Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

In tissues obtained from patients undergoing gastrectomy, the activities of 12 enzymes involved in pyrimidine nucleotide synthesis: cytidine triphosphate (CTP) synthetase, deoxycytidine monophosphate (dCMP) deaminase, thymidine monophosphate (dTMP) kinase, uridine (Urd), deoxycytidine (dCyd) and thymidine (dThd) kinases, Urd, deoxyuridine (dUrd) and dThd phosphorylases, cytidine (Cyd) and dCyd deaminases, and DNA polymerase were examined in the eight-well-differentiated and 12 poorly differentiated gastric cancer tissues and the ten normal tissues. These cases were clinically advanced and serosal invasions were evident. Activities of these enzymes were higher in the poorly differentiated tissues than the well differentiated type and in the normal tissues. Significant differences were noted between the poorly differentiated and well-differentiated types, in dTMP kinase (P less than 0.02), dThd kinase (P less than 0.05), dThd phosphorylase (P less than 0.01), and DNA polymerase (P less than 0.05). The authors' findings show that the level of pyrimidine nucleotide synthesis, in both de novo and salvage pathways, is higher in the poorly differentiated gastric cancer tissues than in the well-differentiated type and suggest that antitumor drugs have an increased susceptibility in cases of poorly differentiated gastric carcinoma.
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PMID:Pyrimidine nucleotide synthesis is more extensive in poorly differentiated than in well-differentiated human gastric carcinoma. 291 Apr 29

Pyrimidine metabolism in Pseudomonas fluorescens biotype F, and its ability to grow in liquid culture on pyrimidines and related compounds was investigated. It was found that uracil, uridine, cytosine, cytidine, deoxycytidine, dihydrouracil, dihydrothymine, beta-alanine or beta-aminoisobutyric acid could be utilized by this pseudomonad as a sole nitrogen source. Only uridine, cytidine, beta-alanine, beta-aminoisobutyric acid or ribose were capable of supporting its growth as a sole source of carbon. In solid medium, the pyrimidine analogue 5-fluorouracil or 5-fluorouridine could prevent P. fluorescens biotype F growth at a low concentration while a 20-fold higher concentration of 5-fluorocytosine, 5-fluorodeoxyuridine or 6-azauracil was necessary to block its growth. The pyrimidine salvage enzymes cytosine deaminase, nucleoside hydrolase, uridine phosphorylase, thymidine phosphorylase and cytidine deaminase were assayed. Only cytosine deaminase and nucleoside hydrolase activities could be detected under the assay conditions used. The effect of growth conditions on cytosine deaminase and nucleoside hydrolase levels in the micro-organism was explored. Cytosine deaminase activity was shown to increase if glycerol was substituted for glucose as the sole carbon source or if asparagine replaced (NH4)2SO4 as the sole nitrogen source in each respective medium. In contrast, nucleoside hydrolase activity remained virtually unchanged whether the carbon source in the medium was glucose or glycerol. A decrease in nucleoside hydrolase activity was witnessed when asparagine was present in the medium instead of (NH4)2SO4 as the sole source of nitrogen.
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PMID:Metabolism of pyrimidine bases and nucleosides by Pseudomonas fluorescens biotype F. 314 44

4-N-hydroxy-cytidine was found to substitute for uridine as a pyrimidine supplement for the growth of Escherichia coli Bu(-). Measurement of the incorporation of 4-N-hydroxy-cytidine-2-(14)C into ribonucleic acid and deoxyribonucleic acid revealed that this compound was converted to cytidine or uridine before utilization. Two pathways for metabolism were considered: (i) the reduction of 4-N-hydroxy-cytidine to cytidine followed by deamination, (ii) the direct hydrolysis of hydroxylamine from 4-N-hydroxy-cytidine to yield uridine. A threefold increase in cytidine (deoxycytidine) deaminase (EC 3.5.4.5) activity, when the cells were grown on 4-N-hydroxy-cytidine, suggested the involvement of this enzyme. More direct proof was obtained by purifying the deaminase 185-fold and finding that it released hydroxylamine from 4-N-hydroxy-cytidine at one-fiftieth the rate at which ammonia was removed from cytidine. This result is consistent with the slower rate of growth of the Bu(-) cells on 4-N-hydroxy-cytidine than cytidine and suggests that the second pathway is the major route for utilization of this compound.
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PMID:Metabolism of 4-N-hydroxy-cytidine in Escherichia coli. 494 53

