Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.5.4.1 (cytosine deaminase)
 747 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effect of the aging on the activities of enzymes involved in UMP-CMP metabolism were evaluated in the heart of newborn (1-day-old), young (20-day-old), adult (12-month-old), and aged (30-month-old) chickens. In newborn animals, UMP metabolism proceeds preferentially towards cytidine compounds rather than to breakdown. In addition, two pathways different from those involved in de novo synthesis may contribute to the synthesis of UMP: one, through cytosine deaminase that shows its maximal activity; the other, by uridine kinase, the main "salvage" enzyme of pyrimidine nucleotides. In young chickens, pyrimidine metabolism regards especially UMP. In fact, the lower activities of cytidylate phosphatase and cytosine deaminase, together with the remarkable increase of uridine kinase indicate that the metabolic flux converges on the main salvage pathway. In adult chickens, pyrimidine catabolism is enhanced, as supported by the maximal activity of the enzymes involved in UMP-CMP breakdown. On the contrary, the remarkable reduction of the anabolic enzymes suggests a limited resort to the salvage pathways. Finally, in aged chickens a reduced pyrimidine catabolism and a greater utilization of the salvage pathways appear to take place, thus contributing to the maintenance of pyrimidine nucleotide pool.
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PMID:Influence of age on enzyme activities of pyrimidine metabolism in the chicken heart. 989 51

Cytidine metabolism in the yeast Saccharomyces cerevisiae was analyzed by genetic and biochemical approaches. Disruption of a unique ORF (Genbank accession No. U 20865) bearing homology with eucaryotic or bacterial cytidine deaminases abolished cytidine deaminase activity and resulted in 5-fluorocytidine resistance. The gene encoding cytidine deaminase will be referred to as CDD1 (Genbank accession number AF080089). The ability to isolate mutants resistant to 5-fluorocytidine which mapped to five other loci demonstrated the existence of a complex cytidine metabolic network. Deciphering this network revealed several original features:(1) cytidine entry is mediated by the purine-cytosine transporter (Fcy2p),(2) cytidine is cleaved into cytosine by the uridine nucleosidase (Urh1p),(3) cytidine is phosphorylated into CMP by the uridine kinase (Urk1p),(4) a block in cytosine deaminase (Fcy1p), but not in cytidine deaminase (Cdd1p), constitutes a limiting step in cytidine utilisation as a UMP precursor.
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PMID:New insights into the pyrimidine salvage pathway of Saccharomyces cerevisiae: requirement of six genes for cytidine metabolism. 1050 35