Mechanism of Inhibition of Hepatic Triglyceride Lipase from Human Postheparin Plasma by Apolipoproteins A-I and A-II1

Abstract

The present data describe the mechanism of the inhibitory effects of human plasma apolipoproteins A-I and A-II on hydrolysis of triglyceride catalyzed by hepatic triglyceride lipase using a substrate of triolein particles stabilized with gum arabic in vitro . The experimental data could well be described by a model in which apolipoproteins bound to the surface of lipid substrate particles inhibited the enzyme reaction. The values of K_m obtained were similar with or without inhibitors and the calculated saturation levels of apolipoprotein binding to the lipid were in good agreement with those obtained in independent binding experiments.