Xanthine oxidase/hydrogen peroxide generates sulfur trioxide anion radical (SO3.-) from sulfite (SO3(2-)).
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.
Sun
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Department of Chemistry, West Virginia University, Morgantown 26506.
Shi
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Dalal
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D004578:Electron Spin Resonance Spectroscopy; D006861:Hydrogen Peroxide / Q000378:metabolism*; D013447:Sulfites / Q000378:metabolism*; D013461:Sulfur Oxides / Q000378:metabolism*; D014969:Xanthine Oxidase / Q000378:metabolism*
D013447:Sulfites; D013461:Sulfur Oxides; D006861:Hydrogen Peroxide; D014969:Xanthine Oxidase; C011118:sulfur trioxide