Sequential oligopeptides. Conformational studies of the oligopeptides and a polypeptide with the repeating sequence L ‐norvalyl‐glycyl‐ L ‐proline

Conformational studies of a series of oligopeptides (from the tripeptide to the octadecapeptide) with the repeating sequence L‐norvalyl‐glycyl‐L‐proline and a polytripeptide with this sequence are reported. By means of chiroptical techniques, unordered conformations are found for all oligopeptides in water, trifluoroethanol, and ethylene glycol and for the water‐insoluble polymer in trifluoroethanol. In ethylene glycol the polymer assumes a collagen‐like structure. Infrared studies indicate that all the oligomers, in contrast to the polymer, are unordered in the solid state.