STRUCTURAL THERMODYNAMICS OF HUMAN APOLIPOPROTEIN C 1

该项目的长期目标是确定在分子 在可交换的情况下， 载脂蛋白，从而提供了深入了解的分子机制， 它们在动脉粥样硬化和其他疾病发病机制中的作用 载脂蛋白相关疾病。可交换的载脂蛋白是水- 脂蛋白的可溶性蛋白组分，其介导脂质和 胆固醇的运输和代谢，并发挥关键作用， 动脉粥样硬化、冠心病、中风等的发病机制 主要的人类疾病，包括几种形式的全身性和脑 淀粉样变性载脂蛋白对异质性的结构适应性 脂蛋白复合物和血浆对于他们的健康绝对至关重要 功能，并且必须在拘留中理解，以便阐明 载脂蛋白在正常和疾病中作用的分子机制 states.拟议的工作通过研究来实现这一长期目标 最小的人类的能量结构和折叠路径 血浆载脂蛋白C-1（apoC-1，6 kDa）。apoC-1的能力， 激活卵磷脂：胆固醇酰基转移酶（LCAT）可以解释 胆固醇酯缺乏症患者的正常血浆水平 主要的LCAT激活剂apoA-1。ApoC-1延迟清除 潜在致动脉粥样硬化的富含磷脂的颗粒， 通过apoE介导的低密度低密度脂蛋白受体摄取- 相关路径合成人的热力学和结构分析 apoC-1及其一系列靶向靶向的位点特异性突变体， 预测的两亲性α-螺旋区域将通过使用 远紫外圆二色光谱、差示 扫描量热法和X射线衍射法。该分析将1） 剖析无脂质apoC-1在溶液中的折叠途径，从部分 折叠的单体至完全折叠的寡聚体或脂质结合状态; 2） 在单个氨基酸水平上确定关键因素 为了两亲性α-螺旋的稳定性和协同性， apoC-1的结构; 3）确定apoC-1在各种自身 相关状态，如2D细丝和3D晶体，以提供模型 对于多种功能性载脂蛋白构象。的结果 这一分析将为以下方面提供能量和结构基础： 了解功能性载脂蛋白反应的机制， 有助于了解它们的淀粉样蛋白生成特性，从而导致 在各种疾病中确定合理的治疗靶点 载脂蛋白相关疾病。

The long-term objective of this project is to determine in molecular detain the energetic-structure-function relationship in exchangeable apolipoproteins, thereby providing an insight into molecular mechanisms of their action in the pathogenesis of atherosclerosis and other apolipoprotein-related disorders. Exchangeable apolipoproteins are water- 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 including several forms of systemic and cerebral amyloidosis. Structural adaptability of apolipoproteins to heterogenous lipoprotein complexes and to plasma is absolutely essential for their functions, and has to be understood in detain in order to elucidate molecular mechanisms of apolipoprotein action in normal and in diseased states. The proposed work addresses this long-term goal through studies of the energetics, structure and folding pathway of the smallest human plasma apolipoprotein C-1 (apoC-1, 6 kDa). 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. ApoC-1 delays the clearance of potentially atherogenic triglyceride-rich particles by inhibiting their uptake via the apoE-mediated low-density low-density lipoprotein receptor- related pathway. Thermodynamic and structural analyses of synthetic human apoC-1 and a series of its site-specific mutants targeted towards the predicted amphipathic alpha-helical regions will be carried out by using a combination of far-UV circular dichroism spectroscopy, differential scanning calorimetry, and x-ray diffraction methods. Such analysis will 1) dissect the folding pathway of lipid-free apoC-1 in solution, from partly folded monomeric to fully folded oligomeric or lipid-bound state; 2) determine, at the level of individual amino acids, the critical factors for the stability and cooperatively of the amphipathic alpha-helical structure in apoC-1; 3) determine the conformation apoC-1 in various self- associated status, such as 2D filaments and 3D crystals, to provide models fir a variety of functional apolipoprotein conformations. The results of this analysis will provide the energetic and structural basis for understanding mechanisms of functional apolipoprotein reactions and will help to understand their amyloidogenic properties, thereby leading to identification of rational therapeutic targets in a variety of apolipoprotein-related disorders.