Lipid composition of mitochondria from bovine heart, liver, and kidney

Highly purified preparations of mitochondria from bovine heart, liver, and kidney were isolated and characterized by electron microscopy, oxidative phosphorylation ability, cytochrome c reductase activity, and cytochrome content. Components of lipid extracts of the preparations were determined by thin-layer chromatography, diethylaminoethyl-cellulose column chromatography, and spectrophotometric procedures. The major phospholipids were identified by their chromatographic behavior, IR spectrometry, and paper chromatography of their hydrolysis products. The lipid content of the mitochondria paralleled that of the components of the electron transfer chain, heart mitochondria being richest and liver mitochondria poorest in lipid. Heart mitochondria contain equal concentrations of coenzyme Q and cholesterol (1%); the highest cholesterol content (4.7%) was found in mitochondria from kidney. The phospholipids of mitochondria from the three organs were qualitatively and quantitatively very similar. The major polar lipid components (cardiolipin, choline glycerophosphatides, and ethanolamine glycerophosphatides) were present in a molar ratio of 1:4:4. It is suggested that mitochondria from different sources contain characteristic lipids, mainly phospholipids, of which cardiolipin is particularly diagnostic of the source of the mitochondria.