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:3.5.4.4 (adenosine deaminase)
5,136 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The maximal activities of 5'-nucleotidase, adenosine deaminase and adenosine kinase were measured in quadriceps or soleus muscle from animals in which the sensitivity to insulin was changed. Most conditions caused no effect on the activities but exercise-training increased the activity of adenosine deaminase and cold exposure increased the activity of 5'-nucleotidase in soleus muscle: in addition, ageing decreased markedly the activities of all three enzymes in both muscles. When the activities are based on mg protein they are much higher in both white and brown adipose tissue than in muscle, suggesting that changes in adenosine concentration may be important in changing insulin sensitivity in adipose tissue whereas changes in adenosine receptor number may be more important in muscle.
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PMID:Maximal activities of enzymes involved in adenosine metabolism in muscle and adipose tissue of rats under conditions of variations in insulin sensitivity. 298 53

A microassay requiring as few as 2 X 10(5) cells per assay was developed for systematic analysis of 9 purine enzymes in lymphocytes from equine peripheral blood, spleen, lymph node, thymus and bone marrow. The activities of adenosine deaminase (ADA), purine nucleoside phosphorylase (PNP), adenosine kinase (AK), deoxyadenosine kinase (dAK), deoxycytidine kinase (dCK), 5'-nucleotidase (5'-N), AMP deaminase, hypoxanthine-guanine phosphoribosyl transferase (HGPRT or HPRT), and adenine phosphoribosyl transferase (APRT) were measured by this microassay in lymphocytes from peripheral blood from four different breeds of horses (Arabian, Quarter Horse, Thoroughbred and Shetland Pony). There were no significant differences in the enzyme activities among the various breeds. Peripheral blood lymphocytes (PBL) from foals exhibited enzyme activities similar to those observed for adult animals. All lymphoid tissue contained similar levels of activity for each kinase (AK, dAK and dCK). Spleen had the highest activity for ADA, PNP, 5'-N, and HGPRT. The lowest activity for ADA, APRT, PNP and AMP deaminase was found in thymus. Enzymatic activities that varied the most among the tissue were 5'-N, ADA, APRT, HGPRT and AMP deaminase.
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PMID:Distribution of enzymes of purine metabolism in lymphocytes of horse, Equus caballus. 299 Aug 11

Activities of several adenosine metabolizing enzymes were examined in capillary preparations isolated from rabbit ventricle. Vmax and Km values for 5'-nucleotidase were 2.3 nmol/min/mg and 10 microM, respectively. For adenosine deaminase the corresponding values were 7.8 nmol/min/mg and 32 microM. S-adenosyl-homocysteine hydrolase, which forms adenosine by the hydrolysis of S-adenosylhomo-cysteine, was also present (Vmax, 0.07 nmol/min/mg; Km, 0.81 microM), as were adenosine kinase (Vmax, 0.2 nmol/min/mg; Km, 0.52 microM) and purine nucleoside phosphorylase (Vmax, 13.8 nmol/min/mg; Km, 96 microM). These enzymes were also present in microvessels (capillaries and arterioles) purified from rabbit brain. Activities of several enzymes, especially 5'-nucleotidase and adenosine deaminase, were much lower in myocytes isolated from rabbit ventricle. The study provides evidence that endothelial cells of the microvasculature from heart and brain are capable of activity forming and degrading adenosine. It is possible that adenosine formed by these cells may contribute to the local regulation of blood flow.
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PMID:Adenosine metabolism in microvessels from heart and brain. 300 95

Nucleoside kinases catalyze the initial step leading to the accumulation of deoxypurine nucleotides that occurs in patients with inherited deficiencies of adenosine deaminase (adenosine aminohydrolase, EC 3.5.4.4) and purine-nucleoside phosphorylase (purine-nucleoside:orthophosphate ribosyltransferase, EC 2.4.2.1). This accumulation is thought to interfere with DNA synthesis in lymphocytes and, thus, to cause the immune defects associated with these enzymopathies. However, there is controversy about the identity of the nucleoside kinases that are responsible for intracellular phosphorylation of deoxyadenosine in adenosine deaminase deficiency and deoxyguanosine in purine nucleoside phosphorylase deficiency. To distinguish the nucleoside kinases present in T and B lymphoblastoid cells, we have coupled discontinuous PAGE with autoradiography. This procedure showed that deoxycytidine kinase (NTP:deoxycytidine 5'-phototransferase, EC 2.7.1.74), deoxyadenosine kinase (ATP:deoxyadenosine 5'-phosphotransferase, EC 2.7.1.76), and adenosine kinase (ATP:adenosine 5'-phosphotransferase, EC 2.7.1.20) are all present in both T and B lymphoblasts. While adenosine kinase is expressed at nearly equal levels in B and T cells, the deoxynucleoside kinases are expressed at much lower levels in B cells than in T cells. The autoradiographic data agreed with assays of the nucleoside kinase activities. Molecular weights were determined by using 5-10% polyacrylamide gels. Mr values were 29,000 for adenosine kinase, 41,000 for deoxyadenosine kinase, and 53,000 for deoxycytidine kinase and its isozyme. The reduced expression of deoxycytidine and deoxyadenosine kinases in B lymphoblasts may account for the lower accumulation of deoxypurine nucleotides in B cells as compared with T cells.
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PMID:Nucleoside kinases in T and B lymphoblasts distinguished by autoradiography. 301 44

