Nitrosylmyoglobin as antioxidant - kinetics and proposed mechanism for reduction of hydroperoxides
Source: Free Radical Research, Volume 41, Number 8, 2007 , pp. 892-902(11)
Publisher: Informa Healthcare
Abstract:Nitrosylmyoglobin (MbFeIINO), which is believed to have a protective role during ischemia and reperfusion injury, was oxidized by tert-butyl hydroperoxide (t-BuOOH), and by hydrogen peroxide (H2O2) to the nitrite anion and metmyoglobin (MbFeIII). Further characterization of the reaction of MbFeIINO with excess of t-BuOOH was investigated with respect to reaction stoichiometry, temperature and pH dependence. It was found that the reaction between MbFeIINO with excess of t-BuOOH followed a simple stoichiometry and had moderate pH and temperature dependence with the activation parameters ΔH‡ = 57.4 ± 1.4 kJ mol- 1 and ΔS‡ = - 112.0 ± 5.1 J mol- 1 K- 1, which is consistent with an associative reaction mechanism. Moreover, t-BuOOH-induced oxidation of MbFeIINO did not result in any detectable formation of the hypervalent myoglobin (Mb) species, i.e. perferrylmyoglobin, (√MbFeIV = O) or ferrylmyoglobin (MbFeIV = O), and hereby differed from H2O2-induced oxidation of MbFeIINO, which results in the formation of MbFeIV = O. Based on the obtained results and on published data, different mechanisms for the reaction of the MbFeIINO with t-BuOOH and H2O2 are proposed.
Document Type: Research Article
Affiliations: 1: Department of Seafood Research, Danish Institute for Fisheries Research, Technical University of Denmark, Kgs Lyngby, Denmark 2: Food Chemistry, Department of Food Science, Faculty of Life Science, University of Copenhagen, Frederiksberg C, Denmark 3: Department of Food Science, Research Centre Foulum, University of Aarhus, Tjele, Denmark
Publication date: 2007