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

---

Query: EC:3.5.4.17 (adenosine deaminase)
5,206 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The uptake of adenosine in brush border vesicles of the proximal tubule of the rat kidney has been studied with a filtration technique. The initial rate of uptake was almost 6 times greater in the presence of NaCl than in the presence of KCl. The stimulatory effect of Na+ was strictly dependent on a gradient of Na+ (out greater than in). The time course of uptake showed an overshoot with a maximum at 20 s with a gradient of NaCl, but not with KCl. Inosine and 5'-AMP were produced from adenosine within the vesicles. In the presence of an inhibitor or adenosine deaminase adenosine was not significantly metabolized during the first 20 s of uptake. Thus, kinetic parameters of transport could be studied in the absence of interferences with metabolism. A Km of 1.1 microM and a Vmax of 232 pmol X min-1 X mg protein-1 were calculated for the Na+ gradient-dependent transport. The dependency on a Na+ gradient, the capacity for uphill transport and the high affinity for adenosine situate this transport system apart from the mechanisms of transport of nucleosides described so far. It may be relevant in regard to the role of adenosine in the regulation of glomerular filtration.
...
PMID:Sodium gradient-energized concentrative transport of adenosine in renal brush border vesicles. 647 65

Incubation medium, as previously described (J Histochem Cytochem 27:774, 1979), was used to demonstrate the presence of adenylate cyclase (AC) in myocardium. NaF and ouabain were used to inhibit adenosine triphosphatases (ATP) and NaF and isoproterenol were used as activators of AC. The inhibitory effect of adenosine on AC was blocked by the addition of adenosine deaminase. The addition of tetramisol blocked the influence of the alkaline phosphatases on adenylyl imidodiphosphate hydrolysis. The use of these substances resulted in specific precipitation localized in junctional sarcoplasmic reticulum and sarcolemma. The reaction product was dramatically intensified after activation of AC by NaF or isoproterenol. Preincubation in 10-100 mM of propranolol, for 30 min, blocked AC stimulation by isoproterenol and prevented the appearance of the specific precipitate. The localization of specific precipitate in junctional sarcoplasmic reticulum and subsarcolemmal cisternae corresponds to the localization of Na+, K+ ATPase and may reflect the similar role that AC and Na+, K+ ATPase play in calcium release from sarcoplasmic reticulum of internal and peripheral couplings.
...
PMID:Cytochemical studies of myocardial adenylate cyclase after its activation and inhibition. 669 May 96

In the determination of whether human thymus-leukemia-associated antigen (HThy-L) is a low-molecular-weight form of adenosine deaminase (ADA), both HThy-L and ADA were found to have the same molecular weight of 45,000 as estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The antigen and enzyme displayed a phenomenon of complete identity in immunodiffusion and a high degree of cross-reaction in a competitive radioimmunoassay for HThy-L or ADA. When tested for adenosine-deaminating activity, HThy-L was nearly as active as purified low-molecular-weight ADA from erythrocytes. However, HThy-L and ADA differed in their capacity to combine with the complexing protein isolated from human kidney. Apparently, HThy-L represents a thymic isoenzyme of ADA and is the first antigen to be associated with differentiation of hematopoietic cells for which a functional activity is established.
...
PMID:Identification of human thymus-leukemia-associated antigen as a low-molecular-weight form of adenosine deaminase. 676 72

Ecto-5'-nucleotidase is known to be diminished markedly in activated compared to control mouse macrophages. The level of three purine nucleoside metabolizing enzymes, adenosine deaminase (EC 3.5.4.4), purine nucleoside phosphorylase (EC 2.4.2.1), and adenine phosphoribosyltransferase (EC 2.4.2.7) were measured in the sonicates of different populations of mouse peritoneal macrophages. Levels of adenine phosphoribosyltransferase and purine nucleoside phosphorylase in macrophages that were elicited with sodium caseinate or activated in vivo by prior intravenous injection of Listeria monocytogenes were eight times higher than those in resident cells. Levels of adenosine deaminase also tended to increase and were two times higher in elicited cells than in resident cells. The Km of each enzyme was the same in each cell population. The findings suggest that the levels of the ecto-5'-nucleotidase and of the intracellular enzymes are coordinated.
...
PMID:Metabolism of purines in macrophages. Effect of functional state of the cells. 677 33

