Hydration of biopolymers

Hydration of biopolymers is a mechanism for stabilizing these materials (Fig. 2.78). When proteins are conpletely dry, they tend to decompose. One way of evaluating hydration in polyions is to measure the dielectric constant of a solution containing a dissolved protein as a function of concentration at radio frequency. The dielectric constant falls with increase in concentration and the water per polyion can be calculated by assuming that water bound to the protein no longer makes any contribution to the dielectric constant. Thus, Buchanan calculated the irrotationally bound water from such expaiments. Some of this water is hidden in cavities within the structure of the protein molecule. 

In this case the dihydrate may be of special stability. Warner (57) has discussed possible relations between hydration of biopolymers and ice-like distances of the H-bond acceptor groups of these polymers (57). 

There have been a number of other papers on the hydration of biopolymers the effects of the degree of methylation of pectins on the proton relaxation times of water have been measured 50 l70 relaxation has been used to examine the hydration of bovine and caprine casein,51--54 and solid-state NMR combined with atomic force microscopy has been used to examine the influence of water on the nanomechanical behaviour of cutin.55 The effects of locust bean gum on water diffusion in sugar solutions has shown little effect,56 and the effects of gellan gum hydrogel structure on restricted diffusion has also been considered.57... 

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