Kinetics of human and bovine milk lipoprotein lipase and the mechanism of enzyme activation by apolipoprotein C-II.
The kinetics of human and bovine milk lipoprotein lipase (HM-LPL and BM-LPL, respectively) were compared by varying apolipoprotein C-II (C-II) or triacylglycerol (TG) concentrations. The apparent Km (TG) and Km (C-II) for HM-LPL were 2.2 and 6.7-fold higher than for BM-LPL. Plots of 1/v vs 1/[TG] or 1/[C-II] intercepted the respective abscissas at the same points: C-II had no effect on Km (TG) and TG had no effect on Km (C-II). Replots of slope 1/s vs 1/[C-II] gave straight lines which yielded KA values identical to Km (C-II). It is concluded that the HM-LPL system follows a random, bireactant, rapid equilibrium mechanism as shown previously for BM-LPL.
D000818:Animals; D053304:Apolipoprotein C-II; D001056:Apolipoproteins C / Q000494:pharmacology; D002417:Cattle; D004789:Enzyme Activation / Q000187:drug effects; D006801:Humans; D066298:In Vitro Techniques; D007700:Kinetics; D008071:Lipoprotein Lipase / Q000378:metabolism*; D008892:Milk / Q000201:enzymology*; D008895:Milk, Human / Q000201:enzymology*; D014280:Triglycerides / Q000494:pharmacology
D053304:Apolipoprotein C-II; D001056:Apolipoproteins C; D014280:Triglycerides; D008071:Lipoprotein Lipase