Pyrimidine metabolism and sugar nucleotide synthesis in rat liver

With radioactive precursors, the labelling kinetics of the soluble pyrimidine nucleotides and of RNA were measured in rat liver to determine the contribution of the metabolic flows through synthesis de novo and the salvage pathway. To separate and quantify all pyrimidine nucleotides, an h.p.l.c. tec...

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Bibliographic Details
Published in:Biochemical journal 1990-03, Vol.266 (3), p.777-783
Main Authors: Pels Rijcken, W R, Hooghwinkel, G J, Ferwerda, W
Format: Article
Language:English
Subjects:
Animals
Chromatography, High Pressure Liquid
Hydrolysis
Kinetics
Liver - metabolism
Male
Nucleoside Diphosphate Sugars - metabolism
Pyrimidine Nucleotides - genetics
Pyrimidine Nucleotides - metabolism
Rats
Rats, Inbred Strains
RNA - metabolism
Solubility
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Summary:With radioactive precursors, the labelling kinetics of the soluble pyrimidine nucleotides and of RNA were measured in rat liver to determine the contribution of the metabolic flows through synthesis de novo and the salvage pathway. To separate and quantify all pyrimidine nucleotides, an h.p.l.c. technique was developed using anion-exchange chromatography and reversed-phase chromatography. The concentrations of cytidine nucleotides were in the range of 30-45 nmol/g wet weight, and the concentrations of the uridine phosphates and of the UDP-sugars were approx. 6 and 20 times higher respectively. After a single injection of [14C]orotic acid and of [3H]cytidine, the specific radioactivities were determined as a function of time. The 14C/3H ratio was calculated and gave a good indication of the involvement of the different flows. It could be concluded that UTP derived from synthesis de novo and from the salvage pathway is not completely mixed before being utilized. The flow of the salvage pathway is relatively more directed to RNA synthesis in the nucleus and that of synthesis de novo to cytoplasmic processes. For CTP it could also be concluded that the flow of the salvage pathway was relatively more directed to RNA synthesis in the nucleus. Because of the nuclear localization of the enzyme CMP-NeuAc (N-acetylneuraminate) synthase, special attention was paid to CMP-NeuAc. However, a conclusion about a location about the synthesis of CMP-NeuAc could not unequivocally be drawn, because of the small differences in 14C/3H ratio and the different values for the CDP-lipids.
ISSN:0264-6021
1470-8728
DOI:10.1042/bj2660777