title: Insights from the computational studies on the oxidized as-isolated state of [NiFeSe] hydrogenase from D. vulgaris Hildenborough.
abstract: A density functional theory study of the active site structure and features of the oxygen tolerant [NiFeSe] Hase in the oxidized as-isolated state of the enzyme D. vulgaris Hildenborough (DvH) is reported here. The three conformers reported to be present in the X-ray structure (PDB ID: ) have been studied. The novel bidentate interchalcogen ligand (S-Se) in Conf-I of the [NiFeSe] Hase reported for the first time in hydrogenases (Hase) is found to be of donor-acceptor type with an uneven η(2) L → M σ-bond. The symmetry mismatch at the sp orbital of Se and at the dz(2) orbital of Ni has been identified to be the reason for the inability of Conf-II to convert to Conf-I. NBO analysis shows that the sulfinate ligand peculiar to the state stabilizes the active site through n →π* interactions. The results reveal that the isolated oxidized state of the [NiFeSe] Hase is significantly different from the well-known [NiFe] Hase.
authors.affiliation: Theoretical and Computational Chemistry Laboratory, School of Chemistry, Bharathidasan University, Tiruchirappalli-620 024, India. venuvanalingam@yahoo.com.
authors.forename: Swaminathan Angeline
authors.initials: SA
authors.lastname: Vedha
authors.forename: Gunasekaran
authors.initials: G
authors.lastname: Velmurugan
authors.forename: Rajangam
authors.initials: R
authors.lastname: Jagadeesan
authors.forename: Ponnambalam
authors.initials: P
authors.lastname: Venuvanalingam
mesh_terms: D016969:Desulfovibrio vulgaris / Q000201:enzymology*; D006864:Hydrogenase / Q000737:chemistry / Q000378:metabolism*; D008968:Molecular Conformation; D010084:Oxidation-Reduction; D011789:Quantum Theory
chemical_list: C058560:nickel-iron-selenium hydrogenase; D006864:Hydrogenase