Activities of enzymes involved in the synthesis and degradation of adenosine have been measured in samples of adipose tissue from unmated sheep at various times of the year between January and October and from pregnant and lactating sheep. 5'-Nucleotidase activity increased during the spring in unmated sheep but this increase was suppressed in lactating sheep. Neither adenosine kinase nor adenosine deaminase activities varied significantly between January and October in unmated sheep. Lactation resulted in a rise in adenosine deaminase activity and a small decrease in adenosine kinase activity. Pregnancy had no obvious effect on the activities of any of the three enzymes noted above. Changes in adipocyte mean cell volume and number per g tissue and the concentrations of DNA and protein of the tissue are also described. Results are discussed in relation to changes in the capacity for lipid synthesis and mobilization which occur in response to season, pregnancy and lactation in sheep.
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PMID:Enzymes of adenosine metabolism of sheep adipose tissue: changes in activity with season, pregnancy and lactation. 301 56

Extracts of Babesia divergens were examined for the enzymes which catalyse purine salvage. Adenosine deaminase (EC 3.5.4.4), guanine deaminase (EC 3.5.4.3), inosine phosphorylase (EC 2.4.2.1), purine phosphoribosyltransferases (EC 2.4.2.7, EC 2.4.2.8, EC 2.4.2.22) and nucleoside kinases (EC 2.7.1.15, EC 2.7.1.20, EC 2.7.1.73) were all detected at relatively high activities, whereas nucleotide interconverting enzymes were not detected. Coformycin and 4-amino-5-imidazolecarboxamide were found to be potent inhibitors of adenosine deaminase and guanine deaminase, respectively. The results suggest that B. divergens is capable of synthesizing purine nucleotides via two routes, one involving purine phosphoribosyltransferases and the other employing nucleoside kinases.
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PMID:Purine-metabolizing enzymes in Babesia divergens. 303 31

Depressed activities of the following purine enzymes have been shown to result in immunodeficiencies: adenosine deaminase (ADA), hypoxanthine-guanine phosphoribosyltransferase (HGPRT), and purine nucleoside phosphorylase (PNP). These enzymes and adenosine kinase (AK) were measured in cord blood lymphocytes of premature and small-for-gestational age infants since they have partial immunodeficiencies of unknown biochemical etiology which can persist for many years. We also measured these enzymes in 3 infants with various immunodeficiencies. Activities were compared with appropriate matched control groups. The results indicated normal ADA and PNP but significantly depressed AK (P less than 0.05) and HGPRT (P less than 0.001) activities in 10 premature/SGA infants when compared to 35 full-term normal infants. In the 3 immunodeficient children the results were as follows: Child 1 had a 2- to 3-fold decrease in ADA with normal PNP and AK activities; Child 2 had a 2- to 3-fold decrease in AK, 4-fold decrease in HGPRT with normal PNP and ADA activities; Child 3 had confirmed AIDS and a 4-fold decrease in ADA, 6-fold decrease in HGPRT with normal PNP activity. The possible role of these depressed purine enzyme activities found in lymphocytes is discussed in relation to the imparied immunity seen in these infants.
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PMID:Activities of purine metabolising enzymes in lymphocytes of neonates and young children: correlates with immune function. 311 34

