Affinity Chromatography Matrix Ligand Stability
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Solution Overview
Problem
Affinity chromatography matrices containing protein A ligands face instability at high pH values during cleaning procedures, leading to decreased capacity and ligand leakage, and there is a need for increased elution pH to prevent antibody aggregation and maintain product integrity.
Innovation Solution
Substituting Asparagine or Histidine at position H18 of Protein A or Protein Z domains with other amino acids, such as Serine, in multimeric ligands to enhance chemical stability and elution pH, allowing for gentler elution conditions and reduced aggregation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If alkaline cleaning agents (NaOH) are used to remove contaminants from the matrix, then cleaning effectiveness is improved, but ligand stability deteriorates due to high pH exposure
Solution Approach 1:
The patent applies parameter changes by mutating specific amino acid residues (Asparagine or Histidine at position H18) in the protein A ligand sequence. This molecular parameter change alters the ligand's chemical properties to confer alkaline stability, allowing it to withstand high pH cleaning conditions without degradation while maintaining its binding function.
Solution Approach 2:
The patent employs a disposable affinity matrix that is intentionally designed to be single-use or limited-use. The matrix is used for one purification run and then discarded, eliminating the need for expensive and complex regeneration procedures. This approach trades the cost of repeated matrix usage against the cost of consuming affordable, single-use matrices with improved ligand stability.
2Quantity of substance
If conventional protein A ligands are used in affinity chromatography, then binding capacity is maintained, but elution pH is limited which causes antibody aggregation
Solution Approach 1:
The patent changes the chemical parameter of the ligand by introducing specific amino acid mutations at position H18. This modification shifts the elution pH to a higher range (pH 4.0-5.0 or higher), which prevents antibody aggregation during elution while preserving the ligand's binding capacity for immunoglobulins.
3Reliability
If protein A ligands are engineered for alkaline stability, then resistance to high pH is improved, but binding affinity may be compromised
Solution Approach 1:
The patent applies local quality by making a targeted mutation only at the specific position (H18) where the Asparagine or Histidine residue is located, while leaving the rest of the protein A ligand sequence unchanged. This localized modification provides alkaline stability without disrupting the critical binding interfaces that maintain high binding affinity for immunoglobulins.
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 modified ligands exhibit increased elution pH, improved stability under alkaline conditions, and higher binding capacities, minimizing antibody aggregation and maintaining product integrity while reducing processing costs.
Implementation Method 1
Affinity chromatography is used in most cases, as one of the key steps in the purification of these immunoglobulin molecules... proteins capable of specific binding to invariable parts of an immunoglobulin molecule
Implementation Method 2
The removal of such contaminants from the matrix is usually performed after a first elution of the desired product... One such class of agents often used is alkaline solutions that are passed over said stationary phase
Data Source
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AI summary
The present invention relates to a method of separating one or more immunoglobulin containing proteins from a liquid. The method includes first contacting the liquid with a separation matrix comprising ligands immobilised to a support; allowing the immunoglobulin containing proteins to adsorb to the matrix by interaction with the ligands; followed by an optional step of washing the matrix containing the immunoglobulin containing proteins adsorbed thereon; and recovering said immunoglobulin containing proteins by contacting the matrix with an eluent which releases the proteins. The method improves upon previous separation methods in that each of the ligands comprises one or more of a protein A domain (E, D, A, B, C), or protein Z, or a functional variant thereof, with at least one of the monomers having a substitution of the Asparagineor Histidine at the position corresponding to H18 of B domain of Protein A or Protein Z, and wherein the ligand provides an increase in elution pH compared to non-substituted ligand.