STUDY OF OXIDATIVE RELATIONSHIPS BETWEEN MEMBRANE-LIPIDS AND MYOGLOBIN INVITRO

In order to appreciate the relationship between membrane phospholipids peroxidation and myoglobin oxidation, microsomes, mitochondria and ox ymyoglobin were purified from bovine muscles. Myoglobin oxidation was measured by the decrease of its absorbance at 580 nm and lipid peroxid ation was estimated by TBA assay. Membrane phospholipids, peroxidized by an enzymic system (NADPH, ADP, FeCl3), considerably increased myogl obin oxidation. The percentage of oxidized myoglobin after 40 min at 3 7-degrees-C was : myoglobin alone : 8.2, myoglobin + microsomes: 14.6, myoglobin + mitochondria: 9.1 myoglobin + microsomes and cofactors : 30.5, myoglobin + mitochondria and cofactors 51.7. Membrane lipids per oxidation behaved similarly. The protective role of antioxidants (SOD, mannitol, vitamin E, BHT) for myoglobin oxidation and lipid peroxidat ion, clearly indicates that free radicals are implicated in the oxidat ion process between membranes and myoglobin. Metmyoglobin interaction with hydrogen peroxide (H2O2), generates ferryl myoglobin capable of i nitiating lipid oxidation. The meat pigment myoglobin plays a catalyti c role in lipid peroxidation but is also oxidized by peroxidation prod ucts with hydrogen peroxide as important mediator.