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)

ATPase of 14S dynein, extracted from spermatozoa of the sea urchin, Hemicentrotus pulcherrimus, and partially purified by sucrose density gradient centrifugation, was inhibited non-competitively by palmitoyl CoA at concentrations higher than 20 microns, and was stimulated at concentrations between 2 microns and 10 microns. The effects of palmitoyl CoA on dynein ATPase were reversed by bovine serum albumin (1 mg/ml) and spermine (0.1 and 1 mM). Myristoyl CoA exerted effects similar to those of palmitoyl CoA. Short chain fatty acyl CoAs, such as butyryl CoA, propionyl CoA and acetyl CoA, CoA, Na-palmitate, Na-myristate, and palmitoyl carnitine had hardly any effect on dynein ATPase. Palmitoyl CoA failed to inhibit purified CF1 ATPase from chloroplasts of spinach, ATPase of rat liver mitochondria and alkaline phosphatase from calf intestine.
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PMID:Inhibition by palmitoyl CoA of dynein ATPase from sea urchin spermatozoa. 621

Myoepithelial and secretory cells from the mammary gland of the lactating rat have been isolated, purified, and characterized. Mammary tissue was dissociated with collagenase into basket-like networks of myoepithelial cells and single secretory cells. Because of their larger size, the myoepithelial cell networks could be separated from other mammary and blood cells by differential centrifugation. Isolated secretory cells were purified by isopycnic centrifugation in 25% bovine serum albumin. The purified myoepithelial and secretory cells were viable, as shown by the incorporation of 32P into distinct macromolecules that were separable by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Both myoepithelial and secretory cells retained their characteristic morphology after isolation and purification, as shown by light, transmission, and scanning electron microscopies. The isolated myoepithelial cells were unique and, thus, distinguishable from other mammary cells in a number of respects; they 1) contracted in response to the addition of oxytocin, 2) bound [3H]oxytocin specifically, 3) accounted for the content of alkaline phosphatase and [Na+ + K+]ATPase in mammary tissue, and 4) reacted specifically with antiserum prepared against purified myoepithelial cells. The purified secretory cells were unique in possessing glucose-6-phosphate dehydrogenase activity. The different cell markers not only gave independent estimates of the purity of the cell fractions, but they also may be helpful in identifying mammary cells in stages of differentiation and neoplastic transformation.
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PMID:Purification and characterization of mammary myoepithelial and secretory cells from the lactating rat. 624 56

Inhibition of adenosine triphosphatase (ATPase) by chlorauric acid (Au3+) and gold sodium thiomalate (Au+) was studied in dog brain and kidney and in human kidney enzyme preparations. Au3+ indiscriminately affected ouabain-sensitive (Na+ + K+-dependent) ATPase and ouabain-insensitive (Mg2+-dependent) ATPase with concentrations for 50% inhibition (I50) approximately 10(-6) M. The I50 of Au3+ for Na+ + K+ ATPase was several-fold higher in homogenates than in microsomal fractions. The enzyme was protected by bovine serum albumin. Although Au3+ and Au+ were equipotent against Mg2+ ATPase, Au+ inhibited Na+ + K+ ATPase 2 to 3 times more effectively than did Au3+. The inhibitory action of Au3+ (but not Au+) was potentiated by ascorbic acid, suggesting reduction of Au3+ to Au+ by ascorbic acid. The fractional inhibition of Na+ + K+ ATPase by Au3+ or Au+ was not affected by changing concentrations of NaCl, KCl, MgCl2, ATP, and MgATP. Decreasing pH from 8.0 to 6.8 enhanced both Au+ and Au3+ inhibition. We conclude that gold is one of the most potent nonspecific of Na+ + K+ ATPase, with characteristics differing from other metallic inhibitors of this enzyme system.
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PMID:Inhibition of adenosine triphosphatases by gold. 624 62

