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:2.7.1.1 (hexokinase)
5,274 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Ehrlich ascites tumor cells were permeabilized using low concentrations of digitonin, 8 micrograms/10(6) cells. Permeabilization was monitored by the assay of lactate dehydrogenase released into the incubation medium and of hexokinase partially bound to mitochondria. Integrity of the cellular organelles was unaffected as determined by assay of the mitochondrial enzyme glutamate dehydrogenase. Cells were stained with rhodamine 123 as a mitochondrial specific dye and propidium iodide/mithramycin as DNA specific dyes. The green fluorescence of bound rhodamine 123 versus red fluorescence of DNA in individual cells was analysed by dual parameter flow cytometry. Incubation of cells with inhibitors of mitochondrial energy metabolism, such as, potassium cyanide and carbonyl cyanide m-chlorophenylhydrazone abolished binding of rhodamine 123. Flow cytometric data allowed a correlation between cell position in the mitotic cycle with total mitochondrial activity. In addition, comparison of the characteristics of propidium iodide and ethidium bromide staining further elucidated the molecular basis of the staining with the positively-charged fluorescent dye rhodamine 123.
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PMID:Simultaneous analysis of mitochondrial activity and DNA content in Ehrlich ascites tumor cells by dual parameter flow cytometry. 248 81

1. Red cell pyruvate kinase (EC 2.7.1.40) and hexokinase (EC 2.7.1.1) in high and low potassium (K) dogs were shown to exist as multiple forms which were separable by electrophoresis and ion-exchange chromatography. The R2-type pyruvate kinase, which was determined to be a young type enzyme in canine red cells, was shown to be the predominant form of pyruvate kinase in high K cells. 2. The M2-type pyruvate kinase, a prototype isozyme in erythroid cells, existed in high K dog erythrocytes as well as in high K and low K dog reticulocytes. 3. Isozyme analysis of high K red cell hexokinase also showed a profile similar to that obtained for low K reticulocytes. 4. These results seem to reflect the immaturity of high K erythrocytes, which suggest that an abnormal cell differentiation or maturation may occur at an early stage of erythroid cell proliferation in high K dogs.
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PMID:Inherited persistence of immature type pyruvate kinase and hexokinase isozymes in dog erythrocytes. 270 33

We evaluated whether any monosaccharides inhibit glycolysis in erythrocytes and discovered that D-mannose does. In the presence of D-mannose, glucose can be accurately measured by either the hexokinase procedure or the glucose oxidase procedure. In comparison studies with other glucose preservatives, we found that after 2 h at room temperature glucose decreased by 21 (SD 13) mg/L in D-mannose-treated blood, 93 (SD 10) mg/L in sodium fluoride-treated blood, 28 (SD 21) mg/L in ice-cooled blood, and 144 (SD 28) mg/L in control blood (no preservative treatment). Because D-mannose acted in the early phase of glycolysis, it was a more effective preservative than sodium fluoride; moreover, its use did not preclude measurement of sodium and potassium in the blood samples. D-Mannose did not interfere with other routine chemical tests except for the assay of creatine kinase involving coupled enzymes hexokinase/glucose-6-phosphate dehydrogenase. Creatine kinase could be correctly assayed in the presence of D-mannose by using glucokinase instead of hexokinase. D-Mannose can be used with or without anticoagulant and is compatible with most types of multi-channel automated analyzers.
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PMID:D-mannose as a preservative of glucose in blood samples. 200 64

