Effect of Macroions on the Solvent

Macroions, such as proteins, have an effect on the self-diffusion of a solvent. Thus, the presence of the macroion obstructs the solvent s movement. On the other hand, it binds the solvent and substantial fractions of it may be trapped within the molecule. 

The fluidity of the solvent is changed because of the structure-breaking effects caused by the presence of macroions. Self-diffusion data on water in the presence of proteins allows one to measure their hydration. This is usually measured in water per gram of anhydrous protein. 

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