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 stabi lization of the triple-helical structure of collagen with a natural se quence. The minimum-energy conformation has been determined for a shor t triple-helical segment from the N-terminus of type I bovine skin col lagen, containing 12 residues in each strand. In this conformation, th e 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 an d two Ser residues form hydrogen bonds with backbone carbonyl groups. The estimated total stabilization due to the side-chain interactions i s about -50 kcal/mol out of a total interchain energy of -193.5 kcal/m ol. The study presented here is the first application of conformationa l energy computations to a real sequence in the collagen molecule.