Dihydrouracil is an intermediate breakdown product of uracil. Dihydropyrimidine dehydrogenase catalyzes the reduction of uracil to 5, 6-dihydrouracil then dihydropyrimidinase hydrolyzes 5, 6-dihydrouracil to N-carbamyl-b-alanine. Finally, beta-ureidopropionase catalyzes the conversion of N-carbamyl-b-alanine to beta-alanine. Patients with dihydropyrimidinase deficiency (DPYS; also called 5, 6-dihydropyrimidine amidohydrolase, or DHP; EC 3.5.2.2) exhibit highly increased concentrations of 5, 6-dihydrouracil in urine. The direct measurement of the activity of DHP in patients had been hampered by the fact that the enzyme is expressed almost exclusively in liver tissue. Various neurological abnormalities have been described in this group of patients. (OMIM 222748).
Belongs to the class of organic compounds known as pyrimidones. Pyrimidones are compounds that contain a pyrimidine ring, which bears a ketone. Pyrimidine is a 6-membered ring consisting of four carbon atoms and two nitrogen centers at the 1- and 3- ring positions.
