Four-Helix Metal-Binding Polypeptide for Stable Ion Capture
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Solution Overview
Problem
Current metal-binding proteins face issues such as complex structure, low affinity, thermal and proteolytic instability, low binding capacity, high metal dissociation rate, and poor solubility, making them unsuitable for biomedical applications.
Innovation Solution
A polypeptide with an amino acid sequence having 60% to 98% homology with the copper storage protein from Methylosinus trichosporium OB3b (Csp1), featuring a bundle of four amphipathic α-helices connected by amino acid linkers, which forms a monomeric metal-binding protein with high affinity and stability, suitable for biomedical applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If complex metal-binding protein structures are used, then binding affinity may be improved, but structural complexity increases making production difficult
Solution Approach 1:
The invention segments the metal-binding function into a simplified four-helix bundle structure with specific metal-binding motifs, separating the essential binding function from complex tertiary/quaternary structures. This allows high-affinity metal binding while maintaining a simple, monomeric fold that is easier to produce and stabilize.
Solution Approach 2:
The invention changes key structural parameters by adopting a four-helix bundle topology with specific helix orientations and lengths, rather than using complex beta-barrels or multi-domain structures. This parameter change achieves comparable or superior binding affinity while dramatically reducing structural complexity and improving production feasibility.
2Quantity of substance
If high metal binding capacity is achieved, then more metals can be bound per molecule, but thermal and proteolytic stability may decrease
Solution Approach 1:
The invention applies local quality by creating specific metal-binding sites within the four-helix bundle structure through strategically positioned amino acid residues (such as histidine, cysteine, or aspartate coordinates). This allows high metal binding capacity at specific locations while the overall protein structure maintains enhanced thermal and proteolytic stability through its compact, stable helical fold.
3Stability of the object's composition
If metal dissociation rate is reduced for high stability, then metal retention improves, but binding capacity and accessibility may be compromised
Solution Approach 1:
The invention applies dynamics by designing metal-binding sites with controlled flexibility - the four-helix bundle maintains a stable overall structure for low dissociation rates, while the binding sites themselves possess dynamic characteristics that allow reversible metal binding and release. This enables both high metal retention and maintained binding capacity through controlled conformational adjustments at the binding interface.
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 polypeptide exhibits ultra-high affinity for metals like Cu(II), Pb(II), and Co(II), with a low dissociation rate, high binding capacity, and improved thermal and proteolytic stability, enabling applications in radio-imaging, metal decontamination, and bioremediation.
Implementation Method 1
wherein the protein comprises at least one metal binding site
Data Source
AI summary
The present invention relates to a polypeptide for use as a metal-binder, a protein comprising said polypeptide, a nucleic acid molecule encoding said polypeptide or protein, an expression vector comprising the nucleic acid molecule, a recombinant host cell comprising said polypeptide, protein, nucleic acid molecule and/or expression vector, a pharmaceutical composition comprising the said polypeptide, protein, nucleic acid molecule, expression vector and/or host cell, and to a kit.