We have analyzed thermal unwinding behavior of a biologically relevant collagen
mimetic peptide (PDB ID: 1bkv) through molecular dynamics simulations in
explicit water. Conformational changes of the triple helix were monitored by
introducing a set of local triad vectors and measuring variations in their torsional
angles. Although the molecule fluctuates thermally at 273 K, unwinding
becomes pronounced at 300 K and 330 K. We found that the region containing
Gly-Ile, which is a common cleavage site in collagen, to be an initiation
site for unwinding. Our results suggest that local unwinding of collagen is
spontaneous at physiological temperatures, and it could be a property utilized
for binding by other proteins, such as cleavage enzymes or fibril associated
collagens.