Enzyme action: lock up your waters?: Water and active sites

Water is thought of as the universal solvent for biological macromolecules, and its interaction with the different amino acid side chains of proteins determines their folding. Only a small proportion of the water associated with enzymes is tightly bound, but this can play crucial roles in determining the rates and specificities of reactions. Water itself is a relatively poor nucleophile, and enzymes can employ different strategies to facilitate hydrolytic reactions.