In enzymology, an imidazolonepropionase () is an enzyme that catalyzes the chemical reaction (S)-3-(5-oxo-4,5-dihydro-3H-imidazol-4-yl)propanoate + H2O N-formimidoyl-L-glutamate + H+ Thus, the two substrates of this enzyme are (S)-3-(5-oxo-4,5-dihydro-3H-imidazol-4-yl)propanoate and H2O, whereas its two products are N-formimidoyl-L-glutamate and H+. 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 3-(5-oxo-4,5-dihydro-3H-imidazol-4-yl)propanoate amidohydrolase. Other names in common use include 4(5)-imidazolone-5(4)-propionic acid hydrolase, and imidazolone propionic acid hydrolase. This enzyme participates in histidine metabolism. Structural studies As of late 2007, 6 structures have been solved for this class of enzymes, with PDB accession codes , , , , , and . References EC 3.5.2 Enzymes of known structure