hydrolase, any one of a class of more than 200 enzymes that catalyze the hydrolysis of several types of compounds. Esterases include lipases, which break ester bonds (between a carboxylic acid and an alcohol) in lipids, and phosphatases, which act analogously upon phosphates; a narrower category comprises the nucleases, which are phosphatases that hydrolyze nucleic acids. Glycosidases sever bonds between sugar molecules in carbohydrates. Peptidases hydrolyze peptide bonds (between the carboxylic acid group of one amino acid and the amino group of another) within protein molecules (see proteolytic enzyme). Specific hydrolases also catalyze reactions that break ether (C―O) bonds; carbon–nitrogen (C―N) bonds other than peptide bonds; acid anhydride bonds; carbon–carbon (C―C) bonds; or phosphorus–nitrogen (P―N) bonds.