Solvent effect on chain dimensions and conformations of polysaccharides

5 SOLVENT EFFECT ON CHAIN DIMENSIONS AND CONFORMATIONS OF POLYSACCHARIDES 

The chain properties illustrated above are often described with terms such as stiffness and flexibility . It is important to clarify that stiffness and structural rigidity may not necessarily be alternative to flexibility and structural disorder, since two different concepts enter into the above definitions one is concerned with the number of different accessible conformations, the other with the (average) direction of the sequential bonds, i.e., with the chain topology. 

Order-disorder conformational transitions very often occur on changing physical and/or chemical conditions of polysaccharide solutions. DMSO, for example, is the solvent, which is commonly used as co-solvent for stabilizing or destabilizing ordered solution conformations. Schizophyllan, a triple helical polysaccharide with a [P-D-(l-3)-glc] backbone exhibits a highly cooperative order-disorder transition in aqueous solution. When small quantities of DMSO are added to aqueous solutions the ordered state is remarkably stabilized, as has been observed in the heat capacity curves by means of the DSC technique.  

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