Subfractions obtained from inner mitochondrial membranes incubated with cysteine. I. Fatty acid distribution in phospholipids

Abstract

Sub­ fractions Obtained From Inner Mitochondrial Membranes Incubated With Cysteine. I. Fatty Acid Distribution In Phospholipids. Rev. esp. Fisiol., 30, 37-42. 1974.

Three subfractions from inner membranes from rat liver mitochondria were sepa­ rated by differential centrifugation after incubation in the presence of cysteine; these three subfractions were different in what respects to the fatty acid composition of their phospholipids. One of these subfractions (Subfraction I) which sedimented at 8,500 X g was further treated with ascorbate and fractionated into a new sediment of 8,500 X g and a supernatant. This new lysis would be due to the”¢ fact that the peroxidation induced by cysteine on the phospholipids destroyed almost completely the total content of arachidonic acid and affected linoleic acid in a small proportion; on the contrary, ascorbate destroyed almost completely both fatty acids. The data presented are consistent with the hypothesis of a heterogeneous distribution of the different molecular species of phospholipids and that the subfractions obtained would have their origin in areas of the inner membrane with a different degree of unsatura­ tion of their phospholipids.