Inhibition of lipid peroxidation by calcium ions and their protection of steroid hydroxylase activity from peroxidative damage.

Lipid peroxidation of adrenocortical mitochondria and microsomes was greatly stimulated by addition of 1.0 mM or less ferric ions. In the presence of NADPH-yielding system, the formation of corticosterone from endogeneous cholesterol and exogeneous deoxycorticosterone was inhibited as the concentrations of iron increased. Of interest is the fact that 0.5 mM ferric ion-mediated lipid peroxidation was completely abroagated upon addition of 2 mM calcium ions. Accordingly, protected from the peroxidative damage.