An amyloidosis pathway of Alzheimer’s β-peptide Aβ40 on lipid membranes, the self-coiling of single-stranded protofibrils into thermodynamically stable ring structures, is uncovered. Distinct from Aβ amyloid structures reported previously, the coiled rings observed here exhibit a narrow distribution of diameters centered at ∼170 nm and their circumference thicknesses increase as a longer single-stranded protofibril wraps around the ring, indicating the coaxial loop-by-loop winding of individual protofibrils. Such self-coiling is dominated by elastic properties of the flexible protofibrils subject to thermal fluctuations and surface interactions, as supported by an entropic elasticity model from polymer physics concepts. This work not only provides insights into the fundamental physics of Alzheimer’s β-peptide amyloidosis but also is useful for designing amyloid filament materials.

中文翻译：

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单链原纤维自缠绕成环：脂质膜上阿尔茨海默氏症 β-肽淀粉样变性的途径

揭示了脂质膜上阿尔茨海默氏症 β-肽 Aβ40 的淀粉样变性途径，即单链原纤维自缠绕成热力学稳定的环状结构。与先前报道的 Aβ 淀粉样蛋白结构不同，此处观察到的盘绕环表现出以~170 nm 为中心的狭窄直径分布，并且随着更长的单链原纤维缠绕在环周围，它们的周长厚度增加，表明同轴逐环缠绕的单个原纤维。这种自卷曲主要是受热波动和表面相互作用影响的柔性原纤维的弹性特性，如聚合物物理概念中的熵弹性模型所支持的那样。