(12b) The Thermodynamics of Single Molecule Stretching of Polysaccharides: Implications for Elastic Tissues

Experimental single molecule force?extension measurements were carried out by atomic force microscopy (AFM) on the α-linked polysaccharide, dextran over the temperature range 5°C ? 70°C. This enabled the separation of the entropy and enthalpy components of the conformational change (click). The contribution of entropy to the Gibbs energy of the conformational transformation was found to be small (< 18 J mol^-1 K^-1) demonstrating that the click is largely enthalpic in nature.The temperature dependence of the click region serves to counteract the temperature dependence of the entropic chain and this may be a natural mechanism to provide more consistent elastic properties over a wide range of environmental conditions. The energy input from stretching is large and the conformational transformation serves to reduce the heat generated from this stretching and we propose that this may be a reason for the existence of these clicks in elastic tissues.