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Modeling an Enzyme Active Site using Molecular Visualization Freeware
Published on: December 25, 2021
Of folding and function: understanding active-site context through metalloenzyme design.
Kinesha L Harris1, Sunghyuk Lim, Sonya J Franklin
1Department of Chemistry, University of Iowa, Iowa City, Iowa 52242, USA.
Inorganic Chemistry
|December 5, 2006
Summary
Researchers designed novel metalloproteins and metallopeptides by inserting metal-binding loops into protein scaffolds. Loop modifications influenced metal binding and protein folding, with implications for biomolecular design and function.
Area of Science:
- Biomolecular design
- Protein engineering
- Bioinorganic chemistry
Background:
- Protein scaffolds can be engineered with metal-binding sites.
- The modular-turn-substitution approach creates novel metalloproteins and metallopeptides.
- Lanthanide-binding loops can be introduced into unrelated protein scaffolds.
Purpose of the Study:
- To investigate the effect of loop substitutions on metal binding affinity and protein folding.
- To create lanthanide-binding metallopeptides and a metallohomeodomain.
- To explore the functional consequences of metal-binding loop insertion.
Main Methods:
- Modular-turn-substitution using EF-hand loops.
- Chimeric peptide design with varied loop residues (Asn, Glu, Ala, Asp).
- Fluorescence resonance energy transfer (FRET) for metal affinity (Tb(III)).
- Circular dichroism (CD) spectroscopy for protein folding.
- Cloning and expression of a lanthanide-binding homeodomain (C2).
Main Results:
- Metal affinity for Tb(III) varied with loop residue: Asp/Asn > Ala/Glu.
- Asp/Asn residues stabilized loop structure and promoted peripheral helix folding.
- Engineered homeodomain (C2) showed increased helicity upon Tb(III) binding.
- The C2 protein did not promote phosphate or DNA cleavage, unlike smaller peptides.
Conclusions:
- Loop residue identity significantly impacts metal binding and protein folding.
- Modular substitution is effective in creating functional metalloproteins and metallopeptides.
- Context (peptide vs. full domain) affects metal accessibility and function.
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