Hydrogen bonding in the triple-helix

The increased level of detail obtained from high resolution crystal structures of triple-helical peptides and the residue specific properties that can be defined by NMR studies on15N-enriched peptides has given new information on hydrogen bonding in the triple-helix. In particular, it has given details about the principle originally posed by Ramachandran to try to maximize the hydrogen bonding in the collagen triple-helical structure in the face of the lack of direct favorable interactions. Now it can be seen that by the participation of water, and by the summation of many weak hydrogen bonding patterns, the structure is largely stabilized through hydrogen bonding, as indicated by calorimetry. The CaH…O=C hydrogen bonds, the water mediated NH…CO bonds, and the hydroxyproline-water hydrogen bonds proposed by Ramachandran have been visualized and now defined in the triple-helix.