Studies were carried out with intact mitochondria isolated from human astrocytoma, oat cell carcinoma and melanoma which were propagated in athymic mice. These human tumor mitochondria were capable of coupled oxidative phosphorylation. They also showed significant uncoupler-stimulated ATPase if defatted bovine serum albumin was included in the assay media. However, the uncoupler response curves were different and the magnitude of the ATPase activity was lower than could be obtained with mitochondria of a normal tissue, such as liver. Some of these characteristics were also exhibited by mitochondria from several animal hepatomas and Ehrlich ascites tumor. In the three tumors studied, mitochondria from oat cell carcinoma were more labile, whereas higher respiratory control ratios and greater stimulation of ATPase by uncouplers were obtained with melanoma mitochondria. The mitochondrial ATPase was not the major cellular ATPase in any of the three tumors. This was indicated by a low inhibition of the ATPase activity of tumor cell homogenates by oligomycin. A very large fraction of the cellular ATPase activities was recovered in the microsomal fractions.
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PMID:Oxidative phosphorylation and ATPase activities of human tumor mitochondria. 624 84

A 32-yr-old man with goitrous hypothyroidism due to an iodide-trapping defect is described. He was admitted because of goiter which had been increasing in size. His parents were unrelated, and no cases of goiter were found in his family. On admission, serum T3 was 39 ng/dl, serum T4 was 1.0 micro g/dl, and serum TSH was 217 micro U/ml. His 24-h thyroidal 131 I uptake was 0.05%. Antithyroid antibodies were negative. In a tracer study, the thyroidal 131 I uptakes were 6.3% at 2 h, 4.0% at 6 h, and 0.9% at 24 h after iv injection of the radioiodide. The decline in the neck counts was linear and parallel to that in the serum 131 I. The 24-h urinary excretion of 131 I was 92%. The saliva to serum and gastric juice to serum ratios of 131 I concentrations at 2 h were very low (0.95 and 0.97, respectively). After the administration of iodine (14 mg in Lugol's solution/day for 10 days), serum T3 was 228 ng/dl, serum T4 was 6.8 micro g/dl, and serum TSH was 24 micro U/ml. Some biochemical studies were carried out using the patient's thyroid tissue. In a kinetic study on iodide trapping by thyroid slices, the thyroid to medium ratio of iodide concentration in the patient's tissue was constantly about 0.1, in contrast to 1.5-4.0 in a control subject. The microsomal peroxidase activity in the patient's thyroid, assessed by iodination of bovine serum albumin, was about 3-fold that in a control subject on the basis of DNA content. Both ouabain-sensitive and -insensitive thyroidal Na+ -K+ -ATPase activities were present. These results suggest that the iodide-trapping defect in this patient was due to an impairment in the specific iodide carrier system rather than in the Na+ -K+ -ATPase itself.
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PMID:Goitrous hypothyroidism due to iodide-trapping defect. 627 3

Arachidonic acid and unsaturated C18 fatty acids at concentrations near 10(-5) M markedly inhibited (H+ + K+)-ATPase in hog or rat gastric membranes. Arachidonic acid was a more potent inhibitor than unsaturated C18 fatty acids, but the involvement of the metabolites of arachidonic acid cascade was ruled out. Linolenic acid inhibited the formation of phosphoenzyme and the K+ -dependent p-nitrophenylphosphatase activity of the hog ATPase. Treatment with fatty acid-free bovine serum albumin abolished only the inhibitory effect of the fatty acid on the phosphatase activity without restoring the overall ATPase action. These data suggest the existence of at least two groups of hydrophobic binding sites in the gastric ATPase for unsaturated long-chain fatty acids which affect differentially the catalytic reactions of the ATPase. (H+ + K+)-ATPase in rat gastric membranes was found more susceptible to the fatty acid inhibition and also more unstable than the ATPase in hog gastric membranes. The presence of a millimolar level of lanthanum chloride or ethylene glycol bis(beta-aminoethyl ether)-N,N'-tetraacetic acid stabilized the rat ATPase probably via the inhibition of Ca2+ -dependent phospholipases in the gastric membranes.
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PMID:Inhibition of gastric (H+ + K+)-ATPase by unsaturated long-chain fatty acids. 629 67

A novel procedure for isolating totally inverted preparations of submitochondrial particles by sonication of beef heart mitochondria is described. The procedure involves only differential centrifugation in 0.25 M sucrose containing 0.15 M KCl. The submitochondrial particles have 96% of their cytoplasmic face cytochrome c-binding sites sequestered within the particles. Mild sonication exposes cytochrome c-binding sites to the medium. The oligomycin-sensitive ATPase of sonic-derived submitochondrial particles, like that of electron transport particles, is inhibited 98% by exogenous isolated ATPase inhibitor protein. NADH oxidase activity in these particles is inhibited by oligomycin. The respiratory control index (uncoupled rate/oligomycin-inhibited rate) is approximately 3.4 and can be increased by washing the particles with medium containing bovine serum albumin.
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PMID:Isolation of totally inverted submitochondrial particles by sonication of beef heart mitochondria. 629 96

