title: Xanthine oxidase/hydrogen peroxide generates sulfur trioxide anion radical (SO3.-) from sulfite (SO3(2-)).
abstract: In the presence of hydrogen peroxide (H2O2), xanthine oxidase has been found to catalyze sulfur trioxide anion radical (SO3.-) formation from sulfite anion (SO3(2-)). The SO3.- radical was identified by ESR (electron spin resonance) spin trapping, utilizing 5,5-dimethyl-l-pyrroline-l-oxide (DMPO) as the spin trap. Inactivated xanthine oxidase does not catalyze SO3.- radical formation, implying a specific role for this enzyme. The initial rate of SO3.- radical formation increases linearly with xanthine oxidase concentration. Together, these observations indicate that the SO3.- generation occurs enzymatically. These results suggest a new property of xanthine oxidase and perhaps also a significant step in the mechanism of sulfite toxicity in cellular systems.
authors.affiliation: Department of Chemistry, West Virginia University, Morgantown 26506.
authors.forename: X
authors.initials: X
authors.lastname: Sun
authors.forename: X
authors.initials: X
authors.lastname: Shi
authors.forename: N S
authors.initials: NS
authors.lastname: Dalal
mesh_terms: D004578:Electron Spin Resonance Spectroscopy; D006861:Hydrogen Peroxide / Q000378:metabolism*; D013447:Sulfites / Q000378:metabolism*; D013461:Sulfur Oxides / Q000378:metabolism*; D014969:Xanthine Oxidase / Q000378:metabolism*
chemical_list: D013447:Sulfites; D013461:Sulfur Oxides; D006861:Hydrogen Peroxide; D014969:Xanthine Oxidase; C011118:sulfur trioxide