Structural Thermodynamics of Human Apolipoprotein C-1

该项目的长期目标是确定分子的能量-结构-功能 可交换载脂蛋白和脂蛋白的关系，从而提供了一个深入了解分子 脂蛋白在动脉粥样硬化和其他脂蛋白相关疾病发病机制中的作用 疾病可交换载脂蛋白是脂蛋白的可溶性蛋白组分， 以及胆固醇的转运和代谢，并在动脉粥样硬化的发病机制中起关键作用， 冠心病、中风和其他主要的人类疾病。结构稳定性和组成 脂蛋白的变异性对其功能至关重要，必须详细了解， 阐明脂蛋白在正常和疾病状态下作用的分子机制。拟议工作 通过对能量学、结构和脂质结合功能的详细研究， 两种小的人血浆载脂蛋白apoC-1和apoA-2。ApoC-1延迟清除潜在的 通过apoE介导的低密度脂蛋白抑制其摄取， 受体相关通路apoC-1激活卵磷脂：胆固醇酰基转移酶（LCAT）的能力可能 解释了主要LCAT缺乏受试者中胆固醇酯的正常血浆水平 激活剂apoA-1。ApoA-2从高密度脂蛋白（HDL）中置换apoA-1的能力影响了 HDL的抗动脉粥样硬化功能。无脂和脂结合人体的能量和结构分析 将进行apoA-2、apoC-1和一系列针对关键结构区域的apoC-1突变体的研究 通过使用远-和近-UV圆二色性和荧光光谱的组合， 显微镜法、差示扫描量热法和X射线衍射法。这种分析将决定，在 单个氨基酸的水平，apoC-1中关键结构元件对其折叠、稳定性和 脂质结合特性;确定Lp稳定性的关键决定因素及其与 脂蛋白代谢过程中脂蛋白之间的载脂蛋白转移;使apoC-1结晶， 分析其晶体结构，这可能为功能性载脂蛋白构象提供模型。的 结果将为了解脂蛋白的分子机制提供能量和结构基础 在正常和疾病状态下的作用。

The long-term objective of this project is to determine in molecular detail the energetic-structure-function relationship in exchangeable apolipoproteins and lipoproteins, thereby providing an insight into molecular mechanisms of lipoprotein action in the pathogenesis of atherosclerosis and other Upoprotein-related diseases. Exchangeable apolipoproteins are soluble protein components of lipoproteins that mediate lipid and cholesterol transport and metabolism and play crucial roles in the pathogenesis of atherosclerosis, coronary heart disease, stroke and other major human disorders. Structural stability and compositional variability of lipoproteins are essential for their functions, and have to be understood in detail in order to elucidate molecular mechanisms of lipoprotein action in normal and in diseased states. The proposed work addresses this long-term goal through detailed studies of the energetics, structure and lipid binding function of two small human plasma apolipoproteins, apoC-1 and apoA-2. ApoC-1 delays the clearance of potentially atherogenic triglyceride-rich particles by inhibiting their uptake via the apoE-mediated low-density lipoprotein receptor-related pathway. The ability of apoC-1 to activate lecitin:cholesterol acyltransferase (LCAT) may account for normal plasma levels of cholesterol esters in subjects with deficiency of the major LCAT activator, apoA-1. ApoA-2 ability to displace apoA-1 from high-density lipoproteins (HDL) affects the antiatherogenic functions of HDL. Energetic and structural analyses of lipid-free and lipid-bound human apoA-2, apoC-1 and a series of apoC-1 mutants targeted towards key structural regions will be carried out by using a combination of far- and near-UV circular dichroism and fluorescence spectroscopy, electron microscopy, differential scanning calorimetry, and x-ray diffraction methods. Such analysis will determine, at the level of individual amino acids, the roles of key structural elements in apoC-1 for its folding, stability and lipid binding properties; identify critical determinants for the Lp stability and their relation to the kinetics of apolipoprotein transfer among lipoproteins in the course of lipoprotein metabolism; crystallize apoC-1 and analyze its crystal structure that may provide a model for a functional apolipoprotein conformation. The results will provide the energetic and structural basis for understanding molecular mechanisms of lipoprotein action in normal and diseased states.