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首页> 外文期刊>Quarterly Reviews of Biophysics >Aggregation behavior of the amyloid model peptide NACore
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Aggregation behavior of the amyloid model peptide NACore

机译：淀粉样蛋白模型肽乳酸盐的聚集行为

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The aggregation of the 11 residue long NACore peptide segment of alpha-synuclein (68-GAVVTGVTAVA-78) has been investigated using a combination of cryogenic transmission electron microscopy (cryo-TEM), small- and wide-angle X-ray scattering, and spectroscopy techniques. The aqueous peptide solubility is pH dependent, and aggregation was triggered by a pH quench from pH 11.3 to approximately pH 8 or 6, where the average peptide net charge is weakly negative (pH 8), or essentially zero (pH 6). Cryo-TEM shows the presence of long and stiff fibrillar aggregates at both pH, that are built up from beta-sheets, as demonstrated by circular dichroism spectroscopy and thioflavin T fluorescence. The fibrils are crystalline, with a wide angle X-ray diffraction pattern that is consistent with a previously determined crystal structure of NACore. Of particular note is the cryo-TEM observation of small globular shaped aggregates, of the order of a few nanometers in size, adsorbed onto the surface of already formed fibrils at pH 6. The fibrillation kinetics is slow, and occurs on the time scale of days. Similarly slow kinetics is observed at both pH, but slightly slower at pH 6, even though the peptide solubility is here expected to be lower. The observation of the small globular shaped aggregates, together with the associated kinetics, could be highly relevant in relation to mechanisms of secondary nucleation and oligomer formation in amyloid systems.
机译：使用低温透射电子显微镜（Cryo-TEM），小和广角X射线散射的组合研究了11个残基长乳突肽（68-GavvtGVTava-78）的α-突触核苷酸（68-Gavvtgvtava-78）的聚集。光谱技术。肽溶解度是pH依赖性的，并通过pH 11.3至约pH 8或6的pH淬火触发聚集，其中平均肽净电荷是弱阴性（pH8），或基本上为零（pH6）。 Cryo-Tem显示在两种pH下的长且僵硬的纤维状聚集体，其由β-薄片构成，如圆形二色光谱和硫蛋白T荧光所证明的那样。原纤维是结晶的，具有广角X射线衍射图案，其与先前确定的甲孔的晶体结构一致。特别值得注意的是小球形聚集体的低温TEM观察，其尺寸的尺寸为几纳米的阶数，吸附在pH6上已经形成的原纤维的表面上。纤维化动力学缓慢，并在时间尺度上发生天。同样地，在两种pH下观察到缓慢的动力学，但在pH6时略微慢，即使肽溶解度预期降低。将小球形聚集体与相关的动力学一起观察，与淀粉样蛋白系统中的次级成核和低聚物形成的机制有关。

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