Characteristics of triacylglycerol and partial acylglycerol hydrolysis by human plasma lipoprotein lipase.
The rates of reaction of human lipoprotein lipase (EC 3.1.1.34) with triacylglycerol and partial acylglycerol substrates have been compared as a function of the concentration of lipase cofactor protein (apolipoprotein C-II). The data indicate that the dissociation constant for monoacylglycerol is approximately three orders of magnitude greater than for diacylglycerols, indicating that only when the concentrations of higher acylglycerols become vanishingly small will significant monoacylglycerol hydrolysis (from 1-monoacylglycerol generated by isomerization of the 2-substituted primary product) be mediated by the lipase. This is in spite of the fact that maximal reaction velocities with each of the potential substrates are similar. A 'lipolytic cycle' is proposed to explain binding and dissociation of substrates with cofactor-lipase complex during catabolism of triacylglycerols.
D001053:Apolipoproteins / Q000378:metabolism; D004075:Diglycerides / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D004798:Enzymes / Q000097:blood*; D005989:Glycerides / Q000378:metabolism; D006801:Humans; D006868:Hydrolysis; D007700:Kinetics; D008066:Lipolysis; D008071:Lipoprotein Lipase / Q000378:metabolism*; D008079:Lipoproteins, VLDL / Q000378:metabolism; D014280:Triglycerides / Q000378:metabolism*
D001053:Apolipoproteins; D004075:Diglycerides; D004798:Enzymes; D005989:Glycerides; D008079:Lipoproteins, VLDL; D014280:Triglycerides; D008071:Lipoprotein Lipase