Solid-Phase Chelator Chains for Stable Protein Purification
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Solution Overview
Problem
Existing immobilized metal affinity chromatography (IMAC) methods face issues with metal leaching and instability in the presence of chelators and reducing agents, leading to reduced protein binding capacity and contamination of eluates.
Innovation Solution
A solid-phase chelator material with polyamine groups and aminopolycarboxylic acid (APA) groups connected via bifunctional or trifunctional linkers, forming linear or branched chelator chains, providing high stability and affinity for histidine-tagged proteins.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If iminodiacetic acid (IDA) is used as a tridentate chelator for IMAC, then the material can be obtained easily and with low cost, but metal ions are leached into the buffers reducing protein binding capacity and eluates are contaminated with metal ions
Solution Approach 1:
The patent uses a composite chelator structure combining IDA with additional coordinating groups (such as nitrilotriacetic acid or hydroxymethylphosphonic acid groups) to create a multi-dentate chelating system. This composite approach maintains the ease of IDA manufacture while significantly improving metal ion stability by increasing the coordination number from 3 to 5 or 6, preventing metal leaching into buffers.
2Reliability
If tetradentate chelators such as NTA are used for IMAC, then metal leaching is reduced, but metal ions are removed by EDTA or reductants like DTT in the lysis buffer
Solution Approach 1:
The patent creates a composite chelator with 5 or 6 coordinating groups per metal ion binding site. This enhanced coordination geometry creates such a stable metal-chelator complex that even strong chelators like EDTA and reductants like DTT cannot effectively compete for the metal ions, thereby resolving the vulnerability of tetradentate systems.
3Reliability
If pentadentate chelators are used for IMAC, then metal ion stability is improved and resistance to EDTA is increased, but the number of free coordination sites for protein binding is reduced
Solution Approach 1:
The patent designs the chelator system to serve multiple functions simultaneously: the first 5 or 6 coordinating groups ensure stable metal ion binding and resistance to chelators/reductants, while additional coordinating groups remain available to bind histidine residues of target proteins. This multi-functional design resolves the trade-off between stability and binding capacity.
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 material exhibits enhanced stability against alkaline solutions and chelating agents, maintaining high protein binding capacity and purity, even in the presence of EDTA and DTT, with improved yield and reduced contamination.
Implementation Method 1
a solid-phase chelator material comprising a solid phase, polyamine groups bound to the solid phase and chelating groups bound to the polyamine groups
Implementation Method 2
each chelating group comprises one or several aminopolycarboxylic acid groups (APA groups)
Implementation Method 3
the principle of this method is basing upon the introduction of a plurality of histidine groups to the amino acid side chain of the proteins, which gives them a higher affinity towards immobilized metal ions
Data Source
AI summary
A solid-phase chelator material usable for the purification of proteins. The solid-phase chelator material comprises a solid phase, polyamine groups bound to the solid phase and chelating groups bound to the polyamine groups. At least a part of the polyamine groups is connected with at least two chelating groups per polyamine group. Each chelating group comprises one or several aminopolycarboxylic acid groups (APA groups), with the proviso that the number of APA groups per polyamine group connected with at least two cheating groups is at least three.