Mowri H O, Patsch J R, Gotto A M, Patsch W
Department of Medicine, Baylor College of Medicine, Houston, Tex, USA.
Arterioscler Thromb Vasc Biol. 1996 Jun;16(6):755-62. doi: 10.1161/01.atv.16.6.755.
Hepatic lipase has a demonstrated dual role in plasma lipid transport in that it participates in the removal of remnants of triglyceride-rich lipoproteins from the circulation and in the metabolism of plasma HDL. The study presented here investigated the substrate properties for hepatic lipase of HDL differing in density and apolipoprotein (apo) composition. Rates of fatty acid liberation were twofold higher in HDL2 compared with the respective HDL3 subspecies. Within each density class, enzyme-catalyzed fatty acid release was nearly twofold higher from HDL containing apoA-II compared with HDL devoid of apoA-II. When native HDL3 devoid of apoA-II was reconstituted with dimeric apoA-II in vitro, rates of fatty acid liberation in reconstituted particles were similar to those in native HDL3 containing apoA-II. HDL containing apoA-II competed more effectively with small VLDL for binding of hepatic lipase than HDL devoid of apoA-II. HDL3, particularly apoA-II-containing HDL3, reduced lipolysis of triglyceride and total fatty acid liberation in small VLDL. We conclude that the substrate properties of HDLs for hepatic lipase are influenced by both their size and apoA-II content. Moreover, size as well as apoA-II content may indirectly affect remnant clearance.
肝脂酶在血浆脂质转运中具有双重作用，它参与从循环中清除富含甘油三酯的脂蛋白残粒以及血浆高密度脂蛋白（HDL）的代谢。本文所述研究调查了密度和载脂蛋白（apo）组成不同的HDL对肝脂酶的底物特性。与相应的HDL3亚类相比，HDL2中的脂肪酸释放速率高出两倍。在每个密度类别中，与不含apoA-II的HDL相比，含apoA-II的HDL经酶催化的脂肪酸释放量高出近两倍。当体外将不含apoA-II的天然HDL3与二聚体apoA-II重组时，重组颗粒中的脂肪酸释放速率与含apoA-II的天然HDL3中的相似。含apoA-II的HDL比不含apoA-II的HDL更有效地与小极低密度脂蛋白（VLDL）竞争肝脂酶的结合。HDL3，特别是含apoA-II的HDL3，可减少小VLDL中甘油三酯的脂解和总脂肪酸释放。我们得出结论，HDL对肝脂酶的底物特性受其大小和apoA-II含量的影响。此外，大小以及apoA-II含量可能间接影响残粒清除。
