Raman Spectroscopic Insights of Phase-Separated Insulin Aggregates
Sandip Dolui, Anupam Roy, Uttam Pal, Shubham Kundu, Esha Pandit, Bhisma N. Ratha, Ranit Pariary, Achintya Saha, Anirban Bhunia, Nakul C. Maiti
Abstract
was similar to that of freshly prepared aqueous protein solution enriched in helical conformation. The peak intensity was significantly weak in the fibrillar aggregates, and it appeared as a good Raman signature to follow the phase separation and the aggregation behavior of insulin and similar other proteins. Tyrosine phenoxy moieties in the protein may maintained its H-bond donor-acceptor integrity throughout the course of fibril formation; however, it entered in more hydrophobic environment in its journey of fibril formation. In addition, it was noticed that oligomeric bovine insulin maintained the orientation/conformation of the disulfide bonds. However, in the fibrillar state, the disulfide linkages became more strained and preferred to maintain a single conformation state.