Alkali-Resistant Immunoglobulin-Binding Polypeptide via Site-Directed Mutagenesis
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Solution Overview
Problem
Current polypeptides used for binding to immunoglobulins lack sufficient alkali resistance, making them unsuitable for applications involving alkali treatments or harsh chemical conditions.
Innovation Solution
Development of novel polypeptides with specific amino acid sequences that provide enhanced alkali resistance, maintaining binding ability even under severe alkali conditions, using computational chemistry and protein engineering techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional polypeptides are used for binding to immunoglobulins, then binding capability is achieved, but alkali resistance is insufficient
Solution Approach 1:
The patent applies parameter changes by systematically mutating specific amino acid residues in the polypeptide sequence. Key substitutions include replacing position 29 with Glycine, position 33 with Serine, position 35 with Alanine, and position 43 with Serine. These parameter changes in the molecular structure directly improve alkali resistance while preserving immunoglobulin binding capability, resolving the technical contradiction between reliability and stability.
2Ease of operation
If polypeptide ligands are exposed to alkali conditions for virus deactivation or carrier washing, then purification process is enabled, but polypeptide stability deteriorates
Solution Approach 1:
The patent addresses this contradiction by changing the chemical parameters of the polypeptide through site-directed mutagenesis. The specific amino acid substitutions (Gly at position 29, Ser at position 33, Ala at position 35, Ser at position 43) modify the polypeptide's chemical properties to resist alkali-induced degradation, enabling the purification process to proceed without compromising polypeptide stability.
Solution Approach 2:
The patent applies preliminary action by pre-modifying the polypeptide sequence with stabilizing mutations before exposure to alkali conditions. This preliminary structural modification ensures the polypeptide is already equipped with resistance to alkali damage before the actual purification process begins, preventing stability deterioration during virus deactivation or carrier washing steps.
3Stability of the object's composition
If existing Protein A variants are used to improve alkali resistance, then some stability is achieved, but binding specificity and affinity are compromised
Solution Approach 1:
The patent applies local quality by making targeted, localized amino acid substitutions at specific positions (29, 33, 35, 43) rather than global modifications. This localized approach allows the polypeptide to maintain its overall structure and binding interface integrity while introducing alkali resistance only where needed, thus preserving binding specificity and affinity while improving stability.
Solution Approach 2:
The patent carefully selects specific parameter changes at critical positions that do not disrupt the immunoglobulin-binding interface. The mutations are chosen to affect only the structural stability and alkali resistance parameters, leaving the binding-specific parameters unchanged, thereby resolving the contradiction between stability improvement and binding capability maintenance.
Data Source
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AI summary
An object of the present invention is to provide novel polypeptides that are capable of binding to an immunoglobulin and have high stability against alkali. The present invention relates to proteins having the amino acid sequence of SEQ ID No:1 or 2.