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)

Phthalate esters have shown to stimulate the latent ATPase [EC 3.6.1.3] activity and induce mitochondrial swelling. Among the tested phthalate esters, di-n-butyl phthalate (DBP) exhibited the greatest activity, and the activity decreased progressively as the alkyl chain was lengthened or shortened. The DBP-stimulated ATPase was oligomycin-sensitive. The degree of stimulation of the ATPase was proportional to the extent of mitochondrial swelling induced by DBP in 0.1 M Tris-HCl (pH 7.2) containing 0.25 M sucrose. However, the swelling was dependent on the tonicity of the solution or the concentration of chloride ions, while the stimulation of ATPase was independent of these factors. Swelling was strongly induced by DBP at slightly acidic rather than neutral or alkaline pH. The pH-activity curve of DBP-stimulated ATPase was in inverse correlation with that of swelling, which showed a rather flat maximum at pH 8.0. When bovine serum albumin (BSA) was added to a solution containing mitochondria before addition of DBP, swelling was no longer caused by DBP, though the latent ATPase was stimulated to the same extent in the absence of added BSA.
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PMID:Effects of phthalate esters on the latent ATPase and swelling of mitochondria. 1 58

The effect of ouabain, a specific sodium-potassium dependent adenosine triphosphatase (Na+-K+-ATPase) inhibitor, on antigen-induced histamine release was studied using guinea pig lung fragments sensitized in vitro with rabbit antibodies against bovine serum albumin. Histamine was assayed spectrofluorometrically. When sensitized tissue had been preincubated with ouabain (less than or equal to 1.0 x 10(-4) M) for 10 min prior to antigenic challenge, release of histamine was significantly inhibited (maximum 54%, p less than 0.001, N=9, paired t test). The most significant inhibition was obtained near the optimal concentration of antigen. The inhibition was dependent on the length of preincubation (less than or equal to 20 min), and was partially reversible upon washing the tissue removing the ouabain. Ouabain did not seem to prolong the duration of the histamine release process. Increase in potassium ion (less than or equal to 1.1 x 10(-2)M) inhibited the histamine release and had additive effects to ouabain action. Dibutyryl cyclic AMP (less than or equal to 5 x 10(-3) M), which could enhance the release, strongly antagonized the inhibition. Glucose removal from the medium did not abolish the ouabain effect. The results seem to indicate that immunologic release of histamine is under the influence of the membrane Na+-K+-ATPase activity.
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PMID:Inhibition of antigen-induced histamine release by ouabain. 5 30

Certain bioflavonoids inhibit the glycolysis of variety of tumor cells by interfering with the generation of adenosine diphosphate and inorganic phosphate which are required for glycolysis. Tetra- and pentahydroxy flavones with hydroxyl groups as 3, 3', 4', 5, and 7 (e.g., quercetin) are the most active. They inhibit the activity of isolated Na+-K+-adenosinetriphosphatase of the plasma membrane and of mitochondrial adenosinetriphosphatase, but under appropriate conditions do not interfere with the ion transport increase the the translocation efficiency of the ion pump. It was shown that in several tumor cells loosely coupled ion pumps are responsible for the high rate of aerobic glycolysis, the effect of quercetin on the growth of several cell lines was examined. Since bicarbonate and serum albumin were found to counteract the effect of quercetin, the cells were grown in tissue cultures at low concentrations of these compounds. Pronounced inhibition of growth was observed at 5 to 20 mug of quercetin per ml of growth medium.
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PMID:The effect of flavonoids on aerobic glycolysis and growth of tumor cells. 12 7

