Surface pressure-dependent conformation change of apolipoprotein-derived amphipathic α-helices
Surface pressure-dependent conformation change of apolipoprotein-derived amphipathic α-helices
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DOI：
10.1194/jlr.m034462
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发表时间：
2013-06-01
影响因子：
6.5
通讯作者：
Small, Donald M.
中科院分区：
文献类型：
--
作者：
Mitsche, Matthew A.;Small, Donald M.
两亲性α-螺旋（A α H）是可交换载脂蛋白的主要结构基序。可交换载脂蛋白中的α-氢化物在血浆脂蛋白表面吸附、重塑和解吸，以响应其大小或组成的变化。三油酸甘油酯/水（TO/W）界面被用作模型表面，以研究在脂蛋白样界面的吸附和解吸的A α Hs。我们以前报道，A α H肽自发吸附到TO/W界面，但当从系统中除去过量的肽时，它们仅从表面部分解吸。这一发现表明，“可交换”载脂蛋白实际上是部分可交换的，并且仅响应于压缩或组成变化而从表面解吸。在这里，我们开发了一个热力学和动力学模型来描述这种现象的基础上的载脂蛋白A-I（C46）的C-末端46个氨基酸在TO/W界面的界面压力（Pi）的变化。该模型表明，载脂蛋白至少有两个界面构象，是在表面浓度和PI依赖的平衡。这种基于实验数据的双态表面平衡模型与Pi（t）的动态变化一致，为研究血浆脂蛋白的选择性代谢和清除以及脂蛋白重构过程提供了新的思路。
Amphipathic alpha-helices (A alpha H) are the primary structural motif of exchangeable apolipoproteins. A alpha Hs in exchangeable apolipoproteins adsorb, remodel, and desorb at the surface of plasma lipoproteins in response to changes in their size or composition. A triolein/water (TO/W) interface was used as a model surface to study adsorption and desorption of A alpha Hs at a lipoprotein-like interface. We previously reported that A alpha H peptides spontaneously adsorb to a TO/W interface, but they only partially desorb from the surface when the excess peptide was removed from the system. This finding suggests that "exchangeable" apolipoproteins are in fact partially exchangeable and only desorb from a surface in response to compression or change in composition. Here, we develop a thermodynamic and kinetic model to describe this phenomenon based on the change in the interfacial pressure (Pi) of the C-terminal 46 amino acids of apolipoprotein A-I (C46) at a TO/W interface. This model suggests that apolipoproteins have at least two interfacial conformations that are in a surface concentration and Pi-dependent equilibrium. This two-state surface equilibrium model, which is based on experimental data and is consistent with dynamic changes in Pi(t), provides insights into the selective metabolism and clearance of plasma lipoproteins and the process of lipoprotein remodeling.