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 article 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 (see companion article in this issue) find that this peptide undergoes an inverse temperature transition (ITT), leading to a folding at ∼40-60°C. In addition, an unfolding transition is identified at unusually high temperatures approaching the normal boiling point of water. Due to the small size of the system, two broad temperature regimes are found: The ITT regime at ∼10-60°C and the unfolding regime at ∼ T > 60°C, where the peptide has a maximum probability of being folded at T ≈ 60°C. 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 hydrogenbond 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.