Orotidine 5'-phosphate decarboxylase

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Orotidine 5'-monophosphate decarboxylase

E. coli OMP decarboxylase, drawn from PDB 1EIX

Other names: OMP decarboxylase, Orotidylic decarboxylase, Orotate decarboxylase, UMP synthase
Protein Structure/Function
Molecular Weight: 26,500 monomer (E.coli) (Da)
Structure: Dimer in solution
Protein type: Enzyme Decarboxylase
Functions: Converts OMP to UMP
Taxa expressing: Plants, fungi, bacteria and animals
Cell types: Cytoplasm
Subcellular localization: General
Pathway(s): Pyrimidine metabolism
Enzymatic Data
Cofactor(s): None
Enzyme Regulation: Product inhibition
Medical/Biotechnological data
Diseases: Oroticaciduria II
Pharmaceuticals: allopurinol
Related information
Related articles: BRENDA and ENZYME

Orotidine 5'-phosphate decarboxylase is an enzyme involved in pyrimidine metabolism.


The enzyme converts orotidine monophosphate (OMP) to uridine monophosphate (UMP) by liberating carbon dioxide. It is known for being an extraordinarily efficient catalyst capable of accelerating the uncatalyzed reaction rate by a factor of 1017. To put it in perspective, the enzyme can catalyze the substrate in 18 milliseconds, in a reaction that would take 78 million years to complete without the enzyme. [1][2]

Unicellular vs Multicellular Function

In yeast and bacteria OMP decarboxylase is a single-function enzyme. However, in mammals, OMP decarboxylase is part of a single protein with two catalytic activities. This bifunctional enzyme is named UMP synthase and it also catalyzes the preceding reaction in pyrimidine nucleotide biosynthesis, the transfer of ribose 5-phosphate from 5-phosphoribosyl-1-pyrophosphate to orotate to form OMP.[3]


  1. Radzicka A, Wolfenden R. (1995). "A proficient enzyme". Science. 6 (267): 90–93. PMID 7809611.
  2. Miller BG, Wolfenden R. (2002). "Catalytic proficiency: the unusual case of OMP decarboxylase". Annu Rev Biochem. 71: 847–885. PMID 12045113.
  3. Yablonski MJ, Pasek DA, Han BD, Jones ME, Traut TW. (1996). "Intrinsic activity and stability of bifunctional human UMP synthase and its two separate catalytic domains, orotate phosphoribosyltransferase and orotidine-5'-phosphate decarboxylase". J Biol Chem. 271 (18): 10704–10708. PMID 8631878. line feed character in |title= at position 146 (help)

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