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)

The adenylate cyclase and Na+ -K+ ATPase activities decreased on storage at 4 degrees C as well as on freezing and thawing of the rat heart sarcolemma. Treatment of the sarcolemmal fraction with phospholipase C and trypsin also depressed the adenylate cyclase and Na+ -K+ ATPase activities; the Na+ -K+ ATPase was more sensitive to these treatments than the adenylate cyclase. When the sarcolemmal enzyme activities were determined in the presence of different concentrations of some cations the adenylate cyclase activity was enhanced and the Na+ -K+ ATPase activity was depressed by monovalent cations (Na+, K+, Rb+, Cs+, Li+, and NH+4). Divalent cations such as Sr2+, Ba2+, Co2+, and Mn2+ had biphasic or no effects on the adenylate cyclase activity but inhibited the Na+ -K+ ATPase activity. Although Ca2+, Ni2+, Cd2+, Cu2+, Hg2+, and Zn2+ depressed both Na+ -K+ ATPase and adenylate cyclase activities, the degree of inhibition of these enzymes was different. These results reveal the role of membrane integrity for full expression of the adenylate cyclase and Na+ -K+ ATPase activities, whereas both monovalent and divalent cations appear to regulate sarcolemma-bound enzyme activities.
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PMID:Role of membrane integrity and cation interaction for heart sarcolemmal adenylate cyclase and Na+-K+ ATPase. 630 75

Enzymatic activity which hydrolyzes diadenosine 5',5"'-P1,P4-tetraphosphate (Ap4A) yielding ADP has been identified in extracts of eubacteria, Escherichia coli and Acidaminococcus fermentans, and of a highly thermophilic archaebacterium, Pyrodictum occultum. Specific Ap4A (symmetric) pyrophosphohydrolase from Escherichia coli K12 has been purified almost 400-fold. The preparation was free of phosphatase, ATPase, phosphodiesterase, AMP-nucleosidase, and adenylate kinase. The Ap4A pyrophosphohydrolase molecular weight estimated by gel filtration is 27,000 +/- 1,000. Activity maximum is at pH 8.3. The Km value computed for Ap4A is 25 +/- 3 microM. The sulfhydryl group(s) is essential for enzyme activity. Metal chelators, EDTA, and o-phenanthroline, inhibit Ap4A hydrolysis; I0.5 values are 3 and 50 microM, respectively. Co2+ is a strong stimulator with an almost 100-fold increase in rate of Ap4A hydrolysis and a plateau in the range of 100-500 microM Co2+, when compared with the nonstimulated hydrolysis. Other transition metal ions, Mn2+, Cd2+, and Ni2+, stimulate by factors of 8, 3.5, and 3.5, respectively, with optimal concentrations in the range 200-500, 2-5, and 4-8 microM, respectively. Zn2+, Cu2+, and Fe2+, up to 30 microM, are without effect and they inhibit at higher concentrations. Mg2+ or Ca2+, in the absence of other divalent metal ions, are weak stimulators (1.5-fold stimulation occurs at 1-2 mM concentration), but act synergistically with Co2+ at its suboptimal concentrations. Stimulation in the presence of 10 microM Co2+ and either 1 mM MgCl2 or CaCl2 increases up to 75-fold. The same degree of synergy is found at 10 microM Co2+ and either 2-5 mM spermidine or 0.5-1.5 mM spermine. Besides Ap4A, bacterial Ap4A pyrophosphohydrolase hydrolyzes effectively Ap5A and Gp4G, and, to some extent, p4A, Ap6A, and Ap3A yielding in each case corresponding nucleoside diphosphate as one of the products.
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PMID:Catabolism of diadenosine 5',5"'-P1,P4-tetraphosphate in procaryotes. Purification and properties of diadenosine 5',5"'-P1,P4-tetraphosphate (symmetrical) pyrophosphohydrolase from Escherichia coli K12. 631 72

Vacuolar membrane vesicles of Saccharomyces cerevisiae accumulate Ca2+ ion in the presence of ATP, not in the presence of ADP or adenyl-5'-yl imidodiphosphate. Calcium transport showed saturation kinetics with a Km value of 0.1 mM and optimal pH of 6.4. Ca2+ ion incorporated in the vesicles was exchangeable and released completely by a protonophore uncoupler, 3,5-di-tert-butyl-4-hydroxybenzilidenemalononitrile (SF6847), or calcium-specific ionophore, A23187. The transport required Mg2+ ion but was inhibited by Cu2+ or Zn2+ ions, inhibitors of H+-ATPase of the vacuolar membrane. The transport activity was sensitive to the H+-ATPase inhibitor N,N'-dicyclohexylcarbodiimide, but not to oligomycin or sodium vanadate. SF6847 or nigericin blocked Ca2+ uptake completely, but valinomycin stimulated it 1.35-fold. These results indicate that an electrochemical potential difference of protons is a driving force for this Ca2+ transport. The ATP-dependent formation of the deltapH in the vesicles and its partial dissipation by CaCl2 were demonstrated by fluorescence quenching of quinacrine. This Ca2+ uptake by vacuolar membrane vesicles is suggested to be catalyzed by a Ca2+/H+ antiport system.
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PMID:Calcium transport driven by a proton motive force in vacuolar membrane vesicles of Saccharomyces cerevisiae. 634 90

