Identical subcellular distribution of palmitoyl-CoA and arachidonoyl-CoA synthetase activities in human blood platelets.

Fractionation of human blood platelets showed that palmitoyl-CoA synthetase and arachidonoyl-CoA synthetase activities had an identical distribution among subcellular fractions. The activity was highest with arachidonic acid as substrate in all fractions, with an enzyme activity of 50 nmol/min per mg of protein, in a 'dense-tubular-system'-enriched fraction. The ratio activities with arachidonate and palmitate as substrates was about 1.5 in all fractions. Heat inactivation did not distinguish between arachidonoyl-CoA synthetase and a palmitoyl-CoA synthetase. On the other hand, heat inactivation indicated two pools of long-chain acyl-CoA synthetases: one in a mitochondria- and one in the dense-tubular-system-enriched fraction.