Mechanism for exclusion of 5-fluorouracil from DNA

5-Fluorodeoxyuridine 5'-triphosphate is hydrolyzed by the enzyme deoxyuridine triphosphate diphosphohydrolase (EC 3.6.1.23). Uracil-DNA glycosylase removes 5-fluorouracil (FUra) from FUra-containing DNA similar to its removal of uracil from uracil-containing DNA. The absence of FUra in DNA following exposure of cells to FUra can be explained by the activities of these two enzymes.