Urea, Guanidine Hydrocloride and 2,2,2-Trifluoroethanol Can Change the Amyloid Fibril Formation of Model Proteins: A Spectroscopic Study

Abstract

The influence of external agents on proteins function and structure is essential to elucidate the unfolding pathways and the protein self-assemble properties. The knowledge of the protein amyloid fibril formation process is important due to the fields that this subjected is related, in particular for the neurodegenerative disorders as Parkinson's and Alzheimer's diseases. In the present study we evidenced the influence of different external agents on the Bovine Serum Albumin (BSA) and Lysozyme amyloid fibril formation by means of UV-Vis and Fluorescence spectroscopy. Concerning BSA, the presence of urea (< 3M) was able to induce the formation of amyloid fibrils at 328 K and increasing urea concentration the amount of protein in the amyloid form also increases. Moreover, a different effect was evidenced by the presence of TFE, where BSA underwent an amorphous aggregation process, leading even to the flocculation of BSA. Interestingly the presence of both urea and TFE up to 5% induces the appearance of amyloid fibrils, instead of amorphous aggregation. Regarding GndHCl, it was not able to induce the formation of amyloid fibrils in neither BSA nor Lysozyme. It is interesting that GndHCl and Urea are well-known as protein denaturant agents, however, their interaction in the protein surface is quite different, such a difference could lead the protein to different final conformations, including the amyloid fibril one. This study indicates that the hydration shell can play an important role in the amyloid aggregation process.Acknowledgements: FAPESP (grant # 2012/01953-9) CNPq (grant # 479229/2011-2, # 303048/2012-3).