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)

Methylxanthines (MX) inhibit cell division in sea urchin and clam eggs. This inhibitory effect is not mediated via cAMP. MX also inhibit respiration in marine eggs, at concentrations which inhibit cleavage. Studies showed that no changes occurred in ATP and ADP levels in the presence of inhibitory concentrations of MX, indicating an extra-mitochondrial site of action for the drug. Subsequent studies revealed decreased levels of NADP+ and NADPH, when eggs were incubated with inhibitory concentrations of MX, but no change in levels of NAD+ and NADH. MX did not affect the pentose phosphate shunt pathway and did not have any effect on the enzyme NAD+ -kinase. Further studies showed a marked inhibitory effect on the glutathione reductase activity of MX-treated eggs. Reduced glutathione (GSH) could reverse the cleavage inhibitory effect of MX. Moreover, diamide, a thiol-oxidizing agent specific for GSH in living cells, caused inhibition of cell division in sea urchin eggs. Diamide added to eggs containing mitotic apparatus (MA) could prevent cleavage by causing a dissolution of the formed MA. Both MX and diamide inhibit a Ca2+-activated ATPase in whole eggs. The enzyme can be reactivated by sulfhydryl reducing agents added in the assay mixture. In addition, diamide causes an inhibition of microtubule polymerization, reversible with dithioerythritol. All experimental evidence so far suggests that inhibition of mitosis in sea urchin eggs by MX is mediated by perturbations of the in vivo thiol-disulfide status of target systems, with a primary effect on glutathione levels.
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PMID:Effects of caffeine and other methylxanthines on the development and metabolism of sea urchin eggs. Involvement of NADP and glutathione. 1 15

1) The rate of 2,3-bisphosphoglycerate breakdown is independent of pH value. 2) The adenine nucleotide pattern at alkaline pH values with its characteristic lowering of ATP and the accompanying accumulation of fructose-1,6-bisphosphate is caused by a relative excess of the activity of the hexokinase-phosphofructokinase system as compared wity pyruvate kinase. 3) The breakdown of adenine nucleotides proceeds via AMP mainly through phosphatase and not via AMP deaminase. 4) The constancy of the sum of nucleotides as long as glucose is present is postulated to be due to resynthesis via adenosine kinase which competes successfully with adenosine deaminase. 5) A procedure is given to calculate ATPase activity of glucose-depleted red cells. The results indicate that the ATPase activity is less at lower pH values and declines with time. An ATPase with a high Km for ATP is postulated. 6) During glucose depletion ATP production is mostly derived from the breakdown of 2,3-bisphosphoglycerate and the supply from the pentose phosphate pool both of which proceed at a constant rate. The contribution of pentose phosphate from the breakdown of adenine nucleotides amounts to 40% of the lactate formed at pH 6.8 and is about twice the lactate at pH 8.1.
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PMID:The breakdown of adenine nucleotides in glucose-depleted human red cells. 4 52

Red blood cells from 7 out of 13 patients with chronic uremia were found to have increased intracellular concentrations of sodium associated with a reversible inhibition of ouabain-sensitive Na efflux when incubated in control plasma. Although mean Na-K-ATPase activity of RBC hemolysates was only moderately decreased (21.8 +/- 1.5 vs. 26.5 +/- 1.8 nmol Pi/mg protein/h), enzyme kinetics revealed a significant increase in KmATP values for this enzyme in uremic RBCs (1.01 +/- 0.1 vs. 0.58 +/- 0.03; p less than 0.001) which was closely correlated to serum creatinine concentration (r = 0.9034). While aerobic glycolysis was unaltered, an increase in glucose-6-phosphate dehydrogenase activity was observed, i.e. the enzyme initiating the pentose-phosphate cycle. In addition, intracellular ATP concentrations of uremic RBCs were significantly higher than ATP concentrations of control RBCs (2.13 +/- 0.22 vs. 1.32 +/- 0.06 mmol/l RBC; p less than 0.01). These data suggest that high intracellular concentrations of Na and ATP in uremic RBCs partially result from a competitive reversible inhibition of the transport ATPase by uremic toxins.
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PMID:Functional and metabolic studies on red blood cell sodium transport in chronic uremia. 13 Dec 54

