Mechanism of action of lipoprotein lipase and hepatic triglyceride lipase.

Lipoprotein lipase (LPL) and hepatic triglyceride lipase (H-TGL) were isolated from human postheparin plasma, and their interfacial properties were examined with mixed monolayers of trioleoylglycerol and phosphatidylcholine. LPL showed a surface pressure optimum between 20 and 22 mN/m, whereas H-TGL activity decreased at lipid packing densities of greater than 20 mN/m. LPL activity toward monolayers containing 2 mol percent trioleoylglycerol was enhanced 2.6-fold by the addition of 5 mol percent cholesteryl oleate; cholesteryl ester had no effect on H-TGL activity. We suggest that differences in interfacial properties account for the lipoprotein specificity of these lipolytic enzymes.