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:3.6.1.3 (ATPase)
65,361 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Amphiphiles are known to modulate the activity of ATPase, phospholipase A2, adenylate and guanylate cyclase amongst others and relax vascular smooth muscle. The effect of two amphiphiles, lysophosphatidylcholine (LPC) and digitonin on the activity of nitric oxide synthase (NOS), as measured by conversion of radiolabeled L-arginine to L-citrulline, has been studied. Neither digitonin (0.01 mmol/l) nor LPC (0.01 mmol/l) influenced NOS activity in endothelial cell homogenates. Digitonin but not LPC stimulated NOS in intact endothelial cells. NOS activity was markedly inhibited by L- but not by D-omega-nitroarginine (D-NNA, 0.1 mmol/l). L-NNA or D-NNA data demonstrate no effect of amphiphiles on isolated NOS. NOS activation may occur as a result of detergent action on the membrane.
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PMID:Effect of amphiphiles on nitric oxide synthase in endothelial cells. 751 49

The amphiphile lysophosphatidylcholine (LPC) modulates the activity of membrane-associated enzymes such as phospholipase A2, adenylate and guanylate cyclases and ATPase. LPC also relaxes vascular smooth muscle through production of nitric oxide. On the basis of reports that bradykinin translocates nitric oxide synthase (NOS) from the membrane to the cytosol, we investigated whether a similar translocation occurs with LPC. It was found that LPC translocated NOS from the membrane to the cytosolic fraction. Total NOS activity remained at the control level.
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PMID:Intracellular translocation of endothelial nitric oxide synthase by lysophosphatidylcholine. 754 Jul 65

Alterations in extracellular (pHo) and/or intracellular pH (pHi) have significant effects on the apical Na+ conductive transport in tight epithelia. They influence apical membrane Na+ conductance via a direct effect on amiloride-sensitive apical Na+ channel activity and indirectly through effects on the basolateral Na+/K(+)-ATPase. Changes in pH also modulate the hormonal regulation of apical Na+ conductive transport. The pH sensitive steps in hormone action include: (i) hormone-receptor binding, (ii) increase in intracellular cyclic 3',5'-adenosine monophosphate (cAMP), (iii) mobilization of intracellular free Ca2+ ([Ca2+]i), and (iv) incorporation of new channels into the apical membrane or recruitment of existing channels. Alternately, changes in pH induce secondary effects via alterations in [Ca2+]i. A reciprocal relationship between pHi and [Ca2+]i has been demonstrated in renal epithelial cells. Natriferic hormones induce a significant increase in pHi. There is a strong temporal relation between hormone-induced increase in pHi and overall increase in transepithelial Na+ transport. This suggests that changes in pHi act as an intermediate in the second messenger cascade initiated by the hormones. Several natriferic hormones activate Na(+)-H+ exchanger, H(+)-ATPase, H+/K(+)-ATPase, H+ conductive pathways in cell membranes or potential-induced changes in pHi. However, changes in pHi do not seem to be essential for the hormone effect on Na+ conductive transport. It is suggested that the role of pHi changes during hormone action is permissive rather than strictly obligatory.
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PMID:Regulation of apical Na+ conductive transport in epithelia by pH. 774 46

