title: Chain length dependence of phosphatidylcholine hydrolysis catalyzed by lipoprotein lipase. Effect of apolipoprotein C-II.
abstract: The effect of apolipoprotein C-II (apoC-II) on the bovine milk lipoprotein lipase (LpL)-catalyzed hydrolysis of a homologous series of saturated phosphatidylcholines was examined with respect to the fatty acyl chain length of the substrates. Dilauryl-, dimyristoyl-, dipalmitoyl-, and distearoylphosphatidylcholine solubilized by Triton X-100 and sonicated vesicles of dimyristoylphosphatidylcholine were used as substrates. The maximal rate of the LpL-catalyzed hydrolysis of each of these lipids was determined in the absence and presence of apoC-II. The activation factor (the ratio of enzyme activity with apoC-II to that without the activator protein) increased with increasing mol ratios of apoC-II to LpL and was maximal at a ratio of approximately 50. At all apoC-II/LpL mole ratios tested, the activation factor increased as a function of fatty acyl chain length. A quantitative relationship between fatty acyl chain length and the extent of maximal activation of LpL by apoC-II was observed: the logarithm of the activation factor is a linear function of the number of carbon atoms of a single fatty acyl chain of the substrates.
mesh_terms: D000818:Animals; D053304:Apolipoprotein C-II; D001053:Apolipoproteins / Q000494:pharmacology*; D001056:Apolipoproteins C; D002417:Cattle; D005260:Female; D008071:Lipoprotein Lipase / Q000378:metabolism*; D008433:Mathematics; D008892:Milk / Q000201:enzymology; D017830:Octoxynol; D010713:Phosphatidylcholines / Q000378:metabolism*; D011092:Polyethylene Glycols; D012995:Solubility; D013329:Structure-Activity Relationship
chemical_list: D053304:Apolipoprotein C-II; D001053:Apolipoproteins; D001056:Apolipoproteins C; D010713:Phosphatidylcholines; D011092:Polyethylene Glycols; D017830:Octoxynol; D008071:Lipoprotein Lipase