Stabilization of the triple-helical structure of natural collagen by side-chain interactions

Conformational energy computations have been used to demonstrate that side-chain-backbone interactions contribute substantially to the stabilization of the triple-helical structure of collagen with a natural sequence. The minimum-energy conformation has been determined for a short triple-helical segment from the N-terminus of type I bovine skin collagen, containing 12 residues in each strand. In this conformation, the side chains of three Arg and four Met residues fold tightly against the triple-helical backbone, forming numerous atomic contacts with the neighboring strand. In addition, the polar groups of the three Arg and two Ser residues form hydrogen bonds with backbone carbonyl groups. The estimated total stabilization due to the side-chain interactions is about -50 kcal/mol out of a total interchain energy of -193.5 kcal/mol. The study presented here is the first application of conformational energy computations to a real sequence in the collagen molecule.