Headgroup specificity of lecithin cholesterol acyltransferase for monomeric and vesicular phospholipids
Headgroup specificity of lecithin cholesterol acyltransferase for monomeric and vesicular phospholipids
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DOI：
10.1016/s1388-1981(00)00075-5
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发表时间：
2000-07-19
影响因子：
4.8
通讯作者：
Rosseneu, M
中科院分区：
文献类型：
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作者：
Christiaens, B;Vanloo, B;Rosseneu, M
在这项研究中，我们研究了磷脂头基团的性质和磷脂的大分子结构，无论是作为单体还是作为脂质基质掺入，如何影响卵磷脂胆固醇酰基转移酶(LCAT)的活性。作为底物，我们使用1，2-bis-(1-pyrenebutanoyl)-phosphatidylcholine，1，2-bis-(1-pyrenebutanoyl)phosphatidylethanolamine和1，2-bis-(1-pyrenebutanoyl)-phosphatidyl-alcohols，作为单体或掺入到由二棕榈酰磷脂酰胆碱醚组成的小单层囊泡中。用荧光法和高效液相色谱仪测定了芘标记磷脂的水解率。计算了不同底物的V-max和K-m。数据表明，单体磷脂酰胆碱(PC)的V-max比磷脂酰乙醇胺(PE)和磷脂酰醇高10-30倍，而K-m值与之相当。当荧光底物被加入到二棕榈酰磷脂酰胆碱醚囊泡中时，我们观察到PE和磷脂醇的V-max增加了4到10倍，而K-m没有明显的变化。PC的V-max保持不变。导致鱼眼病(FED)的天然LCAT突变体及其在Cos-1细胞中表达的类似突变体对单体PC和PE具有类似的活性。这些数据表明，LCAT的活性既由磷脂的分子结构决定，也由其大分子性质决定。单体底物上的LCAT活性依次为：磷脂酰胆碱、磷脂酰乙醇胺、磷脂酰丙醇、磷脂酰乙醇酯、磷脂酰乙二醇酯。PE和磷脂醇加入到二棕榈酰磷脂酰胆碱的基质中会降低磷脂头基团的特异性。(C)2000 Elsevier Science B.V.保留所有权利。
In this study, we investigated how the nature of the phospholipid head group and the macromolecular structure of the phospholipid, either as a monomer or incorporated into a lipid matrix, influence the activity of lecithin cholesterol acyltransferase (LCAT). As substrates we used 1,2-bis-(1-pyrenebutanoyl)-phosphatidylcholine, 1,2-bis-(1-pyrenebutanoyl)phosphatidylethanolamine and 1,2-bis-(1-pyrenebutanoyl)-phosphatidyl-alcohols, either as monomers or incorporated into small unilamellar vesicles consisting of dipalmitoylphosphatidylcholine ether. The rate of hydrolysis of the pyrene-labeled phospholipids was determined both by fluorescence and by high performance liquid chromatography. V-max and K-m were calculated for the different substrates. The data show that V-max is 10- to 30-fold higher for the hydrolysis of monomeric phosphatidylcholine (PC) compared to phosphatidylethanolamine (PE) and the phosphatidylalcohols, while K-m values are comparable. When the fluorescent substrates were incorporated into dipalmitoylphosphatidylcholine ether vesicles, we observed a 4- to 10-fold increase of V-max for PE and the phosphatidylalcohols, and no significant change for K-m. V-max for PC remained the same. Natural LCAT mutants causing Fish-Eye Disease (FED) and analogues of these mutants expressed in Cos-1 cells, had similar activity on monomeric PC and PE. These data suggest that the activity of LCAT is determined both by the molecular structure of the phospholipid and by its macromolecular properties. The LCAT activity on monomeric substrates decreases as: phosphatidylcholine >> phosphatidylethanolamine congruent to phosphatidylpropanol congruent to phosphatidylethanol congruent to phosphatidylethyleneglycol. The incorporation of PE and the phosphatidylalcohols into a matrix of dipalmitoylphosphatidylcholine decreases the specificity of the phospholipid head group. (C) 2000 Elsevier Science B.V. All rights reserved.