ROLE OF PHOSPHOLIPIDS IN OXIDATIVE PHOSPHORYLATION AND MITOCHONDRIAL STRUCTURE

Abstract

The addition of small amounts (50 μg protein) of heated snake venom to respiring preparations of mitochondria from rat liver or kidney brings about an uncoupling of oxidation from phosphorylation as measured by a fall in the P/O ratio. When larger amounts (250 μg protein) of heated venom are added a rapid decline in the respiratory activity eventually takes place which coincides with a breakdown in the mitochondrial structure. On addition of smaller amounts (e.g. 7.5 μg protein) of heated venom to liver or kidney mitochondria there occurs a release of soluble proteins including enzymes, e.g. ATP-ase.Various phospholipids are able to exert a specific protective effect against the uncoupling action of heated venom. Albumin exhibits a non-specific effect but glutathionine, which helps to maintain the respiratory activity of mitochondria in the presence of heated venom, does not prevent the accompanying fall in the P/O ratio.The importance of the structural integrity of mitochondria for their enzymic activities is discussed, special reference being made to the role of phospholipids.