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Density functional and reduction potential calculations of Fe4S4 clusters
Rhonda A Torres1, Timothy Lovell, Louis Noodleman
1Department of Molecular Biology TPC-15, The Scripps Research Institute, La Jolla, California 92037, USA.
Journal of the American Chemical Society
|February 13, 2003
Summary
Density functional theory accurately predicts the reduction potentials of iron-sulfur clusters in proteins. Protein and solvent interactions significantly influence these potentials, impacting biological electron transfer.
Area of Science:
- Biophysical Chemistry
- Computational Chemistry
- Bioinorganic Chemistry
Background:
- Iron-sulfur clusters are vital redox centers in numerous proteins.
- Understanding their electronic properties is crucial for deciphering biological electron transfer mechanisms.
Purpose of the Study:
- To computationally investigate the electronic structure and reduction potentials of [Fe(4)S(4)(SCH(3))(4)](n)()(-) clusters across all five oxidation states.
- To assess the influence of protein and solvent environments on these redox potentials.
Main Methods:
- Density functional theory (DFT) geometry optimizations.
- Calculation of reduction potentials including environmental effects using a continuum dielectric model.
Main Results:
- DFT calculations show good agreement with experimental data for cluster geometries and reduction potentials.
- Protein and solvent effects significantly modulate the redox properties of iron-sulfur clusters.
- Calculated properties for the all-ferrous [Fe(4)S(4)](0) state match experimental observations.
Conclusions:
- DFT is a reliable tool for predicting the redox behavior of iron-sulfur clusters.
- Amide dipoles and hydrogen bonding interactions are key factors in tuning the redox potentials of these clusters in proteins.
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