1e3d: Difference between revisions

The primary and three-dimensional structures of a [NiFe] hydrogenase, isolated from D. desulfitricans ATCC 27774 were determined, by nucleotide, analysis and single-crystal X-ray crystallography. The three-dimensional, structural model was refined to R=0.167 and Rfree=0.223 using data to 1.8, A resolution. Two unique structural features are observed: the [4Fe-4S], cluster nearest the [NiFe] centre has been modified [4Fe-3S-3O] by loss of, one sulfur atom and inclusion of three oxygen atoms; a three-fold disorder, was observed for Cys536 which binds to the nickel atom in the [NiFe], centre. Also, the bridging sulfur atom that caps the active site was found, to have partial occupancy, thus corresponding to a partly activated, enzyme. These structural features may have biological relevance. In, particular, the two less-populated rotamers of Cys536 may be involved in, the activation process of the enzyme, as well as in the catalytic cycle., Molecular modelling studies were carried out on the interaction between, this [NiFe] hydrogenase and its physiological partner, the tetrahaem, cytochrome c3 from the same organism. The lowest energy docking solutions, were found to correspond to an interaction between the haem IV region in, tetrahaem cytochrome c3 with the distal [4Fe-4S] cluster in [NiFe], hydrogenase. This interaction should correspond to efficient electron, transfer and be physiologically relevant, given the proximity of the two, redox centres and the fact that electron transfer decay coupling, calculations show high coupling values and a short electron transfer, pathway. On the other hand, other docking solutions have been found that, despite showing low electron transfer efficiency, may give clues on, possible proton transfer mechanisms between the two molecules.

1E3D is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/Desulfovibrio_desulfuricans Desulfovibrio desulfuricans] with MG, F3S, SF4, FSX, FNE and H2S as [http://en.wikipedia.org/wiki/ligands ligands]. Structure known Active Sites: FE1, FE2, NI1 and NI2. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1E3D OCA].  

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