Structure analysis of a collagen-model peptide with a (Pro-Hyp-Gly) sequence repeat.

The crystal structure of a triple helical peptide (Pro-Hyp-Gly)10 has been determined at 1.9 A resolution. Single crystals grown by the hanging drop method, diffracted to a resolution of 1.8 A. The polymer-like structure of the triple helical repeat Pro-Hyp-Gly was in accordance with the 7/2 model proposed for collagen and very similar to the previously determined structure with a Pro-Pro-Gly sequence repeat. The solvent structure was also very similar to that previously observed, showing similar hydration patterns, but different crystal packing. The presence of hydroxyproline did not have any effect on the molecular structure or the hydration structure. This is in accordance with the recent finding that the inductive effect of the hydroxyl group attached to the Cgamma atom of hydroxyproline enhances collagen stability rather than the extensive water network.