The biosynthesis of 2'-deoxyuridine monophosphate (dUMP) has been studied in a cytidine- and uracil-requiring mutant of Salmonella typhimurium (DP-55). The dUMP pool and the thymidine monophosphate (dTMP) pool of DP-55, grown in the presence of (3)H-uracil and unlabeled cytidine, are found to have the same specific activities. However, only 30% of the dUMP and the dTMP is synthesized from a uridine nucleotide. Seventy per cent is derived directly from a cytosine compound. The identification and partial purification of a Mg(2+)-dependent 2'-deoxycytidine triphosphate (dCTP) deaminase from S. typhimurium suggests that the combined action of dCTP deaminase and 2'-deoxyuridine triphosphate pyrophosphatase accounts for 70% of the dUMP, and therefore the dTMP, synthesized in vivo. The introduction of a thymine requirement (i.e., a block in thymidylate synthetase) into DP-55 results in a 100-fold increase in the size of the dUMP pool. However, the relative contribution of the uridine and cytidine pathways to dUMP synthesis is unaltered. The high dUMP pool is accompanied by extensive catabolism of dUMP to uracil. Partial thymine starvation of the cells results in a significant increase in the dUMP and dCTP pools. Moreover, an increase in the contribution of the dCTP pathway to dUMP synthesis is observed. As a result of these changes the catabolism of dUMP to uracil is augmented.
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PMID:Deoxycytidine triphosphate deaminase: identification and function in Salmonella typhimurium. 554 39

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

Apolipoprotein (apo) B mRNA editing is the specific deamination of cytidine (nucleotide 6666) to uridine in apoB mRNA. We isolated a full-length cDNA clone encoding the rabbit apoB mRNA editing protein (REPR), a subunit of the editing complex. Rabbit REPR is analogous to a rat enterocyte 27-kDa protein that has been shown to have cytidine deaminase activity. Like rat REPR, rabbit REPR edited synthetic apoB RNA when mixed with chicken enterocyte extract. Surprisingly, the REPR also acquired editing activity when mixed with extracts from various organs of the rabbit (liver, gallbladder, stomach, intestine, adrenals, thyroid, testes, spleen, kidney, and lung) or the chicken (kidney and liver). In contrast, the rabbit REPR mRNA was found only in the small and large intestine. Thus, the auxiliary protein(s) of the apoB mRNA editing complex, which are essential for editing activity, exist in organs devoid of significant apoB mRNA editing or apoB synthesis. REPR requires zinc for its catalytic activity. We mutated putative zinc-coordinating residues (His61, Cys93, Cys96) and 2 additional residues (Glu63, Pro92) of the rabbit REPR that are conserved in other cytidine or deoxycytidylate deaminases and in rat REPR. The wild-type and mutant REPR cDNAs each produced 28-kDa proteins when transcribed and translated in vitro. Compared with the wild-type editing activity, the mutations of His61-->Ala, Glu63-->Ala, Cys93-->Ala, and Cys96-->Ala abolished or greatly reduced editing activity, whereas the mutations of His61-->Cys (which also can coordinate zinc) and Pro92-->Ala had a lesser effect. These results indicate that His61, Cys93, and Cys96 are essential for editing activity, probably because they coordinate zinc, whereas Glu63 also is essential, because it may be involved in the deaminase reaction. In addition, the widespread distribution of the auxiliary factor(s) portends their involvement in other RNA editing reactions.
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PMID:Cloning and mutagenesis of the rabbit ApoB mRNA editing protein. A zinc motif is essential for catalytic activity, and noncatalytic auxiliary factor(s) of the editing complex are widely distributed. 806 16

Pyrimidine salvage enzyme activities in cell-free extracts of Toxoplasma gondii were assayed in order to determine which of these enzyme activities are present in these parasites. Enzyme activities that were detected included phosphoribosyltransferase activity towards uracil (but not cytosine or thymine), nucleoside phosphorylase activity towards uridine, deoxyuridine and thymidine (but not cytidine or deoxycytidine), deaminase activity towards cytidine and deoxycytidine (but not cytosine, cytidine 5'-monophosphate or deoxycytidine 5'-monophosphate), and nucleoside 5'-monophosphate phosphohydrolase activity towards all nucleotides tested. No nucleoside kinase or phosphotransferase activity was detected, indicating that T. gondii lack the ability to directly phosphorylate nucleosides. Toxoplasma gondii appear to have a single non-specific uridine phosphorylase enzyme which can catalyze the reversible phosphorolysis of uridine, deoxyuridine and thymidine, and a single cytidine deaminase activity which can deaminate both cytidine and deoxycytidine. These results indicate that pyrimidine salvage in T. gondii probably occurs via the following reactions: cytidine and deoxycytidine are deaminated by cytidine deaminase to uridine and deoxyuridine, respectively; uridine and deoxyuridine are cleaved to uracil by uridine phosphorylase; and uracil is metabolized to uridine 5'-monophosphate by uracil phosphoribosyltransferase. Thus, uridine 5'-monophosphate is the end-product of both de novo pyrimidine biosynthesis and pyrimidine salvage in T. gondii.
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PMID:Pyrimidine salvage pathways in Toxoplasma gondii. 845

