Heparin-Activated Enzyme System of Human Plasma. ∗

Abstract

Summary

1. In distinction to the Sf 20-400 lipoproteins, the Sf 6 lipoprotein of the human is not a good substrate for fatty acid release by the heparin-activated enzyme system of plasma. 2. The serum tributyrinase activity is not enhanced significantly after heparin injection. 3. The lipolysis of the lipoprotein triglycerides is significantly inhibited by fatty acid itself. 4. The fatty acid release resulting from the incubation of suitable lipoproteins with post-heparin plasma is unaffected by oxygen, the antioxidant α-naphthol; and sulfhydryl inhibitors; anaerobiosis with nitrogen produces at most a 10% increase in fatty acid release. Fatty acid release is inhibited at most 10% by ATP and Co A, and at most 5% by either compound. The inhibition by DFP suggests the enzyme to be an esterase.