Structural changes of a simple peptide—Trpzip-1—in aqueous solutions and the corresponding hydration phenomena under the influence of temperature

Abstract

Trpzip-1, a simple β-hairpin, is a rare example of peptide with stable secondary structure and can be a convenient model to study temperature-related processes that potential prion or amyloid proteins undergo. Although its sequence is simple, the exact processes which the peptide undergoes in aqueous solutions are quite complex and not well understood. The selection of well-established experimental (DSC, FTIR) and theoretical methods allowed to describe, on the molecular level, the sequence of Trpzip-1 structural transitions. Our results we can indicate and explain peculiarities concerning initial oligomerization and two-step denaturation mechanism. The analysis of water structure surrounding the peptide at various temperatures reveals that the hydration sphere of its monomeric, oligomeric, and unfolded states is enhanced in comparison to the “bulk” water, but in each case, it exhibits different properties. Our observations may be of general nature in terms of structural changes of peptides and accompanying phenomena in solutions.