The Existence of a Long-Chain Acyl-CoA Synthetase in Homogenates of Human Blood Platelets

Abstract

The presence of a long-chain acyl-CoA synthetase in human platelets is demonstrated. The activity was reproducibly assayed in small samples by the formation of acyl-carnitine from fatty acids, CoA, ATP, and carnitine in the presence of carnitine palmityltransferase. The activity increased with increasing carbon number from C₁₀ to C₁₆, suggesting only one long-chain acyl-CoA synthetase in human platelets. The enzyme is probably localized within the cell membrane as the enzyme was latent in intact platelets. The activity in 22 fasting, healthy individuals was 8 to 23 nmol/min/10⁹ platelets, or about 0.5 to 1.5 U/ml packed cells. The activity is compatible with the activity found in several organs from the rat, and with reported rates of fatty acid incorporation into platelet lipids.

Key Words:

• Acyl-CoA synthetase
• enzyme activity
• enzyme assay
• enzyme localization
• human blood platelets