Molecular study and partial characterization of iron-only hydrogenase in Desulfovibrio fructosovorans.

An iron-only hydrogenase was partially purified and characterized from Desulfovibrio fructosovorans wild-type strain. The enzyme exhibits a molecular mass of 56 kDa and is composed of two distinct subunits HydA and HydB (46 and 13 kDa, respectively). The N-terminal amino acid sequences of the two subunits of the enzyme were determined with the aim of designing degenerate oligonucleotides.

The cytochrome c3-[Fe]-hydrogenase electron-transfer complex: structural model by NMR restrained docking.

Cytochrome c(3) (M(r) 13000) is a low redox potential cytochrome specific of the anaerobic metabolism in sulfate-reducing bacteria. This tetrahemic cytochrome is an intermediate between the [Fe]-hydrogenase and the cytochrome Hmc in Desulfovibrio vulgaris Hildenborough strain. The present work describes the structural model of the cytochrome c(3)-[Fe]-hydrogenase complex obtained by nuclear magnetic resonance restrained docking.

Hydrogenases in the "active" state: determination of g-matrix axes and electron spin distribution at the active site by 1H ENDOR spectroscopy.

Hydrons and electrons are substrates for the enzyme hydrogenase, but cannot be observed in X-ray crystal structures. High-resolution 1H electron nuclear double resonance (ENDOR) spectroscopy offers a means to detect the distribution of protons and unpaired electrons. ENDOR spectra were recorded from frozen solutions of the nickel-iron hydrogenases of Desulfovibrio gigas and Desulfomicrobium baculatum, in the "active" state ("Ni-C" EPR signal) and analyzed by orientationally selective simulation methods.

Structural model of the Fe-hydrogenase/cytochrome c553 complex combining transverse relaxation-optimized spectroscopy experiments and soft docking calculations.

Fe-hydrogenase is a 54-kDa iron-sulfur enzyme essential for hydrogen cycling in sulfate-reducing bacteria. The x-ray structure of Desulfovibrio desulfuricans Fe-hydrogenase has recently been solved, but structural information on the recognition of its redox partners is essential to understand the structure-function relationships of the enzyme. In the present work, we have obtained a structural model of the complex of Fe-hydrogenase with its redox partner, the cytochrome c(553), combining docking calculations and NMR experiments.

Crystal structure of the oxidised and reduced acidic cytochrome c3from Desulfovibrio africanus.

Unique among sulphate-reducing bacteria, Desulfovibrio africanus has two periplasmic tetraheme cytochromes c3, one with an acidic isoelectric point which exhibits an unusually low reactivity towards hydrogenase, and another with a basic isoelectric point which shows the usual cytochrome c3reactivity. The crystal structure of the oxidised acidic cytochrome c3of Desulfovibrio africanus (Dva.a) was solved by the multiple anomalous diffraction (MAD) method and refined to 1.