title: Nitric oxide, cytochrome c oxidase and myoglobin: competition and reaction pathways.
abstract: 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.
authors.affiliation: Department of Biochemical Sciences and CNR Institute of Molecular Biology and Pathology, University of Rome La Sapienza, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Giuffrè
authors.forename: Elena
authors.initials: E
authors.lastname: Forte
authors.forename: Maurizio
authors.initials: M
authors.lastname: Brunori
authors.forename: Paolo
authors.initials: P
authors.lastname: Sarti
mesh_terms: 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
chemical_list: D009211:Myoglobin; D009569:Nitric Oxide; D003576:Electron Transport Complex IV; D009584:Nitrogen; D010100:Oxygen