An account on the factors determining the extra stability of the -hairpin from B1 domain of protein G.

The folding-unfolding of a 16 residue polypeptide, a -hairpin in B1 domain of protein G is investigated here to account for the factors assisting the extra stability of the polypeptide in the presence of an explicit solvent and even when a denaturant like urea is present in the medium. It is observed here that the backbone H-bond network well defines the folded state and is even capable of forming the folded state, but it is not the only criteria for making a stable -hairpin fold. Factors such as the side chain H-bonds and the alignment of the certain hydrophobic group side chains play a prominent role in preserving the -hairpin structure and thus providing an extra stability to the hairpin architecture.