POLYMERS OF TRIPEPTIDES AS COLLAGEN MODELS .7. SYNTHESIS AND SOLUTION PROPERTIES OF 4 COLLAGEN-LIKE POLYHEXAPEPTIDES

A number of polyhexapeptides have been synthesized in order to incorporate (Gly-Ala-Pro), (Gly-Pro-Ala) and (Gly-Ala-Ala) sequences into the collagen-fold conformation. The polyhexapeptides studied were (Gly-Ala-Pro-Gly-Pro-Pro)n, (Gly-Pro-Ala-Gly-Pro-Pro)n, (Gly-Ala-Pro-Gly-Pro-Ala)n and (Gly-Ala-Ala-Gly-Pro-Pro) n, and physico-chemical measurements indicate that each of these is collagen-like in aqueous solution. Hydrogen exchange and thermal stability studies also suggest that these polymers have only one hydrogen bond per tripeptide unit, and that their transition temperatures are quite different from those predicted by current theories. These results are in basic agreement with the observations of the following paper, based on X-ray diffraction measurements, that the four polyhexapeptides are also collagen-like in the solid state, with one hydrogen bond per triplet. It is suggested that conclusions drawn from these synthetic polymers apply equally well to collagen itself. © 1969.