title: Synthesis and biological activity of 5-fluoro-2',3'-dideoxy-3'-fluorouridine and its 5'-phosphate.
abstract: 5-Fluoro-2',3'-dideoxy-3'-fluorouridine (3'-FFdUrd) and 5-fluoro-2',3'-dideoxy-3'-fluorouridine 5'-phosphate (3'-FFdUMP) have been synthesized, and their interactions with thymidine (dThd) phosphorylase and thymidylate (dTMP) synthetase, respectively, have been examined. 3'-FFdUrd is not a substrate for dThd phosphorylase, but is a weak, noncompetitive inhibitor (Ki = 1.7 mM). 3'-FFdUMP inhibits dTMP synthetase competitively with deoxyuridylate (Ki = 0.13 mM) when both the substrate and inhibitor are present simultaneously. However, in the presence of 5,10-methylenetetrahydrofolate, the inhibition increases with time in a first-order manner (konobsd = 0.029 s-1). A complex is formed between [6-3H]3'-FFdUMP and dTMP synthetase, which is isolable on nitrocellulose filters, and has a dissociation rate (koffobsd = 1.4 X 10(-2) min-1) similar to that of the potent inhibitor 5-fluoro-2'-deoxyuridylate (koffobsd = 1.3 X 10(-2) min-1) from its ternary complex with dTMP synthetase. These results are explained in terms of a two-stage model involving the initial formation of a reversible adsorption complex, followed by a slow conversion to a tight-binding catalytic complex.
mesh_terms: D000818:Animals; D002455:Cell Division / Q000187:drug effects; D003856:Deoxyuracil Nucleotides / Q000138:chemical synthesis* / Q000633:toxicity; D015224:Dideoxynucleosides; D054306:Dideoxynucleotides; D005467:Floxuridine / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000633:toxicity; D007202:Indicators and Reagents; D007700:Kinetics; D007939:Leukemia L1210 / Q000503:physiopathology; D008175:Lung Neoplasms / Q000201:enzymology; D008780:Methyltransferases / Q000037:antagonists & inhibitors*; D051379:Mice; D010430:Pentosyltransferases / Q000037:antagonists & inhibitors*; D013939:Thymidine Phosphorylase / Q000037:antagonists & inhibitors*; D013940:Thymidylate Synthase / Q000037:antagonists & inhibitors*
chemical_list: D003856:Deoxyuracil Nucleotides; D015224:Dideoxynucleosides; D054306:Dideoxynucleotides; D007202:Indicators and Reagents; D005467:Floxuridine; C040052:5-fluoro-2',3'-dideoxy-3'-fluorouridine; C040053:5-fluoro-(2',3')-dideoxy-3'-fluorouridine 5'-phosphate; D008780:Methyltransferases; D013940:Thymidylate Synthase; D010430:Pentosyltransferases; D013939:Thymidine Phosphorylase