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 activity of the erythrocyte enzymes: glucose-6-phosphate dehydrogenase, pyruvate kinase, glutathion reductase and ATPase were measured in 8 patients with untreated myelomatosis. Glucose-6-phosphate dehydrogenase was significantly increased. Glucose-6-phosphate dehydrogenase values were negatively correlated with the glomerular filtration rate as measured by 51Cr-EDTA clearance. The results support the existence of a shortened red cell survival in peripheral blood related to the degree of renal insufficiency.
Scand J Haematol 1976 Sep
PMID:Erythrocyte enzymes in myelomatosis. 13 47

A Mg2+- and Ca2+-dependent ATPase at the outer surface of human peripheral lymphocytes and hematopoietic cell lines has been studied. The enzyme activity varied about 60 fold between the extremes of the cell lines tested. There was no simple relationship between surface-ATPase activity and cell surface area. Nor was the presence of villi or any other morphological characteristic at the cell surface decisive for the degree of surface-ATPase activity. A correlation was, however, found between the ATPase activity and a phenomenon probably involving a contractile process namely immunoglobulin secretion, but it was not possible to establish an interdependence of these cell characteristics.
Acta Physiol Scand 1976 Sep
PMID:Mg2+- and Ca2+-stimulated ATPase at the outer surface of human peripheral lymphocytes and hematopoietic cell lines. Correlation between enzyme activity and immunoglobulin secretion. 13 77

"Substrate inhibition", which has been described earlier for myosin Ca-ATPase in low ionic strength KCl solution [1], is found to take place also at high KCl concentration and under partial modification of enzyme thiol groups with p-CMB. "Substrate inhibition" disappeared when increasing Ca2+ concentration up to 25-40 mM. These kinetic properties are characteristic for fresh isolated enzyme and myosin preparations stored in 0.5 M KCl. They may change under storage of enzyme preparations at higher KCl concentrations: no "substrate inhibition" is observed after 6-8-day storage of myosin preparations in 3 M KCl at the presence of 4-5 mM CaCl2. The data on optical rotation dispersion and analytical ultracentrifugation have shown that the storage of myosin in 3 M KCl is accompanied by structural changes of the protein.
Biokhimiia 1976 Sep
PMID:[Effect of storage conditions on the kinetic properties of myosin ATPase]. 13 84

Treatment of ascites tumor cells with dextran sulfate resulted in a marked inhibition of the incorporation of [14C]valine into protein in the presence of a high Na+ medium. Amino acid incorporation was restored after i.p. injection of these cells into mice or by exposure of the cells to ascites fluid in vitro. In a medium high in K+ and low in Na+, [14C]valine incorporation into protein took place in dextran treated cells. Rotenone inhibited the reaction, which could be restored by addition of both inorganic phosphate and either glucose or glucose 6-phosphate. Quercetin, an inhibitor of the Na+-K+-ATPase, markedly depressed the incorporation of [14C]valine into protein in intact sdviyrd tumor cells in a high Na+ medium. There was little or no inhibition of protein synthesis in dextran sulfate treated cells when tested in a high K+-low Na+ medium. These experiments suggest a relationship between protein synthesis and the operation of the membranous Na+-K+-ATPase.
Cancer Res 1976 Sep
PMID:Protein synthesis in dextran sulfate-treated ascites tumor cells. 13 42

1. The effects of reserpine and harman derivatives on the sodium transport across the frog bladder were examined using a short-circuit current method. The effects of harman derivatives on the Na,K-ATPase activity of the frog kidney were also investigated. 2. Reserpine and harman derivatives inhibited active sodium transport of the frog bladder and their inhibitory effect decreased as reserpine greater than harmine greater than harmaline = harman greater than harmalol. 3. Harman derivatives inhibited Na,K-ATPase activity of the frog kidney. 4. These results suggest that reserpine and harman derivatives inhibit active sodium transport by suppressing the Na,K-ATPase activity of the frog bladder.
Pflugers Arch 1976 Sep 03
PMID:The inhibitory effect of reserpine on the active sodium transport across the frog bladder. 13 61

A procedure was developed for the analytical isolation of brush border and basal lateral plasma membranes of intestinal epithelial cells. Brush border fragments were collected by low speed centrifugation, disrupted in hypertonic sorbitol, and subjected to density gradient centrifugation for separation of plasma membranes from nuclei and core material. Sucrase specific activity in the purified brush border plasma membranes was increased fortyfold with respect to the initial homogenate. Basal lateral membrane were harvested from the low speed supernatant and resolved from other subcellular components by equilibrium density gradient centrifugation. Recovery of Na, K-ATPase activity was 94%, and 61% of the recovered activity was present in a single symmetrical peak. The specific activity of Na, K-ATPase was increased twelvefold, and it was purified with respect to sucrase, succinic dehydrogenase, NADPH-cytochrome c reductase, nonspecific esterase, beta-glucuronidase, DNA, and RNA. The observed purification factors are comparable to results reported for other purification procedures, and the yield of Na, K-ATPase is greater by a factor of two than those reported for other procedures which produce no net increase in the Na, K-ATPase activity. Na, K-ATPase rich membranes are shown to originate from the basal lateral plasma membranes by the patterns of labeling that were produced when either isolated cells or everted gut sacs were incubated with the slowly permeating reagent 35S-p-(diazonium)-benzenesulfonic acid. In the former case subsequently purified Na, K-ATPase rich and sucrase rich membranes are labeled to the same extent, while in the latter there is a tenfold excess of label in the sucrase rich membranes. The plasma membrane fractions were in both cases more heavily labeled than intracellular protein. Alkaline phosphatase and calcium-stimulated ATPase were present at comparable levels on the two aspects of the epithelial cell plasma membrane, and 25% of the acid phosphatase activity was present on the basal lateral membrane, while it was absent from the brush border membrane. Less than 6% of the total Na, K-ATPase was present in brush border membranes.
J Membr Biol 1976 Sep 17
PMID:Analytical isolation of plasma membranes of intestinal epithelial cells: identification of Na, K-ATPase rich membranes and the distribution of enzyme activities. 13 16

