Cluster Orbital Theory Based on Massbauer Effect Investigations of the (Iron)4-Sulfur Clusters of Clostridium pasteurianum Ferredoxin

Hermann Eicher, Fritz Parak, Ludwig Bogner, Klaus Gersonde

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Abstract

A cluster orbital theory is developed, which allows the calculation of Mossbauer spectra of oxidized and reduced ferredoxin of Clostridium pasteurianum under the conditions of low temperature (4.2 K) and high external magnetic field [formula omitted]. The calculations are based on the symmetry properties of the problem and the way in which these symmetries are reflected in the (iron)4-sulfur cluster wave function. The assumed cubic Td symmetry of the cluster implies an isotropic interaction with the applied external magnetic field, where the average g-tensor is taken to be g=1.944 in accordance with ESR results. The magnetic hyperfine interaction of the cluster electrons with the magnetic dipole moments of the iron nuclei is defined by two parameters x and [formula omitted] reflecting trigonal point symmetry C3V of each iron site. These parameters are determined by a least squares fit of the experimental Mossbauer spectrum of reduced ferredoxin at 4.2 K and Hext = 2 T. In correspondence with the theory, x and [formula omitted] have been proved to be independent of Hext. Despite neglecting small deviations from Td and C3V point symmetry of the center of the cluster and the iron sites, respectively, theory and experiments are in reasonable good agreement.

Original languageEnglish
Pages (from-to)683-691
Number of pages9
JournalZeitschrift fur Naturforschung - Section C Journal of Biosciences
Volume29
Issue number11-12
DOIs
StatePublished - 1 Dec 1974

Keywords

  • Clostridium pasteurianum
  • Cluster Orbital Theory
  • Ferredoxin
  • Mössbauer Effect

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