Assessing the role of osmolytes on the conformational harmony of islet amyloid polypeptide.

Several pathological disorders have known linkages with the misfolding and abnormal oligomerization of peptides and proteins and their accumulation into numerous aggregates. One such peptide is human islet amyloid polypeptide (hIAPP) responsible for amyloid aggregation in type 2 diabetes. This aggregation can be altered by osmolytes, which are natural agents that can alter the environment surrounding of hIAPP. Here, we implemented several replica-exchange molecular dynamics (REMD) simulations to examine the effects of the denaturing osmolyte urea and the protective osmolyte trimethylamine N-oxide (TMAO) on amyloid aggregation and on the conformational ensemble of the hIAPP peptide. We analyzed specific modulations in hIAPP peptide and observed a state shift in the conformational population of hIAPP. Our results confirmed that urea restricted the peptide aggregation and led to the formation of unfolded conformations, whereas TMAO promoted folding and a compact state of the hIAPP peptide.