Computational studies of modified [Fe3S4] clusters: Why iron is optimal

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

This work reports density functional computations of metal-substituted models of biological [Fe3S4] clusters in oxidation states [MFe2S4]+/0/−1 (M = Mn, Fe, Co, Ni, Cu, Zn, and Mo). Geometry optimization with a dielectric screening model is shown to provide a substantial improvement in structure, compared to earlier used standard procedures. The error for average Fe–S bonds decreased from 0.038 Å to 0.016 Å with this procedure. Four density functionals were compared, B3LYP, BP86, TPSS, and TPSSh. B3LYP and to a lesser extent TPSSh energies were inconsistent with experiment for the oxidized [Fe3S4]+ cluster. BP86 (and to a slightly lesser extent TPSS) was within expected theoretical and experimental uncertainties for all oxidation states, the only qualitative error being 5 kJ/mol in favor of the MS = 3/2 configuration for the [Fe3S4]+ cluster, so BP86 was used for quantitative results. Computed reorganization energies and reduction potentials point directly towards the [Fe3S4] cluster as the superior choice of electron carrier, with the [ZnFe2S4] cluster a close second. In addition, partially and fully Mo-substituted clusters were investigated and found to have very low reorganization energies but too negative reduction potentials. The results provide a direct rationale why any substitution weakens the cluster as an electron carrier, and thus why the [Fe3S4] composition is optimal in the biological clusters.
Original languageEnglish
JournalJournal of Inorganic Biochemistry
Volume102
Issue number1
Pages (from-to)87-100
ISSN0162-0134
DOIs
Publication statusPublished - 2008

Keywords

  • Density functional theory
  • Reorganization energy
  • Electron transfer
  • Iron–sulfur proteins
  • Reduction potential

Cite this

@article{f7db1519940c466d9cd3c27c90654ea2,
title = "Computational studies of modified [Fe3S4] clusters: Why iron is optimal",
abstract = "This work reports density functional computations of metal-substituted models of biological [Fe3S4] clusters in oxidation states [MFe2S4]+/0/−1 (M = Mn, Fe, Co, Ni, Cu, Zn, and Mo). Geometry optimization with a dielectric screening model is shown to provide a substantial improvement in structure, compared to earlier used standard procedures. The error for average Fe–S bonds decreased from 0.038 {\AA} to 0.016 {\AA} with this procedure. Four density functionals were compared, B3LYP, BP86, TPSS, and TPSSh. B3LYP and to a lesser extent TPSSh energies were inconsistent with experiment for the oxidized [Fe3S4]+ cluster. BP86 (and to a slightly lesser extent TPSS) was within expected theoretical and experimental uncertainties for all oxidation states, the only qualitative error being 5 kJ/mol in favor of the MS = 3/2 configuration for the [Fe3S4]+ cluster, so BP86 was used for quantitative results. Computed reorganization energies and reduction potentials point directly towards the [Fe3S4] cluster as the superior choice of electron carrier, with the [ZnFe2S4] cluster a close second. In addition, partially and fully Mo-substituted clusters were investigated and found to have very low reorganization energies but too negative reduction potentials. The results provide a direct rationale why any substitution weakens the cluster as an electron carrier, and thus why the [Fe3S4] composition is optimal in the biological clusters.",
keywords = "Density functional theory, Reorganization energy, Electron transfer, Iron–sulfur proteins, Reduction potential",
author = "Kepp, {Kasper Planeta}",
year = "2008",
doi = "10.1016/j.jinorgbio.2007.07.025",
language = "English",
volume = "102",
pages = "87--100",
journal = "Journal of Inorganic Biochemistry",
issn = "0162-0134",
publisher = "Elsevier",
number = "1",

}

Computational studies of modified [Fe3S4] clusters: Why iron is optimal. / Kepp, Kasper Planeta.

In: Journal of Inorganic Biochemistry, Vol. 102, No. 1, 2008, p. 87-100.

Research output: Contribution to journalJournal articleResearchpeer-review

TY - JOUR

T1 - Computational studies of modified [Fe3S4] clusters: Why iron is optimal

AU - Kepp, Kasper Planeta

PY - 2008

Y1 - 2008

N2 - This work reports density functional computations of metal-substituted models of biological [Fe3S4] clusters in oxidation states [MFe2S4]+/0/−1 (M = Mn, Fe, Co, Ni, Cu, Zn, and Mo). Geometry optimization with a dielectric screening model is shown to provide a substantial improvement in structure, compared to earlier used standard procedures. The error for average Fe–S bonds decreased from 0.038 Å to 0.016 Å with this procedure. Four density functionals were compared, B3LYP, BP86, TPSS, and TPSSh. B3LYP and to a lesser extent TPSSh energies were inconsistent with experiment for the oxidized [Fe3S4]+ cluster. BP86 (and to a slightly lesser extent TPSS) was within expected theoretical and experimental uncertainties for all oxidation states, the only qualitative error being 5 kJ/mol in favor of the MS = 3/2 configuration for the [Fe3S4]+ cluster, so BP86 was used for quantitative results. Computed reorganization energies and reduction potentials point directly towards the [Fe3S4] cluster as the superior choice of electron carrier, with the [ZnFe2S4] cluster a close second. In addition, partially and fully Mo-substituted clusters were investigated and found to have very low reorganization energies but too negative reduction potentials. The results provide a direct rationale why any substitution weakens the cluster as an electron carrier, and thus why the [Fe3S4] composition is optimal in the biological clusters.

AB - This work reports density functional computations of metal-substituted models of biological [Fe3S4] clusters in oxidation states [MFe2S4]+/0/−1 (M = Mn, Fe, Co, Ni, Cu, Zn, and Mo). Geometry optimization with a dielectric screening model is shown to provide a substantial improvement in structure, compared to earlier used standard procedures. The error for average Fe–S bonds decreased from 0.038 Å to 0.016 Å with this procedure. Four density functionals were compared, B3LYP, BP86, TPSS, and TPSSh. B3LYP and to a lesser extent TPSSh energies were inconsistent with experiment for the oxidized [Fe3S4]+ cluster. BP86 (and to a slightly lesser extent TPSS) was within expected theoretical and experimental uncertainties for all oxidation states, the only qualitative error being 5 kJ/mol in favor of the MS = 3/2 configuration for the [Fe3S4]+ cluster, so BP86 was used for quantitative results. Computed reorganization energies and reduction potentials point directly towards the [Fe3S4] cluster as the superior choice of electron carrier, with the [ZnFe2S4] cluster a close second. In addition, partially and fully Mo-substituted clusters were investigated and found to have very low reorganization energies but too negative reduction potentials. The results provide a direct rationale why any substitution weakens the cluster as an electron carrier, and thus why the [Fe3S4] composition is optimal in the biological clusters.

KW - Density functional theory

KW - Reorganization energy

KW - Electron transfer

KW - Iron–sulfur proteins

KW - Reduction potential

U2 - 10.1016/j.jinorgbio.2007.07.025

DO - 10.1016/j.jinorgbio.2007.07.025

M3 - Journal article

VL - 102

SP - 87

EP - 100

JO - Journal of Inorganic Biochemistry

JF - Journal of Inorganic Biochemistry

SN - 0162-0134

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