Istituto di Biofisica     
Lenci F., Sgarbossa A., Bramanti E. Effects of hypericin on the structure and aggregation properties of b-amyloid peptides. In: European Biophysics Journal With Biophysics Letters, vol. 39 pp. 1493 - 1501. Springer, 2010.
We have determined the secondary structure of 1-40 b-amyloid peptides by Fourier-transform infrared spectroscopy (FTIR) and characterized the peptide photophysical properties before and after self-assembly by using intrinsic tyrosine steady-state and time-resolved Xuorescence. All measurements were performed in the presence and absence of hypericin (Hyp), an exogenous natural polycyclic pigment that has been shown to inhibit Wbril formation and has also been used as a Xuorescent probe. We monitored the time course of the aggregation process measuring 405 nm light diVusion at 90 and used thioXavin T to reveal the presence of Wbrils. FTIR quantitative analysis evidenced a prevalent random conformation at t = 0 with and without Hyp. Fibrils showed a predominant parallel b-sheet structure and a small percentage of b-helix. The results of Xuorescence measurements showed that Hyp does signiWcantly interact with peptides in b-sheet conformation. In conclusion, hypericin does hinder the formation of Wbrils, but the percentages of parallel b-sheets were not signiWcantly diVerent from those found in samples not treated with Hyp.
DOI: 10.1007/s00249-010-0607-x
Subject eimer's disease
Fluorescence spectroscopy
FTIR spectroscopy
Secondary structure

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