PHYSICAL BIOCHEMISTRY AND BIOLOGY OF AMYLOID B-PROTEIN

B 淀粉样蛋白的物理生物化学和生物学

• 批准号: 7112180
• 负责人: DAVID B. TEPLOW
• 金额: $ 19.74万
• 依托单位: UNIVERSITY OF CALIFORNIA LOS ANGELES
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-04-01 至 2011-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7112180
• 关键词: Alzheimer' s disease; acyl group; amyloid proteins; amyloidosis; cerebral degeneration; chemical kinetics; conformation; hydropathy; ionic bond; light scattering; mass spectrometry; molecular dynamics; molecular pathology; neuropathology; neurotoxins; oligopeptides; organic brain syndrome; peptide chemical synthesis; protein folding; protein structure function; thermodynamics

In Alzheimer's disease (AD), progressive deposition of amyloid beta-protein (Abeta) fibrils, "amyloid plaques," occurs in the brain. However, neuronal dysfunction may occur prior to plaque formation. Structure-neurotoxicity studies have revealed progressively smaller toxic assemblies, including protofibrils, paranuclei, and ADDLs. In rodents, Abeta oligomers can inhibit long-term potentiation (LTP), a model for learning and memory. In AD patients, Abeta oligomers are present in levels significantly greater than in agematched normal individuals. Biophysical, cell culture, animal, and human studies thus all support the hypothesis that oligpmerization of Abeta is a key event in AD pathogenesis. If so, then the development of therapeutic strategies depends on elucidation of the mechanism(s) of pathologic protein folding, oligomerization, and higher-order assembly. Continuing efforts in our laboratory to understand the earliest steps in Abeta assembly, Abeta monomer folding and oligomerization, have revealed key structural features. These include turn formation in the Val24-Lys28 region of the unstructured Abeta monomer and interactions among the central hydrophobic cluster (Leu17-Ala21), N-terminus, and C-terminus. The four aims comprising this application seek to test mechanistic hypotheses emanating from these observations. Aim 1. To determine the mechanisms of turn formation in the Val24-Lys28 region of Abeta. a. To determine the role of hydrophobic interactions. b. To determine the role of electrostatic interactions. c. To determine the role of amino-acid turn propensity. Aim 2. To determine the mechanisms of intramolecular folding and early Abeta oligomerization. a. To determine the structural dynamics of central hydrophobic cluster (CHC)-C-terminus interactions. b. To determine the structural dynamics of CHC-N-terminus interactions. c. To determine the effects of alternative turn conformations on Abeta monomer structure and oligomerization. Aim 3. To use O?>N acyl migration chemistry to implement a new, quasisynchronous system for studies of Abeta42 folding and self-assembly. a. To synthesize 26-O-acyl-isoAbeta42 (26-AIAbeta42) and study the time-dependent changes in peptide secondary and quaternary structure following initiation of O?>N acyl migration. b. To use quasielastic light scattering spectroscopy to determine kinetic and thermodynamic parameters of Abeta42 self-assembly. c. To use ion mobility spectroscopy-mass spectrometry to monitor early oligomerization events in Abeta self-assembly. d. To synthesize and study the biophysical and biological behavior of Na-protected 26-AIAbeta42. Aim 4. To determine how structural features shown to be critical in controlling Abeta folding and oligomerization affect peptide neurotoxicity.

在阿尔茨海默病 (AD) 中，β-淀粉样蛋白 (Abeta) 纤维进行性沉积，即“淀粉样斑块” 发生在大脑中。然而，神经元功能障碍可能在斑块形成之前发生。结构-神经毒性 研究表明有毒组件逐渐变小，包括原纤维， 核旁和 ADDL。在啮齿类动物中，Abeta 寡聚物可以抑制长时程增强 (LTP)，这是一种模型 学习和记忆。在 AD 患者中，Abeta 寡聚体的水平显着高于年龄匹配的患者 正常人。因此，生物物理学、细胞培养、动物和人类研究都支持 假设 Abeta 寡聚化是 AD 发病机制中的关键事件。如果是的话，那么发展 治疗策略取决于病理性蛋白质折叠机制的阐明， 低聚和高阶组装。我们的实验室不断努力以最早了解 Abeta 组装、Abeta 单体折叠和寡聚的步骤揭示了关键的结构特征。 其中包括非结构化 Abeta 单体的 Val24-Lys28 区域的转角形成和相互作用 位于中央疏水簇 (Leu17-Ala21)、N 末端和 C 末端之间。四大目标 包含此应用程序的目的是测试从这些观察结果中得出的机械假设。 目标 1. 确定 Abeta 的 Val24-Lys28 区域转角形成机制。 一个。确定疏水相互作用的作用。 b.确定静电相互作用的作用。 c.确定氨基酸转向倾向的作用。 目标 2. 确定分子内折叠和早期 Abeta 寡聚化的机制。 一个。确定中央疏水簇 (CHC)-C 末端相互作用的结构动力学。 b.确定 CHC-N 末端相互作用的结构动力学。 c.确定交替转角构象对 Abeta 单体结构和寡聚化的影响。 目标 3. 使用 O?>N 酰基迁移化学来实现一个新的准同步系统 Abeta42 折叠和自组装的研究。 一个。合成26-O-酰基-isoAbeta42 (26-AIAbeta42)并研究肽随时间的变化 O→N酰基迁移引发后的二级和四级结构。 b.使用准弹性光散射光谱测定动力学和热力学参数 Abeta42 自组装。 c.使用离子迁移谱-质谱法监测 Abeta 自组装中的早期寡聚事件。 d.合成Na保护的26-AIAbeta42并研究其生物物理和生物学行为。 目标 4. 确定结构特征如何在控制 Abeta 折叠和 寡聚化影响肽的神经毒性。