Inhibition of lipid peroxidation by heme-nonapeptide derived from cytochrome c

Heme-nonapeptide, derived from cytochrome c, inhibited both the NADPH- and NADH-dependent lipid peroxidation of brain microsomes but, in the case of liver microsomes, this inhibitory effect manifested itself in the presence of SKF-525A (a specific blocker of cytochrome P-450) only. Heme-nonapeptide prevented the transient accumulation of lipid peroxides in microsomes during lipid peroxidation. The oxygen consumption of microsomes in the presence of NADPH or NADH was stimulated by heme-nonapeptide. From these results we concluded that, in vitro, there are two independent mechanisms of lipid peroxidation in liver microsomes. It is suggested that, in vivo, the heme-peptide-sensitive mechanism, observed in brain microsomes, is more important.