1. Endosulfan insecticide is a polychlorinated compound used for controlling a variety of insects; it is practically water-insoluble, but readily adheres to clay particles and persists in soil and water for several years. Its mode of action involves repetitive nerve-discharges positively correlated to increase in temperature. This compound is extremely toxic to most fish and can cause massive mortalities. In fish, it causes marked changes in Na and K concentrations, decrease in blood Ca(2+) and Mg levels and inhibits Na, K and Mg-dependent ATPase (in brain). 2. Bioaccumulation of endosulfan is reported for marine animals; however, freshwater animals (e.g., crayfish) accumulate it to some extent, but they lose the compound rapidly during depuration. Endosulfan is generally less toxic to aquatic invertebrates than fish. However, it causes decreases in adenylate energy charge, oxygen consumption, hemolymph amino acids, succinate dehydrogenase, heart-beat (mussel) and altered osmoregulation. 3. Generally, mammals are less susceptible to endosulfan's toxicity than aquatic animals. The majority of studies conducted on laboratory mammals can be summarized. (a) Neurotoxicity: male rats are more sensitive than females to endosulfan, which decreases brain and plasma acetylcholinesterase activity. Endosulfan I (a metabolite) causes a significant change in norepinephrine, 5-HT and GABA. (b) Renal toxicity: inhibition of MFOs activity was noticed in rats; other effects included changes in proximal convoluted tubules and necrosis of the tubular epithelium. (c) Hepatotoxicity: chemically-induced aminopyrine N-demethylase and aniline hydrolase were found in rat liver, and reduction in the glycogen level occurred. (d) Hematologic toxicity: endosulfan exposure resulted in a significant decrease in the level occurred. (d) Hematologic toxicity: endosulfan exposure resulted in a significant decrease in the erythrocyte glutathione reductase, hemoglobin amount, RBC number and mean corpuscular volume. 4. Respiratory toxicity: involved dyspnea, acute emphysema, cyanosis and hemorrhages in teh interalveolar portions of rat's lungs. 5. Biochemical: in rats, endosulfan caused increased glucose-6-phosphate dehydrogenase activity, blood glucose level, phospholipid contents of the microsomal and surfactant system, and profoundly induced the activity of alcohol dehydrogenase and cytosolic glutathione S-transferases. It also decreased significantly Na+, K+ and Mg(2+) ATPases, plasma calcium level and alkaline phosphatase in the intestinal epithelium. 6. Immunologic toxicity: rat serum antibody titer to tetanus toxin, IgG, IgM and gammaglobulins were significantly reduced. 7. Reproductive toxicity: degenerative changes in the seminiferous epithelium, induction of the rate-limiting enzyme in testosterone production (3beta-hydroxysteroid transferase and 17 beta-hydroxysteroid transferase), histological changes in reproductive organs, testicular atrophy and the occurrence of ovarian cysts were noticed in rat. Reduction in the weight of secondary sex organ was also observed.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Bioaccumulative potential and toxicity of endosulfan insecticide to non-target animals. 790 Sep 59

5-Nitroindole (NI), a mutagenic nitroarene, was assayed for cytotoxic effects on rat hepatocytes. After incubation with 25-100 microM NI, the adenylate energy charge of the hepatocytes decreased significantly as a result of the decrease in ATP and the increase in AMP. ATP depletion correlated well with the effects of NI on mitochondrial electron transfer and energy transduction in hepatocytes. Thus, NI (a) inhibited the antimycin-sensitive hepatocyte respiration; (b) inhibited NADH oxidation by disrupted hepatocyte mitochondria; (c) inhibited L-malate-L-glutamate oxidation by ADP-supplemented mitochondria; (d) in the absence of ADP, stimulated the same substrates and also succinate oxidation by mitochondria; (e) released the latent ATPase activity of mitochondrial F1F0-ATP synthase; (f) shifted the redox level of reduced cytochromes (c + c1) and b towards the oxidized state; (g) inhibited NADH oxidation by disrupted mitochondria in the vicinity of the NADH-dehydrogenase flavoprotein; (h) inhibited Ca2+ uptake by mitochondria using L-malate-L-glutamate as an energy source; (i) inhibited valinomycin-induced, endogenously energized K+ uptake, with little effect on the ATP-induced uptake; and (j) inhibited the MgATP-dependent contraction of Ca(2+)-swollen mitochondria. NI inhibited lipid peroxidation in hepatocytes and also in substrate-supplemented liver microsomes and mitochondria, thus ruling out hydroperoxides as a cause of NI cytotoxicity. Long-term incubation with NI produced loss of hepatocyte viability, as indicated by lactate dehydrogenase leakage.
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PMID:Effect of 5-nitroindole on adenylate energy charge, oxidative phosphorylation, and lipid peroxidation in rat hepatocytes. 794 49

The localization of some membrane-associated enzymes such as alkaline phosphatase, 5'-nucleotidase, glucose-6-phosphatase, Na+,K(+)-adenosine triphosphatase, adenylate cyclase and guanylate cyclase in the Merkel cell-axon complexes, trigeminal ganglia and the principal trigeminal sensory nucleus of the cat was determined at light and electron microscopic level using cytochemical techniques. In the sinus hair follicles (vibrissae), the reaction end product marking alkaline phosphatase and adenosine triphosphatase activities was visualized on the axons running through external follicle epithelium and the 5'-nucleotidase, adenylate- and guanylate cyclase positive reaction was seen to stain the plasma membranes of Merkel cells. In the trigeminal ganglia, the strongest alkaline phosphatase and adenosine triphosphatase activities showed the corresponding areas between the ganglion and satellite cells. 5'-nucleotidase activity was more intense on the neurilemmas and the surrounding glial plasma membranes. In the principle sensory trigeminal nucleus, the central neurons exhibited an intense alkaline phosphatase, 5'-nucleotidase and adenosine triphosphatase activities and much smaller amount of reaction product for adenylate cyclase and guanylate cyclase was observed. In conclusion, membrane-bound enzymes could be histo- and cytochemically demonstrated in all components of primary trigeminal afferent units. Our results have confirmed that the receptor function and the nerve impulses conductance need an intensive molecular and cation exchange, and energy supply.
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PMID:Primary trigeminal afferent neuron of the cat: I. Studies on membrane-bound enzyme histochemistry. 798 69

