Abstract
The experiments were carried out to clarify the role of phospholipid on triglyceride (TG) hydrolysis during the catabolism of triglyceride-rich lipoprotein. Maximal TG hydrolysis of TG-phospholipid liposome by purified bovine milk lipoprotein lipase (LPL) was obtained when liposome containing 0.1mM phosphatidylcholine and 1mM triolein was used as a substrate. When [14C] POPC-[3H] triolein double labelled liposome was incubated with phospholipaseA, TG hydrolysis by LPL was remarkably increased. Incubation with phospholipase C also increased the hydrolysis by LPL. These results suggest that PL hydrolysis may play an important role on TG hydrolysis.
Purified human hepatic triglyceride lipase (HTGL) from post heparin plasma had more phospholipase activity than that of LPL. The human post heparin LPL hydrolysed VLDL-TG for 3 hrs but not in further incubation. Addition of HTGL remarkably increased the hydrolysis of TG, while LPL could not hydrolyse TG in intermediate low density lipoprotein (IDL). These results suggest that LPL can hydrolyse the triglyceride in VLDL but not in IDL and that HTGL might be able to hydrolyse the triglyceride in IDL due to the decrease in PL by the action of phospholpase A in HTGL.
