文章基本信息

标题：Substrate specificity of lipoprotein lipase and endothelial lipase: studies of lid chimeras
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作者：Griffon, Nathalie ; Budreck, Elaine C. ; Long, Christopher J. 等
期刊名称：JLR Papers In Press
印刷版ISSN：0022-2275
电子版ISSN：1539-7262
出版年度：2006
卷号：47
期号：8
页码：1803-1811
DOI：10.1194/jlr.M500552-JLR200
出版社：American Society for Biochemistry and Molecular Biology
摘要：The triglyceride (TG) lipase gene subfamily, consisting of LPL,HL, and endothelial lipase (EL), plays a central role in plasmalipoprotein metabolism. Compared with LPL and HL, EL is relativelymore active as a phospholipase than as a TG lipase. The aminoacid loop or "lid" covering the catalytic site has been implicatedas the basis for the difference in substrate specificity betweenHL and LPL. To determine the role of the lid in the substratespecificity of EL, we studied EL in comparison with LPL by mutatingspecific residues of the EL lid and exchanging their lids. Mutationstudies showed that amphipathic properties of the lid contributeto substrate specificity. Exchanging lids between LPL and ELonly partially shifted the substrate specificity of the enzymes.Studies of a double chimera possessing both the lid and theC-terminal domain (C-domain) of EL in the LPL backbone showedthat the role of the lid in determining substrate specificitydoes not depend on the nature of the C-domain of the lipase.Using a kinetic assay, we showed an additive effect of the ELlid on the apparent affinity for HDL₃ in the presence of theEL C-domain. Abbreviations: appK_m, apparent affinity of the enzyme for the phospholipid present in HDL₃ as substrate; C-domain, C-terminal domain; EL, endothelial lipase; PL, phospholipid; TG, triglyceride; TG/PL ratio, ratio of triglyceride lipase activity to phospholipase activity Supplementary key words hepatic lipase • triglyceride • phospholipid