Separating Agent Alkaline CIP Stability via Amino Acid Substitution
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Solution Overview
Problem
Separating agents with single-chain antibodies bound to carriers experience a significant decrease in dynamic binding capacity when continually treated with cleaning-in-place (CIP) under alkaline pH conditions due to the amino acid sequence of the antibody.
Innovation Solution
The use of a separating agent with specific amino acid substitutions, where lysine residues near the recognition site are replaced with other residues and lysine residues far from the site are added, ensuring that all lysine residues, including those inserted or substituted, are replaced with non-cysteine residues, and a cysteine residue at position 96 is substituted, to maintain binding capacity under alkaline conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single-chain antibody is used as a separating agent and bound to a carrier surface, then the separating agent can effectively separate target substances from mixed liquids, but the dynamic binding capacity significantly decreases when continually treated by cleaning-in-place under alkaline pH conditions
Solution Approach 1:
The patent applies local quality by making specific amino acid substitutions at different locations of the single-chain antibody. Lysine residues at the recognition site (positions 30-50) are replaced with non-cysteine residues to maintain binding capacity under alkaline conditions, while lysine residues at distant positions (positions 1-29 and 51-107) are replaced with cysteine residues that can form stable bonds with the carrier. This localized differentiation of substitution strategies at different parts of the antibody molecule resolves the contradiction between maintaining binding capacity and ensuring stability under alkaline CIP conditions.
Solution Approach 2:
The patent changes the chemical parameters of the antibody by substituting specific amino acid residues. The replacement of lysine residues with different amino acids (non-cysteine at recognition site, cysteine at distant positions) fundamentally alters the chemical properties of the antibody at specific locations, enabling it to resist alkaline degradation while maintaining target binding capability. This parameter change approach directly addresses the deterioration of dynamic binding capacity under alkaline conditions.
2Ease of manufacture
If lysine residues are present in the single-chain antibody sequence, then the antibody can be easily bound to the carrier surface, but the dynamic binding capacity decreases under alkaline pH cleaning conditions
Solution Approach 1:
The patent applies local quality by differentiating the treatment of lysine residues based on their location. Lysine residues at the recognition site are replaced with non-cysteine residues to preserve binding function, while lysine residues at distant positions are replaced with cysteine residues for stable carrier attachment. This spatially differentiated approach ensures both ease of manufacture (through carrier binding) and reliability (through maintained binding capacity under alkaline conditions).
Solution Approach 2:
The patent inverts the conventional approach by not simply removing all lysine residues or using the same substitution strategy throughout. Instead, it uses opposite substitution strategies for different locations: non-cysteine residues at the recognition site versus cysteine residues at distant positions. This inverted differentiation strategy resolves the contradiction between ease of carrier binding and reliability under alkaline conditions.
Data Source
AI summary
Provided is a separating agent that does not have a significantly reduced dynamic binding capacity (DBC) to a target substance even when the separating agent is continually CIP-treated under alkaline pH conditions. The separating agent includes a carrier and a protein, wherein the protein is a given protein, and a surface of the carrier and a lysine residue in the protein are bound by a chemical bond.