Partial purification and characterization of dihydropyrimidinases from calf and rat liver

The partial purification of rat and calf liver dihydropyrimidinase (EC 3.5.2.2) is described. Molecular weights of the native calf and rat liver enzymes were estimated by gel-filtration chromatography to be 252,000 and 266,000 daltons, respectively. Subunit molecular weights of the calf and rat liver enzyme were estimated by SDS-gel electrophoresis to be 59,000 and 62,000 daltons, respectively. The native enzyme in both species is thought to comprise four subunits. The purified enzyme from both species was capable of catalyzing the hydrolytic ring opening of dihydrouracil, 5-phenylhydantoin, hydantoin, and alpha-phenylsuccinimide.