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)

Plasma membrane vesicles were isolated from a subline of L929 mouse fibroblasts grown on defined medium in the absence of serum. These vesicles were not significantly contaminated by mitochondria or endoplasmic reticulum. The isolation procedure, a modification of that originally developed by McKeel and Jarett (McKeel, D.W., and Jarett, L. (1970) J. Cell Biol. 44, 417-432) employs mechanical homogenization in isotonic medium followed by differential centrifugation. The resultant plasma membrane vesicles take up radioactivity when exposed to uniformly labeled nucleosides. Two subfractions of the plasma membrane were isolated, distinguished by their differing activity of 5'-nucleotidase and (Na+,K+)-stimulated ATPase, two well known plasma membrane enzyme markers. Uptake of nucleoside radioactivity was extensively studied in one subfraction; it was linear with time and membrane concentration over ranges used for the studies. Apparent Km values for uptake of radioactivity from adenosine, inosine, and uridine were 7.1 +/- 26 muM, respectively. Uptake of radioactivity from all three nucleosides exhibits a broad pH optimum from pH 7 to pH 9, but falls off rapidly at lower pH. N-Ethylmaleimide was an effective inhibitor of uptake of radioactivity from all three nucleosides; uptake of radioactivity from uridine is more sensitive than uptake of radioactivity from the purine nucleosides. Adenosine inhibited uptake of radioactivity from inosine more than from uridine. Inosine inhibited the uptake of radioactivity from adenosine, but uridine did not. Caffeine and 6-methylaminopurine riboside (6-N-methyladenosine differentially inhibit uptake of radioactivity from adenosine and inosine, and thus the vesicles apparently possess seperate transport systems for uptake of radioactivity from purine nucleosides and from uridine.
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PMID:Transport mechanisms in isolated plasma membranes. Nucleoside processing by membrane vesicles from mouse fibroblast cells grown in defined medium. 0 4

Net synthesis of adenosine 5'-triphosphate (ATP) in energy-depleted cells of Escherichia coli was observed when an inwardly directed protonmotive force was artificially imposed. In wild-type cells, ATP synthesis occurred whether the protonmotive force was dominated by the membrane potential (negative inside) or the pH gradient (alkaline inside). Formation of ATP did not occur unless the protonmotive force exceeded a value of 200 mV. Under these conditions, no ATP synthesis was found when cells were exposed to an inhibitor of the membrane-bound Ca2+- and Mg2+- stimulated adenosine triphosphatase (EC 3.6.1.3), dicyclohexylcarbodiimide, or to a proton conductor, carbonylcyanide-p-trifluoromethoxyphenyl-hydrazone. Adenosine triphosphatase-negative mutants failed to show ATP synthesis in response to either a membrane potential or a pH gradient. ATP synthesis driven by a protonmotive force was observed in a cytochrome-deficient mutant. These observations are consistent with the chemiosmotic hypothesis of Mitchell (1961, 1966, 1974).
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PMID:Protonmotive force as the source of energy for adenosine 5'-triphosphate synthesis in Escherichia coli. 0 27

Adenosine triphosphatase (ATPase) activated by Mg2+ or Ca2+ ions was detected in single mechanoreceptors (Pacini's corpuscles) of cat; addition of Ca2+ (10(-5)M) to Mg-ATP-ase increased the activity by the factor of 1.6. The activity optimum of Mg- or Co-ATPase was in the alkaline pH zone. A high substrate specificity of Mg, Ca-ATPase was shown. Parachlorinemercury-benzoate (5muM) considerably reduced the activity of Mg, Ca-ATPase, whereas oubain (10(-5)M) failed to affect it significantly. It is supposed that Mg, Ca-ATPase of Pacini's corpuscles was close to actomyosine -like proteins.
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PMID:[Mg, Ca-activated ATP-ase of Pacinian corpuscles]. 0 96

Adenosine 5'-triphosphate (ATP) synthesis driven by an artificially imposed membrane potential in right-side-out membrane vesicles of Escherichia coli was investigated. Membrane vesicles prepared in the presence of adenosine diphosphate were loaded with K+ by incubation with 0.5 M potassium phosphate. Addition of valinomycin resulted in the synthesis of 0.2 to 0.3 nmol of ATP/mg of membrane protein, whereas no synthesis was observed after addition of nigericin. Addition of K+, dicyclohexylcarbodiimide, carbonylcyanide p-trifluoromethoxyphenylhydrazone, or azide to the assay buffer inhibited ATP synthesis. Adenosine diphosphate and Mg2+ were found to be required. Ca2+, which can replace Mg2+ for the hydrolytic activity of the Mg2+-adenosine triphosphatase (ATPase) (EC 3.6.1.3), could not replace Mg2+ in the synthetic reaction and, in fact, inhibited ATP synthesis even in the presence of Mg2+. Strain NR-70, a mutant lacking the Mg2+-ATPase, was unable to synthesize ATP using an artificially imposed membrane potential. Additionally, the Mg2+-ATPase was found to contain tightly bound ATP.
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PMID:Adenosine 5'-triphosphate synthesis energized by an artificially imposed membrane potential in membrane vesicles of Escherichia coli. 0 30

