1h2r
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(New page: 200px<br /><applet load="1h2r" size="450" color="white" frame="true" align="right" spinBox="true" caption="1h2r, resolution 1.4Å" /> '''THREE-DIMENSIONAL STR...)
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Revision as of 14:16, 20 November 2007
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THREE-DIMENSIONAL STRUCTURE OF NI-FE HYDROGENASE FROM DESULFIVIBRIO VULGARIS MIYAZAKI F IN THE REDUCED FORM AT 1.4 A RESOLUTION
Overview
BACKGROUND: The active site of [NiFe] hydrogenase, a heterodimeric, protein, is suggested to be a binuclear Ni-Fe complex having three, diatomic ligands to the Fe atom and three bridging ligands between the Fe, and Ni atoms in the oxidized form of the enzyme. Two of the bridging, ligands are thiolate sidechains of cysteinyl residues of the large, subunit, but the third bridging ligand was assigned as a non-protein, monatomic sulfur species in Desulfovibrio vulgaris Miyazaki F hydrogenase., RESULTS: The X-ray crystal structure of the reduced form of D. vulgaris, Miyazaki F [NiFe] hydrogenase has been solved at 1.4 A resolution and, refined to a crystallographic R factor of 21.8%. The overall structure is, very similar to that of the oxidized form, with the exception that the, third monatomic bridge observed at the Ni-Fe site in the oxidized enzyme, is absent, leaving this site unoccupied in the reduced form. CONCLUSIONS:, The unusual ligand structure found in the oxidized form of D. vulgaris, Miyazaki F [NiFe] hydrogenase was confirmed in the reduced form of the, enzyme, with the exception that the electron density assigned to the, monatomic sulfur bridge had almost disappeared. On the basis of this, finding, as well as the observation that H2S is liberated from the, oxidized enzyme under an atmosphere of H2 in the presence of its electron, carrier, it was postulated that the monatomic sulfur bridge must be, removed for the enzyme to be activated. A possible mechanism for the, catalytic action of the hydrogenase is proposed.
About this Structure
1H2R is a Protein complex structure of sequences from Desulfovibrio vulgaris with MG, SF4, F3S and NFE as ligands. Active as Cytochrome-c3 hydrogenase, with EC number 1.12.2.1 Full crystallographic information is available from OCA.
Reference
Removal of the bridging ligand atom at the Ni-Fe active site of [NiFe] hydrogenase upon reduction with H2, as revealed by X-ray structure analysis at 1.4 A resolution., Higuchi Y, Ogata H, Miki K, Yasuoka N, Yagi T, Structure. 1999 May;7(5):549-56. PMID:10378274
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