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)

1) The rate of 2,3-bisphosphoglycerate breakdown is independent of pH value. 2) The adenine nucleotide pattern at alkaline pH values with its characteristic lowering of ATP and the accompanying accumulation of fructose-1,6-bisphosphate is caused by a relative excess of the activity of the hexokinase-phosphofructokinase system as compared wity pyruvate kinase. 3) The breakdown of adenine nucleotides proceeds via AMP mainly through phosphatase and not via AMP deaminase. 4) The constancy of the sum of nucleotides as long as glucose is present is postulated to be due to resynthesis via adenosine kinase which competes successfully with adenosine deaminase. 5) A procedure is given to calculate ATPase activity of glucose-depleted red cells. The results indicate that the ATPase activity is less at lower pH values and declines with time. An ATPase with a high Km for ATP is postulated. 6) During glucose depletion ATP production is mostly derived from the breakdown of 2,3-bisphosphoglycerate and the supply from the pentose phosphate pool both of which proceed at a constant rate. The contribution of pentose phosphate from the breakdown of adenine nucleotides amounts to 40% of the lactate formed at pH 6.8 and is about twice the lactate at pH 8.1.
 ...
PMID:The breakdown of adenine nucleotides in glucose-depleted human red cells. 4 52

The activity of myocardial adenosine kinase (E.N. 2.7.1.20) in a number of species was assayed. Rat heart contained the highest specific activity. From this source adenosine kinase was purified in a simple way 80-fold, until it was free of adenosine deaminase activity. A molecular weight of about 39 000 was measured. NSC 113939 (1), NSC 113940 and 8-azaadenosine inhibited myocardial adenosine kinase. Dipyridamole stimulated the enzyme at high adenosine levels, and inhibited at low substrate concentrations. A number of divalent cations could (partially) substitute for Mg2+. The optimal concentration of MgCl2 or MnCl2 was about 0.5 mM; concentrations exceeding 1 mM inhibited severely. An apparent Km for ATP of 0.1 mM was measured, whereas an apparent Km for adenosine of 0.5 muM was was found. The latter increased to 3.3 muM, when dipyridamole was added. Replacement of ATP by GTB or ITP increased the activity, and UTP and CTP were inferior as a phosphate donor.
 ...
PMID:Partial purification and properties of rat-heart adenosine kinase. 7 32

Intact cells of Bacillus cereus catalyze the breakdown of exogenous AMP to hypoxanthine and ribose 1-phosphate through the successive action of 5'-nucleotidase, adenosine deaminase, and inosine phosphorylase. Inosine hydrolase was not detectable, even in crude extracts. Inosine phosphorylase causes a "translocation" of the ribose moiety (as ribose 1-phosphate) inside the cell, while hypoxanthine remains external. Even though the equilibrium of the phosphorolytic reaction favors nucleoside synthesis, exogenous inosine (as well as adenosine and AMP) is almost quantitatively transformed into external hypoxanthine, since ribose 1-phosphate is readily metabolized inside the cell. Most likely, the translocated ribose 1-phosphate enters the sugar phosphate shunt, via its prior conversion into ribose 5-phosphate, thus supplying the energy required for the subsequent uptake of hypoxanthine in B. cereus.
 ...
PMID:Utilization of exogenous purine compounds in Bacillus cereus. Translocation of the ribose moiety of inosine. 10 Apr 97

The syntheses of N1- and N2-isopropylformycin (10, 11), formycin 3',5'-cyclic and 2',3'-cyclic phosphate (3,7) and their N-methyl and N-isopropyl derivatives (13, 15, 19, 23) are described. It was observed that substitution at N1 or N2 with a bulky alkyl group or cyclic phosphorylation of the ribose moiety made formycin resistant to adenosine deaminase.
 ...
PMID:Cyclic phosphates of formycin. 20 7

