Lipid oxidation induced by oxymyoglobin and metmyoglobin with involvement of H(2)O(2) and superoxide anion.

The role of oxymyoglobin oxidation in lipid oxidation was studied in a myoglobin-liposome system. The pro-oxidant effect of oxymyoglobin towards lipid oxidation was concentration-dependent. At equimolar concentrations, oxymyoglobin showed higher pro-oxidative activity towards lipid than metmyoglobin (p < 0.05). These results suggested that the process of oxymyoglobin oxidation is involved in catalyzing lipid oxidation. The addition of catalase into the oxymyoglobin-liposome system resulted in significantly decreased oxidation of oxymyoglobin and lipid (p < 0.05) suggesting a role for H(2)O(2) in the interaction between oxymyoglobin and lipid. The addition of Superoxide dismutase was without effect (p > 0.05) suggesting that Superoxide anion was not directly involved in mediating oxidation of oxymyoglobin and lipid. Albumin was added as a control for a non-specific protein antioxidant; it did not affect oxymyoglobin or lipid oxidation (p > 0.05). Our in vitro results support the hypothesis that the actual process of oxymyoglobin oxidation is a catalyst of lipid oxidation with H(2)O(2) a major factor.