Protein hydration layer binding sites

Membrane inactivation depends on how closely anions can approach cationic binding sites. Poorly solvated ions show the strongest binding. They are also known to be the most effective protein denaturants (65). The Stokes law hydrated radius of the toxic bromide anion is about 1.2 A, that of the relatively nontoxic fluoride about 1.6 A and that of the cryoprotective acetate anion 2.2 A. Biological membranes usually appear in thin sections as three-layered structures 60 to 100 A thick. In view of this relatively large cross section, accessibility of binding sites becomes of obvious importance. 

Another important problem where water aets as a lubricant is the motion of nonspeeifleally bound protein along a DNA chain. Proteins travel to find the specific binding site. Such a motion is greatly faeilitated by water molecules in the hydration layer. 

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