title: Oxidation of carbon monoxide by perferrylmyoglobin.
abstract: Perferrylmyoglobin is found to oxidize CO in aerobic aqueous solution to CO2. Tryptophan hydroperoxide in the presence of tetra(4-sulfonatophenyl)-porphyrinate-iron(III) or simple iron(II)/(III) salts shows similar reactivity against CO. The oxidation of CO is for tryptophan hydroperoxide concluded to depend on the formation of alkoxyl radicals by reductive cleavage by iron(II) or on the formation of peroxyl radicals by oxidative cleavage by iron(III). During oxidation of CO, the tryptophan peroxyl radical was depleted with a rate constant of 0.26 ± 0.01 s(-1) for CO-saturated aqueous solution of pH 7.4 at 25 °C without concomitant reduction of the iron(IV) center. Carbon monoxide is as a natural metabolite accordingly capable of scavenging tryptophan radicals in myoglobin activated by peroxides with a second-order rate constant of (3.3 ± 0.6) × 10(2) L mol(-1) s(-1), a reaction that might be of importance in cellular membranes of the intestine for protection of tissue against radical damage during meat digestion.
authors: Instituto de Quı́mica de São Carlos, Universidade de São Paulo , Av. Trabalhador São Carlense 400, CP 780, CEP 13560-970 São Carlos, SP, Brazil.
authors: Silvia H
authors: SH
authors: Libardi
authors: Leif H
authors: LH
authors: Skibsted
authors: Daniel R
authors: DR
authors: Cardoso
mesh_terms: D000818:Animals; D002248:Carbon Monoxide / Q000737:chemistry*; D004578:Electron Spin Resonance Spectroscopy; D006736:Horses; D006863:Hydrogen-Ion Concentration; D007501:Iron / Q000737:chemistry; D007700:Kinetics; D009211:Myoglobin / Q000737:chemistry*; D010084:Oxidation-Reduction
chemical_list: D009211:Myoglobin; D002248:Carbon Monoxide; D007501:Iron