The mechanism of retraction of the longitudinal flagellum of Ceratium tripos was studied by making extracted models of the flagellum. Non-detergent models extracted in low ionic strength medium containing 1 M-glucose, 10 mM-EDTA, and 50 mM-Tris X HCl buffer (pH 8.0), retracted when Ca2+, Mg2+, Ba2+, Sr2+, Mn2+ or Cd2+ was applied locally with a glass capillary. A demembranated model of the flagellum was made with an extraction medium containing 0.8-1.0 M-glucose, 20 mM-Tris-acetate (pH 7.8), 2 mM-EGTA, 5-7 mM-MgSO4, 0.1 M-potassium glutamate and 0.1% Triton X-100. The model required a concentration of Mg2+ of a few mmol/l for successful reactivation of both retraction and undulation, and about 0.1 M-potassium glutamate (or sodium glutamate) for reactivation of undulation. Neither type of motion of the models could be reactivated above 35 degrees C. Ca2+ induced the retraction at pCa 5.5 or less. In addition to Ca2+, Mn2+, Ba2+, Sr2+ and Cd2+ also induced retraction but Mg2+, La3+ or Tb3+ did not. Although ATP was required for undulation, it was not required for retraction. Co-incubation with hexokinase to remove contaminating ATP did not suppress the retraction. The potent ATPase inhibitor, orthovanadate, inhibited undulation at 10 micron but did not inhibit retraction even at 2 mM. SH blockers, N-ethylmaleimide and dithio-bis-nitrobenzoic acid strongly suppressed undulation but had no effect on retraction. Calmodulin inhibitors, trifluoperazine and chlorpromazine, also had no effect on retraction. These data indicate that undulation is generated by a 9 + 2 microtubular axoneme using energy released by hydrolysis of ATP and that retraction can be induced by Ca2+ without a requirement for ATP.
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PMID:Extraction model of the longitudinal flagellum of Ceratium tripos (Dinoflagellida): reactivation of flagellar retraction. 385 92

1. Intracellular concentrations of intermediates and cofactors of glycolysis were measured in guinea-pig cerebral cortex slices incubated under varying conditions. 2. Comparison of mass-action ratios with apparent equilibrium constants for the reactions of glycolysis showed that hexokinase, phosphofructokinase and pyruvate kinase catalyse reactions generally far from equilibrium, whereas phosphoglucose isomerase, aldolase, phosphoglycerate kinase, phosphoglycerate mutase, enolase, adenlyate kinase and creatine phosphokinase are generally close to equilibrium. The possibility that glyceraldehyde 3-phosphate dehydrogenase may catalyse a ;non-equilibrium' reaction is discussed. 3. Correlation of changes in concentrations of substrates for enzymes catalysing ;non-equilibrium' reactions with changes in rates of glycolysis caused by alteration of the conditions of incubation showed that hexokinase, phosphofructokinase, pyruvate kinase and possibly glyceraldehyde 3-phosphate dehydrogenase are subject to metabolic control in cerebral cortex slices. 4. It is suggested that the glycolysis is controlled by two regulatory systems, the hexokinase-phosphofructokinase system and the glyceraldehyde 3-phosphate dehydrogenase-pyruvate kinase system. These are discussed. 5. It is concluded that the rate of glycolysis in guinea-pig cerebral cortex slices is limited either by the rate of glucose entry into the slices or by the hexokinase-phosphofructokinase system. 6. It is concluded that addition of 0.1mm-ouabain to guinea-pig cerebral cortex slices causes inhibition of either glyceraldehyde 3-phosphate dehydrogenase or phosphoglycerate kinase or both, in a manner independent of the known action of ouabain on the sodium- and potassium-activated adenosine triphosphatase.
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PMID:Control of glycolysis in cerebral cortex slices. 422 84

1. Cerebral-cortex mitochondria, after purification by using high-density sucrose solutions, were extracted with Triton X-100. The total hexokinase activity of the intact mitochondria was increased by 50-80% in the Triton extracts. 2. Triton X-100 was removed from mitochondrial extracts by a combination of ammonium sulphate fractionation and DEAE-cellulose chromatography. Mitochondrial hexokinase remained soluble after removal of extractant. 3. The behaviour of solubilized mitochondrial hexokinase was compared with soluble cytoplasmic hexokinase from the same samples of cerebral cortex on identical columns of DEAE-cellulose. Two peaks were eluted from each source of hexokinase. The distribution between hexokinase peaks was similar for the two sources. Peak I (approx. 80% of the total hexokinase) from each was eluted at identical concentrations of potassium chloride and slight differences were observed in the elution profiles for peak II. 4. The purified mitochondrial hexokinase showed the following kinetic properties: peak I, K(m)(ATP) 0.60mm, K(m)(glucose) 0.042mm; peak II, K(m)(ATP) 0.66mm, K(m)(glucose) 0.043mm. The purified cytoplasmic hexokinase Michaelis constants were: peak I, K(m)(ATP) 0.56mm, K(m)(glucose) 0.048mm; peak II, K(m)(ATP) 0.68mm, K(m)(glucose) 0.062mm. 5. Although no significant differences between mitochondrial and cytoplasmic hexokinases were noted in chromatographic behaviour or in the kinetic properties studied, the purified mitochondrial enzyme was activated slightly (approx. 20%) by Triton X-100, in contrast with the cytoplasmic enzyme, which was not affected. 6. The results, taken to indicate basic similarity between mitochondrial and cytoplasmic hexokinases, are discussed in relation to the role of the two sources of enzyme in the metabolism of the tissue.
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PMID:Cerebral-cortex hexokinase. Comparison of properties of solubilized mitochondrial and cytoplasmic activities. 547 53

