Conformational studies on sequential polypeptides. Part VII. Structural investigations on (Pro-Phe-Gly)n and (Phe-Pro-Gly)n.

The conformational properties of (Pro-Phe-Gly)n and (Phe-Pro-Gly)n were investigated both in the solid state and in solution. In solid state X-ray diffraction patterns seem to indicate that (Pro-Phe-Gly)n assumes a single chain triple helical structure. In solution, by circular dichroism studies, it was possible to show the existence of beta-bends in the presence of ethylene glycol. Similar studies carried out on (Phe-Pro-Gly)n showed no collagen or polyproline II-like structure in the solid state. In solution the beta-bend formation was apparent in all the solvent systems studied.