Hydrolysis

Definition

In chemistry, hydrolysis refers to a chemical reaction in which molecules are split by the addition of a molecule of water. One fragment of the parent molecule gains a hydrogen ion (H⁺), while the other group receives a hydroxyl group (OH⁻).

Hydrolytic reactions catalyzed by both acid and base are common, for example, the hydrolysis of amides or esters. Their hydrolysis occurs when a nucleophile (water or a hydroxyl anion) attacks the carbonyl group of the ester or amide. In water, hydroxyl ions are better nucleophiles than water itself. In acid, the carbonyl group becomes protonated, and this leads to easier nucleophilic attack. The products of the hydrolysis of amides and esters are a carboxylic acid and an amine, and a carboxylic acid and an alcohol, respectively.

Under physiological conditions, in which the concentrations of a hydrolysable reactant and its products are low (on the order of 10⁻³–10⁻⁶molar), the hydrolysis reaction, such as the hydrolysis of a peptide to...