Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.6.1.3 (ATPase)
 65,361 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A simple and fast ion pair reversed-phase high-performance liquid chromatographic method has been developed for the simultaneous determination of ATP, ADP, AMP, GTP, GDP, IMP, NADP+, NADPH+, NAD+, NADH, ADP-ribose, inosine, adenosine, hypoxanthine, and xanthine. This method allows us to have a complete picture of the most important nucleotides present in fresh human erythrocytes. Furthermore it is particularly useful in the study of the erythrocyte adenine nucleotide catabolism allowing the detection of degradation products such as IMP, inosine, adenosine, hypoxanthine, and xanthine. The separation of the compounds under investigation is achieved in less than 15 min using a reversed-phase 3-micron Supelcosil LC-18 column and adding tetrabutylammonium, as ion-pair agent, to the buffers. The short time of analysis, the high reproducibility of the system, and the accurate evaluation of the compounds of interest make this method particularly suitable for routine analysis. Finally it is possible to use this assay as an alternative method of measuring activities of enzymes which catalyze reactions involving some of these compounds, as in the case of Na+-K+ ATPase, AMP deaminase, and adenosine deaminase.
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PMID:A very fast ion-pair reversed-phase HPLC method for the separation of the most significant nucleotides and their degradation products in human red blood cells. 282 56

Changes in the biophysical and biochemical character of membranes brought about by ethanol have been emphasized in the underlying mechanism of alcohol toxicity. Membrane enzymes such as Na+, K+ activated ATPase, 5'-nucleotidase, and gamma-glutamyl transpeptidase were studied in cerebral cortex, cerebellum, and brain stem of rats subjected to acute and short term ethanol toxicity. Acute ethanol toxicity was induced by intraperitoneal injection of 1 ml of 7M ethanol per 100 g body weight of rat and the animals were sacrificed half an hour after the administration. Short term ethanol toxicity was induced by intraperitoneal injections of 0.5 ml (7 M ethanol) per 100 g weight of the rat for 7 days and the animals were sacrificed half an hour after the last injection. In acute ethanol toxicity the activity of Na+, K+-activated ATPase was found to decrease significantly in cerebral cortex and brain stem, while in short term alcohol toxicity, the activity was found to increase in cerebral cortex and cerebellum. The activity of gamma-glutamyl transpeptidase was found to increase in all the three regions in acute and short term ethanol toxicity. No change in the activity of 5'-nucleotidase was observed in any of the regions either in acute or in chronic ethanol toxicity. While a significant increase in the activity of adenosine deaminase was found in cerebral cortex, cerebellum, and brain stem in acute ethanol toxicity, the same was found to decrease significantly in cerebral cortex and a persistent increase in brain stem in short term ethanol toxicity. The above changes in the activities of the enzyme were discussed with reference to the well known changes in the membrane structure and consequent alteration in brain function.
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PMID:Acute and short term effects of ethanol on membrane enzymes in rat brain. 286 24

Attempts to identify mechanisms by which calcium antagonists might influence intracellular metabolism have not yet yielded conclusive findings. In this study bepridil, verapamil, nifedipine, and nisoldipine were found to have no influence on the rate of rat heart myosin adenosine triphosphatase or the calcium dependence of myofibrillar adenosine triphosphatase. None of these calcium antagonists alters the rate of reaction of any of the adenine nucleotide catabolic or adenosine salvage enzymes, adenylate kinase, creatine kinase, adenosine kinase, adenosine deaminase, or 5' nucleotidase, in extracts of rat heart. All four compounds, however, reduced, apparently in a non-specific manner, the rate of uptake of adenosine by myocytes isolated from rat heart. It is concluded that calcium antagonists may, through intercalation with the sarcolemmal membrane, inhibit efflux of adenosine formed by catabolism of adenine nucleotides in ischaemic myocytes. This might offer therapeutic advantage since the intracellular concentration of adenosine would thereby be increased, allowing an increased rate of incorporation of adenosine into the adenosine triphosphate pool in reoxygenated myocardium.
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PMID:Calcium antagonists and adenine nucleotide metabolism in rat heart. 349 85

