Structural models for the N‐ and C‐terminal telopeptide regions of interstitial collagens

AbstractSecondary‐structure prediction has been used to investigate the conformation of the N‐ and C‐terminal telopeptides for type I and type III collagen. The three predictive methods (Chou and Fasman, Robson and co‐workers, Lim) indicate mainly aperiodic conformations. A common structural motif is provided by the positioning of β‐turns, particularly in the vicinity of the residue sites involved in intermolecular cross‐links. An alternative model to that of Helseth et al [(1979) Biopolymers 18, 3005–3014] for the secondary structure of the N‐terminal telopeptide of type I collagen is proposed. The general features of these two contrasting structures have been surveyed by model‐building techniques employing molecular graphics and energy minimization. The role of the telopeptide component in the structural design of the biomaterial collagen is assessed. Notably, the alternative model clearly serves to demonstrate the compatibility of current cross‐linking evidence with the quasi‐hexagonal model for the packing of molecules within a collagen fibril.