Structure Of Beta Amyloid Fibrils

β淀粉样原纤维的结构

• 批准号: 6836954
• 负责人: Richard D Leapman
• 金额: --
• 依托单位: OFFICE OF THE DIRECTOR, NATIONAL INSTITUTES OF HEALTH
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/6836954
• 关键词: Alzheimer's disease; amyloid proteins; cell component structure /function; cell growth regulation; cerebral degeneration; fibrinopeptide; mass spectrometry; molecular assembly /self assembly; neurofilament; neuropil; protein sequence; protein structure; protein structure function; scanning transmission electron microscopy; structural biology; transmission electron microscopy

Alzheimer's disease is associated with the abnormal deposits of amyloid beta protein (Ab) that occurs as fibrils within the cerebral neuropil. To characterize the way in which these fibrils assemble under different pH conditions, we have performed transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM) on synthetic full-length Ab peptides as well as various Ab peptides with truncated sequences. TEM images of negatively stained preparations provide information about the fibril width and morphology, and STEM analysis of unstained preparations provides a quantitative determination of the mass-per-length (MPL) and thus the numbers of beta-sheets within fibrils. Taken together the results reveal how the structure of fibrils grown from Alzheimer-related Ab peptides depend on the growth conditions, including protein concentration and pH. MPL measurements reveal the existence of fundamental fibrillizing units, or "protofilaments," consisting of well-defined numbers of cross-beta sheets. Variations in fibril morphology at the EM level are being used by scientists in NIDDK to correlate with atomic-level information about the peptide backbone conformation obtained from NMR spectroscopy. Recent STEM measurements have shown that fibrils composed of double beta sheets form under different growth conditions than fibrils containing triple beta sheets.

阿尔茨海默氏病与淀粉样β蛋白（AB）的异常沉积有关，淀粉样蛋白（AB）作为脑神经纤维内的原纤维发生。为了表征这些原纤维在不同的pH条件下组装的方式，我们对合成全长AB肽以及各种具有截短序列的AB肽进行了透射电子显微镜（TEM）和扫描透射电子显微镜（STEM）。否定染色制剂的TEM图像提供了有关原纤维宽度和形态的信息，而对未染色的制剂的茎分析提供了对质量长度（MPL）的定量确定，从而提供了原纤维中β片的数量。总而言之，结果揭示了与阿尔茨海默氏症相关的AB肽生长的原纤维结构如何取决于生长条件，包括蛋白质浓度和pH。 MPL测量结果揭示了由定义明确的跨β床单组成的基本纤维化单元或“原丝”。 NIDDK中的科学家使用了EM水平的原纤维形态的变化，以与原子级有关从NMR光谱获得的肽骨架构象的信息相关。最近的茎测量结果表明，在不同生长条件下形成的双β片组成的原纤维比含三β片的原纤维。