title: Theoretical characterization of the "very rapid" Mo(V) species generated in the oxidation of xanthine oxidase.
abstract: Density functional theory calculations of the "very rapid" Mo(V) intermediate of xanthine oxidase (XO) result in a square pyramidal geometry with end-on coordination of the model substrate. The Mo-C8 distance is 3.18 A, longer than previously reported from ENDOR experiments (<2.4 A Howes; et al. Biochemistry 1996, 35, 1432; 2.7-2.9 A Mandikandan; et al. J. Am. Chem. Soc. 2001, 123, 2658). Theoretical gas-phase isotropic hyperfine coupling constants A(iso)(C8) (B3LYP/BSII, 7.68 MHz; B3P86/BSII, 8.64 MHz) compare well with experimental values for the "very rapid" Mo(V) intermediate of XO with xanthine (8.8 MHz, Howes et al.) and 2-hydroxy-6-methylpurine (7.9 MHz, Mandikandan et al.). Absolute values of A(iso) of the metal-bound substrate oxygen are similar in magnitude to that of experiment.
authors.affiliation: Department of Chemistry and Biochemistry, Old Dominion University, Hampton Boulevard, Norfolk, Virginia 23529, USA. cbayse@odu.edu
authors.forename: Craig A
authors.initials: CA
authors.lastname: Bayse
mesh_terms: D001665:Binding Sites; D008956:Models, Chemical; D008982:Molybdenum / Q000737:chemistry* / Q000378:metabolism; D010084:Oxidation-Reduction; D014969:Xanthine Oxidase / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D008982:Molybdenum; D014969:Xanthine Oxidase