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)

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

Cytidine deaminase from Escherichia coli contains 1 mol of tightly bound zinc per enzyme subunit (Yang, C., Carlow, D., Wolfenden, R., & Short, S.A. (1992) Biochemistry 31, 4168-4174). When the metal liganding residues Cys-129 and Cys-132 were replaced by Ala, and His-102 was replaced by Ala, Asn, or Gln, deaminase activities of cell extracts containing these mutant enzymes were decreased by several orders of magnitude relative to that of the wild-type enzyme. After purification, each mutant protein was found to contain less than 0.2 mol of zinc per enzyme subunit, except mutant H102Q, which contained 1 mol of zinc per subunit. The activity of each mutant enzyme increased in the presence of added zinc but never attained wild-type activity. Mutant H102N was unique in that this protein could be purified as a stable apoenzyme, activated by added zinc, and then inhibited by EDTA. This mutant enzyme bound zinc with an apparent Kd value of 6.0 x 10(-10) M and regained maximal activity in the presence of 1 mol of zinc per subunit. Affinities of the mutant cytidine deaminases for the transition-state analogue, 5-fluoropyrimidin-2-one ribonucleoside (3,4) hydrate, were found to decrease in rough proportion to kcat/Km over a range spanning several orders of magnitude. This variation in catalytic efficiency arose mainly from effects on kcat, indicating the involvement of zinc coordination in the catalytic process rather than in substrate binding.
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PMID:Mutations affecting transition-state stabilization by residues coordinating zinc at the active site of cytidine deaminase. 820 80