Reversible Conversion of Nitroxyl Anion to Nitric Oxide by Superoxide Dismutase

Superoxide dismutase (SOD) rapidly scavenges superoxide (O- 2) and also prolongs the vasorelaxant effects of nitric oxide (NO), thought to be the endothelium-derived relaxing factor. This prolongation has been ascribed to prevention of the reaction between O- 2with NO. We report that SOD supports a...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 1991-12, Vol.88 (23), p.10860-10864
Main Authors: Murphy, Michael E., Sies, Helmut
Format: Article
Language:English
Subjects:
Absorption spectra
Analytical, structural and metabolic biochemistry
Animals
Biochemistry
Biological and medical sciences
Catalase - metabolism
Cattle
Copper - pharmacology
Enzymes
Erythrocytes - enzymology
Free Radicals
Fundamental and applied biological sciences. Psychology
Hydrochlorides
Intermediary metabolites. Miscellaneous
Isoenzymes - blood
Isoenzymes - metabolism
Kinetics
Liver - enzymology
nitric oxide
Nitric Oxide - metabolism
Nitrogen Oxides - metabolism
nitroxyl anions
Other biological molecules
Oxidases
Oxidation
Oxides
Oxyhemoglobins - metabolism
Spectrophotometry
Superoxide Dismutase - blood
Superoxide Dismutase - metabolism
Superoxides
Wavelengths
Xanthines
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Summary:Superoxide dismutase (SOD) rapidly scavenges superoxide (O- 2) and also prolongs the vasorelaxant effects of nitric oxide (NO), thought to be the endothelium-derived relaxing factor. This prolongation has been ascribed to prevention of the reaction between O- 2with NO. We report that SOD supports a reversible reduction of NO to NO-. When cyanamide and catalase were used to generate NO-in the presence of SOD, NO was measured by the conversion of HbO2to MetHb. When SOD[Cu(I)] was exposed to NO anaerobically, NO-was trapped by MetHb forming nitrosylmyoglobin. When NO was generated by 3-morpholinosydnonimine hydrochloride in the presence of SOD, NO-or a similar reductant was formed, which reduced catalase compound II and promoted the formation of the catalase[Fe(III)]-NO complex. It is, therefore, conceivable that SOD may protect NO and endothelium-derived relaxing factor by a mechanism in addition to O- 2scavenging and that NO-may be a physiologically important form of endothelium-derived relaxing factor.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.88.23.10860