Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.5.4.4 (adenosine deaminase)
 5,136 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Opposing changes were discovered in the liver and blood of rats aged 1-1 1/2 months with alloxan diabetes as regards the content of adenine, xanthine plus guanine, uric acid and the activity of adenine-, adenosine-, guanine deaminase and 5'-nucleotidase. The ratio of the activity of adenosine deaminase to that of 5'-nucleotidase correlating with the level of glycemia might be the most informative test in the diagnosis of the depth of the discovered metabolic disorders in alloxan diabetes.
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PMID:[Characteristics of purine and nucleotide metabolism in juvenile rats with alloxan diabetes]. 664 35

Erythrocytes of five strains of mice had ATP concentrations of ca 2.7 mumol/ml packed cells, while those of CBA mice were 23% lower, and those of BALB/C mice were 40% lower. The ratio of the concentrations of ATP and GTP were ca 3.3 in four strains but greater than 27 in three other strains. When erythrocytes from different mouse strains were incubated with radioactive precursors, appreciable strain differences were found in the apparent activities of adenine and hypoxanthine-guanine phosphoribosyltransferase, adenosine kinase, adenosine deaminase, guanine deaminase and xanthine oxidase. The activities of adenosine deaminase and guanine deaminase in sera of mice of different strains also varied.
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PMID:Variation in erythrocyte purine metabolism among mouse strains. 668 81

N6-methyladenine (6-methylaminopurine [6-MA]), a plant growth regulator and a normal constituent of nucleic acids, has been found to inhibit the growth of Trypanosoma cruzi, Leishmania braziliensis, L. donovani, L. tarentolae, L. mexicana, and Crithidia fasciculata. The extent of growth inhibition in these organisms is related to the sensitivity of guanine deaminase (guanine aminohydrolase, EC 3.5.4.3), adenine deaminase (adenine aminohydrolase, EC 3.5.4.2), and adenosine hydrolase and phosphorylase. 6-MA was not an inhibitor of the purine phosphoribosyltransferases. Of the trypanosomid flagellates tested. Trypanosoma cruzi was most susceptible to 6-MA. Neither adenine deaminase (as found in the leishmaniae and C. fasciculata) nor adenosine deaminase (as found in mammalian cells) could be demonstrated in T. cruzi. Guanine deaminase, which is strikingly inhibited by 6-MA in T. cruzi, appears to play a major role in the purine salvage pathway of this organism, as judged from growth experiments and enzyme inhibition studies. Enzyme sensitivities to 6-MA vary greatly depending upon the organism. Rabbit liver guanine deaminase was shown to be insensitive to 6-MA at the concentrations used in this study.
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PMID:Inhibition of growth and purine-metabolizing enzymes of trypanosomid flagellates by N6-methyladenine. 699 36

The mode of degradation of adenosine by extracts of Aspergillus terricola was suggested to be affected preliminary by adenosine deaminase to inosine and the resulting ribonucleoside was then degraded hydrolytically to give hypoxanthine and ribose. With regard to guanosine, the same extracts could initially catalyze the hydrolytic cleavage of guanosine to guanine and ribose. The resulting base was then deaminated to give xanthine by guanine deaminase. Addition of arsenate to the reaction mixture or dialyzing the extract did not affect the observed hydrolytic activity indicating the absence of phosphorylase activity or phosphorylase-phosphatase activities in the extracts.
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PMID:Mode and extent of degradation of adenosine and guanosine by extracts of Aspergillus terricola. 755 35

Recent studies on the tissue distribution and developmental regulation of adenosine deaminase (ADA) activity in mice show that very high ADA levels exist in the murine alimentary tract (tongue, esophagus, forestomach, proximal small intestine) and at the fetal-maternal interface. To understand the role of ADA in these tissues, we measured the levels of three other enzymes involved in purine catabolism, purine nucleoside phosphorylase (PNP), guanine deaminase (GDA), and xanthine dehydrogenase (XDH), to see how their levels correlated with ADA activity. Our results show that the highest level of PNP, GDA, and XDH is present in the proximal small intestine. Levels of these purine catabolic enzymes are much lower in the tongue, esophagus, forestomach, and fetal-maternal interface in marked contrast to ADA distribution. We also determined mRNA levels encoding PNP, XDH, and ADA in a variety of tissues. Tissue-specific differences in PNP, XDH, and ADA activity correlated with RNA abundance, indicating that the regulation of gene expression is at the level of mRNA production. Thus, ADA is part of a purine catabolic pathway leading to the production of uric acid that is present at the highest known level in the proximal small intestine. ADA may have additional roles in other tissues.
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PMID:The highest levels of purine catabolic enzymes in mice are present in the proximal small intestine. 822 98

