MbO2とmetMbのリノ-ル酸の酸化に対する触媒作用の比較〔英文〕

概要

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There is little information on the catalytic activity of Mb02 for unsaturated lipid oxidation. The catalytic function of Mb02 was compared with that of metMb for linoleate oxidation in aqueous dispersion at 5°C for one hr and pH 6.3. Oxidation of linoleate was estimated by determining the oxygen dissolved in the reaction mixture using an oxygen electrode. Mb02 at a concentration of 5 or 10 μM had a catalytic effect similar to that of metMb in the early stage of the reaction, but became less effective than metMb in the later part of the reaction. NaN3 inhibited the oxidation catalyzed by metMb but not that by Mb02. At 0.2 μM of catalyst, MbO2 gave the same rate of linoleate oxidation as metMb and heat denatured Mb. NaN3 had a little inhibitory effect on these catalyzed oxidations. The oxidations of linoleate catalyzed by both Mb02 and metMb at concentrations of 7 μM were inhibited more or less by the addition of BSA, ascorbic acid, cysteine, glutathion, and ribose but not by the addition of the following substances: glucose, nicotinic acid, nicotinamide, histidine, lysine, methionine, trimethylamine, and trimethylamine oxide. From these results, it is postulated that MbO2 has a catalytic function on unsaturated lipid oxidation comparable to that of metMb, especially at a lower concentration ratio of Mb to unsaturated lipid.