In enzymology, a carboxymethylhydantoinase () is an enzyme that catalyzes the chemical reaction L-5-carboxymethylhydantoin + H2O N-carbamoyl-L-aspartate Thus, the two substrates of this enzyme are L-5-carboxymethylhydantoin and H2O, whereas its product is N-carbamoyl-L-aspartate. This enzyme belongs to the family of hydrolases, those acting on carbon-nitrogen bonds other than peptide bonds, specifically in cyclic amides. The systematic name of this enzyme class is L-5-carboxymethylhydantoin amidohydrolase. This enzyme is also called hydantoin hydrolase. References EC 3.5.2 Enzymes of unknown structure