Hereditary non-spherocytary haemolytic anaemias have their cause in enzymopathies of the pentose phosphate cycle and the glycolysis of the erythrocytes. The 11 known enzyme defects of the erythrocytary glycolysis in consequence of the reduced preparation of adenosine triphosphatase condition a deficient stability of the membrane of the erythrocytes. Therefore, the increased autohaemolysis in normal osmotic resistance is a reference to these forms of anaemia, which are particularly to be differentiated from hereditary sperocytoses. In Middle Europe the deficiency of pyruvate kinase plays the greatest part among the otherwise rarely diagnosed enzymopenic haemolytic anaemias.
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PMID:[Defects in erythrocyte glycolysis enzymes as the cause of nonspherocytic hemolytic anemia]. 13 17

The histochemistry of the hepatic parenchymal cells was studied in four Callithrix jacchus. A large amount of glycogen was noted throughout the lobules while the UDPG-GT and the phosphorylases were found unevenly distributed by the hepatic strands with different degrees of reactivity. Near the central vein one of the livers showed PAS-positive nuclear corpuscles that were more conspicuous in the hepatic cells with a larger amount of cytoplasmic glycogen and weaker UDPG-GT and phosphorylase reactivities. G-6PA (in a larger amount) and LDH (in a moderate amount) were found evenly distributed in the hepatic strands. F-1-6PA was seen sometimes with a stronger reactivity at the peripheral part of the lobules. The enzymes of the pentose shunt (G-6PDH, 6-PGDH and NADPH-2-TR) reacted strongly and as a rule evenly distributed near the hepatic lobules. Occasionally they reacted more intensely in the row of hepatic cells disposed just around the central vein. Cytochrome oxidase showed a very faint reaction. Cis-aconitase and ICDH were weak or moderate. NADH-2-TR more than SDH more than MDH were seen frequently diffused near the hepatic strands. SDH and MDH in some instances showed a stronger reactivity in the row or group of hepatic cells around the central vein. ATPase at pH 6.3 was negative in the marmoset liver; ATPase at pH 7.4 was mainly found in the wall of the portal area vessels; ATPase at pH 8.5 showed a stronger reactivity in the cytoplasm of the hepatic cells and ATPase at pH 9.4 was more abundant in the bile capillaries. The reactivity of the lipid metabolism enzymes was moderate with regard to alpha-GPDH or negligible with regard to beta-OHBDH. Acid phosphatase showed a stronger reaction, but almost limited to the Kupffer cells. The hepatic cells showed only a moderate amount of RNA. Some enzymes of the protein metabolism, such as GDH and leucine aminopeptidase showed a stronger reactivity while some others, such as alanyl aminopeptidase and MAO, were seen diffused near the hepatic lobules in a small amount. Enzymes of the mucopolysaccharide metabolism were not found at all (beta-glucuronidase) or showed only a weak reactivity, such as xylitol dehydrogenase.
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PMID:Histochemical data on the liver of the marmoset (Callithrix jacchus). 16 44

Enzymopathies are described concerning the enzymes of the oxidative pentose phosphate pathway including the glutathion system, of the majority of glycolytic enzymes as well as of the ATPase, adenylate kinase and pyrimidine-5'-nucleotidase. The distribution and the frequency of the enzymopathies differ strongly in the various regions of the world. Glucose-6-phosphate dehydrogenase and pyruvate kinase show the highest frequency. The detected polymorphism of the pathological enzyme variants is one of the reasons for the fact that no correlation between the decrease of the catalytic activity and the severity of the anaemias has been found. For the identification of risk-groups more precise methods are necessary. Till now the detailed relationships between enzymopathy and non-spherocytic haemolytic anaemias are not clarified. Furthermore the molecular mechanism of the instability of pathological enzyme variants is not yet clear.
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PMID:[Enzyme deficient non-spherocytic hemolytic anemias]. 67 10

Hexokinase is a phosphotransferase that catalyzes phosphoryl transfer from ATP to glucose much more rapidly than the transfer from ATP to water (i.e., hydrolysis). Dimethyl sulfoxide has opposite effects on these two phosphotransferase activities: it enhances ATP hydrolysis and inhibits glucose phosphorylation. Xylose, a sugar that is non-phosphorylatable by hexokinase, enhances ATPase activity which is additive to activation by dimethyl sulfoxide, indicating that the mechanism of activation by dimethyl sulfoxide is different from that of xylose. These results suggest that it is possible to change the specificity of the enzyme in the presence of dimethyl sulfoxide.
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PMID:Effect of dimethyl sulfoxide on phosphoryl transfer catalyzed by yeast hexokinase. 131 74

