Mutated Protein A Ligand Alkaline Stability
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Solution Overview
Problem
Current affinity chromatography matrices containing protein A ligands face instability at alkaline pH values, leading to decreased binding capacities and ligand leakage, and struggle with selective separation of monomeric immunoglobulins from host cell proteins and aggregates, especially at low pH levels.
Innovation Solution
Mutated immunoglobulin- or Fc-binding proteins with altered Asparagine or Histidine residues at specific positions, such as H18 of the B domain of Protein A or Protein Z, which allow for improved dissociation and elution of immunoglobulins and Fc-containing proteins at higher pH values, enhancing chemical stability and selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If native or recombinant protein A ligands are used in affinity chromatography matrices, then high affinity and selectivity for immunoglobulins are achieved, but the matrices exhibit instability at alkaline pH values leading to decreased binding capacities and ligand leakage
Solution Approach 1:
The patent applies parameter changes by substituting specific amino acid residues (Asparagine at positions 21, 23, or 43) in the protein A ligand sequence with alternative amino acids. This molecular-level parameter change fundamentally alters the ligand's chemical stability properties, enabling it to withstand alkaline pH conditions (pH 12-14) without degradation, thereby resolving the contradiction between maintaining high binding capacity and achieving alkaline stability.
Solution Approach 2:
The patent creates a composite affinity chromatography matrix by combining the engineered protein A ligand (with mutated Asparagine residues) with a support matrix. This composite structure integrates the high affinity and selectivity of protein A with the mechanical stability of the support, while the engineered ligand provides resistance to alkaline degradation, thus achieving both reliability and compositional stability.
2Productivity
If conventional protein A matrices are used, then effective capture of immunoglobulins is achieved, but selective separation of monomeric immunoglobulins from host cell proteins and aggregates at low pH is difficult
Solution Approach 1:
The patent utilizes parameter changes in the ligand's amino acid sequence (substituting Asparagine residues) to modify the pH-dependent binding characteristics. This enables the matrix to maintain high affinity for immunoglobulins at capture pH while creating differential elution behavior at low pH, allowing monomeric immunoglobulins to elute selectively while host cell proteins and aggregates remain bound or elute at different conditions, thus achieving both high productivity and manufacturing precision.
3Ease of operation
If alkaline cleaning solutions are applied to remove contaminants, then effective regeneration of the matrix is achieved, but the proteinaceous ligands are exposed to harsh conditions resulting in decreased capacities
Solution Approach 1:
The patent applies parameter changes at the molecular level by mutating Asparagine residues in the ligand sequence, which fundamentally enhances the ligand's resistance to alkaline hydrolysis. This enables the matrix to undergo repeated alkaline cleaning cycles (exposure to pH 12-14) without significant loss of binding capacity, thus achieving ease of operation for matrix regeneration while maintaining reliability of binding performance.
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 proteins and matrices achieve increased elution pH for target proteins while maintaining high yield and purity, allowing for effective separation and reduced aggregation, thus improving the efficiency and cost-effectiveness of bioprocessing.
Implementation Method 1
proteins capable of specific binding to invariable parts of an immunoglobulin molecule
Implementation Method 2
An example of such a protein is staphylococcal protein A, containing domains capable of binding to the Fc and Fab portions of IgG immunoglobulins
Implementation Method 3
Such removal usually involves a procedure known as cleaning-in-place (CIP), wherein agents capable of eluting contaminants from the stationary phase are used
Data Source
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AI summary
The invention discloses an immunoglobulin-binding protein comprising one or more mutated immunoglobulin-binding domains (monomers) of staphylococcal Protein A (E, D, A, B,C) or protein Z or a functional variant thereof, wherein in at least one of the one or more mutated monomers, the asparagine or histidine at the position corresponding to H18 of the B domain of Protein A or of Protein Z has been deleted or substituted with a firstaminoacidresidue which is not proline or asparagine and wherein, if the amino acid residue at position 57 is proline and the aminoacid residue at position 28 is asparagine, then the amino acid residue at the position corresponding to H18 of the B domain of protein A or of protein Zis not serine, threonine or lysine.