Alteration of membrane fluidity during enzymatic methylation of membrane phosphatidyl-ethanolamine (PE) and neutralization of negative charges of membrane proteins due to methylation of carboxyl groups may contribute to sperm motility. Therefore, enzymatic phospholipid methylation and carboxymethylation, and the consequences of their inhibition on motility, were studied using human sperm. These studies gave the following results. Human sperm homoganates contained two phospholipid N-methyltransferases (PMT) which converted PE to phosphatidylcholine (PC) in the presence of S-adenosylmethionine (SAM). The first PMT converted PE to phosphatidyl-N-methylethanolamine (PME). In had a Km of 4.0 microM and a pH optimum of 8.0. The second PMT converted PME to phosphatidyl-N,N-dimethylethanolamine and PC. It had a Km of 71 microM and a pH optimum of 10.0. Spermatozoa also contained protein carboxymethylase (PCM) and methyl aceptor protein (MAP). The intracellular levels of S-adenosylhomocysteine (SAH), an inhibitor of SAM-mediated methylations, were increased by adding adenosine (100 microM), L-homocysteine thiolactone (L-HCT, 10 microM), and erythro-9-(2-hydroxy-3-nonyl)-adenine (EHNA, 10 microM), an inhibitor of adenosine deaminase, to human sperm ejaculates that had been diluted with sodium phosphate buffer at pH 7.4 and 25 degrees. The motility index of each sperm suspension was determined every hour for 4 hr. In the presence of the mixture of adenosine, L-HCT and EHNA, the motility index was depressed by 57%. Under similar conditions, phospholipid methylation was depressed by 48%. Similar experiments were also conducted in the presence of 3-deazaadenosine (Deaza, 80 microM), a selective inhibitor of SAH hydrolase. In the presence of adenosine and L-HCT, Deaza depressed the motility index by 60% and phospholipid methylation by 86%. The potencies of SAH in the inhibition of phospholipid methylation and protein carboxymethylation in sperm homogenates had the following order: PMT I greater than PCM greater than PMT II. These observations indicate that the PMT system and/or the PCM-MAP system play a significant role in the regulation of human sperm motility.
...
PMID:Depression of human sperm motility by inhibition of enzymatic methylation. 686 Mar 62

Adenosine deaminase was purified 3038-fold to apparent homogeneity from human leukaemic granulocytes by adenosine affinity chromatography. The purified enzyme has a specific activity of 486 mumol/min per mg of protein at 35 degrees C. It exhibits a single band when subjected to sodium dodecyl sulphate/polyacrylamide-gel electrophoresis, non-denaturing polyacrylamide-gel electrophoresis and isoelectric focusing. The pI is 4.4. The enzyme is a monomeric protein of molecular weight 44000. Both electrophoretic behaviour and molecular weight differ from those of the low-molecular-weight adenosine deaminase purified from human erythrocytes. Its amino acid composition is reported. Tests with periodic acid-Schiff reagent for associated carbohydrate are negative. Of the large group of physiological compounds tested as potential effectors, none has a significant effect. The enzyme is specific for adenosine and deoxyadenosine, with Km values of 48 microM and 34 microM respectively. There are no significant differences in enzyme function on the two substrates. erythro-9-(2-Hydroxy non-3-yl) adenine is a competitive inhibitor, with Ki 15 nM. Deoxycoformycin inhibits deamination of both adenosine and deoxyadenosine, with an apparent Ki of 60-90 pM. A specific antibody was developed against the purified enzyme, and a sensitive radioimmunoassay for adenosine deaminase protein is described.
...
PMID:Purification, characterization and radioimmunoassay of adenosine deaminase from human leukaemic granulocytes. 694 96

Adenosine and ATP depressed resting O2 uptake in frog sartorius. This action was blocked by low levels of caffeine and by 8-phenyltheophylline. It was mimicked by a polymer of adenosine. Adenosine also decreased radioactive calcium uptake in muscles. Potassium and magnesium content were increased while sodium and calcium content were decreased by adenosine. Adenosine did not decrease oxygen uptake in muscles from frogs sacrificed in winter months. However, adenosine deaminase, which inactivates adenosine by removing the amino group, increased oxygen uptake, calcium content and lactate release of these muscles. Our results suggest that adenosine reduces resting metabolism, possibly through reducing passive leaks of electrolytes.
...
PMID:Effect of adenosine on oxygen uptake and electrolyte content of frog sartorius muscle. 697 47

