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Updated: Aug 29, 2026

Chemiluminescence-based Assays for Detection of Nitric Oxide and its Derivatives from Autoxidation and Nitrosated Compounds
Published on: February 16, 2022
Xanthine oxidase converts nitric oxide to nitroxyl that inactivates the enzyme
Mohammad Saleem1, Hiroshi Ohshima
1International Agency for Research on Cancer, 150 Cours Albert Thomas, 69372 Lyon Cedex 08, France.
Abstract:
Xanthine oxidase (XO) was found to convert nitric oxide (NO* ) released from spermine-NONOate to nitroxyl (HNO), the one-electron reduction product of NO*, in the presence of its substrate hypoxanthine under anaerobic conditions. Under these conditions, XO lost its activity. Upon aerobic incubation of XO with its substrate, neither conversion of NO* to HNO nor inactivation of the enzyme was observed. Angeli's salt (an HNO generator) or synthetic peroxynitrite inactivated XO at low concentrations, whereas high concentrations of diethylamine-NONOate (an NO* donor) and SIN-1 (which generates peroxynitrite by releasing both NO* and superoxide) were required to inactivate XO. These results suggest that HNO generated by XO under anaerobic conditions inactivates XO. As both XO and NO* synthase are activated and/or induced in ischemia-reperfusion injury, HNO formed by XO may contribute to pathogenesis by exerting its potent oxidation activity against a variety of biological compounds.
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