Nitric oxide reacts with the single-electron reduced active site of cytochrome c oxidase (Articolo in rivista)

Type
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  • Nitric oxide reacts with the single-electron reduced active site of cytochrome c oxidase (Articolo in rivista) (literal)
Anno
  • 2002-01-01T00:00:00+01:00 (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#doi
  • 10.1074/jbc.M201514200 (literal)
Alternative label
  • Giuffrè A, Barone MC, Brunori M, D'Itri E, Ludwig B, Malatesta F, Müller HW, Sarti P (2002)
    Nitric oxide reacts with the single-electron reduced active site of cytochrome c oxidase
    in The Journal of biological chemistry (Print)
    (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#autori
  • Giuffrè A, Barone MC, Brunori M, D'Itri E, Ludwig B, Malatesta F, Müller HW, Sarti P (literal)
Pagina inizio
  • 22402 (literal)
Pagina fine
  • 22406 (literal)
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  • cited By (since 1996)24 (literal)
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  • http://www.scopus.com/inward/record.url?eid=2-s2.0-0037151049&partnerID=40&md5=a041e41907bfb9e9ad1c661bae77e8de (literal)
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  • 277 (literal)
Rivista
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  • 25 (literal)
Note
  • Scopu (literal)
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  • Department of Biochemical Sciences, CNR Institute of Molecular Biology and Pathology, University of Rome la Sapienza, I-00185 Rome, Italy; Institute of Biochemistry, Molecular Genetics, University of Frankfurt, Biozentrum, D-60439 Frankfurt, Germany; Department of Pure and Applied Biology, University of l'Aquila, I-67100 L'Aquila, Italy. (literal)
Titolo
  • Nitric oxide reacts with the single-electron reduced active site of cytochrome c oxidase (literal)
Abstract
  • The reduction kinetics of the mutants K354M and D124N of the Paracoccus denitrificans cytochrome oxidase (heme aa3) by ruthenium hexamine was investigated by stopped-flow spectrophotometry in the absence/presence of NO. Quick heme a reduction precedes the biphasic heme a3 reduction, which is extremely slow in the K354M mutant (k1 = 0.09 ± 0.01 s-1; k2 = 0.005 ± 0.001 s-1) but much faster in the D124N aa3 (k1 = 21 ± 6 s-1; k2 = 2.2 ± 0.5 s-1). NO causes a very large increase (> 100-fold) in the rate constant of heme a3 reduction in the K354M mutant but only a ~5-fold increase in the D124N mutant. The K354M enzyme reacts rapidly with O2 when fully reduced but is essentially inactive in turnover; thus, it was proposed that impaired reduction of the active site is the cause of activity loss. Since at saturating [NO], heme a3 reduction is ~100-fold faster than the extremely low turnover rate, we conclude that, contrary to O2, NO can react not only with the two-electron but also with the single-electron reduced active site. This mechanism would account for the efficient inhibition of cytochrome oxidase activity by NO in the wild-type enzyme, both from P. denitrificans and from beef heart. Results also suggest that the H+-conducting K pathway, but not the D pathway, controls the kinetics of the single-electron reduction of the active site. (literal)
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