Pyrimidine biosynthesis occurs both in the body and through organic synthesis.
De novo biosynthesis of pyrimidine [ edit ]
The first three enzymes are all coded by the same gene in
Metazoa ( CAD). In Fungi, a similar protein exists but lacks the dihydroorotase function: another protein catalyzes the second step.
In other organisms (
Bacteria, Archaea and the other Eukaryota), the first three steps are done by three different enzymes.
Pyrimidine catabolism [ edit ]
Pyrimidines are ultimately
catabolized (degraded) to CO, 2 H, and 2O urea. Cytosine can be broken down to uracil, which can be further broken down to N-carbamoyl-β-alanine, and then to beta-alanine, CO 2, and ammonia by beta-ureidopropionase. Thymine is broken down into β-aminoisobutyrate which can be further broken down into intermediates eventually leading into the citric acid cycle.
β-aminoisobutyrate acts as a rough indicator for rate of DNA turnover.
Pharmacotherapy [ edit ]
Modulating the pyrimidine metabolism pharmacologically has therapeutical uses.
Pyrimidine synthesis inhibitors are used in active moderate to severe rheumatoid arthritis and psoriatic arthritis. Examples include Leflunomide and Teriflunomide.
References [ edit ]
External links [ edit ]