中文摘要：

利用傅立叶红外（FFIR）和飞秒二维红外（2DIR）光谱手段，以位于肽链骨架上的酰胺-I带为结构探针，跟踪研究了淀粉样6体1～25氨基酸残基片段（Aβ1-25）在酸性条件下的聚集过程．通过对其在不同聚集阶段的多肽构象及聚集结构动力学的考察，发现在此条件下AD。搦片段聚集过程中存在不同聚集程度的聚集体，也存在一定量的无规则卷曲．聚集的初态和终态具有可测量的IR光谱指纹，特别是2DIR光谱指纹，从对角峰的非均匀和均匀展宽贡献、节线取向、非对角峰的布局等方面都能表现出来．讨论了聚集体中酰胺单元之间、多肽质骨架之间及其和溶剂分子之间的动态相互作用．

英文摘要：

Fourier transform infrared （FTIR） and femtosecond two-dimensional infrared （2D IR） methods were used to monitor the aggregation process of amyloid-beta （Aβ） fragment （amino acid residue 1-25, Aβ1-25） under acidic condition, using the amide-I mode located on peptide backbone as structural probe. The conformation of Aβ1-25 peptide and its structural dynamics during aggregation were examined. The results showed that Aβ1-25 formed a mixture of structures with different aggregation degrees, and random coil as well. The initial and final states both exhibit measurable IR signatures. In particular, the 2D IR fingerprints were reflected in the inhomogeneous and homogeneous linewidths, nodal line orientation, and the distributions of the off-diagonaL peaks. Based on these results, dynamical interactions between amide units, between peptide backbones, and solvent molecules were discussed.