The enzymes involved in the metabolism of fluorouracil include not only DPD, but also others such as orotate phosphoribosyltransferase (OPRT), thymidylate synthase (TS), and thymidine phosphorylase (TP).
Sanada et al., "The expression profiles of orotate phosphoribosyltransferase and dihydropyrimidine dehydrogenase in gastric cancer and their clinical significance," Oncology Reports, vol.
Fukushima, "Thymidylate synthase, dihydropyrimidine dehydrogenase, orotate phosphoribosyltransferase
mRNA and protein expressionlevels in solid tumors in large scale population analysis," International Journal of Molecular Medicine, vol.
coli K-12 that requires pyrimidine in minimal growth medium, due to suboptimal expression ofthe enzyme orotate phospho-ribosyltransferase coded for by the orotate phosphoribosyltransferase
(pyrE) gene (16).
In the analysis of urine from patients with orotic acidurias caused by orotate phosphoribosyltransferase
(EC 18.104.22.168) and ornithine transcarbamylase (EC 22.214.171.124) deficiency (data not shown), an easily identifiable but relatively broad peak of OA was observed.
It could be caused by the inhibition of orotate phosphoribosyltransferase
by accumulating abnormal metabolites.