Hydrolysis of long-chain fatty acyl-CoA in homogenates of human blood platelets: The existence of a platelet palmitoyl-CoA hydrolase

Abstract

The existence of a very active long-chain fatty acyl-CoA hydrolase in homogenates of human blood platelets is reported. The highest activity was found with palmitoyl-CoA as the substrate. Palmitoyl-CoA hydrolase activity was not found in intact platelets indicating that the enzyme is localized within the platelet membrane. No palmitoyl-CoA hydrolase activity was found in fasting plasma. Mg²⁺, Mn²⁺, Ca²⁺ and Triton X-100 inhibited the palmitoyl-CoA hydrolase activity, Sulphydryl reagents had no effect, whereas high concentrations of D- and L-carnitine inhibited the activity. Carnitine palmitoyltransferase did not interfere with the assay of palmitoyl-CoA hydrolysis as the activity of carnitine-palmitoyl hydrolase was less than 1% of the palmitoyl-CoA hydrolase activity.

Key Words:

• acyl-Co A
• enzyme activity
• enzyme assay
• human blood platelets
• palmitoyl-CoA hydrolase