Spontaneous unwinding of a labile domain in a collagen triple helix

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.