刚果红
圆二色性
化学
纤维
四级结构
硫黄素
负染色法
淀粉样蛋白(真菌学)
分子质量
蛋白质三级结构
结晶学
离子强度
蛋白质二级结构
生物物理学
构象变化
生物化学
电子显微镜
生物
蛋白质亚单位
有机化学
酶
吸附
无机化学
水溶液
医学
阿尔茨海默病
病理
物理
光学
疾病
基因
作者
Chuan‐He Tang,Yehui Zhang,Wen Qi-biao,Qingrong Huang
摘要
The amyloid fibrils formed by heating 1.0% (w/v) kidney bean phaseolin (7S globulin) solution at pH 2.0 with an ionic strength of 20 mM at 85 °C were characterized using transmission electron microscopy (TEM), atomic force microscopy (AFM), binding of thioflavin T (Th T) and Congo Red dyes, and circular dichroism spectroscopy. The morphology of the formed fibrils was closely dependent upon heating time from 15 to 720 min. The diameters of the fibrils formed at various times were similar, but the mean contour length progressively increased with heating time. The Th T maximum fluorescence also progressively increased with heating time. The heating process caused remarkable changes in secondary, tertiary, and quaternary conformations of the phaseolin, but the extents of the changes were closely related to the heating time. With a short heating time (e.g., 15 min), the β-strand content decreased from 38.7 to 22.9%, but further heating resulted in recovery of β-strand structure. The tertiary and quaternary conformations gradually became flexible and unfolded upon heating. Gel electrophoresis analysis indicated that heating disrupted the polypeptides of phaseolin, leading to the formation of fragments with lower molecular mass (e.g., <10 kDa after 360 min). The results suggest that the amyloid fibril formation of phaseolin (7S globulin) involved the disruption of its polypeptides, as well as conformational changes at secondary, tertiary, and quaternary structural levels. This appears to be the first direct observation of amyloid fibrils from legume 7S storage globulin.
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