The activity and some kinetic properties of RBC Na+,K(+)-ATPase (EC 3.6.1.37) were investigated in essential hypertensives (EH; 40 subjects) and normotensives (NT; 20 subjects). A decrease in ouabain-sensitive 86Rb uptake as well as ouabain-sensitive ATPase activity was found in EH. [Na+]i and [K+]i of EH did not show any statistical difference from NT. Na+,K(+)-ATPase showed a reduced Mg2+ activation and the apparent Km value for Mg2+ was 2-fold increased in the EH group. The influence of temperature on the Na+,K(+)-ATPase showed a reduced modulation and a minor activity peak at 37 degrees C in the patients, consequently the calculated activation energy of the enzyme was increased at temperatures lower than 40 degrees C. Increased RBC adenylate energy charge (EC) was observed in EH when compared with NT. A negative correlation between EC and total Na+,K(+)-ATPase activity was found when all subjects were compared and also in both groups, showing a possible pump involvement in the regulation of the RBC metabolic flux in EH. These data provide evidence about some modifications in active Na+,K+ transport and in EC in RBC which allows a further characterization of membrane cation fluxes in EH.
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PMID:Erythrocyte Na+,K(+)-ATPase properties and adenylate energy charge in normotensives and in essential hypertensives. 800 87

Bovine tryptophanyl-tRNA synthetase (TrpRS, E.C.6.1.1.2) is unable to catalyze in vitro formation of Ap4A in contrast to some other aminoacyl-tRNA synthetases. However, in the presence of L-tryptophan, ATP-Mg2+ and ADP the enzyme catalyzes the Ap3A synthesis via adenylate intermediate. Ap3A (not Ap4A) may serve as a substrate for TrpRS in the reaction of E.(Trp approximately AMP) formation and in the tRNA(Trp) charging. The Km value for Ap3A was higher than the Km for ATP (approx. 1.00 vs. 0.22 mM) and Vmax was 3 times lower than for ATP. The Zn(2+)-deficient enzyme catalyzes Ap3A synthesis in the absence of exogenous ADP due to ATPase activity of Zn(2+)-deprived TrpRS. The inability of mammalian TrpRS to synthesize Ap4A, might be considered as a molecular tool preventing the removal of Zn2+ due to chelation by Ap4A and therefore preserving the enzyme activity.
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PMID:P1,P3-bis(5'-adenosyl)triphosphate (Ap3A) as a substrate and a product of mammalian tryptophanyl-tRNA synthetase. 807 May 80

The systems regulating the levels of Ca(2+)-Mg2+, Ca(2+)-ATPase and potential-dependent absorption of Ca2+ as well as content of cyclic nucleotides, beta-adrenoreceptors, activities of adenylate-, guanylate cyclases and phosphodiesterase were studied in the synaptosomes of rat brain cortex in evolving myocardial infarction. In addition, reverse absorption of noradrenaline, dopamine and serotonin was studied. In one of the animal groups myocardial infarction was simulated after stress. The myocardial infarction, affecting the systems of Ca2+ regulation, caused an increase in reverse absorption of dopamine and serotonin simultaneously with accumulation of lactate in the synaptosomes. In myocardial infarction developed after stress adenylate cyclase was activated, reverse absorption of dopamine was decreased and the content of lactate tended to decrease as compared with the infarction formed without stress effects.
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PMID:[Systems for regulating the level of Ca2+, cyclic nucleotides, and reverse absorption of neurotransmitters in isolated nerve endings of the rat brain during development of myocardial infarct]. 809 86

1. Adenine nucleotide concentrations and metabolism in red blood cells (RBC) and RBC ghosts from psoriatic patients and healthy subjects were compared. 2. The ATP and total adenine nucleotide levels and the adenylate energy charge (EC) were elevated in the blood from psoriatic patients. 3. The rate of glycolytic production of ATP by intact RBC was unchanged, but the Na+, K(+)-ATPase activity of RBC ghosts was decreased significantly in psoriasis. 4. Results suggest that the defect in adenine nucleotide metabolism is a systemic manifestation of psoriasis, and that the quantification of adenine nucleotides in RBC and in whole blood samples may be of pathophysiological value in psoriatic lesion.
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PMID:Energy metabolism of human erythrocytes in psoriasis. 813 28


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