The mechanism of transport of basic amino acids into vacuoles of cells of the yeast Saccharomyces cerevisiae was investigated in vitro. Right-side-out vacuolar membrane vesicles were prepared from purified vacuoles. Arginine was taken up effectively by the vesicles only in the presence of ATP, not in the presence of ADP or AMP-adenosyl-5'-yl imidodiphosphate. It was exchangeable and was released completely by a protonophore, 3,5-di-tert-butyl-4-hydroxybenzilidenemalononitrile (SF6847). The transport required Mg2+ ion but was inhibited by Cu2+, Ca2+, or Zn2+ ions. The transport activity was sensitive to the ATPase inhibitor N,N'-dicyclohexylcarbodiimide (DCCD), but not to oligomycin or sodium vanadate. SF6847 or nigericin blocked arginine uptake completely, but valinomycin had no effect. ATP-dependent formation of a delta pH across the membrane vesicles was shown by quenching of 9-aminoacridine fluorescence. These results indicate that DCCD-sensitive, Mg2+-ATPase of vacuolar membranes is essential as an energy-donating system for the active transport, and that an electrochemical potential difference of protons is a driving force of this basic amino acid transport. Arginine transport showed saturation kinetics with a Km value of 0.6 mM and the mechanism was well explained by an H+/arginine antiport.
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PMID:Active transport of basic amino acids driven by a proton motive force in vacuolar membrane vesicles of Saccharomyces cerevisiae. 645 Jul 64

The ATPase activity of purified coupling factor 1 (CF1) of spinach chloroplasts [EC 3.6.1.3] was reversibly enhanced in some aqueous organic solvents, notably methanol, ethanol, and acetone. Pretreatment of CF1 with 20% (v/v) methanol did not affect the subsequent activity. The activity depended entirely on the final concentration of methanol in the reaction mixture. In the presence of 20% methanol, the Km of Ca2+-ATPase from ATP was lowered from 0.4 mM to 0.2 mM. Not only Ca2+, but also Cd2+, Mg2+, Mn2+, and Zn2+ supported the ATPase activity at rates of higher than 7 mumol.mg protein-1 . min-1. Co2+, Ni2+, and Pb2+ supported the activity at rates of 0.5-1.0 mumol.mg protein-1 . min-1. The activities supported by the following cations, if any, were less than 0.2 mumol.mg protein-1 . min-1; Ba2+, Cu2+, Fe2+, Hg2+, Sn2+, and Sr2+. The optimum concentration of methanol for Ca2+-ATPase and Mg2+-ATPase activities was about 30% (v/v). The optimum pH values for Ca2+-ATPase and Mg2+-ATPase activities were about 8.0 and 8.8, respectively. The enhancing effect of organic solvents appears to be associated with their relative lipophilic character as defined by the octanol-water partition coefficient. The Ca2+-ATPase activities of th trypsin-activated and the heat-activated CF1 were inhibited and their Mg2+-ATPase activities were enhanced by the presence of methanol in the reaction mixture.
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PMID:Enhancement of adenosine triphosphatase activity of purified chloroplast coupling factor 1 in aqueous organic solvent. 645 34

Iron-deficient rats were co-exposed to manganese and lead to study lipid peroxide formation and contents of lead, manganese, copper, iron, zinc and calcium in the brain. Concurrent exposure to lead and manganese increased the lipid peroxidation potential of brain in iron-deficient rats. The concentration of lead, manganese and copper in the brain of iron-deficient rats increased to a greater magnitude after concurrent exposure to manganese and lead, compared with that observed after the exposure of either of the metals alone. Since copper is a potent inhibitor of transport ATPase in the brain, its significant increase, coupled with increased lipid peroxidation in the brain of iron-deficient rats, may be responsible for enhanced susceptibility of iron-deficient rats to the neurotoxic effects after the combined exposure to lead and manganese.
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PMID:Concurrent exposure of lead and manganese to iron-deficient rats: effect on lipid peroxidation and contents of some metals in the brain. 671 79

