Bonding, polysaccharide-water interactions

Four features of a polymer solute figure prominently in the polysaccharide-water interactions, viz., bonding, branching, ionization, and nonuniformity of the repeating structure (Glass, 1986). 

It is well known the tendency of polysaccharides to associate in aqueous solution. These molecular associations can deeply affect their function in a particular application due to their influence on molecular weight, shape and size, which determines how molecules interact with other molecules and water. There are several factors such as hydrogen bonding, hydrophobic association, an association mediated by ions, electrostatic interactions, which depend on the concentration and the presence of protein components that affect the ability to form supramolecular complexes. 

In the present work, we extend the method to compensate for the hydrogen bonds present in carbohydrates. The hydroxylated character of carbohydrate polymers influences between-chain interactions through networks of hydrogen bonds that occur during crystallization. Frequently, several possible attractive interactions exist that lead to different packing arrangements, and several allomorphic crystalline forms have been observed for polysaccharides such as cellulose, chitin, mannan and amylose. The situation is even more complex when water or other guest molecules are present in the crystalline domains. Another complication is that polysaccharide polymorphism includes different helix shapes as well. 

Hydrogen bonds and ionic, hydrophobic (Greek, water-fearing ), and van der Waals interactions are individually weak, but collectively they have a very significant influence on the three-dimensional structures of proteins, nucleic acids, polysaccharides, and membrane lipids. 

When (S-lg adsorbs at the air-water interface in the presence of PS three phenomena can occur (i) the polysaccharide adsorbs at the interface on its own in competition with the protein for the interface (competitive adsorption) (ii) the polysaccharide complexates with the adsorbed protein mainly by electrostatic interactions or hydrogen bonding (Dickinson, 2003), and (iii) because of a limited thermodynamic compatibility between the protein and polysaccharide, the polysaccharide concentrates the adsorbed protein. In a previous work we have shown that the existence of competitive or cooperative adsorption between the (3-lg and the PS could be deduced from the comparison of rr-time curves for the single biopolymers and for the mixtures (Baeza et al., 2005b). 

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