Chromatography Packing Material with pH-Dependent Ligand Binding
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Solution Overview
Problem
Current packing materials for liquid chromatography face challenges in efficiently adsorbing and desorbing proteins or peptides without being influenced by the isoelectric point of the protein or the concentration of salt in the solution, limiting their ability to concentrate and recover biopolymers from dilute cell culture solutions.
Innovation Solution
A packing material is developed with α-amino acids or aminomethyl benzoic acid immobilized on a hydrophilic base matrix via amide or urethane bonds, allowing for pH-dependent adsorption and desorption of biopolymers, enhancing binding capacity and reducing salt concentration dependencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional hydrophilic packing materials with immobilized functional groups are used, then proteins can be adsorbed and purified, but the adsorption capacity is limited and the process is influenced by the isoelectric point of the protein and salt concentration in the solution
Solution Approach 1:
The invention utilizes pH as a controllable parameter to switch the packing material between hydrophobic (adsorptive) and hydrophilic (non-adsorptive) states. By adjusting the pH of the mobile phase, the same packing material can adsorb proteins across different isoelectric points and salt concentrations, then selectively elute them, thereby achieving both high adsorption capacity and broad adaptability without being constrained by protein-specific properties.
Solution Approach 2:
The packing material comprises a composite structure with a hydrophilic base matrix and hydrophobic functional groups (such as phenyl, benzyl, or naphthyl groups) attached thereto. This composite design allows the material to exhibit pH-dependent hydrophobicity: at low pH, the hydrophobic groups dominate and adsorb proteins; at high pH, the hydrophilic base matrix dominates and releases proteins. This composite structure enables high adsorption capacity while maintaining independence from protein isoelectric point and salt concentration.
2Reliability
If hydrophobic interaction chromatography is used to maintain protein activity, then proteins can be separated in mild solvents, but the adsorption capacity per unit volume is limited
Solution Approach 1:
The invention employs pH as a switching parameter to enhance adsorption capacity while maintaining protein activity. By operating at low pH where the packing material is hydrophobic, significantly higher adsorption capacities are achieved compared to conventional hydrophobic interaction chromatography. The same system then uses high pH to elute proteins under mild conditions that preserve their physiological activity, thus resolving the contradiction between adsorption capacity and protein reliability.
Solution Approach 2:
The packing material dynamically changes its hydrophobicity in response to pH changes in the mobile phase. At low pH, it adopts a hydrophobic state with high adsorption capacity; at high pH, it transitions to a hydrophilic state that releases proteins while maintaining their activity. This dynamic adaptability allows the system to optimize both adsorption capacity and protein reliability throughout the chromatographic process.
3Quantity of substance
If reversed-phase chromatography is used to achieve high adsorption capacity, then proteins can be concentrated, but the proteins are denatured due to organic solvent requirements
Solution Approach 1:
The invention uses pH changes instead of organic solvent concentration changes to control adsorption and elution. At low pH, the packing material is hydrophobic and adsorbs proteins with high capacity similar to reversed-phase chromatography. For elution, high pH is used to make the packing material hydrophilic, releasing proteins in aqueous buffers that maintain their structural integrity. This parameter substitution eliminates the need for organic solvents during elution while preserving both adsorption capacity and protein reliability.
4Quantity of substance
If the ligand amount on the packing material is increased to enhance adsorption capacity, then more protein can be bound, but the packing material becomes less selective and harder to regenerate
Solution Approach 1:
The invention uses pH as a selective switching parameter that affects all hydrophobic groups uniformly. Even with high ligand density, the pH change causes simultaneous deactivation of all hydrophobic groups, maintaining selectivity based on protein hydrophobicity differences. The regeneration process is simplified because increasing pH to a basic range simultaneously elutes all adsorbed proteins and restores the packing material to its hydrophilic state, making regeneration efficient and straightforward regardless of ligand amount.
Data Source
AI summary
To provide a novel packing material for liquid chromatography capable of separating and purifying, or collecting and recovering, a biopolymer such as a protein or a peptide by adsorption and desorption by a pH change without being influenced by the isoelectric point of the protein or by the salt concentration in a solvent in which the biopolymer such as the protein is dissolved, and to provide a process for concentrating and recovering a desired biopolymer such as a protein or a peptide from a large amount of dilute cell culture solution by means of such a packing material. Separation and purification, or collection and recovery, of a biopolymer, is carried out by liquid chromatography by means of a packing material for liquid chromatography comprising a base matrix and a ligand immobilized to the base matrix, wherein the base matrix is a hydrophilic base matrix having alcoholic hydroxy groups on its surface, the ligand is at least one ligand selected from the group consisting of an α-amino acid represented by the following formula (1): RCH(NH2)COOH (1) wherein R is an aromatic group or a C5-7 non-ionic aliphatic group, and an aminomethyl benzoic acid, and the ligand is immobilized to the base matrix by an amide bond or an urethane bond via the amino group contained in the compound represented by the formula (1).