An electron microscopic study was performed to elucidate the ultrastructural alterations of the cerebrum in experimental copper loading. Copper acetate solution was administered intravenously to nine adult dogs in a dose of 1.5 mg free copper per kilogram of body weight every other day for 13 to 112 days. Eight adult dogs were used for control. Tissue for ultrastructural examination and determination of copper concentration was taken from the cerebral cortex, cerebral medulla, caudate nucleus, and thalamus. The copper concentration was determined by atomic absorption spectrophotometry. 1) Copper Concentration of the Cerebrum Mean copper concentration in each part of the brain of the copper loaded dogs increased about two-fold of each mean value of the control group. No significant correlation was observed between copper concentration and the total dosage or duration of administration. 2) Ultrastructural Findings It was noteworthy that many osmiophilic concentric lamellar structures (or myelin figures) were observed in nerve cells, especially neuronal processes-both axons and dendrites, rather than in glial cells. The same structures were found within mitochondria in endothelial cells of capillaries and arterioles. Vascular feet of astrocytes abutting these capillaries displayed marked edematous swelling. From these findings, I considered the following possibility; 1) These lamellar structures in nerve cells were thought to be autophagic vacuoles and residual bodies derived from disintegrated organelles especially mitochondria digested by lysosomal enzymes in autophagic process. As many of them were found in nerve cells rather than in glial cells, I considered that copper is more toxic to nerve cells than to glial cells. 2) The same structures were found within mitochondria in endothelial cells of capillaries and arterioles. In their formation, it was assumed that lysosomal enzymes were not concerned. As copper is a divalent metal and is known to be an ATPase inhibitor, I speculate that copper nonenergizes mitochondria and then cristae fuse and roll into scroll. These become denser and consequently intramitochondrial lamellar structures are formed. These alterations of mitochondria are thought to influence the permeability of the blood-brain barrier.
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PMID:[An electron microscopic study of the cerebrum in experimental copper loading (author's transl)]. 727 87

Wilson's disease is an autosomal recessive, inherited disorder of copper metabolism. In normal individuals, copper homeostasis is controlled by the balance between intestinal absorption of dietary copper and hepatic excretion of excess copper in bile. In Wilson's disease, hepatic copper is neither excreted in bile nor incorporated into ceruloplasmin and copper accumulates to toxic levels. The Wilson's disease gene (WND) encodes a putative copper-transporting protein that is expressed almost exclusively in the liver. The predicted structure of the protein product is that of a P-type ATPase with striking homology to bacterial copper transporters and the gene product of another inherited disorder of copper metabolism, Menkes' disease. A rat model of Wilson's disease has recently been identified. The Long-Evans Cinnamon (LEC) rat manifests elevated hepatic copper, defective incorporation of copper into ceruloplasmin, and reduced biliary excretion of copper. The rat homologue of the WND is abnormal in LEC rats. Clinical manifestations of Wilson's disease arise directly from copper-induced damage to hepatocytes (hepatic presentation) or indirectly after the release of copper from the liver with subsequent damage to the brain (neuropsychiatric presentation) and other organs. Genetic heterogeneity (different mutations in a single gene) may account for some of the variability in Wilsonian presentations. The diagnosis of Wilson's disease depends on the demonstration of disordered copper metabolism, manifested as elevated urinary and hepatic copper and low ceruloplasmin levels. However, none of the abnormal findings in Wilson's disease is pathognomonic. Genetic diagnosis, in the absence of family studies, is likely to be difficult since many different mutations result in the disease. Management of Wilson's disease involves decreasing excess levels of copper accumulated in the liver, brain, and other organs. Copper chelation therapy, to increase urinary excretion of copper, is the mainstay of treatment. In addition, oral zinc therapy may be useful at decreasing absorption of dietary copper and rendering tissue copper nontoxic, by increasing the formation of complexes with copper-binding proteins. Liver transplantation can be necessary for individuals with acute hepatic failure or complications of cirrhosis. Gene therapy may evolve in the future; however, medical management is effective in most patients.
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PMID:Wilson's disease: a new gene and an animal model for an old disease. 755 82

Copper(II) complexes were encapsulated in human red blood cells in order to test their possible use as antioxidant drugs by virtue of their labile character. ESR spectroscopy was used to verify whether encapsulation in red blood cells leads to the modification of such complexes. With copper(II) complexes bound to dipeptides or tripeptides, an interaction with hemoglobin was found to be present, the hemoglobin having a strong coordinative site formed by four nitrogen donor atoms. Instead, with copper(II) complexes with TAD or PheANN3, which have the greatest stability. ESR spectra always showed the original species. Only the copper(II) complex with GHL gave rise to a complicated behavior, which contained signals from iron(III) species probably coming from oxidative processes. Encapsulation of all copper(II) complexes in erythrocytes caused a slight oxidative stress, compared to the unloaded and to the native cells. However, no significant differences were observed in the major metabolic properties (GSH, glycolytic rate, hexose monophosphate shunt, Ca(2+)-ATPase) of erythrocytes loaded with different copper(II) complexes, with the exception of methemoglobin levels, which were markedly increased in the case of [Cu(GHL)H-1] compared to [Cu(TAD)]. This latter finding suggests that methemoglobin formation can be affected by the type of complex used for encapsulation, depending on the direct interaction of the copper(II) complex with hemoglobin.
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PMID:Copper(II) complexes encapsulated in human red blood cells. 759 66

The gene defective in Menkes disease, an X-linked recessive disturbance of copper metabolism, has been isolated and predicted to encode a copper-binding P-type ATPase. We determined the complete exon-intron structure of the Menkes disease gene, which spans about 150 kb of genomic DNA. The gene contains 23 exons, and the ATG start codon is in the second exon. All of the exon-intron boundaries were sequenced and conformed to the GT/AT rule, except for the 5' splice site of intron 9. A preliminary comparison demonstrated a striking similarity between the exon structures of the Menkes and Wilson disease genes, giving insight into their evolution.
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PMID:Characterization of the exon structure of the Menkes disease gene using vectorette PCR. 760 65


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