Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.5.1.4 (deaminase)
 5,113 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have developed a one-dimensional thin-layer chromatography procedure that resolves the initial substrate uracil and its catabolic derivatives dihydrouracil, N-carbamoyl-beta-alanine (NCBA) and beta-alanine. This separation scheme also simplifies the preparation of the radioisotopes of N-carbamoyl-beta-alanine and dihydrouracil. Combined, these methods make it possible to assay easily and unambiguously, jointly or individually, all three enzyme activities of uracil catabolism: dihydropyrimidine dehydrogenase, dihydropyrimidinase, and N-carbamoyl-beta-alanine amidohydrolase. Earlier reports had presented data suggesting that these three enzyme activities were combined in a complex because they appeared to be controlled at a single genetic locus [Dagg, C. P., Coleman, D.L., & Fraser, G.M. (1964) Genetics 49, 979-989] and because they appeared able to channel metabolites [Barrett, H.W., Munavalli, S.N., & Newmark, P. (1964) Biochim. Biophys. Acta 91, 199-204]. Although the three enzymes from rat liver have similar sizes, with apparent molecular weights of 218 000 for dihydropyrimidine dehydrogenase, 226 000 for dihydropyrimidinase, and 234 000 for NC beta A amidohydrolase, they are easily separated from each other. Kinetic studies show no evidence of substrate channeling and therefore do not support a model for an enzyme complex. The earlier reports may be explained by our studies on the amidohydrolase, which suggest that under certain conditions this enzyme may become the rate-limiting step in uracil catabolism.
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PMID:Pyrimidine catabolism: individual characterization of the three sequential enzymes with a new assay. 643 73

Pyrimidine ribonucleoside catabolic enzyme activities of the opportunistic pathogen Pseudomonas pickettii were examined. Of the pyrimidine and related compounds tested, only dihydrouracil (nitrogen source) and ribose (carbon source) supported growth. Thin-layer chromatographic separation of the uridine and cytidine catabolities produced by P. pickettii extracts indicated that this pseudomonad contained nucleoside hydrolase activity. Its presence was confirmed by enzyme assay. Hydrolase activity was elevated in both glucose- and ribose-grown cells relative to succinate-grown cells. Nucleoside hydrolase activity was depressed when dihydrouracil served as a nitrogen source. Cytosine deaminase activity was present in extracts prepared from succinate-, glucose- or ribose-grown cells when (NH4)2SO4 served as the nitrogen source although cells grown on glucose or ribose exhibited a higher enzyme activity. Cytosine deaminase activity was not detected in extracts prepared from cells grown on dihydrouracil as a nitrogen source. Both dihydropyrimidine dehydrogenase and dihydropyrimidinase activities were measurable in P. pickettii. The dehydrogenase activity was higher with NADH than with NADPH as its nicotinamide cofactor when uracil served as its substrate. Carbon source did not affect dehydrogenase or dihydropyrimidinase activity greatly but both activities were diminished in cells grown on the nitrogen source dihydrouracil.
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PMID:Pyrimidine ribonucleoside catabolic enzyme activities of Pseudomonas pickettii. 771 Feb 77