Ferricyanide-mediated oxidation of ferrous nitrosylated sperm whale myoglobin involves the formation of the ferric nitrosylated intermediate

Paolo Ascenzi, Giovanni Petrella, Massimo Coletta

Research output: Contribution to journalArticlepeer-review

Abstract

Ferricyanide-mediated oxidation of ferrous oxygenated and carbonylated myoglobin (Mb(II)-O2 and Mb(II)-CO, respectively) is limited by O2 and CO dissociation, respectively, then the transient deoxygenated derivative (Mb(II)) is rapidly oxidized. Here, kinetics of ferricyanide-mediated oxidation of ferrous nitrosylated sperm whale myoblobin (Mb(II)-NO) is reported. Unlike for Mb(II)-O2 and Mb(II)-CO, ferricyanide reacts with Mb(II)-NO forming first a transient ferric nitrosylated species (Mb(III)-NO), followed by the {radical dot}NO dissociation from Mb(III)-NO. Values of the second-order rate constant for ferricyanide-mediated oxidation of Mb(II)-NO (i.e., for the formation of the transient Mb(III)-NO species) and of the first-order rate constant for {radical dot}NO dissociation from Mb(III)-NO (i.e., for Mb(III) formation) are (1.3 ± 0.2) × 106 M-1 s-1 and 7.6 ± 1.3 s-1, respectively, at pH 8.3 and 20.0 °C. Since {radical dot}NO dissociation from Mb(II)-NO is very slow, and (unlike O2 and CO) {radical dot}NO is a ligand for both Mb(II) and Mb(III), Mb(II)-NO can be oxidized without requiring {radical dot}NO dissociation.

Original languageEnglish
Pages (from-to)871-876
Number of pages6
JournalBiochemical and Biophysical Research Communications
Volume359
Issue number4
DOIs
Publication statusPublished - Aug 10 2007

Keywords

  • Ferricyanide
  • Ferricyanide-mediated oxidation
  • Ferrous nitrosylated sperm whale myoblobin
  • Kinetics

ASJC Scopus subject areas

  • Biochemistry
  • Biophysics
  • Molecular Biology

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