Glucose transport into adipocytes of the rat was measured by monitoring the conversion of [1-(14)C]glucose into (14)CO(2). Glucose transport was made rate-limiting by increasing the flux through the pentose phosphate pathway with phenazine methosulphate, an agent that rapidly reoxidizes NADPH. Under these conditions, the observed rate of glucose disappearance from the incubation medium was about 20% higher than the rate of conversion of the C-1 of glucose into (14)CO(2). Apparent rates of glucose transport were significantly increased by insulin, H(2)O(2), adenosine and nicotinic acid. Stimulation of the apparent rate of glucose transport by insulin was dependent on adipocyte concentration, the hormone being most effective at relatively high cell concentrations. Adenosine and nicotinic acid further enhanced the maximum stimulation of glucose transport by insulin. Potentiation of insulin action by adenosine was more pronounced at lower cell concentrations. At relatively high cell concentrations the stimulatory action of insulin was markedly decreased by adenosine deaminase. Stimulation of apparent rates of glucose transport by the compounds noted above were antagonized by agents that increased intracellular cyclic AMP concentrations (theophylline and isoprenaline) and by dibutyryl cyclic AMP. Intracellular concentrations of cyclic AMP were significantly lowered when adipocytes were incubated with insulin, H(2)O(2), adenosine or nicotinic acid. These effects were observed under basal conditions or when intracellular cyclic AMP concentrations were elevated by theophylline or isoprenaline. On the basis of the above data, we suggest that insulin, H(2)O(2), adenosine and nicotinic acid may all stimulate glucose transport in rat adipocytes by lowering the intracellular cyclic AMP concentration. These data therefore support the hypothesis that cyclic AMP inhibits glucose transport in rat adipocytes.
 ...
PMID:Stimulation of glucose transport in rat adipocytes by insulin, adenosine, nicotinic acid and hydrogen peroxide. Role of adenosine 3':5'-cyclic monophosphate. 22 Sep 63

The effect of adenosine was tested on the energetic metabolism of fed rat liver cells after isolation. The cells were incubated in a buffered saline medium with glucose (5 mM) and adenosine (1 mM) for 30 minutes at 37 degrees C. This increased the concentration of the adenylic nucleotides ATP (+57 per cent, ADP (+39 per cent). Cyclic AMP was increased (+50 per cent) and the intracellular inorganic phosphate decreased (-22 per cent). These changes were accompaned by a decrease of glycogenolysis, glucose consumption and lactate production. Measurement of glycolytic intermediates showed decreased concentrations of fructose 1,6-bis-phosphate and 3-phosphoglycerate proportional to the increase in ATP concentration. The near-equilibrium of the glyceraldehyde 3-phosphate dehydrogenase-phosphoglycerate kinase system was not modified by adenosine. The decrease of the NAD+/NADH ratio along with the increase of the ATP/ADP X PO4 ratio explains the decrease of 3-phosphoglycerate. The decrease in glucose consumption can be explained by the cross over at the phosphofructokinase stage with the decrease of fructose 1,6-bisphosphate. The major part of adenosine was deaminated as indicated by an increase in the production of ammonia and urea. The effects of inosine, or adenosine along with an inhibitor of adenosine deaminase (pentostatin) suggest that adenosine acts on the glucose consumption through adenylic nucleotides. However the increase of the adenylic nucleotide level cannot totally explain the other metabolic changes: decrease of the NAD+/NADH cytoplasmic ratio, constancy of this ratio in mitochondria, decrease of gluconeogenesis from lactate. A direct action of adenosine can therefore be expected.
 ...
PMID:The influence of adenosine on intermediary metabolism of isolated hepatocytes. 23 80

All of the superoxide dismutase isozymes of Escherichia coli have been shown to occur in the cell matrix, and none have been found in the periplasm. This was the case with both E. coli B and E. coli K-12, whether grown on a low phosphate medium or on a Trypticase soy-yeast extract medium. Alkaline phosphatase was used as a marker of the periplasm; adenosine deaminase and glucose 6-phosphate dehydrogenase were used as matrix markers, and consistent results were obtained by osmotic shock, spheroplast formation, and use of a diazonium salt that penetrates the periplasm but cannot cross the plasma membrane. A previous report that the iron-containing superoxide dismutase of E. coli is a periplasmic enzyme is now seen to have been in error.
 ...
PMID:Intracellular localization of the superoxide dismutases of Escherichia coli: a reevaluation. 33 Apr 99

