Electron microscopic evidence for elastin-like supramolecular organization in synthetic polytripeptides

Electron microscope studies have been carried out on polytripeptides comprising the sequences -Pro-X-Gly- and -X-Pro-Gly- (X = Val, Ile, Met). These polymers have previously been shown to either contain or lack secondary structure. The formation of aligned filaments and also, in some cases, of banded fibers has been demonstrated. Independent of predicted solution conformation the supramolecular structures appeared to be very similar to those previously demonstrated for elastin and its soluble derivatives. The possibility that supramolecular organization is not a necessary consequence of molecular ordered structures is put forward and discussed. With respect to the molecular structure of elastin, the results suggest caution in the interpretation of electron microscope observation at the molecular scale.