Self-assembly and hydrogelation of an amyloid peptide fragment
Self-assembly and hydrogelation of an amyloid peptide fragment
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DOI：
10.1021/bi8000616
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发表时间：
2008-04-22
期刊：
影响因子：
2.9
通讯作者：
Pochan, Darrin J.
中科院分区：
文献类型：
--
作者：
Krysmann, Marta J.;Castelletto, Valeria;Pochan, Darrin J.
已经在水溶液中研究了淀粉样蛋白β肽的片段的自组装，该片段已经被证明在淀粉样蛋白纤维化中是关键的。关于A β的纤维化，文献中有相互矛盾的报道（16-20），即，KLVFF，我们的结果揭示了这一点。在稀溶液中，NH 2-KLVFF-COOH的自组装强烈地受到苯丙氨酸单元之间的芳香族相互作用的影响，如通过UV光谱和圆二色性所揭示的。傅里叶变换红外（FTIR）光谱揭示了β-片层的功能，在更浓的溶液，也干膜的光谱。X射线衍射和低温透射电子显微镜（cryo-TEM）为β折叠淀粉样蛋白原纤维的形成提供了进一步的支持。冷冻TEM图像与那些从传统的干燥和负染色的TEM标本的比较突出了显着的影响，样品制备的形态。溶液中的样品和干燥样品的FTIR数据的比较也突出了干燥对自组装结构的强烈影响。在更浓的磷酸盐缓冲盐水（PBS）溶液中，观察到NH 2-KLVFF-COOH的凝胶化。这被认为是由肽上的静电荷的屏蔽引起的，这使得β折叠能够聚集成纤维状凝胶网络。探讨了水凝胶的流变性，并通过光散射和小角X射线散射研究了结构。
The self-assembly of a fragment of the amyloid beta peptide that has been shown to be critical in amyloid fibrillization has been studied in aqueous solution. There are conflicting reports in the literature on the fibrillization of A beta (16-20), i.e., KLVFF, and our results shed light on this. In dilute solution, self-assembly of NH2-KLVFF-COOH is strongly influenced by aromatic interactions between phenylalanine units, as revealed by UV spectroscopy and circular dichroism. Fourier transform infrared (FTIR) spectroscopy reveals beta-sheet features in spectra taken for more concentrated solutions and also dried films. X-ray diffraction and cryo-transmission electron microscopy (cryo-TEM) provide further support for beta-sheet amyloid fibril formation. A comparison of cryo-TEM images with those from conventional dried and negatively stained TEM specimens highlights the pronounced effects of sample preparation on the morphology. A comparison of FTIR data for samples in solution and dried samples also highlights the strong effect of drying on the self-assembled structure. In more concentrated phosphate-buffered saline (PBS) solution, gelation of NH2-KLVFF-COOH is observed. This is believed to be caused by screening of the electrostatic charge on the peptide, which enables beta sheets to aggregate into a fibrillar gel network. The rheology of the hydrogel is probed, and the structure is investigated by light scattering and small-angle X-ray scattering.