The metabolism of radiolabelled glucose and glutamine was measured in individual cattle embryos produced by in vitro maturation and fertilization of oocytes, and culture with bovine oviductal epithelial cells. Metabolism of glucose through the pentose-phosphate pathway increased almost 15 times and the total metabolism of glucose 30 times, during development from the two-cell to the expanded blastocyst stage. The first marked increase in glucose metabolism did not occur until between the eight- and 16-cell stages, the time of activation of the embryonic genome. Conversely, the metabolism of glutamine was high in two- and four-cell embryos and then decreased to reach a minimum at the compacted morula to blastocyst stage, possibly because of degradation of maternally derived enzymes. Blastocyst expansion was accompanied by significant increases in the metabolism of glucose and glutamine, presumably reflecting the increased energy demands of Na(+)-K+ ATPase necessary for formation and maintenance of the blastocoel.
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PMID:Developmentally related changes in the metabolism of glucose and glutamine by cattle embryos produced and co-cultured in vitro. 151 13

In continuation of earlier studies on murine neoplastic liver lesions, we characterized by histochemical methods the phenotype of hepatocellular adenomas and carcinomas induced by single injections of diethylnitrosamine (1.25, 2.5, or 5.0 micrograms/g of body weight) in 15-day-old C57BL/6 x male C3H F1 mice. The hepatocellular adenomas were composed predominantly of basophilic cells but stored excessive amounts of fat and glycogen in large portions of the tumors. Irrespective of the carcinogenic dose, the adenomas showed a consistent histochemical pattern. Glycogen synthase and phosphorylase were highly active in the hepatocytes that stored glycogen. In cells poor in, or free of, this polysaccharide, these enzymes were only moderately active or even inactive. In glycogen-storing parts of the adenomas, the activity of adenylate cyclase was reduced compared with normal liver parenchyma, but in fat-storing portions it was elevated. In a few adenomas, uniform increase in adenylate cyclase activity could be encountered. The levels of ATPase, acid phosphatase, and glucose-6-phosphatase were either increased or decreased. Glucose-6-phosphate dehydrogenase and glyceraldehyde-3-phosphate dehydrogenase showed an increased activity in all adenomas compared with preneoplastic foci, which in turn exhibited a higher glucose-6-phosphate dehydrogenase and glyceraldehyde-3-phosphate dehydrogenase activity than the surrounding parenchyma or the liver of untreated controls. The hepatocellular carcinomas showed remarkable histochemical changes compared with adenomas. The levels of fat and glycogen and the activities of glycogen synthase, phosphorylase, and in most cases also that of glucose-6-phosphate dehydrogenase, were reduced significantly. In contrast, adenylate cyclase, glucose-6-phosphatase, glyceraldehyde-3-phosphate dehydrogenase, and also alkaline phosphatase showed a striking elevation in developing carcinomas. Similar, although more pronounced, histochemical changes were seen in the advanced hepatocellular carcinomas. These observations indicated that progression from adenomas to hepatocellular carcinomas was associated with a change in the activity of several enzymes involved in cell membrane function, glycogen metabolism, the oxidative pentose phosphate pathway, and glycolysis.
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PMID:Histochemical profile of mouse hepatocellular adenomas and carcinomas induced by a single dose of diethylnitrosamine. 184 80

The effects of phenylhydrazine hydrochloride (5, 10 and 20 mM) on the energy metabolism of red cells of rats were studied. There were found an 1.3-2-fold increase of lactate formation, an up to seven-fold accumulation of pyruvate and of the flux via the oxidative pentose pathway. The stimulation of the glycolysis was caused by 1) a large decline of the ATP concentration and a corresponding increase of ADP and AMP, and 2) by the stimulation of the actual activities of the Na+,K(+)-ATPase and Ca+(+)-ATPase owing to a greater permeability of the plasma membrane. A significant increase of the Ca+(+)-influx was demonstrated. A decline of the sum of adenine nucleotides after 60 and 90 min of incubation with phenylhydrazine was not accompanied by accumulation of hypoxanthine.
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PMID:Stimulation of rat red blood cell glycolysis by phenylhydrazine hydrochloride. 214 86


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