Mutated Protein L Polypeptide Alkali Stability
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Solution Overview
Problem
Current Protein L-based separation matrices for immunoglobulins and antibody fragments have limited alkali stability, requiring less desirable cleaning agents and affecting their binding capacity and selectivity.
Innovation Solution
A kappa light chain-binding polypeptide with mutated binding domains of Peptostreptococcus Protein L, featuring specific amino acid mutations such as asparagines changed to histidines or tyrosines, providing enhanced alkali stability while maintaining affinity for kappa light chains.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Protein L-based separation matrices are used for immunoglobulin purification, then high selectivity and binding affinity for kappa light chains are achieved, but alkali stability is limited requiring less desirable cleaning agents
Solution Approach 1:
The patent applies parameter changes by modifying the amino acid sequence of Protein L binding domains through site-directed mutagenesis. Specific asparagine residues at positions 10, 45, and 60 are mutated to histidine, tyrosine, or glutamine to enhance alkali stability while preserving binding functionality. This chemical parameter modification allows the matrix to withstand harsher cleaning conditions.
Solution Approach 2:
The patent enables the recovery and reuse of the separation matrix by improving its resistance to alkaline cleaning agents. The mutated Protein L domains can endure repeated cleaning-in-place cycles with NaOH solutions, allowing the expensive chromatography media to be regenerated and reused multiple times without significant capacity loss.
2Object-generated harmful factors
If Protein L matrices are cleaned with alkaline solutions, then contaminants are removed from the stationary phase, but binding capacity is reduced due to alkali sensitivity
Solution Approach 1:
The patent modifies the chemical parameters of Protein L by changing specific amino acid residues (N10H, N45H, N60Y/Q) to increase resistance to alkaline degradation. This allows the matrix to undergo thorough cleaning with 0.1-1.0 M NaOH solutions while retaining 90% or more of its original binding capacity after multiple cleaning cycles.
Solution Approach 2:
The patent provides prior protection against alkali damage by pre-modifying the Protein L structure with stabilizing mutations before exposure to harsh cleaning conditions. The mutated binding domains are inherently more resistant to alkaline hydrolysis and denaturation, cushioning them against the harmful effects of repeated cleaning-in-place procedures.
3Reliability
If Protein L is used to bind kappa light chains with high affinity, then selective purification is achieved, but alkali tolerance is reduced to only 15 mM NaOH for 80 cycles
Solution Approach 1:
The patent changes the chemical parameters of Protein L binding domains through specific amino acid substitutions. The N10H, N45H, and N60Y/Q mutations enhance the structural stability and alkali resistance of the binding domains, enabling them to withstand significantly higher concentrations of NaOH (0.1-1.0 M) over extended cleaning cycles while maintaining their kappa light chain binding affinity.
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 mutated polypeptide exhibits improved alkali stability and maintained affinity for kappa light chains, allowing for more effective cleaning and regeneration of chromatography matrices without compromising binding performance.
Implementation Method 1
The highly selective binding of Protein A to the Fc chain of immunoglobulins provides for a generic step with very high clearance of impurities and contaminants
Implementation Method 2
Protein L is however a rather alkali-sensitive protein compared to e.g. Protein A and only tolerates 15 mM NaOH for 80 cycles using 15 min contact time with 90% remaining binding capacity
Data Source
AI summary
The present relates to a polypeptide that binds to an immunoglobulin or a fragment thereof. More specifically, it relates to a kappa light-chain binding polypeptide with high binding affinity and improved alkali stability. The one kappa light-chain binding comprises a mutated binding domain of Peptostreptococcus Protein L, derived from any one of the amino acid sequences SEQ ID NO:10, SEQ ID NO:11, SEQ ID NO:12, SEQ ID NO:13, SEQ ID NO:14, SEQ ID NO:15, SEQ ID NO:16, SEQ ID NO:17 or SEQ ID NO:18, said amino acid sequences having N6H, N41H and N56Y or N56Q mutations.