Dihydropyrimidine amidohydrolase is a zinc metalloenzyme.

Bovine liver dihydropyrimidine amidohydrolase (EC 3.5.2.2) has been subjected to atomic absorption analysis. Three different preparations of homogeneous enzyme indicated that the enzyme contains 4.3 +/- 0.3 g atoms of Zn2+ per mol of enzyme or 1.1 g atoms of Zn2+ per subunit. No Co2+, Mn2+, Mg2+ or Cd2+ was detected. Exhaustive dialysis against either o-phenanthroline or EDTA did not reduce enzyme activity; however, prolonged incubation with dipicolinic acid resulted in inactivation which can be reversed by either Zn2+ or Co2+ but not Mg2+.