Fragmented sarcoplasmic reticulum was prepared from the rabbit heart. The function of vesicles was characterized by the activities of Mg++ and ATP-dependent 'Calcium-Binding' and Ca-ATPase. A fluorescence probe, 1-anilino-8-naphthalene sulfonate (ANS) was employed to examine the physicochemical changes in vesicular membranes. Chlorpromazine, dl-propranolol and lidocaine inhibited Calcium-Binding activity and increased ANS-fluorescence. There was a good correlation between the changes in two parameters. The potency of three drugs on both parameters decreased in the above-mentioned order. These drugs, however, induced no change in the ANS-fluorescence associated by serum albumin or lecithin. The drugs would act presumably at lipid-protein interfaces in vesicles to increase ANS-fluorescence. Both Ca-ATPase and Basic-ATPase were inhibited by dl-propranolol. These results suggest that the inhibitory action of dl-propranolol on the calcium transport system is ascribable to direct physicochemical effects on vesicular membranes.
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PMID:Studies on calcium transport system in cardiac sarcoplasmic vesicles and its inhibition by dl-propranolol. 13 44

1. When complete hydrolysis of glycerophosphlipids and sphingomyelin in the outer membrane leaflet is brought about by treatment of intact red blood cells with phospholipase A2 and sphingomyelinase C, the (Ca2+ + Mg2+)-ATPase activity is not affected. 2. Complete hydrolysis of sphingomyelin, by treatment of leaky ghosts with spingomyelinase C, does not lead to an inactivation of the (Ca2+ + Mg2+)-ATPase. 3. Treatment of ghosts with phospholipase A2 (from either procine pancreas of Naja naja venom), under conditions causing an essentially complete hydrolysis of the total glycerophospholipid fraction of the membrane, results in inactivation of the (Ca2+ + Mg2+)-ATPase by some 80--85%. The residual activity is lost when the produced lyso-compounds (and fatty acids) are removed by subsequent treatment of the ghosts with bovine serum albumin. 4. The degree of inactivation of the (Ca2+ + Mg2+)-ATPase, caused by treatment of ghosts with phospholipase C, is directly proportional to the percentage by which the glycerophospholipid fraction in the inner membrane layer is degraded. 5. After essentially complete inactivation of the (Ca2+ + Mg2+)-ATPase by treatment of ghosts with phospholipase C from Bacillus cereus, the enzyme is reactivated by the addition of any of the glycerophospholipids, phosphatidylserine, phosphatidylcholine, phosphatidylethanolamine or lysophosphatidylcholine, but not by addition of sphingomyeline, free fatty acids or the detergent Triton X-100. 6. It is concluded that only the glycerophospholipids in the human erythrocyte membrane are involved in the maintenance of the (Ca2+ + Mg2+)-ATPase activity, and in particular that fraction of these phospholipids located in the inner half of the membrane.
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PMID:The lipid requirement of the (Ca2+ + Mg2+)-ATPase in the human erythrocyte membrane, as studied by various highly purified phospholipases. 13 46

1. p-Aminophenol, a known nephrotoxin, has been studied as a model for phenacetin-induced renal damage. 2. Respiration, oxidative phosphorylation and ATPase activity were inhibited in mitochondria isolated from the kidneys of treated rats; this could not be reversed by the addition of exogenous loosely bound cofactors and bovine serum albumin to the assay medium. 3. After treatment the mitochondrial levels of sodium and calcium were increased, potassium decreased and magnesium unaltered. 4. Mitochondria isolated from treated rats showed ultrastructural damage. 5. The results are interpreted to indicate that renal tubular cell mitochondrial injury is important in triggering cortical analgesic renal damage.
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PMID:An experimental model of analgesic-induced renal damage--some effects of p-aminophenol on rat kidney mitochondria. 14 69

Rat liver lysosomes were lysed and subfractionated by differential centrifugation through 0.2M-NaCl to yield a membranous pellet. This membrane fraction contains less than 20% of the lysosomal protein, adenosine triphosphatase activity of about 1.2mumol/min per mg of protein, 120nmol of thiol groups/mg of protein and at least 16 protein and glycoprotein bands on sodium dodecyl sulphate/polyacrylamide-gel electrophoresis. The gel patterns of membranes isolated from lysosomes after treatment with (1) [125I]iodidehydrogen peroxide-lactoperoxidase, (2) toluene 2,4-di-isocyanate-activated bovine serum albumin, (3) trypsin and (4) subtilisin indicate that most of the membrane proteins are exposed to the cytoplasm. These exposed proteins are candidates for intracellular receptors which recognize either substances that are to be degraded or vesicles containing those substances.
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PMID:Properties of the membrane proteins of rat liver lysosomes. The majority of lysosomal membrane proteins are exposed to the cytoplasm. 15 36

