Hydrolases are 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. Nucleases, which are phosphatases hydrolyze nucleic acids. Glycosidases break 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. Digestion of macromolecules involves hydrolysis in which the anhydro bonds are broken down by the addition of water with the help of enzymes. These enzymes are called hydrolases.