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Detection of the optical bands of molybdenum(V) in DMSO reductase ( Rhodobacter capsulatus ) by low‐temperature MCD spectroscopy
Author(s) -
Benson Neil,
Farrar Jaqui A.,
McEwan Alastair G.,
Thomson Andrew J.
Publication year - 1992
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(92)80760-e
Subject(s) - molybdenum , molybdenum cofactor , chemistry , rhodobacter , pterin , electron paramagnetic resonance , spectroscopy , crystallography , hyperfine structure , photochemistry , inorganic chemistry , cofactor , nuclear magnetic resonance , atomic physics , organic chemistry , enzyme , biochemistry , physics , quantum mechanics , mutant , gene
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 ∼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).