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Xanthine oxidase/hydrogen peroxide generates sulfur trioxide anion radical (SO .− 3 ) from sulfite (SO 2− 3 )
Author(s) -
Xuan Sun,
Xianglin Shi,
N. S. Dalal
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)80522-i
Subject(s) - sulfite , hydrogen peroxide , chemistry , sulfur trioxide , sulfur , ion , inorganic chemistry , xanthine oxidase , sulfite oxidase , radiochemistry , photochemistry , sulfur dioxide , biochemistry , enzyme , organic chemistry
In the presence of hydrogen peroxide (H 2 O 2 ), xanthine oxidase has been found to catalyze sulfur trioxide anion radical (SO .− 3 ) formation from sulfite anion (SO 2− 3 ). The SO .− 3 radical was identified by ESR (electron spin resonance) spin trapping, utilizing 5,5‐dimethyl‐1‐pyrroline‐1‐oxide (DMPO) as the spin trap. Inactivated xanthine oxidase does not catalyze SO .− 3 radical formation, implying a specific role for this enzyme. The initial rate of SO .− 3 radical formation increases linearly with xanthine oxidase concentration. Together, these observations indicate that the SO .− 3 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.