ROLE OF SPECIFIC GLYCOPEPTIDES OF HUMAN SERUM LIPOPROTEINS IN ACTIVATION OF LIPOPROTEIN LIPASE
ROLE OF SPECIFIC GLYCOPEPTIDES OF HUMAN SERUM LIPOPROTEINS IN ACTIVATION OF LIPOPROTEIN LIPASE
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DOI：
10.1161/01.res.27.4.595
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发表时间：
1970-01-01
影响因子：
20.1
通讯作者：
BIER, DM
中科院分区：
文献类型：
--
作者：
HAVEL, RJ;SHORE, VG;BIER, DM
在血清脂蛋白存在的情况下，脂蛋白脂肪酶与脂肪乳形成酶-底物复合物。密度非常低的脂蛋白和密度很高的脂蛋白都有这种特性，但密度非常低的脂蛋白每单位重量的蛋白质活性要高得多。在这项研究中，活性，表示为产生一半最大游离脂肪酸速率的量，从极低密度脂蛋白和高密度脂蛋白中分离出的特异糖肽在含有牛奶脂酶和每毫升1.8毫克甘油三酯的培养液中进行了测试，高密度脂蛋白的两种主要多肽在每毫升100µg时几乎没有活性，极低密度脂蛋白的未分离载脂蛋白的活性与天然脂蛋白相似（约为4µg/ml）。其中两个多肽具有活性：一个与羧基末端谷氨酸在0.45至0.60µg/ml之间，一个与羧基末端丙氨酸在1.8.2.8µg/ml之间。后一种肽的一些制剂活性较低，在高水平时受到抑制。从极低密度脂蛋白中提取的另外三个糖肽类没有活性。来自原发性胆汁性肝硬化患者的低密度脂蛋白和来自该部分特定升高的患者的密度为1.04至1.06的脂蛋白，都含有活性糖肽，具有相当大的活性（5至11µg/ml）。这些研究表明，脂蛋白脂肪酶对乳化甘油三酯的作用需要特定的糖肽，并表明它们是血浆甘油三酯肝外利用机制的重要组成部分。
Lipoprotein lipase forms an enzyme-substrate complex with fat emulsions in the presence of serum lipoproteins. Lipoproteins of very low density and high density have this property, but the former are much more active per unit weight of protein. In this investigation, the activity, expressed as quantity giving half-maximal rate of production of free fatty acids, of specific glycopeptides isolated from very low density and high density lipoproteins was tested in an incubation mixture containing lipoprotein lipase from cows' milk and 1.8 mg triglyceride per ml. The two major polypeptides of high density lipoproteins were virtually inactive in amounts up to 100 µg per ml. Activity of the unfractionated apoproteins of very low density lipoprotein was similar to that of the native lipoprotein (about 4 µg/ml). Two of its polypeptides were active: one with carboxyl-terminal glutamic acid at 0.45 to 0.60µg/ml and one with carboxyl-terminal alanine at 1.8.2.8 µg/ml. Some preparations of the latter peptide were less active and inhibited at high levels. Three other glycopeptides from very low density lipoprotein were inactive. Low density lipoprotein from subjects with primary biliary cirrhosis and a lipoprotein of density 1.04 to 1.06 from a subject with specific elevation of this fraction, both containing the active glycopeptides, had considerable activity (5 to 11 µg/ml). These studies indicate that specific glycopeptides are required for the action of lipoprotein lipase on emulsified triglycerides and suggest that they are important components of the mechanism for extra-hepatic utilization of plasma triglycerides.