The present study was undertaken to demonstrate and characterize potentiation of ventricular overdrive suppression by adenosine. To substantiate that adenosine has an enhanced effect on overdrive suppression, it would be necessary to demonstrate that adenosine increases pause duration independent of slowing spontaneous pre-drive rate. In isolated perfused guinea pig hearts with surgically induced complete atrioventricular block, the effect of adenosine (2-20 microM) on pause duration was compared to two alternative means of slowing the pre-drive rate, i.e., hypothermia (28.0 degrees C to 34.0 degrees C) and cesium chloride (0.3-1.0 mM). The slope value of the linear regression line describing the relationship between pre-drive cycle length and pause duration for adenosine (15.8) was significantly greater than control (1.7), hypothermia (1.7), and cesium chloride (5.4). The competitive adenosine antagonist, aminophylline (60 microM), when infused at the initiation of overdrive during adenosine administration, significantly reduced the effect of adenosine on pause duration by 72.9 +/- 4.2% (mean +/- SEM). The reduction in pause duration by aminophylline was specific for adenosine and did not occur under control conditions or during cesium chloride administration. During hypoxia, aminophylline and adenosine deaminase, when infused at the initiation of overdrive, caused 72.3 +/- 5.6 and 63.3 +/- 6.1% reductions in pause duration, respectively. Endogenous adenosine levels rose significantly with hypoxia (1,687 +/- 202 vs. 36 +/- 4 pmol/min per g during normoxia) and increased significantly further during hypoxic overdrive (3,004 +/- 323 pmol/min per g). In isolated guinea pig Purkinje fibers (n = 4), adenosine (20 microM) increased pause duration by 73.6 +/- 9.9% while only minimally affecting the pre-drive cycle length (7.6 +/- 3.8%). These fibers, when stimulated at 1.5 Hz, also displayed an adenosine-induced reduction in action potential duration at 90% repolarization (16 +/- 2 msec). In addition, we demonstrated that adenosine had an enhanced effect on pause duration in the presence of ouabain (1 microM)-induced attenuation of overdrive suppression. Thus, in isolated Purkinje fibers, it is unlikely that the potentiating effect of adenosine on pause duration, which is independent of its chronotropic effect, is mediated via an enhancement of sodium potassium adenosine triphosphatase pump activity. The effect of adenosine is likely to be secondary to a direct action on outward potassium conductance.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Role of adenosine on ventricular overdrive suppression in isolated guinea pig hearts and Purkinje fibers. 404 82

The synthesis of fluorescent derivatives of nucleosides and nucleotides, by reaction with isatoic anhydride in aqueous solution at mild pH and temperature, yielding their 3'-O-anthraniloyl derivatives, is here described. The N-methylanthraniloyl derivatives were also synthesized by reaction with N-methylisatoic anhydride. Upon excitation at 330-350 nm these derivatives exhibited maximum fluorescence emission at 430-445 nm in aqueous solution with quantum yields of 0.12-0.24. Their fluorescence was sensitive to the polarity of the solvent; in N,N-dimethylformamide the quantum yields were 0.83-0.93. The major differences between the two fluorophores were the longer wavelength of the emission maximum of the N-methylanthraniloyl group and its greater quantum yield in water. All anthraniloyl derivatives, as well as the N-methylanthraniloyl ones, had virtually identical fluorescent properties, regardless of their base structures. The ATP derivatives showed considerable substrate activity as a replacement of ATP with adenylate kinase, guanylate kinase, glutamine synthetase, myosin ATPase and sodium-potassium transport ATPase. The ADP derivatives were good substrates for creatine kinase and glutamine synthetase (gamma-glutamyl transfer activity). The GMP and adenosine derivatives were substrates for guanylate kinase and adenosine deaminase, respectively. All derivatives had only slightly altered Km values for these enzymes. While more fluorescent in water, the N-methylanthraniloyl derivatives were found to show relatively low substrate activities against some of these enzymes. The results indicate that these ribose-modified nucleosides and nucleotides can be versatile fluorescent substrate analogs for various enzymes.
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PMID:New ribose-modified fluorescent analogs of adenine and guanine nucleotides available as substrates for various enzymes. 613 22

The activities of 5'-nucleotidase (5'-ribonucleoside phosphohydrolase, EC 3.1.3.5); adenosine deaminase (adenosine aminohydrolase, EC 3.5.4.4); AMP deaminase (AMP aminohydrolase, EC 3.5.3.6), and ATP-(Mg2+)-ase (ATP phosphohydrolase, EC 3.6.1.3) were assayed in mitochondria of normal and regenerating rat liver 5'-Nucleotidase (5'Nase) and ATP-(Mg2+)-ase activities were compared with similar enzyme activities in the plasma membrane (PM) fraction, obtained from the same biological material. In the regenerating liver, 5'Nase for dTMP diminished its activity by 56% (24 h after partial hepatectomy) and 35 +/- 4% for all substrates in the PM fraction (48 h after operation). In mitochondria, 5'Nase for dTMP manifests sigmoidal substrate activity curve (in contrast with all substrates in the PM fraction and remaining substrates in mitochondria). In vivo 5-azacytidine (a) administered 1 h after partial hepatectomy, prevented changes of 5'Nase activity: (b) administered 24 or 48 h after partial hepatectomy, stabilized low 5'Nase activity (in mitochondria for dTMP, in the PM fraction for all substrates) and decreased ATP-(Mg2+)-ase activity by 51 and 31% in mitochondria and the PM fraction respectively.
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PMID:A distinctive activity of 5'-nucleotidase for dTMP in rat liver mitochondria. 615 75

