Order-disorder conformational transition in succinoglycan: calorimetric measurements

Differential scanning microcalorimetry was performed on succinoglycan samples from different sources in order to better understand the thermally induced order-disorder conformational transition of the polysaccharide. The shape of thermograms, as well as the melting temperature, were related to the content or distribution of the succinate groups at least in salt-free solution. With increasing polysaccharide and/or salt concentration, the change in the shape of the thermogram was attributed to a progressive screening of the succinate contribution to the order-disorder conformational transition instead of a change in the transition mechanism. In the presence of salt, contrary to the rheological behavior, the calorimetric results were found to be independent of the thermal history of the samples. This suggests a very low enthalpic contribution of the interchain interactions present in succinoglycan solutions. Possible contributions that could explain some discrepancies with results already published in the literature are discussed.