Nitric oxide, cytochrome c oxidase and myoglobin: competition and reaction pathways.
It is relevant to cell physiology that nitric oxide (NO) reacts with both cytochrome oxidase (CcOX) and oxygenated myoglobin (MbO(2)). In this respect, it has been proposed [Pearce, L.L., et al. (2002) J. Biol. Chem. 277, 13556-13562] that (i) CcOX in turnover out-competes MbO(2) for NO, and (ii) NO bound to reduced CcOX is "metabolized" in the active site to nitrite by reacting with O(2). In contrast, rapid kinetics experiments reported in this study show that (i) upon mixing NO with MbO(2) and CcOX in turnover, MbO(2) out-competes the oxidase for NO and (ii) after mixing nitrosylated CcOX with O(2) in the presence of MbO(2), NO (and not nitrite) dissociates from the enzyme causing myoglobin oxidation.
Giuffrè
Alessandro
A
Department of Biochemical Sciences and CNR Institute of Molecular Biology and Pathology, University of Rome La Sapienza, Italy.
Forte
Elena
E
Brunori
Maurizio
M
Sarti
Paolo
P
D000818:Animals; D001667:Binding, Competitive; D002417:Cattle; D003576:Electron Transport Complex IV / Q000378:metabolism*; D006736:Horses; D009211:Myoglobin / Q000378:metabolism*; D009569:Nitric Oxide / Q000378:metabolism*; D009584:Nitrogen / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism; D013057:Spectrum Analysis
D009211:Myoglobin; D009569:Nitric Oxide; D003576:Electron Transport Complex IV; D009584:Nitrogen; D010100:Oxygen