On the Mechanism of Inactivation of Xanthine Oxidase by Cyanide

作者：Vincent Massey, Dale E. Edmondson · 发表于：Journal of Biological Chemistry · 年份：1970 · DOI：10.1016/s0021-9258(18)62575-x · 被引用次数：367 · 研究领域：Cassava research and cyanide、Porphyrin Metabolism and Disorders、Folate and B Vitamins Research

Abstract The inactivation of xanthine oxidase by cyanide is accompanied by the extraction of sulfur from the protein which is eliminated as thiocyanate. When the cyanide inactivation is carried out under anaerobic conditions, partial reduction of the enzyme occurs, equivalent to approximately a 2-electron uptake per eq of thiocyanate released. Cyanide-inactivated enzyme can be largely reactivated by incubation with Na2S. Experiments with 35S-labeled Na2S reveal that the reactivation is accompanied by the reincorporation of sulfur into the protein. Treatment of such 35S-labeled enzyme with cyanide results in inactivation again and the elimination of 35S-labeled thiocyanate.