Adenosine and the adenosine deaminase inhibitor erythro-9-(2-hydroxy-3-nonyl) adenine (EHNA), separately and in combination, were added to the perfusate of isolated rat hearts which were then subjected to ischaemia or anoxia. The effect of these infusates on the vascular competence of the myocardium subjected to oxygen deprivation of from 15-90 min was compared to control hearts. Vascular competence at selected time intervals was assessed from the distribution of injected. 1% sodium fluorescein in the cut surface of the ventricles. A region of non-perfusion surrounding the left ventricular lumen and involving 25% of the ventricular myocardium developed within 15 min of anoxic perfusion, with little change thereafter. Adenosine had no significant effect on this. The no-reflow phenomenon following ischaemia had similar distribution, but developed more slowly and eventually involved twice as much of the myocardium (59% after 90 min). Surprisingly, pre-treatment with adenosine greatly increased (from 14-46%) the extent of no-reflow after 30 min of ischaemia. Pre-treatment with EHNA caused a slight reduction (59-43%) in its extent but only after 60 min. Thus the no-reflow phenomenon which developed in ischaemic myocardium is unlikely to be due to the reduced vasodilatory action of adenosine.
...
PMID:The influence of adenosine on the no-reflow phenomenon in anoxic and ischaemic hearts. 709 21

Addition of coformycin (0.5 microgram/ml) to a culture medium containing adenine causes in Chinese hamster fibroblasts a lethal depletion of IMP. Resistant variants have been recovered, some of which exhibit increased adenylate deaminase activity. (Debatisse et al., J. Cell. Physiol., 106:1-11, 1981). The selective medium was made more specific for the isolation of this class of variants by supplementation with azaserine. The hyperactive variants remained sensitive to coformycin concentrations above that used for their selection and were unstable. Their frequency was not increased by ethyl methane sulfonate mutagenesis. The resistant phenotype and the increased activity of adenylate deaminase behaved as semidominant traits in hybrids. No change was detected in the Km for AMP, the cofactor requirement, or the chromatographic properties of adenylate deaminase in the variants. Through stepwise selection in media supplemented with increasing coformycin concentrations, unstable clones with adenylate deaminase activity up to 150-fold the wild-type level were isolated; from an unstable clone, a stable subclone with reduced resistance and enzyme activity was recovered. Evidence that increased adenylate deaminase activity is the manifestation of overaccumulation of the enzyme protein was supplied by the correlation of enzyme activity with the intensity of a protein band comigrating with purified adenylate deaminase during sodium dodecyl sulfate-polyacrylamide gel electrophoresis of cell extracts. Several unidentified additional bands showed comparable quantitative changes. The striking similarity between the adenylate deaminase-overproducing lines and unstable dihydrofolate reductase-overproducing lines generated by gene amplification strongly suggests that the coformycin-resistant variants also resulted from amplification of an adenylate deaminase gene.
...
PMID:Stepwise isolation and properties of unstable Chinese hamster cell variants that overproduce adenylate deaminase. 716 15

Application of heat to aqueous solutions of nucleoside dialdehydes (periodate-oxidized nucleosides) affords the corresponding alpha,beta-unsaturated aldehydes. The reaction was first discovered during studies with adenosine deaminase and was initially investigated enzymatically until the nature of the chemical transformation was determined. A UV peak at 230-250 n, characteristic of the alpha,beta-unsaturated aldehyde group, was obtained by difference spectroscopy and affords a more practical means to study the reaction. Adenosine dialdehyde, obtained by periodate oxidation of adenosine, afforded the same product upon heating as obtained by periodate oxidation of 9-(5-deoxy-beta-D-erythro-ent-4-enofuranosyl)adenine. Further proof of identity was obtained by reduction of these compounds with sodium borohydride and comparison of the dialchols obtained to each other and to a known unsaturated dialcohol. Heating of nucleoside dialdehydes at any time is not recommended. The exact composition of nucleoside dialdehydes used in previous and current biological studies is open to question.
...
PMID:Heat-induced formation of alpha,beta-unsaturated nucleoside dialdehydes and their activity with adenosine deaminase. 740 Nov 6


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

---