The histochemical distribution of 14 enzymes in the human amnion at term are described. Adenosine triphosphatase, 5'-nucleotidase, acid phosphatase and nonspecific esterase show continuous gradations of enzyme activity. Cells with intense activity are prominent in acid phosphatase and nonspecific esterase preparations. A distinct subpopulation of amniotic cells can be defined by their alkaline phosphatase activity. The possible correlations with morphological studies are discussed.
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PMID:Enzyme histochemical patterns in the normal human amnion: amniotic histochemical patterns. 4 99

Adenosine triphosphatase enzymatic activity was investigated in human approximatively normal, dysplastic and neoplastic mammary tissue, by three different methods. Staining intensity varied within wide limits; myoepithelial cells and blood vessels showed similar enzymatic activity. Epithelial cells reacted only faintly, or not at all; carcinoma cells were never labelled. Stromal response was highly variable. The calcium-cobalt method of Padykula and Herman gave more intense reactions than the lead-nitrate procedure of Wachstein and Meisel, either in the original form or according to the modifications recommended by Russo and Wells. With the latter method the sharpness of stain deposits on the different structures was markedly enhanced. The functional significance of ATPase activity is discussed.
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PMID:ATPase activity in the breast: a comparison between three methods. 9 Dec 95

The biochemical effects of the nonsteroidal compound Centchroman were observed in healthy, adult, female rhesus monkeys. The compound was administered at the antifertility dose (.625 mg/kg) for 22 days in a cycle. No marked weight changes were seen in the Fallopian tube, ovary, adrenal or pituitary as a result of treatment. Uterine weight increased significantly, however (p less than .01). In the Fallopian tube, levels of glycogen and protein increased significantly (p less than .01), lactic acid decreased significantly (p less than .01), and nonprotein nitrogen was unchanged as a result of treatment. Similar changes were observed in the uterus, and in addition, total total phospholipid concentration rose significantly (p less than .01) in the uterus. The activities of beta-glucuronidase, acid and alkaline phosphatases and glucose-6-phosphate dehydrogenase (G-6-PD) in the Fallopian tube were unchanged due to treatment. Adenosine triphosphatase (ATPase) and malic dehydrogenase activities were significantly stimulated (p less than .01) and lactic dehydrogenase activity was significantly depressed (p less than .01). In the uterus, beta-glucuronidase and acid and alkaline phosphatase activity were unaltered, however, the activities of ATPase and the dehydrogenases of glucose-6-phosphate, lactate and malate were markedly increased (p less than .01). It is suggested that the antifertility effect of Centchroman may be due principally to the ability of the compound to elicit estrogen-like responses in the Fallopian tube and uterus.
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PMID:Effect of 3,4-trans-2,2-dimethyl-3-phenyl-4-P-(beta-pyrrolidinoethoxy) phenyl -7-methoxy chroman (centchroman) on the biochemistry of the fallopian tube and uterus of rhesus monkeys (Macaca mulatta). 12 88

Adenosine triphosphatase (ATPase) activities were compared in platelets of asthmatic and nonasthmatic children. Significantly elevated Mg2+- and Ca2+-dependent ATPase activities were found in particulate and soluble fractions of platelets from nonsteroid-treated asthmatic children compared to steroid-treated asthmatic and nonasthmatic children. The most pronounced increase (greater than twofold) occurred in the Ca2+-ATPase of the soluble fraction which contains platelet contractile protein. Intact cell surface of ecto ATPase activity was not significantly increased in platelets of asthmatic children. The findings are consistent with adrenergic imbalance in asthma involving depressed adenylate cyclase activity (beta-adrenergic) and increased ATPase activity (alpha-adrenergic) and may relate to abnormal platelet aggregation patterns.
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PMID:Increased adenosine triphosphatase activity in platelets of asthmatic children. 12 27

Adenosine triphosphatase (ATPase) was studied in tissue homogenates and subcellular fractions derived from human cadaver kidneys maintained in an organ preservation unit for transplantation. The activity of ouabain-sensitive ATPase was highest in the medulla, intermediate in the cortex and lowest in the papilla, The cortical enzyme activity diminished with time during maintenance perfusion of the kidneys. Similar concentrations of K+, Na+, Mg++, ATP and MgATP were required for half-maximal rates of ouabain-sensitive ATPase activity from the cortex or the medulla. The sensitivity of the enzyme to ouabain from both parts of the kidney was similar. K+ antagonized inhibition of the enzyme by ouabain. Chlormerodrin, mersalyl, mercaptomerin and ethacrynic acid were inhibitors of the enzyme.
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PMID:Ouabain-sensitive adenosine triphosphatase from human kidneys. 12 73

Adenosine triphosphatase (ATPase) was studied in tissue homogenates and subcellular fractions derived from human cadaver kidneys maintained in an organ preservation unit for transplantation. The activity of ouabain-sensitive ATPase was highest in the medulla, intermediate in the cortex and lowest in the papilla. The cortical enzyme activity diminished with time during maintenance perfusion of the kidneys. Similar concentrations of K+, Na+, Mg++, ATP and MgATP were required for half-maximal rates of ouabain-sensitive ATPase activity from the cortex or the medulla. The sensitivity of the enzyme to ouabain from both parts of the kidney was similar. K+ antagonized inhibition of the enzyme by ouabain. Chlormerodrin, mersalyl, mercaptomerin and ethacrynic acid were inhibitors of the enzyme.
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PMID:Oubain-sensitive adenosine triphosphatase from human kidneys. 12 74


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