title: Oxygen activation at mononuclear nonheme iron centers: a superoxo perspective.
abstract: Dioxygen (O(2)) activation by iron enzymes is responsible for many metabolically important transformations in biology. Often a high-valent iron oxo oxidant is proposed to form upon O(2) activation at a mononuclear nonheme iron center, presumably via intervening iron superoxo and iron peroxo species. While iron(IV) oxo intermediates have been trapped and characterized in enzymes and models, less is known of the putative iron(III) superoxo species. Utilizing a synthetic model for the 2-oxoglutarate-dependent monoiron enzymes, [(Tp(iPr2))Fe(II)(O(2)CC(O)CH(3))], we have obtained indirect evidence for the formation of the putative iron(III) superoxo species, which can undergo one-electron reduction, hydrogen-atom transfer, or conversion to an iron(IV) oxo species, depending on the reaction conditions. These results demonstrate the various roles that the iron(III) superoxo species can play in the course of O(2) activation at a nonheme iron center.
authors.affiliation: Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, 207 Pleasant St. SE, Minneapolis, Minnesota 55455, USA.
authors.forename: Anusree
authors.initials: A
authors.lastname: Mukherjee
authors.forename: Matthew A
authors.initials: MA
authors.lastname: Cranswick
authors.forename: Mrinmoy
authors.initials: M
authors.lastname: Chakrabarti
authors.forename: Tapan K
authors.initials: TK
authors.lastname: Paine
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Fujisawa
authors.forename: Eckard
authors.initials: E
authors.lastname: Münck
authors.forename: Lawrence
authors.initials: L
authors.lastname: Que
mesh_terms: D002384:Catalysis; D005290:Ferric Compounds / Q000737:chemistry*; D007656:Ketoglutaric Acids / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D019159:Nonheme Iron Proteins / Q000737:chemistry*; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization; D013059:Spectrum Analysis, Raman
chemical_list: D005290:Ferric Compounds; D007656:Ketoglutaric Acids; D019159:Nonheme Iron Proteins; D010100:Oxygen