From the Research
The enzyme that catalyzes the conversion of orotate to UMP in pyrimidine synthesis is OMP decarboxylase. This enzyme functions in the final step of the de novo pyrimidine biosynthetic pathway, where it decarboxylates orotidine 5'-monophosphate (OMP) to form uridine 5'-monophosphate (UMP) 1. OMP decarboxylase is essential in pyrimidine metabolism as UMP serves as a precursor for all other pyrimidine nucleotides needed for RNA and DNA synthesis. The enzyme works by removing a carboxyl group from the orotate portion of OMP without requiring any cofactors, making it one of the most efficient enzymes known 2. The other enzymes listed have different functions:
- Carbamoyl phosphate synthetase II catalyzes an earlier step in pyrimidine synthesis
- Thymidylate synthase converts dUMP to dTMP
- CPS I functions in the urea cycle
- HGPRT is involved in purine salvage pathways 3, 4, 5. Key characteristics of OMP decarboxylase include its ability to catalyze the decarboxylation of OMP to UMP without the need for cofactors, and its high efficiency in doing so, as evidenced by studies on its structure and mechanism 1, 2. Overall, OMP decarboxylase plays a critical role in pyrimidine synthesis, and its unique characteristics make it an essential enzyme in this pathway.