Determination of maximal Na,K-ATPase activity in isolated plasma membranes is generally hampered by the vesicular nature of the preparation, limiting access of ATP and ions to one face or the other of the transmembrane protein. Detergents are often used to make the vesicles permeable to the substrates; however, the detergent/protein ratio is extremely critical for optimal activation. The use of bovine serum albumin as a detergent buffer is described. With this method the amount of membrane protein in the assay can be varied over a wide range, with full detergent activation. The method has been used for assay of Na,K-ATPase activity of membranes from dog kidney, rabbit brain, and electric organ of eel.
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PMID:Assay of Na,K-ATPase in plasma membrane preparations: increasing the permeability of membrane vesicles using sodium dodecyl sulfate buffered with bovine serum albumin. 630 51

Membrane-bound (Na+ + K+)-ATPase from pig kidney outer medulla shows apparent heterogeneity in its ATP-binding site population when assays are carried out in the presence of K+. This finding has been interpreted as being due to interaction between (at least) two subunits, each containing an ATP-binding site. Treating the membrane-bound enzyme with the detergent, C12E8, has been shown to solubilize enzymatically active alpha beta-protomers. We show that in the dissolved enzyme all ATP-binding sites in the population are identical both in the absence and in the presence of K+, which would be consistent with an abolition of identical both in the absence and in the presence of K+, which would be consistent with an abolition of subunit-subunit interaction. This supports previous suggestions that enzyme solubilized by C12E8 is monomeric and that the membrane-bound enzyme is not. Differential extraction of enzyme-containing membranes with C12E8 yielded preparations with an ATP-binding capacity of up to 5.8 nmol per mg protein, measured by the method of Lowry et al. (Lowry, O.H., Rosebrough, N.J., Farr, A.L. and Randall, R.J. (1951) J. Biol. Chem. 193, 265-275), with bovine serum albumin as standard. Evidence is presented that makes it likely that preparations with an ATP-binding capacity of 7.5 nmol per mg protein (as determined by the above-mentioned assay) will be obtainable. This corresponds to an alpha beta-protomer molecular weight of 133 000 which approximates closely to the minimum value found in the literature for an alpha beta-protomer (i.e., 126 000).
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PMID:ATP binding to solubilized (Na+ + K+)-ATPase. The abolition of subunit-subunit interaction and the maximum weight of the nucleotide-binding unit. 630 18

The effects of polyunsaturated fatty acids on brain edema formation have been studied in rats. Intracerebral injection of polyunsaturated fatty acids (PUFAs), including linolenic acid (18:3) and arachidonic acid (20:4), caused significant increases in cerebral water and sodium content concomitant with decreases in potassium content and Na+- and K+- dependent adenosine triphosphatase activity. There was gross and microscopic evidence of edema. Saturated fatty acids and monounsaturated fatty acid were not effective in inducing brain edema. The [125I]-bovine serum albumin spaces increased twofold and threefold at 24 hours with 18:3 and 20:4, respectively, indicating vasogenic edema with increased permeability of brain endothelial cells. Staining of the brain was observed five minutes after injection of Evans blue dye followed by arachidonic acid perfusion. A major decrease in brain potassium content was evidence of concurrent cellular (cytotoxic) edema as well. The induction of brain edema by arachidonic acid was dose dependent and maximal between 24 and 48 hours after perfusion. Dexamethasone (10 mg/kg) was effective in ameliorating the brain edema, whereas a cyclooxygenase inhibitor, indomethacin (10 mg/kg), was not. These data indicate that arachidonic acid and other PUFAs have the ability to induce vasogenic and cellular brain edema and further support the hypothesis that the degradation of phospholipids and accumulation of PUFAs, particularly arachidonic acid, initiate the development of brain edema in various disease states.
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PMID:Induction of brain edema following intracerebral injection of arachidonic acid. 630 72


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