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Updated: Aug 6, 2026
06:53
Magnetometric Characterization of Intermediates in the Solid-State Electrochemistry of Redox-Active Metal-Organic Frameworks
Published on: June 9, 2023
Geometry, spin coupling, and dielectric control of redox potentials in [4Fe-4S] Clusters
Peter S Rice1, Bruno Jacob1, Khushbu Agarwal1
1Physical Sciences Division, Pacific Northwest National Laboratory, Richland, WA, 99352, USA.
Summary
Iron-sulfur clusters are vital for redox reactions. Their redox potential is mainly tuned by electrostatic and solvation effects, with geometry playing a minor role in fine-tuning.
Area of Science:
- Biochemistry and Biophysics
- Bioinorganic Chemistry
Background:
- Iron-sulfur (Fe-S) clusters are essential biological cofactors enabling critical redox reactions.
- The precise mechanisms for tuning the redox potential of Fe-S clusters in ferredoxin-like proteins are still under investigation.
Purpose of the Study:
- To investigate how cysteine ligand orientation and environmental factors influence the redox properties of [4Fe-4S] clusters.
- To elucidate the molecular basis of redox potential tuning in ferredoxin-like proteins.
Main Methods:
- Statistical analysis of over 1000 [4Fe-4S] protein structures from the Protein Data Bank (PDB).
- Application of broken-symmetry and extended broken-symmetry density functional theory (DFT) calculations.
Main Results:
- Identified five predominant ligand configurations for [4Fe-4S] clusters in natural protein structures.
- Found that adiabatic electron affinity varies by less than 0.1 V across predominant configurations, indicating geometry's secondary role in fine-tuning.
- Demonstrated that electrostatic and solvation effects are the primary determinants of the overall redox potential range.
Conclusions:
- Protein structure geometry offers localized fine-tuning of Fe-S cluster redox properties.
- Environmental factors, specifically electrostatics and solvation, are the dominant forces controlling the broad range of redox potentials observed in Fe-S proteins.
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