J. Am. Chem. Soc., 118(5), 1113 - 1117. ja953317l

X-ray Absorption Spectroscopy of Dimethyl Sulfoxide Reductase from Rhodobacter sphaeroides

Graham N. George,^* James Hilton, and K. V. Rajagopalan

Contribution from the Stanford Synchrotron Radiation Laboratory, SLAC, Stanford University, P.O. Box 4349, MS 69, Stanford, California, 94309-0210, and the Department of Biochemistry, School of Medicine, Duke University, Durham, North Carolina 27710

Received September 29, 1995

Abstract:

X-ray absorption spectroscopy at the molybdenum K-edge has been used to probe the molybdenum coordination of Rhodobacter sphaeroides dimethyl sulfoxide reductase. The molybdenum site of the oxidized protein possesses a novel Mo(VI) mono-oxo site (Mo=O at 1.68 ) with additional coordination by approximately four thiolate ligands at 2.44 and probably one oxygen or nitrogen at 1.92 . The reduced Mo(IV) form of the enzyme is a des-oxomolybdenum with 3-4 thiolates at 2.33 and two different Mo-O/N ligands at 2.16 and 1.92 . Similarly, the stable Mo(V) glycerol-inhibited species is found to be a des-oxomolybdenum with approximately four thiolate ligands at 2.40 and (probably) two similarly coordinated oxygen or nitrogen ligands at 1.96 .