The present study was conducted in order to clarify the role of the glia in brain purine metabolism. This, in connection with the clarification of the etiology of the neurological manifestations associated with some of the inborn errors of purine metabolism in man. Purine nucleotide content, the capacity for de novo and salvage purine synthesis and the activity of several enzymes of purine nucleotide degradation, were assayed in primary cultures of rat astroglia in relation to culture age. The capacity of the intact cells to produce purine nucleotides de novo exhibited a marked decrease with the culture age, but the activity of hypoxanthine-guanine phosphoribosyltransferase (HGPRT), catalyzing salvage nucleotide synthesis, increased. Aging was also associated with a marked increase in the activity of the degradation enzymes AMP deaminase, purine nucleoside phosphorylase (PNP) and guanine deaminase (guanase). The activity of adenosine deaminase and of AMP-5'-nucleotidase, increased markedly during the first 17 days in culture, but decreased thereafter. The results indicate that purine nucleotide metabolism in the cultured astroglia is changing with aging to allow the cells to maintain their nucleotide pool by reutilization of preformed hypoxanthine, rather than by de-novo production of new purines. Aging is also associated with increased capacity for operation of the adenine nucleotide cycle, contributing to the homeostasis of adenine nucleotides and to the energy charge of the cells. In principle, the age-related alterations in purine metabolism in the astroglia resemble those occurring in the maturating neurons, except for the capacity to produce purines de novo, which exhibited inverse trends in the two tissues. However, in comparison to the neurons, the cultured astroglia possess the capacity for a more intensive metabolism of purine nucleotides.
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PMID:Developmental changes in purine nucleotide metabolism in cultured rat astroglia. 877 Jun 61

The activities of purine salvage enzymes in tachyzoites from a cyst-forming strain of Toxoplasma gondii were determined using HPLC. Six enzymes were assayed both in vitro and in vivo: adenosine deaminase, guanine deaminase, purine nucleoside phosphorylase, xanthine oxidase, hypoxanthine-guanine phosphoribosyltransferase and adenine phosphoribosyltransferase. In vitro, the tachyzoites were cultured in the human myelomonocytic cell line THP-1, for 24 h to 96 h. Neither guanine deaminase nor hypoxanthine-guanine phosphoribosyltransferase activity was detected in 24 and 96 h cultures. In vivo, in controls and infected animals, the purine nucleoside phosphorylase and adenosine deaminase activities were the most important activities both in sera and cerebral tissue in comparison with the other activities. It was also noted that the infection modified the enzymatic activities of this purine salvage pathway, in particular, the guanine deaminase cerebral activity of infected mice was 20-fold lower than the value of controls. The treatment of mice with 2',3'-dideoxyinosine, a purine analog, at the dose of 100 mg.kg(-1).d for 30 days, induced an important increase of all enzymatic activities in the brains in comparison with control animals. These data suggest that one target of 2',3'-dideoxyinosine is the purine metabolism.
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PMID:Purine pathway enzymes in a cyst forming strain of Toxoplasma gondii. 1057 52

The synthesis and enzyme inhibition studies of a novel ring-expanded acyclic nucleoside analogue are reported. Compound has been found to be a competitive inhibitor of both adenosine deaminase (ADA) and guanine deaminase (GDA; guanase) with K(i)'s equal to 1.52+/-0.34 x 10(-4) M and 2.97+/-0.25 x 10(-5) M, respectively. Inhibition of two enzymes of purine metabolism may bear beneficial implications in antiviral therapy.
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PMID:A unique ring-expanded acyclic nucleoside analogue that inhibits both adenosine deaminase (ADA) and guanine deaminase (GDA; guanase): synthesis and enzyme inhibition studies of 4,6-diamino-8H-1-hydroxyethoxymethyl-8-iminoimidazo[4,5-e][1,3]diazepine. 1167 21

