Libardi, Silvia H4; Skibsted, Leif Horsfelt5; Cardoso, Daniel R4
1 Food Chemistry, Department of Food Science, Faculty of Science, Københavns Universitet2 Universidade de Sao Paulo3 Design and Consumer Behavior, Department of Food Science, Faculty of Science, Københavns Universitet4 Universidade de Sao Paulo5 Design and Consumer Behavior, Department of Food Science, Faculty of Science, Københavns Universitet
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.
Journal of Agricultural and Food Chemistry, 2014, Vol 62, Issue 8, p. 1950-1955