title: Spectroscopic and electronic structure studies of a dimethyl sulfoxide reductase catalytic intermediate: implications for electron- and atom-transfer reactivity.
abstract: The electronic structure of a genuine paramagnetic des-oxo Mo(V) catalytic intermediate in the reaction of dimethyl sulfoxide reductase (DMSOR) with (CH(3))(3)NO has been probed by electron paramagnetic resonance (EPR), electronic absorption, and magnetic circular dichroism (MCD) spectroscopies. EPR spectroscopy reveals rhombic g- and A-tensors that indicate a low-symmetry geometry for this intermediate and a singly occupied molecular orbital that is dominantly metal centered. The excited-state spectroscopic data were interpreted in the context of electronic structure calculations, and this has resulted in a full assignment of the observed MCD and electronic absorption bands, a detailed understanding of the metal-ligand bonding scheme, and an evaluation of the Mo(V) coordination geometry and Mo(V)-S(dithiolene) covalency as it pertains to the stability of the intermediate and electron-transfer regeneration. Finally, the relationship between des-oxo Mo(V) and des-oxo Mo(IV) geometric and electronic structures is discussed relative to the reaction coordinate in members of the DMSOR enzyme family.
authors.affiliation: Department of Chemistry and Chemical Biology, The University of New Mexico, MSC03 2060, 1 University of New Mexico, Albuquerque, New Mexico 87131-0001, USA.
authors.forename: Regina P
authors.initials: RP
authors.lastname: Mtei
authors.forename: Ganna
authors.initials: G
authors.lastname: Lyashenko
authors.forename: Benjamin
authors.initials: B
authors.lastname: Stein
authors.forename: Nick
authors.initials: N
authors.lastname: Rubie
authors.forename: Russ
authors.initials: R
authors.lastname: Hille
authors.forename: Martin L
authors.initials: ML
authors.lastname: Kirk
mesh_terms: D055162:Biocatalysis; D004583:Electrons; D007506:Iron-Sulfur Proteins / Q000737:chemistry*; D015394:Molecular Structure; D010088:Oxidoreductases / Q000737:chemistry*; D013057:Spectrum Analysis
chemical_list: D007506:Iron-Sulfur Proteins; D010088:Oxidoreductases; C045664:dimethyl sulfoxide reductase