Characterization of the lipolytic activity of endothelial lipase.
Characterization of the lipolytic activity of endothelial lipase.
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发表时间：
2002-06
影响因子：
6.5
通讯作者：
M. McCoy;Gwo-Shing Sun;D. Marchadier;C. Maugeais;J. M. Glick;D. Rader
中科院分区：
文献类型：
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作者：
M. McCoy;Gwo-Shing Sun;D. Marchadier;C. Maugeais;J. M. Glick;D. Rader
内皮脂肪酶（EL）是甘油三酯脂肪酶基因家族中的一个新成员。使用放射性标记的脂质底物，我们的特点是这种酶的脂解活性相比，脂蛋白脂肪酶（LPL）和肝脂肪酶（HL）使用条件培养基从细胞感染重组腺病毒编码的每一种酶。在不存在血清的情况下，EL具有明显可检测的甘油三酯脂肪酶活性。血清对EL的甘油三酯脂肪酶和磷脂酶活性均呈剂量依赖性抑制。EL的甘油三酯脂肪酶与磷脂酶活性的比率为0.65，相比之下，HL的比率为24.1，LPL的比率为139.9，将EL置于LPL的脂解谱的另一端。EL的脂肪酶活性也不受载脂蛋白C-II（apoC-II）的影响，表明EL与HL一样，不需要apoC-II进行激活。与LPL一样，EL的两种脂肪酶活性均被1 M NaCl抑制，但HL则不然。EL，相对于HL和LPL，水解分离的脂蛋白组分中的脂质的相对能力也使用FFA的生成作为终点进行了检查。正如预期的那样，基于三种酶的相对甘油三酯脂肪酶活性，富含甘油三酯的脂蛋白、乳糜微粒、VLDL和IDL被LPL和HL有效水解。EL水解HDL比其他脂蛋白组分更有效，LDL是所有酶的不良底物。
Endothelial lipase (EL) is a new member of the triglyceride lipase gene family previously reported to have phospholipase activity. Using radiolabeled lipid substrates, we characterized the lipolytic activity of this enzyme in comparison to lipoprotein lipase (LPL) and hepatic lipase (HL) using conditioned medium from cells infected with recombinant adenoviruses encoding each of the enzymes. In the absence of serum, EL had clearly detectable triglyceride lipase activity. Both the triglyceride lipase and phospholipase activities of EL were inhibited in a dose-dependent fashion by the addition of serum. The ratio of triglyceride lipase to phospholipase activity of EL was 0.65, compared with ratios of 24.1 for HL and 139.9 for LPL, placing EL at the opposite end of the lipolytic spectrum from LPL. Neither lipase activity of EL was influenced by the addition of apolipoprotein C-II (apoC-II), indicating that EL, like HL, does not require apoC-II for activation. Like LPL but not HL, both lipase activities of EL were inhibited by 1 M NaCl. The relative ability of EL, versus HL and LPL, to hydrolyze lipids in isolated lipoprotein fractions was also examined using generation of FFAs as an end point. As expected, based on the relative triglyceride lipase activities of the three enzymes, the triglyceride-rich lipoproteins, chylomicrons, VLDL, and IDL, were efficiently hydrolyzed by LPL and HL. EL hydrolyzed HDL more efficiently than the other lipoprotein fractions, and LDL was a poor substrate for all of the enzymes.