APOBEC-1, which mediates the editing of apolipoprotein (apo) B mRNA, is the only known member of the C (cytidine)-->U (uridine) editing enzyme subfamily of the cytidine deaminase supergene family. Here we report the cloning of APOBEC-2, another member of the subfamily. Human and mouse APOBEC-2 both contain 224 amino acid residues, and their genes are mapped to syntenic regions of human chromosome 6 (6p21) and mouse chromosome 17. By phylogenetic analysis, APOBEC-2 is shown to be evolutionarily related to APOBEC-1, and analysis of substitution rates indicates that APOBEC-2 is a much better conserved gene than APOBEC-1. APOBEC-2 mRNA and protein are expressed exclusively in heart and skeletal muscle. APOBEC-2 does not display detectable apoB mRNA editing activity. Like other editing enzymes of the cytidine deaminase superfamily, APOBEC-2 has low, but definite, intrinsic cytidine deaminase activity. The identification of APOBEC-2 indicates that APOBEC-1 is not the only member of the C-->U editing enzyme subfamily, which, like the A (adenosine)-->I (inosine) subfamily of editing enzymes, must encompass at least two and possibly more different deaminase enzymes. It suggests that the C-->U editing affecting apoB mRNA and other RNAs is not an isolated event mediated by a single enzyme but involves multiple related proteins that have evolved from a primordial gene closely related to the housekeeping enzyme cytidine deaminase.
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PMID:APOBEC-2, a cardiac- and skeletal muscle-specific member of the cytidine deaminase supergene family. 1040 81

To elucidate the biological significance of extracellular adenine compounds, the effects of adenosine (Ado) on cellular levels of adenine compounds, especially adenosine triphosphate (ATP), in PC12 cells were studied. Ado and inosine but not adenosine 5'-monophosphate, adenosine 5'-diphosphate, ATP, guanosine, cytosine, thymidine, and uridine, significantly enhanced cellular ATP levels in PC12 cells in time- and dose-dependent manners. Various P1 receptor agonists of Ado did not enhance the ATP level. In addition, theophylline, an antagonist of P1 receptors, did not inhibit the Ado-evoked ATP enhancement. These results suggest that the Ado receptor is not involved in the augmentation of the cellular ATP level induced by Ado in PC12 cells. The ATP-enhancing effect of Ado was potentiated by dipyridamole, an inhibitor of Ado uptake, or coformycin, an inhibitor of Ado deaminase. The effect of Ado on the ATP level was also observed when PC12 cells were incubated in glucose-free medium. Together these results suggest that enhancement of cellular ATP levels in PC12 cells by extracellular Ado might be acceleration of ATP synthesis through the Ado salvage system using hypoxanthine-guanine phosphoribosyltransferase rather than Ado kinase since 5'-iodotubercidin, an inhibitor of Ado kinase, had no effect on the enhancement elicited by Ado.
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PMID:Enhancement of cellular adenosine triphosphate levels in PC12 cells by extracellular adenosine. 1191 23

Lawrence, N. L. (University of Alabama, Birmingham) and Yun-Chuan Tsan. Reaction of spores and cells of Bacillus cereus with pyrimidine ribosides. J. Bacteriol. 83:228-233. 1962.-Cytidine deaminase and uridine ribosidase were essentially inactive in heat-resistant spores of Bacillus cereus T, but the activity increased as the spores germinated and proceeded to the vegetative form. The activity of germinated spores on cytidine was evident only after several hours lag, but then was nearly equal to that of vegetative cells. Cytosine deaminase was absent from all these preparations, but deoxycytidine was deaminated at nearly the same rate as cytidine. In the absence of added phosphate, cytidine was converted to uracil by intact vegetative cells more completely than was uridine.
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PMID:Reactions of spores and cells of Bacillus cereus with pyrimidine ribosides. 1446 6


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