Of the human salvage enzymes that deaminate ribonucleosides, two--cytidine deaminase and adenosine deaminase--have been found particularly useful for diagnostic purposes. In humans, no enzymes are present that can directly deaminate the bases of these ribonucleosides. Indeed, the only enzyme present that can directly deaminate a base is guanine deaminase, and the diagnostic usefulness of this enzyme has been well documented. The aim of this study is to identify the origin of the ammonia formed when human sera and tissue extracts are incubated with buffered guanosine, and to clarify whether the ammonia comes from the deamination of guanosine by guanosine deaminase or is produced as a result of deamination of guanine formed as a breakdown product of guanosine by purine nucleoside phosphorylase (PNP). Apparent deamination of guanosine by guanosine deaminase in human sera and tissue extracts was found to be due to two enzymes acting in tandem when the products of the reaction were examined by HPLC. The ribose was first removed from guanosine by PNP to form guanine, which was then deaminated to xanthine by guanine deaminase.
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PMID:Guanosine deaminase in human serum and tissue extracts--a reappraisal of the products. 1472 35

To find general metabolic profiles of purine ribo- and deoxyribonucleotides in potato (Solanum tuberosum L.) plants, we looked at the in situ metabolic fate of various (14)C-labelled precursors in disks from growing potato tubers. The activities of key enzymes in potato tuber extracts were also studied. Of the precursors for the intermediates in de novo purine biosynthesis, [(14)C]formate, [2-(14)C]glycine and [2-(14)C]5-aminoimidazole-4-carboxyamide ribonucleoside were metabolised to purine nucleotides and were incorporated into nucleic acids. The rates of uptake of purine ribo- and deoxyribonucleosides by the disks were in the following order: deoxyadenosine > adenosine > adenine > guanine > guanosine > deoxyguanosine > inosine > hypoxanthine > xanthine > xanthosine. The purine ribonucleosides, adenosine and guanosine, were salvaged exclusively to nucleotides, by adenosine kinase (EC 2.7.1.20) and inosine/guanosine kinase (EC 2.7.1.73) and non-specific nucleoside phosphotransferase (EC 2.7.1.77). Inosine was also salvaged by inosine/guanosine kinase, but to a lesser extent. In contrast, no xanthosine was salvaged. Deoxyadenosine and deoxyguanosine, was efficiently salvaged by deoxyadenosine kinase (EC 2.7.1.76) and deoxyguanosine kinase (EC 2.7.1.113) and/or non-specific nucleoside phosphotransferase (EC 2.7.1.77). Of the purine bases, adenine, guanine and hypoxanthine but not xanthine were salvaged for nucleotide synthesis. Since purine nucleoside phosphorylase (EC 2.4.2.1) activity was not detected, adenine phosphoribosyltransferase (EC 2.4.2.7) and hypoxanthine/guanine phosphoribosyltransferase (EC 2.4.2.8) seem to play the major role in salvage of adenine, guanine and hypoxanthine. Xanthine was catabolised by the oxidative purine degradation pathway via allantoin. Activity of the purine-metabolising enzymes observed in other organisms, such as purine nucleoside phosphorylase (EC 2.4.2.1), xanthine phosphoribosyltransferase (EC 2.4.2.22), adenine deaminase (EC 3.5.4.2), adenosine deaminase (EC 3.5.4.4) and guanine deaminase (EC 3.5.4.3), were not detected in potato tuber extracts. These results suggest that the major catabolic pathways of adenine and guanine nucleotides are AMP --> IMP --> inosine --> hypoxanthine --> xanthine and GMP --> guanosine --> xanthosine --> xanthine pathways, respectively. Catabolites before xanthosine and xanthine can be utilised in salvage pathways for nucleotide biosynthesis.
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PMID:Profiles of purine biosynthesis, salvage and degradation in disks of potato (Solanum tuberosum L.) tubers. 1684 29


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