| 内容提要: |
Assembly and fibrillation of amyloid proteins are believed to have a key role in the etiology of various human diseases including Alzheimer’s, Parkinson’s, Huntington’s and type II diabetes. Insights into the conformational changes and the formation process during amyloid fibrillation are essential for the clinical diagnose and drug discovery. To study the changes in secondary, tertiary, and quaternary structures and the alteration in the density of states during the amyloid fibrillation, bovine insulin in 20% acetic acid was incubated at 60oC, and its structure was followed by various biophysical techniques including circular dichroism (CD), thioflavin T Fluorescence (ThT), dynamic light scattering (DLS), electron microscopy and terahertz (THz) absorption spectroscopy. The experimental data demonstrated that the reduction of α-helix into β-sheet started at 26h, followed by the aggregation of insulin showed by ThT binding with the transition midpoint at 41h, and by the bulk formation of mature aggregates after about 71h. THz is a quick and non-invasion technique, and thus had the advantage to study the conformational state of biomolecules and tissues. It is the first use of THz to study the amyloid fibrillation in this paper. For the terahertz frequency range of 0.2~3.0THz, there was an apparent increase in both the absorbance and reflective index in THz spectra. Thus, THz is expected to provide a new way of looking into amyloid fibrillation. |