Homotrimeric collagen peptides as model systems for cell adhesion studies.

Introduction Collagen model peptides with high triple-helix propensity can self-associate into the suprahelical structure, but folding/unfolding of such systems is strongly concentration-dependent. Cross-bridging of the three collagenous chains with synthetic templates as well as with native collagen-type or with artificial cystine knots has been successfully applied to overcome the shortcomings of self-assembled triple helices [1]. Aim of the present study was to analyze the conformational properties of a disulfide-crosslinked trimeric collagen model peptide (2 in Figure 1) containing the specific collagen type I motif recognized by the α1β1 and α2β1 integrins, i.e. the hexapeptide sequence portion GFOGER of the α1 chain [2]. Embedding this adhesion epitope into the triple helical collagenous peptide 3 (Figure 1) allowed X-ray structural analysis of the complex with the α2-I domain, which provides within the α2β1 integrin the principal binding site for collagen [3].