1. Oleic acid at low concentrations (0--70 nmol/mg protein) stimulated mitochondrial state 4 respiration 4-fold, increased the apparent enthalpy change of the respiration per gram atom of oxygen consumed from -112 to -208 kJ/O and completely inhibited ATP synthesis without significant effect on the Mg-ATPase activity of mitochondria. 2. Similar effects on mitochondrial respiratory activities were observed with other fatty acids. 3. Bovine serum albumin (BSA) protected mitochondria from the effects of oleic acid irrespective of the order of addition of oleic acid and BSA to mitochondria. The capacity of BSA to bind oleic acid was calculated to be 3.6--7.1 (mean, 4.9) mol of oleic acid/mol of BSA. 4. The response time of mitochondrial respiration to added oleic acid or BSA was 20--25 s.
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PMID:Reversible effects of fatty acids on respiration, oxidative phosphorylation, and heat production of rat liver mitochondria. 15 4

The organization of lipids in sarcoplasmic reticulum membrane was studied with a variety of stearic spin labels and a phosphatidylcholine spin label. The ESR spectra of the spin-labeled membranes consisted of two components, one due to labels in lipid bilayer structure and the other due to more immobilized labels. The relative intensity of the immobilized component increased when the lipid content of the membrane was decreased by treatment with phospholipase A [EC 3.1.1.4] and subsequent washing with bovine serum albumin. Membrane containing 30% of the intact phospholipid, i.e.0.15 mg of phospholipid per mg of protein, showed a spectrum consisting only of the immobilized component (the overall splitting ranged from 58.5 G to 60.5 G). The immobilized component was ascribed to lipids complexed with protein. The fraction of lipids in the two different organizations was determined from the ESR spectrum. The activity of the Ca2+-Mg2+ dependent ATPase [ATP phosphohydrolase, EC 3.6.1.3] was found to increase almost linearly with the lipid bilayer content in the membrane, whereas phosphoenzyme formation was almost independent of the bilayer content. This indicated that the bilayer structure is necessary for the ATPase to attain its full transport activity.
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PMID:Organization of lipids in sarcoplasmic reticulum membrane and Ca2+-dependent ATPase activity. 17 48

Spiroplasma citri was cultured in three different media that supplied cholesterol and fatty acids from: (i) horse serum, (ii) pleuropneumonia-like organism (PPLO) serum fraction, or (iii) bovine serum albumin-fatty acid-cholesterol. The ability of PPLO serum fraction to support growth varied by lot number. Neither PPLO serum fraction nor the bovine serum albumin medium supported growth as well as the horse serum medium. Analysis of cholesterol, lipid phosphorus, and membrane protein showed the horse serum- and PPLO-grown cells to be indistinguishable, but the bovine serum albumin-grown cells were deficient in lipid phosphorus. The three cultures did not show markedly different fatty acid compositions, but, in all cases, the cultures preferentially incorporated palmitic acid and discriminated against linoleic acid. Cultures grown for different times from logarithmic growth through a degenerative phase showed relatively constant ratios of cholesterol/protein and lipid phosphorus/protein. Fatty acid composition was also relatively constant at the different stages. Adenosine triphosphatase and p-nitrophenyl phosphatase were mainly associated with the membrane, whereas reduced nicotinamide adenine dinucleotide oxidase was either readily removed or not associated with the membrane. The reduced nicotinamide adenine dinucleotide oxidase was inactivated at temperatures above 35 degrees C.
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PMID:Composition and enzyme activities of Spiroplasma citri membranes. 19 32


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