D X Ala3 analog of elastin polypentapeptide. An elastomer with an increased young's modulus

The polypentapeptide , H(L X Val1-L X Pro2-D X Ala3-L X Val4- Gly5 )n Val-OMe which is the D X Ala3 analog of the elastomeric polypentapeptide (PPP) of elastin, (L X Val1-L X Pro2-Gly3-L X Val4- Gly5 )n, has been synthesized. Its conformation is compared to that of the PPP and found to be similar with a somewhat stabilized beta-turn. The D X Ala3 analog coacervates to form a more cohesive viscoelastic material and the coacervate when cross-linked by gamma-irradiation exhibits an approximate doubling of the Young's modulus of elasticity. These results are discussed in connection with other related analogs of the polypentapeptide of elastin, which are non-elastomeric, and found to be consistent with a proposed conformationally based librational entropy mechanism of elasticity.