5,6-dihydrouracil + H2O = 3-(carbamoylamino)propanoate + H(+) Binds 2 Zn(2+) ions per subunit. Homotetramer. Carboxylation allows a single lysine to coordinate two zinc ions. Belongs to the metallo-dependent hydrolases superfamily. Hydantoinase/dihydropyrimidinase family.