1. Oligomycin-insensitive ATPase (ATP phosphohydrolase, EC 3.6.1.3) was purified from brown adipose tissue mitochondria. It had a specific activity of 50 units/mg which could be increased up to 85 units/mg by KHCO3. The isolated enzyme represented less than 0.5% of the initial membrane proteins.2. The enzyme had a molecular weight equal to beef heart ATPase and was composed of five subunits with molecular weights of 56 200, 54 300, 33 500, 13 400 and 9500 respectively. 3. Isolated ATPase was labile while cold and was activated by the divalent cations Mn2+, Mg2+, Co2+ and Cd2+. The optimum ATP/Mg2+ ratio found was 1.58 and the enzyme had a maximum activity at pH 8.5; the Km was 220 micrometer. 4. The ATPase activity was 55% inhibited by aurovertin. The isolated enzyme enhanced the fluorescence of aurovertin, quenched by ATP and Mg2+ and enhanced by ADP. 5. Oligomycin sensitivity and cold stability of isolated ATPase was restored by its reconstitution with both brown adipose tissue and beef heart particles depleted of ATPase. 6. The results presented demonstrate that the low ATPase activity of brown adipose tissue mitochondria is due to a reduced content of ATPase.
Biochim Biophys Acta 1977 Sep 15
PMID:Purification and properties of mitochondrial adenosine triphosphatase of hamster brown adipose tissue. 14 14

Millimolar concentrations of Ca2+ stimulate actin polymerization whereas micromolar concentrations of Ca2+ depress polymerization. This latter effect leads to a reduction of ATPase (ATP phosphohydrolase, EC 3.6.1.3) activity of actin during sonication at low Mg2+ concentrations and in the absence of KCl. In the presence of KCl (90 mM) there is activation of ATPase activity by micromolar Ca2+ concentrations. These Ca2+ effects are half-maximal at a Ca2+ concentration of 2-10(-7) M. They can be explained by assuming that that ATPase activity is optimal in a medium range of actin polymer stability and that micromolar Ca2+ concentrations tend to labilize and depolymerize F-actin.
Biochim Biophys Acta 1977 Sep 15
PMID:Dual effect of Ca2+ on ultrasonic ATPase activity and polymerization of muscle actin. 14 17

The role or non-role of NaK ATPase, Mg ATPase, and CaMg ATPase involvement in stabilization of excitable membranes by phenytoin is critically evaluated. There is no substantial evidence to indicate that the membrane-stabilizing effect of phenytoin is due to activation of the NaK ATPase. Previous reports of activation of the NaK ATPase at low potassium and high sodium are probably not due to phenytoin but to a potassium contamination in the phenytoin solution. In vitro experiments do not provide any clear evidence of any alterations of NaK ATPase properties by phenytoin. However, one cannot rule out the possibility that phenytoin alters the efficiency of the sodium-potassium pump. Likewise, the Ca ATPase is not inhibited by phenytoin. However, there is some evidence that the Mg ATPase in synaptic vesicles is substantially inhibited by phenytoin. There is substantial evidence indicating that phenytoin partially blocks passive diffusion of sodium into stimulated nerves. The mechanism by which phenytoin blocks sodium influx and the relationship of this effect to the drug's anticonvulsant action remain to be determined.
Epilepsia 1977 Sep
PMID:The role or non-role of ATPase activation by phenytoin in the stabilization of excitable membranes. 14 33

The ultrahistochemical localization of the "reversed" ATPase activity was investigated. Red muscle fibres showed permanent sarcomere contraction, enzymatic activity in the inner membrane and matrix of mitochondria, and large, osmiophilic, probably calcium-containing structures within mitochondria and on their outside. White muscle fibre sarcomeres were relaxed, and activity within their sarcoplasmic reticulum was marked, but slight in the mitochondria. The relaxed state of the sarcomere in the white muscle fibres is supposed to be connected with inactivation of myofibrillar ATPase by acid preincubation, whereas red muscle contraction indicates that acid preincubation does not inactivate their myofibrillar ATPase. That the product of its activity failed to become visible in the sarcomeres is probably due to imperfection of the method. Two sub-types of red muscle fibres were distinguished: those showing only enzymatic activity in mitochondria, and those containing large intra- and extramitochondrial osmiophilic structures. The origin and composition of these structures is difficult to explain. A relation seems to exist between their presence within mitochondria and outside.
Histochemistry 1977 Sep 22
PMID:The ultrahistochemical picture of the so-called reversed ATPase in the gastrocnemius muscle of the rat. 14 67


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