The simultaneous administration of 3'-deoxyadenosine N1-oxide (3'-dANO) and the adenosine deaminase inhibitors erythro-9-(2-hydroxy-3-nonyl) adenine (EHNA) or 2'-deoxycoformycin (2'-dCF) to mice bearing Ehrlich ascites tumor cells resistant to 3'-dANO resulted in 80%-90% inhibition of tumor growth in vivo. 3'-dANO and 2'-dCF increased the survival time of tumor-bearing mice by a factor of 2. In vitro studies showed that the 3'-dANO resistant Ehrlich cells initiate the metabolism of 3'-dANO by a reduction to 3'-deoxyadenosine, which is converted primarily to 3'-deoxyinosine by adenosine deaminase and, to a small extent, phosphorylated to the cell toxic agent 3'-dATP. By the addition of EHNA or 2'-dCF it was possible to block the formation of 3'-deoxyinosine, resulting in a profound stimulation in the accumulation of 3'-dATP. The development of resistance to 3'-dANO was studied in cell cultures and found to be accompanied by changes in the enzyme activities of the reductase, the adenosine kinase, and the adenosine deaminase.
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PMID:Synergistic effect of 3'-deoxyadenosine N1-oxide and adenosine deaminase inhibitors on growth of Ehrlich ascites tumor cells in vivo. 325 21

The pathways of 2',3'-dideoxyadenosine (ddAdo) metabolism, a selective inhibitor of the replication of human immunodeficiency virus, were investigated with use of the human T-lymphoid cell line CCRF-CEM which is deficient in either deoxycytidine kinase or adenosine kinase activity, or both. At an extracellular concentration of 10 microM, which blocks the cytopathic effect of human immunodeficiency virus in vitro, ddAdo was found to be metabolized to its mono-, di-, and triphosphates and to dideoxyinosine monophosphate (ddIMP). The metabolism of ddAdo in the kinase-deficient mutants was found to be unchanged by comparison with that in parental cells; however, the inhibition of ddAdo deamination to 2',3'-dideoxyinosine (ddIno) by the adenosine deaminase inhibitor, 2'-deoxycoformycin, reduced ddAdo nucleotide formation in deoxycytidine kinase-deficient, adenosine kinase-deficient, and doubly kinase-deficient mutants by 42, 54, and 80%, respectively. Incubation of the CCRF-CEM cells with 20 microM L-alanosine, an amino acid antagonist that inhibits purine biosynthesis at the level of adenylosuccinate/lyase synthetase, resulted in 80% inhibition in the accumulation of ddAdo nucleotides in both wild-type and kinase-deficient mutants and also increased ddIMP accumulation 2- to 3-fold. These findings indicate that ddAdo activation in human T-lymphoblasts can occur by three metabolic pathways: directly, by phosphorylation to ddAMP by the action of either deoxycytidine kinase or adenosine kinase and, indirectly, through deamination to ddIno with consequent phosphorylation of ddIno to ddIMP, and reamination to ddAMP in a reaction catalyzed by adenylosuccinate synthetase/lyase. However, in the absence of 2'-deoxycoformycin, the activation of ddAdo to ddATP in T-lymphoid cells is primarily a function of the indirect route.
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PMID:Metabolic pathways for the activation of the antiretroviral agent 2',3'-dideoxyadenosine in human lymphoid cells. 326 16

The influence of adenosine on the ribonucleotide metabolism in quiescent BALB/c 3T3 cells was studied. The cellular adenine ribonucleotides were labelled by pretreating the cells with [2-3H]-adenine. After addition of adenosine to the cell cultures, the amount and radioactivity of the cellular purine ribonucleotides and the radioactivity of the purine compounds in the medium were determined. It appeared that adenosine gave rise both to rapid catabolism of adenine ribonucleotides with inosine 5'-monophosphate (IMP) as an intermediate and to expansion of the cellular adenosine 5'-triphosphate (ATP) pool. The maximal rates and the apparent activation constants for the two processes have been determined. Experiments with varying concentrations of coformycin (an inhibitor of adenosine 5'-monophosphate [AMP] deaminase and adenosine deaminase) and of 5'-amino-5'-deoxyadenosine (an inhibitor of adenosine kinase), respectively, showed that each compound may almost completely inhibit the adenosine-induced catabolism. This effect can be obtained under conditions where there was little or no effect by the two inhibitors on the rate of expansion of the cellular ATP pool. These results may best be explained by assuming that the process of expansion of the ATP pool is independent of the induced catabolism of adenine ribonucleotides, even though both processes seem to depend on the phosphorylation of adenosine to AMP. The total increase in the pool size of ATP and of guanosine 5'-triphosphate (GTP), both caused by adenosine, seems not to have regulatory effect on adenine ribonucleotide catabolism.
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PMID:Adenosine induction of rapid catabolism of adenine ribonucleotides and independent elevation of the ATP content in quiescent mouse fibroblasts. 326 74


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