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.
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PMID:Cytochemical studies of myocardial adenylate cyclase after its activation and inhibition. 669 May 96

Changes in oxidative metabolism were studied in hepatopancreas, muscle, and hemolymph of the edible crab Scylla serrata, exposed to a sublethal concentration (2.5 ppm) of cadmium chloride. A significant decrease in glycogen, total carbohydrates, and pyruvate and an increase in lactate levels in hepatopancreas and muscle were observed. Hemolymph sugar levels were increased in experimental crabs. An increase in phosphorylase suggested increased glycogenolysis during cadmium toxicity. The decrease in lactate dehydrogenase activity and the increase in lactate content indicated reduced mobilization of pyruvate into the citric acid cycle. Krebs cycle enzymes such as succinate dehydrogenase and malate dehydrogenase were found to be decreased, suggesting impairment of mitochondrial oxidative metabolism as a consequence of cadmium toxicity. Glucose-6-phosphate dehydrogenase activity was increased, suggesting enhanced oxidation of glucose by the HMP pathway. Cytochrome-c oxidase and Mg2+ ATPase activity levels decreased, indicating impaired energy synthesis during cadmium stress. Acid and alkaline phosphatase activities increased, suggesting enhanced breakdown of phosphates to release energy in view of impaired ATPase system during cadmium exposure. A significant decrease in protein and free amino acid and an increase in ammonia, urea, and glutamine levels were observed in the tissues during exposure. An increase in protease, alanine aminotransaminase, and aspartate aminotransaminase suggested increased proteolysis and transamination of amino acids. The increase in glutamate dehydrogenase, AMP deaminase, and adenosine deaminase indicated increased ammonia production. The increased arginase and glutamine synthetase suggested the detoxification or mobilization of ammonia toward the production of urea and glutamine. These results suggest that cadmium affects oxidative metabolism and induces hyperammonemia, and crabs switch over their metabolic profiles toward compensatory mechanisms for the survivability in cadmium-polluted habitats.
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PMID:Changes in oxidative metabolism in selected tissues of the crab (Scylla serrata) in response to cadmium toxicity. 753 86

Adenosine A1 receptor densities were increased in cultured LLC-PK1 and OK cells by chronic treatment with the adenosine receptor antagonists 1,3,7-trimethylxanthine (caffeine, 1 mM) and 1,3-dimethyl-8-cyclopentylxanthine [cyclopentyltheophylline (CPT), < or = 0.4 mM], respectively. The A1 receptor number per cell was increased twofold by 10-day treatments with 1 mM caffeine or 0.1 mM CPT, and the sodium-coupled glucose uptake was augmented twofold by 1 mM caffeine and sevenfold by 0.1 microM CPT (higher doses of CPT were progressively less stimulatory). Glucose uptake was blocked by acute (2-h) treatment with CPT, adenosine deaminase, or calphostin C. Caffeine (1 mM) or CPT (> or = 0.1 mM) inhibited cell proliferation for the first 10 days, then cell growth assumed a normal proliferative rate despite continued presence of antagonist. Cytosolic protein kinase C (PKC) beta-isoform immunoactivity and PKC-beta II mRNA were elevated at least twofold during 10 days of 0.1 mM CPT or 1 mM caffeine treatment. The sustained elevation in sodium-glucose symport and PKC activity observed with adenosine receptor antagonists was similar to acute (2-h) effects of the adenosine A1 agonist R(-)-N6-phenylisopropyladenosine (R-PIA, 0.1-1 microM). Moreover, cell proliferation was increased by adenosine (0.1 microM R-PIA), whereas Na-K-adenosinetriphosphatase activity was unaltered with chronic antagonist or acute adenosine treatments. Caffeine treatment may have some non-adenosine A1 receptor-mediated actions, because it slightly (30%) augmented protein kinase A activity. It is concluded that chronic exposure of proximal tubule cells to caffeine or CPT augments PKC and sodium-glucose transport but retards cell proliferation mainly via adenosine A1 receptor-mediated mechanisms.
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PMID:Upregulated renal adenosine A1 receptors augment PKC and glucose transport but inhibit proliferation. 877 86

The effect of 2-chloroadenosine, stable adenosine analog, and deoxycoformycin, adenosine deaminase inhibitor on brain ATP level and Na-K ATPase activity in ischemia were studied. The brain ATP level was increased after we administered both 2-chloroadenosine and deoxycoformycin, but Na-K ATPase activity did not change after deoxycoformycin. The results suggest that 2-chloroadenosine treatment influenced both the ATP production and membrane permeability due to cerebral ischemia. Deoxycoformycin did not protect the membrane permeability, although it increased the ATP production.
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PMID:The effects of 2-chloroadenosine and deoxycoformycin on the ATP level, Na-K ATPase activity in experimental brain ischemia of gerbil. 887 54


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