title: X-ray absorption spectroscopy of selenate reductase.
abstract: The metal sites of selenate reductase from Thauera selenatis have been characterized by Mo, Se, and Fe K-edge X-ray absorption spectroscopy. The Mo site of the oxidized enzyme has 3 to 4 sulfur ligands at 2.33 A from two molybdopterin cofactors, one Mo=O group at 1.68 A and one Mo-O with an intermediate bond length of 1.81 A. The reduced enzyme has a des-oxo active site, again with about four Mo-S ligands (at 2.32 A) and possibly one oxygen ligand at 2.22 A. The enzyme was found to contain Se in a reduced form (probably organic) although the sequence does not indicate the presence of selenocysteine. The Se is coordinated to both a metal (probably Fe) and a lighter scatterer such as carbon.
authors.affiliation: School of Molecular and Microbial Biosciences, University of Sydney, Sydney, New South Wales 2006, Australia. M.Maher@mmb.usyd.edu.au
authors.forename: Megan J
authors.initials: MJ
authors.lastname: Maher
authors.forename: Joanne
authors.initials: J
authors.lastname: Santini
authors.forename: Ingrid J
authors.initials: IJ
authors.lastname: Pickering
authors.forename: Roger C
authors.initials: RC
authors.lastname: Prince
authors.forename: Joan M
authors.initials: JM
authors.lastname: Macy
authors.forename: Graham N
authors.initials: GN
authors.lastname: George
mesh_terms: D001665:Binding Sites; D018360:Crystallography, X-Ray; D005583:Fourier Analysis; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000737:chemistry*; D013052:Spectrometry, X-Ray Emission; D020628:Thauera / Q000201:enzymology
chemical_list: D010088:Oxidoreductases; C078108:selenate reductase