Cytochrome c oxidase rapidly metabolises nitric oxide to nitrite.
Previous studies have shown that the addition of nitric oxide to cytochrome c oxidase rapidly generates spectral changes compatible with the formation of nitrite at the binuclear haem:copper centre. Here we directly demonstrate nitrite release following nitric oxide addition to the enzyme. The nitrite complex is kinetically inactive and the off rate for nitrite was found to be slow (0.024 min(-1)). However, the presence of reductants enhances the off rate and enables cytochrome oxidase to catalyse the rapid oxidation of nitric oxide to nitrite free in solution. This may play a major role in the mitochondrial metabolism of nitric oxide.
Torres
J
J
Department of Biological Sciences, University of Essex, Wivenhoe Park, Essex CO4 3SQ, Colchester, UK.
Sharpe
M A
MA
Rosquist
A
A
Cooper
C E
CE
Wilson
M T
MT
D003576:Electron Transport Complex IV / Q000378:metabolism*; D009569:Nitric Oxide / Q000378:metabolism*; D009573:Nitrites / Q000378:metabolism*; D010084:Oxidation-Reduction
D009573:Nitrites; D009569:Nitric Oxide; D003576:Electron Transport Complex IV