Mutations of the resistance to 2,6-diaminopurine (apt), which affect adenine phosphoribosyltransferase, fail to permit the growth of Escherichia coli pur mutants (purine auxotrophs which cannot make inosine monophosphate de novo) on the medium with 2,6-diaminopurine (DAP) as the sole source of purines. Addition of a small amount of hypoxantine, but not guanine, stimulated the growth of mutants of pur apt and pur apt+ genotypes on the medium with DAP. The utilization of DAP as purine source in the presence of hypoxantine is blocked by mutations guaC (guanosine monophosphate reductase), add (adenosine deaminase) and pup (purine necleoside phosphorylase), suggesting that DAP are utilized via purine nucleoside phosphorylase and adenosine deaminase. The drm mutation (that increases the level of pentose-1-phosphate in the cell) does not activate the utilization of DAP. The results indicate that a step, that limits the utilization of DAP as the sole source of purines by pur mutants of E. coli, is the deamination of DAP nucleoside.
 ...
PMID:[Genetic control of Escherichia coli K-12 strains' assimilation of 2,6-diaminopurine as a purine source]. 33 31

Purine metabolism and phosphoribosylpyrophosphate content of lymphocytes and erythrocytes were studied in an immunocompetent black male child with a total deficiency of erythrocyte and partial deficiency of lymphocyte adenosine deaminase. The partial genetic deficiency of adenosine deaminase was demonstrated in intact lymphocytes, and was approximately one third of the deaminating activity of control lymphocytes. Intact lymphocytes of the patient did not incorporate adenosine at a faster rate than those of control lymphocytes. The patient's erythrocytes deaminating activity was low and adenine ribonucleotide synthesis from adenosine was increased several fold, while adenine incorporation into purine ribonucleotides was comparable to that of control erythrocytes. Transfusion with packed erythrocytes temporarily improved the deaminating capacity of circulating erythrocytes, but did not reduce the elevated incorporation of adenosine into purine ribonucleotides. Phosphoribosylpyrophosphate content of the patient's lymphocytes and erythrocytes was not diminished. Incubation of erythrocytes with adenosine lowered phosphoribosylpyrophosphate content while incubation with phosphate increased phosphoribosylpyrophosphate content to the same extent in mutant and control erythrocytes.
 ...
PMID:Purine and phosphoribosylpyrophosphate metabolism of lymphocytes and erythrocytes of an adenosine deaminase deficient immunocompetent child. 47 97

To elucidate the mode of action of hexobendine, its effects on some enzyme activities, the uptake of adenosine by rat erythrocytes and changes in the concentration of various myocardial substrates following induced hypoxia in rat were studied. Hexobendine had no effect on the in vitro activities of the adenosine degrading enzyme, adenosine deaminase and of the A-PRTase, HG-PRTase which are associated with the salvage pathways of purine biosyntheses. The uptake of adenosine by rat erythrocytes in vitro was inhibited considerably by hexobendine. Hypoxic states results in a significant decrease in creatine phosphate, ATP, glycogen and glucose contents, and increase in ADP, AMP, adenosine and lactate contents in rat myocardials. These alterations in cardiac metabolism induced by hypoxia were significantly improved by hexobendine given orally in doses of 10 approximately 100 mg/kg. Thus, hexobendine was shown to maintain the normal aerobic energy metabolism of the heart under states of hypoxia. In such states adenosine may be released from tissues and this increase in the available concentration of adenosine in plasma through inhibition of uptake by erythrocytes may be involved in the coronary vasodilating action of hexobendine.
 ...
PMID:[Effects of hexobendine on adenosine metabolism and myocardial energy metabolism (author's transl)]. 74 50


1 2 3 4 5 6 7 8 9 10 Next >>