title: Redox characteristics of the tungsten DMSO reductase of Rhodobacter capsulatus.
abstract: The dimethylsulfoxide reductase (DMSOR) from Rhodobacter capsulatus is known to retain its three-dimensional structure and enzymatic activity upon substitution of molybdenum, the metal that occurs naturally at the active site, by tungsten. The redox properties of tungsten-substituted DMSOR (W-DMSOR) have been investigated by a dye-mediated reductive titration with the concentration of the W(V) state monitored by EPR spectroscopy. At pH 7.0, E(m)(W(VI)/W(V)) is -194 mV and E(m)(W(V)/W(IV)) is -134 mV. Each E(m) value of W-DMSOR is significantly lower (220 and 334 mV, respectively) than that of the corresponding couple of Mo-DMSOR. These redox potentials are consistent with the ability of Mo-DMSOR to catalyze both the reduction of DMSO to DMS and the back reaction, whereas W-DMSOR is very effective in catalyzing the forward reaction, but shows no ability to catalyze the oxidation of DMS to DMSO.
authors.affiliation: Kluyver Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC, Delft, The Netherlands. p.l.hagedoorn@tnw.tudelft.nl
authors.forename: Peter Leon
authors.initials: PL
authors.lastname: Hagedoorn
authors.forename: Wilfred R
authors.initials: WR
authors.lastname: Hagen
authors.forename: Lisa J
authors.initials: LJ
authors.lastname: Stewart
authors.forename: Arefa
authors.initials: A
authors.lastname: Docrat
authors.forename: Susan
authors.initials: S
authors.lastname: Bailey
authors.forename: C David
authors.initials: CD
authors.lastname: Garner
mesh_terms: D002384:Catalysis; D004121:Dimethyl Sulfoxide / Q000737:chemistry / Q000378:metabolism; D004578:Electron Spin Resonance Spectroscopy; D006863:Hydrogen-Ion Concentration; D007506:Iron-Sulfur Proteins; D008982:Molybdenum / Q000737:chemistry / Q000378:metabolism; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000737:chemistry* / Q000378:metabolism; D016354:Rhodobacter capsulatus / Q000201:enzymology*; D017186:Titrimetry / Q000379:methods; D014414:Tungsten / Q000737:chemistry* / Q000378:metabolism
chemical_list: D007506:Iron-Sulfur Proteins; D008982:Molybdenum; D010088:Oxidoreductases; C045664:dimethyl sulfoxide reductase; D014414:Tungsten; D004121:Dimethyl Sulfoxide