Nitric oxide ejects electrons from the binuclear centre of cytochrome c oxidase by reacting with oxidised copper: a general mechanism for the interaction of copper proteins with nitric oxide?
Small increases in NO concentration can inhibit mitochondrial oxygen consumption by reacting at the binuclear haem a3/CuB oxygen reduction site of cytochrome c oxidase. Here we demonstrate that under normal turnover conditions NO reacts initially with the oxidised CuB rather than the haem a3. We propose that hydration of an initial Cu+/NO+ complex forms nitrite, a proton and CuB+; the latter ejects an electron from the binuclear centre and results in the observed (100 s(-1)) reduction of other electron transfer centres in the enzyme (haem a and CuA). These reactions may have implications for the interactions of NO with other copper proteins.
Cooper
C E
CE
Department of Biological Sciences, University of Essex, Central Campus, Colchester, UK. ccooper@essex.ac.uk
Torres
J
J
Sharpe
M A
MA
Wilson
M T
MT
D001665:Binding Sites; D003300:Copper / Q000378:metabolism*; D004579:Electron Transport; D003576:Electron Transport Complex IV / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*; D006418:Heme / Q000031:analogs & derivatives / Q000378:metabolism; D007700:Kinetics; D008667:Metalloproteins / Q000737:chemistry / Q000378:metabolism*; D009569:Nitric Oxide / Q000378:metabolism* / Q000494:pharmacology; D010084:Oxidation-Reduction; D013053:Spectrophotometry
D008667:Metalloproteins; C027728:heme a; D009569:Nitric Oxide; D006418:Heme; D003300:Copper; D003576:Electron Transport Complex IV