Dihydropyrimidinase, hydantoinase, imidase, allantoinase, and dihydroorotase belong to the cyclic amidohydrolase family because of their functional and structural similarities .
Huang, "Allantoinase and dihydroorotase binding and inhibition by flavonols and the substrates of cyclic amidohydrolases," Biochimie, vol.
Huang, "Identification and characterization of a putative dihydroorotase KPN01074, from Klebsiella pneumoniae," Protein Journal, vol.
Huang, "Chemical rescue of the post-translationally carboxylated lysine mutant of allantoinase and dihydroorotase by metal ions and short-chain carboxylic acids," Amino Acids, vol.
coli dihydroorotase (PDB entry 1J79; brown) are shown.
However, IFN-[alpha] was associated with the downregulation of carbamoyl phosphate synthetase 2, aspartate transcarbamylase, and dihydroorotase
(CAD), a protein responsible for the first three enzymatic steps of the pyrimidine biosynthesis pathway.
In this biosynthetic pathway, dihydroorotase that converts glutamine to dihydroorotate, dihydroorotate dehydrogenase that converts dihydroorotate to orotic acid, uridine monophosphate synthetase that converts orotic acid to UMP, 5,-nucleotidase that converts UMP to uridine, uridine nucleosidase that converts uridine to uracil, uridine kinase (udk) that converts cytidine to CMP, uridine/cytidine monophosphate (UMP-CMP) kinase that converts CMP to CDP, nucleoside-diphosphate kinase (ndk) that converts UDP to UTP, apyrase that converts CTP to CDP, inosine triphosphate pyrophosphatase (ITPA) that converts UMP to UTP, CTP synthase that converts UTP to CTP, and cytidine deaminase (cdd) that converts cytidine to uridine were annotated in the H.
In addition, four dihydroorotase genes, two dihydroorotate dehydrogenase genes, three uridine monophosphate synthetase genes, two 5'-nucleotidase genes, one uridine nucleosidase gene, one udk gene, two UMP-CMP kinase genes, one ndk gene, one apyrase gene, one ITPA gene, one CTP synthase gene, and one cdd gene were successfully cloned (Figure S4, Supporting Information).
Dihydroorotase, dihydroorotate dehydrogenase, uridine monophosphate synthetase, 5'-nucleotidase, uridine nucleosidase, udk, UMP-CMP kinase, ndk, apyrase, ITPA, CTP synthase, and cdd involved in the biosynthetic pathway of pyrimidine nucleotides were annotated in the H.
subunit, one is a sugar beet dihydroorotase
, one is a sugar beet translation initiation factor 1A and two others are of a unknown protein type.
The following were chosen from the small chromosome: dtdS, the encoding threonine dehydrogenase; lysA, the encoding diaminopimelate decarboxylase; pntA, the encoding transhydrogenase alpha sub-unit; pyrC, the encoding dihydroorotase
; and tnaA, the encoding tryptophanase.
The first three steps are catalyzed by CAD,  a trifunctional cytoplasmic enzyme cluster containing carbamylphosphate synthetase, aspartate carbamyltransferase, and dihydroorotase