  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.
