title: The millisecond intermediate in the reaction of nitric oxide with oxymyoglobin is an iron(III)--nitrato complex, not a peroxynitrite.
abstract: 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 NO(2) 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 NO(2) stretch at 1282 cm(-1). Greater time resolution techniques will be required to detect the putative iron(III) peroxynitrite complex.
authors.affiliation: Department of Science and Engineering, School of Medicine, Oregon Health & Science University, Beaverton, Oregon 97006-8921, USA.
authors.forename: Erik T
authors.initials: ET
authors.lastname: Yukl
authors.forename: Simon
authors.initials: S
authors.lastname: de Vries
authors.forename: Pierre
authors.initials: P
authors.lastname: Moënne-Loccoz
mesh_terms: D055598:Chemical Phenomena; D007501:Iron / Q000737:chemistry*; D009211:Myoglobin / Q000737:chemistry*; D009566:Nitrates / Q000737:chemistry*; D009569:Nitric Oxide / Q000737:chemistry*; D030421:Peroxynitrous Acid
chemical_list: D009211:Myoglobin; D009566:Nitrates; C017595:oxymyoglobin; D030421:Peroxynitrous Acid; D009569:Nitric Oxide; D007501:Iron