Poly(Pro-Nle-Gly): Can an amorphus polypeptide take up a supramolecular elastinlike structure?

Poly(Pro-Nle-Gly) was found to have a CD spectrum characteristic of a random polypeptide and an x-ray powder pattern that does not reveal any regular secondary structure. In its electron micrograph, however, filaments and fibers were seen. This is a random polymer with supramolecular structure. It suggests that the supramolecular structure seen in electron micrographs of elastin preparations and related polypeptides does not necessarily imply an ordered structure at the molecular level.