A comparative study of the swelling and mechanical properties of vertebrate elastins

The swelling-temperature compensation hypothesis as proposed by Gosline and French (1979) is examined by investigating the physical and mechanical properties of an evolutionary series of vertebrate elastins. Temperature-dependent swelling, low water contents and thermodynamics typical of hydrophobic systems were observed for all elastins except salmon. Salmon elastin, on the other hand, showed temperature-independent swelling and a high water content. Thermodynamic analysis showed that salmon elastin still contained a hydrophobic component. The swelling-temperature compensation hypothesis suggests that the extreme hydrophobic nature of elastin evolved in order to provide the proteins with temperature-dependent swelling and thus, maintaining elastic efficiency over a wide temperature range. All elastins should then be very hydrophobic systems which is inconsistent with the physical chemical results. All vertebrate elastins are not necessarily hydrophobic systems since salmon elastin shows no temperature-dependence to its swelling. The efficiency of a series of vertebrate elastins was measured over 0 to 60°C temperature range using a forced vibration technique. Over a wide frequency range, both lower and higher vertebrate elastins were capable of efficient spring-like behaviour. Both a higher vertebrate, with temperature-dependent swelling, and a lower vertebrate, with no temperaturate-dependence to its swelling, showed elastic efficiency. The swelling-temperature compensation hypothesis must be rejected.Science, Faculty ofZoology, Department ofGraduat