Detection of the optical bands of molybdenum(V) in DMSO reductase (Rhodobacter capsulatus) by low-temperature MCD spectroscopy.
Dimethylsulphoxide (DMSO) reductase from R. capsulatus contains a molybdenum-pterin cofactor at its active site. As prepared the molybdenum is in the 6+ oxidation state, devoid of EPR signals. Stepwise reduction generates an EPR signal characteristic of Mo(V) having hyperfine coupling to a single proton and integrating to less than 25% of the total molybdenum. The low temperature MCD spectrum shows oppositely signed bands between approximately 550-700 nm. These bands are assigned as dithiolene-to-Mo(V) charge transitions. A simple theoretical model can satisfactorily account for the bands in the MCD spectrum. No evidence is found for cysteine coordination to Mo(V).
Benson
N
N
Centre for Metalloprotein Spectroscopy and Biology, School of Chemical Sciences, University of East Anglia, Norwich, UK.
Farrar
J A
JA
McEwan
A G
AG
Thomson
A J
AJ
D002942:Circular Dichroism; D007506:Iron-Sulfur Proteins; D008982:Molybdenum / Q000032:analysis / Q000737:chemistry*; D055095:Optics and Photonics; D010088:Oxidoreductases / Q000737:chemistry* / Q000378:metabolism; D016354:Rhodobacter capsulatus / Q000201:enzymology*; D013696:Temperature
D007506:Iron-Sulfur Proteins; D008982:Molybdenum; D010088:Oxidoreductases; C045664:dimethyl sulfoxide reductase