Reduced nicotinamide adenine dinucleotide phosphate-dependent lipid peroxidation by beef heart submitochondrial particles.

Electron transport particles (ETP) prepared from beef heart mitochondria formed malondialdehyde by NADPH-dependent lipid peroixidation in the presence of ferric ions and ADP or ATP. The reaction was inhibited by MnCl2, EDTA, or radical scavengers, but was not inhibited by p-hydroxymercuribenzoate (PHMB) or respiratory chain inhibitors. The oxidation of NADPH and oxygen consumption by ETP were activated by the addition of ferric ions and APT, and inhibited by inhibitors of lipid peroxidation. This peroxidation system was apparently different from those of liver microsomes and mitochondria as regards the effect of PHMB, optimal pH and the concentration of NADPH for half-maximal reaction velocity.