This family includes the enzymes hydantoinase and oxoprolinase EC:3.5.2.9. Both reactions involve the hydrolysis of 5-membered rings via hydrolysis of their internal imide bonds [1].

1: The amino acid sequence of rat kidney 5-oxo-L-prolinase determined by cDNA cloning [published erratum appears in J Biol Chem 1997 Feb 14;272(7):4646] Ye GJ, Breslow EB, Meister A, Guo-jie GE; J Biol Chem 1996;271:32293-32300. PMID:8943290