Cytochrome c oxidase does not catalyze the anaerobic reduction of NO.
A possible role of reduced cytochrome c oxidase in the metabolism of nitric oxide (NO) has been examined with amperometric and stopped-flow photometric techniques. Reduced purified cytochrome c oxidase and mitochondria showed no catalytic reaction with NO under anaerobic conditions within more than 30 minutes. Only fast binding of NO to the reduced enzyme in a 1:1 stoichiometric ratio was observed. The NO binding rate was strongly decreased in the presence of 1 mM cyanide. These data indicate that, contrary to previous proposals, cytochrome c oxidase in the absence of oxygen does not contribute to physiological NO metabolism.
Stubauer
G
G
Department of Biochemical Sciences, University of Rome La Sapienza, Italy.
Giuffrè
A
A
Brunori
M
M
Sarti
P
P
D000693:Anaerobiosis; D000818:Animals; D001205:Ascorbic Acid / Q000378:metabolism; D002417:Cattle; D004563:Electrochemistry; D003576:Electron Transport Complex IV / Q000378:metabolism*; D007700:Kinetics; D008929:Mitochondria, Heart / Q000201:enzymology* / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism*; D010084:Oxidation-Reduction; D011485:Protein Binding / Q000187:drug effects; D012044:Regression Analysis; D017975:Ruthenium Compounds / Q000378:metabolism; D012966:Sodium Cyanide / Q000494:pharmacology; D013053:Spectrophotometry
D017975:Ruthenium Compounds; C031584:hexammineruthenium; D009569:Nitric Oxide; D003576:Electron Transport Complex IV; D012966:Sodium Cyanide; D001205:Ascorbic Acid