CAD hexamer dehydrates N-carb-L-Asp to (S)-DHO

Stable Identifier
Reaction [transition]
Homo sapiens
N-carbamoyl L-aspartate + H+ <=> (S)-dihydroorotate + H2O, condensation of N-Carbamoyl-L-aspartate to form (S)-Dihydroorotate (ring closure)
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The synthesis of dihydroorotate from N-carbamoyl L-aspartate is catalyzed by the dihydroorotase activity of cytosolic trifunctional CAD (carbamoyl-phosphate synthetase 2, aspartate transcarbamylase, and dihydroorotase) protein. This activity has not been directly demonstrated in experimental studies of the purified human protein, but has been inferred from the behavior of the purified hamster protein and the high degree of sequence similarity between the cloned hamster and human genes (Iwahana et al. 1996). Also on the basis of this similarity, the active human protein is annotated as a hexamer (Lee et al. 1985).

Literature References
PubMed ID Title Journal Year
8619816 Molecular cloning of a human cDNA encoding a trifunctional enzyme of carbamoyl-phosphate synthetase-aspartate transcarbamoylase-dihydroorotase in de Novo pyrimidine synthesis

Ii, S, Yoshimoto, K, Iwahana, H, Takahashi, Y, Itakura, M, Yamaoka, T, Kondo, M, Moritani, M, Fujimura, H

Biochem Biophys Res Commun 1996
Catalyst Activity

dihydroorotase activity of CAD hexamer [cytosol]

Orthologous Events
Cross References
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