Substrate properties of 5-fluorouridine diphospho sugars detected in hepatoma cells.

Abstract

Nucleotide sugars derived from 5-fluorouridine were studied in cultured AS-30D hepatoma cells as well as in kinetic enzyme assays in vitro in comparison with the physiologic uridine diphospho sugars. Hepatoma cells converted 5-fluoro [14C]uridine to 5-fluorouridine diphospho (FUDP) glucose, FUDP-galactose, FUDP-N-acetylglucosamine, FUDP-N-acetylgalactosamine, and trace amounts of FUDP-glucuronate, as analyzed by different systems of high-performance liquid chromatography. 5-Fluoro[14C]uridine and [14C]uridine, at concentrations of 5 microM in the culture medium, were phosphorylated by the cells during 60 min to similar amounts of FUTP and UTP, respectively, while the synthesis of [14]FUDP-sugars was reduced to 14% as compared to that of [14C]UDP-sugars. FUDP-sugars, synthesized by chemical and enzymatic procedures, were assayed in vitro as substrates for enzymes of UDP-sugar metabolism. Km and V values in a range comparable to that of the respective UDP-sugars were determined for FUDP-sugars in the reactions catalyzed by UDP-glucose pyrophosphorylase, galactose-1-phosphate uridylyltransferase, UDP-glucose 4-epimerase, UDP-N-acetylglucosamine 2-epimerase, glycogen synthase, and UDP-glucose dehydrogenase. Our experiments in hepatoma cells and with enzymes in vitro have revealed additional reactions of FUDP-sugar metabolism demonstrating a metabolite pattern analogous to that of UDP-sugars. The amounts of FUDP-sugars formed relative to UDP-sugars in intact cells were smaller than suggested on the basis of their kinetic comparison in vitro.

• Authors: G Weckbecker, D O Keppler
• Journal: Biochemical pharmacology (Biochem Pharmacol) Vol. 33 Issue 14 Pg. 2291-8 (Jul 15 1984) ISSN: 0006-2952 [Print] England
• PMID: 6466351 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Uracil Nucleotides
• Uridine Diphosphate Sugars
• 5-fluorouridine
• Uridine

Topics

• Animals
• Female
• Kinetics
• Liver Neoplasms, Experimental (enzymology, metabolism)
• Rats
• Rats, Inbred Strains
• Stereoisomerism
• Uracil Nucleotides (metabolism)
• Uridine (analogs & derivatives, metabolism)
• Uridine Diphosphate Sugars (chemical synthesis, metabolism)