Properties of human apolipoprotein A-I at the air-water interface.
Properties of human apolipoprotein A-I at the air-water interface.
复制标题
人载脂蛋白 A-I 在空气-水界面的特性。
DOI：
10.1021/bi00557a001
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发表时间：
1980
期刊：
影响因子：
2.9
通讯作者：
Scanu,AM
中科院分区：
文献类型：
--
作者：
Shen,BW;Scanu,AM
贝蒂·W·沈**和AngeloM。摘要：为了研究人载脂蛋白AI(apo-AI)在空气-水界面的性质和结构，我们通过铺展或自发吸附亚相的方法形成了apo-AI的单分子膜。定量分析了膜的单层形成率、力-面积(II-A)曲线和表面电位。我们通过保持(A)总面积或(B)分子总数不变来构建力-面积曲线。用方法a得到的结果与用吸附单层得到的结果是重复性和重叠性的。反过来，方法b获得的结果表明，压力和电位测量都表明了衰老效应，表明apo-AI在大于50A2/氨基酸的区域发生了不可逆变性。当压力低于0.5dyn/cm时，apo-AI单分子膜遵循二维理想气体定律；根据IL4与图的纵坐标截距计算出apo-AI单层的平均分子质量为25000。在较高的压力下，单分子层偏离了理想状态，最近对高密度脂蛋白(HDL)和低密度脂蛋白(LDL)的物理和化学研究表明，载脂蛋白、胆固醇和磷脂在这些脂蛋白的外表面形成了单分子层(Mor-risett等人，1975)。完整脂蛋白的酶促蛋白分解(Aggerbeck等人，1976；Camejo，1969；Pattnaik等人，1976)导致聚集，表明载脂蛋白在维持脂蛋白结构中发挥重要作用。这种稳定性应该与脱辅基蛋白的表面性质密切相关。为了探讨载脂蛋白在两亲界面的行为及其与人血清HDL3表面结构的关系，我们将注意力转向了载脂蛋白AI(apo-AI)，它是血浆高密度脂蛋白的主要蛋白质成分。之所以选择Apo-AI进行这次调查，是因为(1)它是
Betty W. Shen** and AngeloM. Scanu abstract: In order to study the properties and structure of human apolipoprotein AI (apo-AI) at the air-water interface, we formed monolayers of apo-AI by either spreading or spontaneous adsorption from the subphase. The rate of monolayer formation, force-area (II-A) curves, and surface potentials were analyzed quantitatively. We constructed force-area curves by keeping constant either (a) the total area or (b) the total number of molecules. The results obtained by method a were reproducible and superimposable with those obtained from adsorbed monolayers. In turn, the resultsob-tained by method b indicated aging effects by both pressure and potential measurements, suggesting irreversible denaturation of apo-AI at areas larger than 50 A2/amino acid. At pressures lower than 0.5 dyn/cm, apo-AI monolayers followed the two-dimensional ideal gas law; the molecular weight of the apoprotein calculated from the intercept on the ordinate of the IL4 vs. plot had an average value of 25 000. At higher pressures, the monolayer deviated from ideality, and theRecent physical and chemical studies on both high-density lipoproteins (HDL) and low-density lipoproteins (LDL) have suggested that apoproteins, cholesterol, and phospholipids form a monolayer at the outer surface of these lipoproteins (Mor-risett et al., 1975). The enzymatic proteolysis of the intact lipoproteins (Aggerbeck et al., 1976; Camejo, 1969; Pattnaik et al., 1976) results in aggregation, indicating that theapoproteins play an important role in maintaining the lipoprotein structure. Such stabilization should be intimately related to the surface properties of the apoproteins. In order to explore the behavior of apolipoproteins at amphiphilic interfaces and their relation to the surface organization of human serum HDL3, we turned our attention to apolipoprotein AI (apo-AI), which is the major protein component of plasma HDL. Apo-AI was chosen for this investigation because (1) it is the