Hydrolyse

Hydrolyse, in English often referred to as hydrolysis, is a chemical reaction in which a bond within a molecule is cleaved by reaction with water. In hydrolysis, water provides a hydrogen ion and a hydroxide ion or acts as a nucleophile that adds to the substrate, resulting in two or more smaller molecules. The reaction can occur without a catalyst under suitable conditions or can be accelerated by acids, bases, or specific enzymes.

Acid-catalyzed hydrolysis involves protonation of a functional group, enhancing the leaving ability of a group and enabling bond cleavage. Base-catalyzed, or alkaline hydrolysis, uses hydroxide to attack electrophilic centers, typically yielding carboxylate salts and alcohols. Neutral hydrolysis occurs more slowly and may require elevated temperature or prolonged exposure. The rate and outcome depend on substrate structure, pH, temperature, and catalysts.

Substrates commonly subjected to hydrolysis include esters (yielding carboxylic acids and alcohols; saponification is a base-catalyzed ester hydrolysis), amides (to carboxylates and amines), glycosides (to sugars and aglycones), and biomolecules such as proteins (peptide bonds to amino acids) and nucleic acids (to nucleotides or nucleosides). Hydrolysis also degrades polymers like cellulose and other synthetic polyesters.

Enzymes that catalyze hydrolysis are known as hydrolases. Examples include proteases, lipases, amylases, glycosidases, nucleases, and phosphatases. Hydrolysis plays a central role in digestion, metabolism, and the recycling of biomolecules, as well as in numerous industrial processes, such as starch processing, soap production (saponification), and the decomposition of polymers.