Temperature Dependent Conformational Transitions and Hydrogen Bond Dynamics of the Elastin-Like Octapeptide GVG(VPGVG): a Molecular Dynamics Study

A joint experimental / theoretical investigation of the elastin-like octapeptide GVG(VPGVG) was carried out. In this paper a comprehensive molecular dynamics study of the temperature dependent folding and unfolding of the octapeptide is presented. The current study, as well as its experimental counterpart find that this peptide undergoes an "inverse temperature transition", ITT, leading to a folding at about 310-330 K. In addition, an unfolding transition is identified at unusually high temperatures approaching the boiling point of water. Due to the small size of the system two broad temperature regimes are found: the "ITT regime" (at about 280-320 K) and the "unfolding regime" at about T > 330 K, where the peptide has a maximum probability of being folded at approximately 330 K. A detailed molecular picture involving a thermodynamic order parameter, or reaction coordinate, for this process is presented along with a time-correlation function analysis of the hydrogen bond dynamics within the peptide as well as between the peptide and solvating water molecules. Correlation with experimental evidence and ramifications on the properties of elastin are discussed.