Temperature dependence of length of elastin and its polypentapeptide.

Comparison of the temperature dependence of elastomer length of the cross-linked protein, elastin, and of gamma-irradiation cross-linked poly(VPGVG), the polypentapeptide of elastin, with that of latex rubber demonstrate markedly dissimilar behaviors between a classical rubber and the protein and polypeptide elastomers. In the absence of a load latex rubber expands with increasing temperature as is known for classical rubbers comprised of a network of random chains whereas the protein and polypeptide elastomers markedly decrease in length. When under load with a constant applied force, as a classical rubber, latex linearly decreases length with increasing temperature whereas the decrease in length is very non-linear with temperature increase for the protein and polypeptide elastomers. The protein and polypeptide elastomers examined here do not exhibit the characteristic and fundamental temperature dependence of length considered typical of networks of random chains. Accordingly the more complex and even inverse behavior of elastin and the polypentapeptide of elastin in the absence of load require consideration of structural perspectives different from those of a random chain network with negligible interchain interactions.