title: Structure of the active site of sulfite dehydrogenase from Starkeya novella.
abstract: In this paper, we report the results of molybdenum K-edge X-ray absorption studies performed on the oxidized and reduced active sites of the sulfite dehydrogenase from Starkeya novella. Our results provide the first direct structural information on the active site of the oxidized form of this enzyme and confirm the conclusions derived from protein crystallography that the molybdenum coordination is analogous to that of the sulfite oxidases. The molybdenum atom of the oxidized enzyme is bound by two Mo=O ligands at 1.73 A and three thiolate Mo-S ligands at 2.42 A, whereas the reduced enzyme has one oxo at 1.74 A, one long oxygen at 2.19 A (characteristic of Mo-OH2), and three Mo-S ligands at 2.40 A.
authors.affiliation: Department of Geological Sciences, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E2, Canada.
authors.forename: Christian J
authors.initials: CJ
authors.lastname: Doonan
authors.forename: Ulrike
authors.initials: U
authors.lastname: Kappler
authors.forename: Graham N
authors.initials: GN
authors.lastname: George
mesh_terms: D020561:Alphaproteobacteria / Q000201:enzymology*; D001665:Binding Sites; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods; D008024:Ligands; D015394:Molecular Structure; D008982:Molybdenum / Q000737:chemistry; D010084:Oxidation-Reduction; D012680:Sensitivity and Specificity; D013057:Spectrum Analysis / Q000379:methods; D050902:Sulfite Dehydrogenase / Q000737:chemistry*; D014965:X-Rays
chemical_list: D008024:Ligands; D008982:Molybdenum; D050902:Sulfite Dehydrogenase