Enzymic Lipid Peroxidation in Microsomal Fractions from Beef Skeletal Muscle

Enzymic lipid peroxidation in microsomes isolated from beef muscle (longissimus dorsi: LD) has been demonstrated. The reaction requirad NADPH or NADH, ADP, and Fe 2+ or Fe 3+ . The optimum pH of the reaction was approximately 6.5. The rate of oxidation was higher with NADPH than with NADH and also higher with Fe 2+ than with Fe 3+ . For microsomes isolated from the LD muscles stored for 3–11 days postmortem at 4°C, the rate of oxidation at pH 6.8 and with 0.1 mM NADPH, 0.1 mM ADP and 0.015 mM Fe 3+ ranged from 4.89–16.52 nmoles malonaldehyde per mg protein for 30 min incubation at 36°C. Prolonged storage of the intact muscles at 4°C considerably reduced the oxidative enzymic activity of the isolated microsomes.