The iron-sulfur centers of the soluble [NiFeSe] hydrogenase, from Desulfovibrio baculatus (DSM 1743)

EPR and Mössbauer characterization

Authors

  • Miguel TEIXEIRA,

    Corresponding author
    1. Centro de Química Estrutural and Universidade Nova de Lisboa, Lisboa, Portugal
    2. Department of Physics, Emory University, Atlanta, USA
      Correspondence to M. Teixeira, Centro de Quimica Estrutural, Complexo I, Av. Rovisco Pais, P-1096 Lisboa Codex, Portugal
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  • Isabel MOURA,

    1. Centro de Química Estrutural and Universidade Nova de Lisboa, Lisboa, Portugal
    2. School of Chemical Sciences, Department of Biochemistry, University of Georgia, Athens, USA
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  • Guy FAUQUE,

    1. Service de Radioagronomie, Département de Biologie, Centre d'Energie Nucléaire Cadarache, Saint-Paul-Lez-Durance, France
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  • Daniel V. DERVARTANIAN,

    1. School of Chemical Sciences, Department of Biochemistry, University of Georgia, Athens, USA
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  • Jean LEGALL,

    1. School of Chemical Sciences, Department of Biochemistry, University of Georgia, Athens, USA
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  • H. D. PECK Jr.,

    1. School of Chemical Sciences, Department of Biochemistry, University of Georgia, Athens, USA
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  • José J. G. MOURA,

    1. Centro de Química Estrutural and Universidade Nova de Lisboa, Lisboa, Portugal
    2. School of Chemical Sciences, Department of Biochemistry, University of Georgia, Athens, USA
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  • Boi H. HUYNH

    1. Department of Physics, Emory University, Atlanta, USA
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Correspondence to M. Teixeira, Centro de Quimica Estrutural, Complexo I, Av. Rovisco Pais, P-1096 Lisboa Codex, Portugal

Abstract

The soluble (cytoplasmic plus periplasmic) Ni/Fe-S/Se-containing hydrogenase from Desulfovibrio baculatus (DSM 1743) was purified from cells grown in an 57Fe-enriched medium, and its iron-sulfur centers were extensively characterized by Mössbauer and EPR spectroscopies. The data analysis excludes the presence of a [3Fe-4S] center, either in the native (as isolated) or in the hydrogen-reduced states. In the native state, the non-heme iron atoms are arranged as two diamagnetic [4Fe-4S]2+ centers. Upon reduction, these two centers exhibit distinct and unusual Mössbauer spectroscopic parameters. The centers were found to have similar mid-point potentials (∼– 315 mV) as determined by oxidation-reduction titrations followed by EPR.

Enzyme
 

Hydrogenase (EC 1.2.2.1)

Ancillary