Department of Physics, Ningbo University, Ningbo, 315211, China.
Nanoscale. 2013 Jun 7;5(11):4816-22. doi: 10.1039/c3nr00886j. Epub 2013 Apr 24.
The aggregation of amyloid peptides into ordered fibrils is closely associated with many neurodegenerative diseases. The surfaces of cell membranes and biomolecules are believed to play important roles in modulation of peptide aggregation under physiological conditions. Experimental studies of fibrillogenesis at the molecular level in vivo, however, are inherently challenging, and the molecular mechanisms of how surface affects the structure and ordering of amyloid fibrils still remain elusive. Herein we have investigated the aggregation behavior of insulin peptides within water films adsorbed on the mica surface. AFM measurements revealed that the structure and orientation of fibrils were significantly affected by the mica lattice and the peptide concentration. At low peptide concentration (~0.05 mg mL(-1)), there appeared a single layer of short and well oriented fibrils with a mean height of 1.6 nm. With an increase of concentration to a range of 0.2-2.0 mg mL(-1), a different type of fibrils with a mean height of 3.8 nm was present. Interestingly, when the concentration was above 2.0 mg mL(-1), the thicker fibrils exhibited two-dimensional liquid-crystal-like ordering probably caused by the combination of entropic and electrostatic forces. These results could help us gain better insight into the effects of the substrate on amyloid fibrillation.
淀粉样肽的聚集形成有序的纤维与许多神经退行性疾病密切相关。人们认为，在生理条件下，细胞膜和生物分子的表面在调节肽聚集方面起着重要作用。然而，在分子水平上对体内纤维形成进行实验研究具有内在的挑战性，并且表面如何影响淀粉样纤维的结构和有序性的分子机制仍然难以捉摸。在此，我们研究了在云母表面吸附的水膜中胰岛素肽的聚集行为。原子力显微镜测量表明，纤维的结构和取向受到云母晶格和肽浓度的显著影响。在低肽浓度（约 0.05 mg mL(-1)) 下，出现了单层短而取向良好的纤维，平均高度为 1.6 nm。随着浓度增加到 0.2-2.0 mg mL(-1) 的范围，出现了另一种具有 3.8 nm 平均高度的纤维。有趣的是，当浓度高于 2.0 mg mL(-1) 时，较厚的纤维表现出二维类似液晶的有序排列，这可能是熵和静电力共同作用的结果。这些结果可以帮助我们更好地了解基底对淀粉样纤维形成的影响。
