Peroxynitrite-mediated oxidation of ferrous carbonylated myoglobin is limited by carbon monoxide dissociation

Paolo Ascenzi, Chiara Ciaccio, Massimo Coletta

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Peroxynitrite-mediated oxidation of ferrous nitrosylated myoglobin (Mb(II)-NO) involves the transient ferric nitrosylated species (Mb(III)-NO), followed by {radical dot}NO dissociation and formation of ferric myoglobin (Mb(III)). In contrast, peroxynitrite-mediated oxidation of ferrous oxygenated myoglobin (Mb(II)-O2) involves the transient ferrous deoxygenated and ferryl derivatives (Mb(II) and Mb(IV){double bond, long}O, respectively), followed by Mb(III) formation. Here, kinetics of peroxynitrite-mediated oxidation of ferrous carbonylated horse heart myoglobin (Mb(II)-CO) is reported. Values of the first-order rate constant for peroxynitrite-mediated oxidation of Mb(II)-CO (i.e., for Mb(III) formation) and of the first-order rate constant for CO dissociation from Mb(II)-CO (i.e., for Mb(II) formation) are h = (1.2 ± 0.2) × 10-2 s-1 and koff(CO) = (1.4 ± 0.2) × 10-2 s-1, respectively, at pH 7.2 and 20.0 °C. The coincidence of values of h and koff(CO) indicates that CO dissociation represents the rate limiting step of peroxynitrite-mediated oxidation of Mb(II)-CO.

Original languageEnglish
Pages (from-to)931-936
Number of pages6
JournalBiochemical and Biophysical Research Communications
Issue number4
Publication statusPublished - Nov 30 2007


  • Ferrous carbonylated horse heart myoglobin
  • Kinetics
  • Peroxynitrite
  • Peroxynitrite-mediated oxidation

ASJC Scopus subject areas

  • Biochemistry
  • Biophysics
  • Molecular Biology


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