The millisecond intermediate in the reaction of nitric oxide with oxymyoglobin is an iron(III)-nitrato complex, not a peroxynitrite

Erik T. Yukl, Simon De Vries, Pierre Moënne-Loccoz

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(Chemical Equation Presented) The dioxygenation of nitric oxide by oxyheme in globin proteins is a major route for NO detoxification in aerobic biological systems. In myoglobin, this reaction is thought to proceed through an iron(III)-bound peroxynitrite before homolytic cleavage of the O?O bond to form an iron(IV)-oxo and NO2 radical followed by recombination and nitrate production. Single turnover experiments at alkaline pH have revealed the presence of a millisecond high-spin heme intermediate. It is widely presumed that this species is an iron(III)-peroxynitrite species, but detailed characterization of the intermediate is lacking. Using resonance Raman spectroscopy and rapid-freeze quench techniques, we identify the millisecond intermediate as an iron(III)-nitrato complex with a symmetric NO2 stretch at 1282 cm?1. Greater time resolution techniques will be required to detect the putative iron(III) peroxynitrite complex.

Original languageEnglish (US)
Pages (from-to)7234-7235
Number of pages2
JournalJournal of the American Chemical Society
Issue number21
StatePublished - Jun 3 2009


ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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