning polypeptides with modifications that increase its binding affinity for the Fab region of an antibody. Methods include using the polypeptides for isolating, detecting, purifying, measuring and quantifying Fab polypeptides. Other embodiments concern kits, compositions, and solid supports containing the polypeptides and for using the polypeptides for isolating, detecting, purifying, measuring and quantifying Fab polypeptide.