Aggregation of amylin: Spectroscopic investigation

Abstract Apart from its relevance to pathology, protein misfolding disease like Type-II Diabetes Mellitus, caused by amyloids of amylin protein has attracted more attention due to structural changes occurring during the aggregation process. We report extensive spectroscopy data of amylin during fibril formation through Raman, FTIR, CD, UV–vis absorption and photoluminescence (PL) spectroscopy. UV–vis and PL spectrum showed the sigmoidal growth of fibril with a lag time of ~2 days, which is consistent with earlier reported work using dynamic light scattering (DLS). Raman spectra revealed the formation of parallel and anti-parallel β-sheet from 0% to 20% with ageing (1st day to 21st day) at pH 6.5 ± 0.1. The results are corroborated by CD and FTIR data. These show the change in β-sheet by 23% at pH 6.5 ± 0.1, 26% at pH = 1.0 ± 0.1 and 30% at pH = 12 ± 0.1. It is also shown that the formation and conversion of other secondary structures into β-sheet is very sensitive towards the pH and ageing. The study may be used for the development of therapeutic strategies that could inhibit or even reverse the process of aggregation.