Experimental and theoretical conformational studies on polypeptide models of collagen

Abstract
The synthetic polytripeptides poly(Gly-Pro-Ile) and poly(Gly-Ile-Pro) were studied both experimentally (mainly by circular dichroism spectroscopy) and theoretically by quantum mechanical methods. Poly-(Gly-Ile-Pro) adopts a collagen-like structure under favorable conditions while the isomeric poly(Gly-Pro-Ile) does not. Theoretical studies emphasize severe intrastrand interactions which limit the main chain conformations in the case of poly(Gly-Ile-Pro). Both the side chain and the backbone in poly(Gly-Pro-Ile) can take up many different local conformations. Therefore, it seems that the conformational behavior of synthetic polytripeptides can be at least partially explained in terms of local interactions.