Thermodynamics polysaccharide conformation

There are of course, many facets of polymers for which our under-standing is far from complete. Polymers with associating groups bonded to their chains, polymer crystallization, liquid crystalline polymers and charged polymers are examples of areas of active research in polymer physics. These four particular examples are also very pertinent to understanding the functions of important biopolymers, such as DNA, RNA, proteins, and polysaccharides. By learning the fundamentals of chain conformations, thermodynamics, elasticity, and mobility, the readers of this book should be ready to consider these more challenging facets. 

The equilibrium properties in dilute aqueous solution of weakly ionized polysaccharides, e.g. carboxylated natural poly= saccharides, have not been so thoroughly investigated in comparison with other natural and synthetic polyelectrolytes. For instance, a detailed thermodynamic characterization of acid ionization and of counterion binding in terms of combined experimental potentiometric, calorimetric and volumetric data has not been achieved so far for the above types of polysaccharides. Such a description, however, is of obvious relevance for a better understanding of structure-conformation dependent solution properties for this important class of biopolymers. 

At the molecular level, various specific and non-specific solvent-solute interactions may occur in polysaccharide solutions that may result in a change in the conformational shape, solubility, viscosity and other hydrodynamic and thermodynamic properties. Hydrophilic interactions such as hydrogen bonding and electrostatic interactions are believed to be factors that influence the conformation of polysaccharides in solution, although the question is being raised (more and more) as to the implication of patches of hydrophobic intermolecular interactions, especially for chain aggregations. One important feature is the... 

The conformational (non-ionic) free energy, obtained from the radial distribution function for non-ionic chains by Monte Carlo calculations, was used in conjunction with the electrostatic free energy to calculate the actual distribution function of the charged chain segments. The resulting expansion justifies almost quantitatively in many cases the experimental thermodynamic properties (such as pK, H i, etc.) and the dimensional properties (viscosity) of the ionic polysaccharides to which the approach has been applied. 

GMs may also form gels with other polysaccharides, such as xanthans (which are also non-gelling alone) (32) - the most interactive mannans being the ones with the fewest galactose side groups (J3). The interactions are not completely understood and several mechanisms have been presented, but the interactions are basically dependent on the structure and conformation of both polysaccharides as well as on the thermodynamic conditions (34). 

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