Metal Ion-Affinity Peptide Tag for Protein Purification
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Solution Overview
Problem
Current methods for detecting and purifying proteins using metal ion-affinity peptides lack a tag that combines high metal affinity with practical antigenicity, often resulting in non-specific binding or weak antigenic responses.
Innovation Solution
Development of an antibody that binds to a specific metal ion-affinity peptide sequence, enabling both efficient purification through immobilized metal affinity chromatography and effective detection via Western blot and immunoprecipitation, utilizing a peptide sequence like His-Z1-His-Arg-His-Z2-His, where Z1 and Z2 are specific amino acid residues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metal ion-affinity peptide tag (e.g., polyhistidine) is used for protein purification, then metal affinity is improved, but antigenicity deteriorates (weak antigenic response)
Solution Approach 1:
The patent combines a metal ion-binding peptide (containing histidine residues) with a separate antigenic peptide sequence to create a dual-functional tag. This merged structure allows the tag to simultaneously bind metal ions for purification and present antigenic epitopes for detection by antibodies, resolving the contradiction between metal affinity and antigenicity.
Solution Approach 2:
The invention creates a composite peptide tag that integrates two distinct functional domains: a metal-coordinating region (with histidine residues) and an antigenic region. This composite structure enables both purification via immobilized metal affinity chromatography and detection via antibody-based methods, addressing the limitation of conventional single-function tags.
2Difficulty of detecting and measuring
If conventional peptide tags are used for protein detection, then antigenicity is improved, but metal affinity deteriorates (non-specific binding)
Solution Approach 1:
The patent merges the functions of metal binding and antigen recognition into a single integrated peptide tag. The dual-functional design allows the same tag sequence to provide both high metal affinity for specific purification and strong antigenicity for reliable detection, eliminating the need for separate tags and reducing non-specific binding issues.
3Difficulty of detecting and measuring
If a dual-functional peptide tag is designed, then both metal affinity and antigenicity are improved, but device complexity increases
Solution Approach 1:
The dual-functional peptide tag is designed with distinct functional segments: a metal-binding domain (containing coordinated histidine residues) and an antigenic domain. This segmentation allows each region to independently perform its function while being part of a unified, relatively short peptide sequence, minimizing overall complexity while maintaining dual functionality.
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 antibody allows for specific and efficient detection, isolation, and purification of recombinant proteins with minimal non-specific background staining, leveraging both metal affinity and antigenicity for robust protein analysis.
Implementation Method 1
The principle behind IMAC lies in the fact that many transition metal ions, e.g., nickel, zinc and copper, can coordinate to the amino acids histidine, cysteine, and tryptophan via electron donor groups on the amino acid side chains.
Implementation Method 2
An antibody that binds to a peptide which is relatively hydrophilic, is capable of exhibiting appropriate biological activity, and has a relatively high affinity for coordinating metals.
Data Source
AI summary
Processes for the detection and purification of peptides and proteins comprising a metal ion-affinity peptide having a high affinity for coordinated metals and also being highly antigenic are described. Antibodies for use in the processes are also described.