1. The oxidation of butyrate, hexanoate and octanoate by rat-liver mitochondria suspended in a tris-potassium chloride medium in the presence of malate and serum albumin has been investigated. 2. The oxidation of butyrate to acetoacetate was markedly decreased by the addition of a system competitive for ATP (hexokinase-glucose). 3. Serum albumin or tricarboxylic acid-cycle intermediates prevented the inhibition by hexokinase and in their presence a greater proportion of the oxygen consumption was contributed by the tricarboxylic acid cycle. The results suggest that the energy supply for fatty acid activation is either compartmentalized in a spatial or kinetic sense or there exists a special activating mechanism not involving ATP. 4. Malate and other tricarboxylic acid-cycle intermediates caused substantial reduction (to beta-hydroxybutyrate) of the acetoacetate formed during the oxidation of butyrate, hexanoate and octanoate.
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PMID:The effect of hexokinase and tricarboxylic acid-cycle intermediates on fatty acid oxidation and formation of ketone bodies by rat-liver mitochondria. 594 42

Erythrocyte glycolysis has been studied in the anaemia associated with protein-energy malnutrition (PEM) in Kivu. Several results were compatible with a lowering of the mean age of the erythrocyte population, notably raised levels of glucose-6-phosphate, hexokinase, Na+-K+- adenosinetriphosphatases and potassium, and low sodium concentration. Non-significant differences were observed for glucose utilization, lactate formation, and for concentrations of fructose-6-phosphate, fructose-1,6-diphosphate, adenosine diphosphate and pyruvate kinase; there was no gross disturbance of cation transport. The level of adenosine triphosphate was slightly decreased and that of 2,3-bisphosphoglycerate was not elevated, in spite of anaemia. The latter could not be explained by an instability of this metabolite. It is concluded that slight erythrocyte glycolytic abnormalities may occur in the anaemia of Kivu PEM, but that they are not the main cause of the haemolysis observed in this syndrome.
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PMID:Erythrocyte glycolysis in protein-energy malnutrition. 629 Jan 7

Most biological fluids contain both neutral and acid alpha-glucosidase. Optimal conditions were therefore developed for the selective determination of the activity of neutral and acid alpha-glucosidase, using 2-step, discontinuous assays. In the first step of the assay of neutral alpha-glucosidase, glucose was liberated from maltose (citrate-phosphate buffer, pH 6.8, 20 mmol/l maltose, 25 mmol/l turanose). Under these incubation conditions, turanose inhibited the residual activity of acid alpha-glucosidase almost completely without influencing the activity of neutral alpha-glucosidase. In the first step of the acid alpha-glucosidase assay, glucose was liberated from maltose (citrate-phosphate buffer, pH 3.8, 50 mmol/l maltose, 2 mol/l potassium chloride). Under these incubation conditions, potassium ions stimulate the activity of acid alpha-glucosidase and simultaneously inhibit almost completely the residual activity of neutral alpha-glucosidase. In the second step of the assay of neutral and acid alpha-glucosidase, the liberated glucose was measured by hexokinase/glucose-6-phosphate dehydrogenase. The effect of turanose and potassium ions on neutral and acid alpha-glucosidase from human urine was characterized.
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PMID:Selective determination of the activities of neutral and acid alpha-glucosidase using discontinuous assays. 635 65

The action of Lonidamine [1-(2,4-dichlorobenzyl)-1-H-indazol-3-carboxylic acid] on oxygen consumption and the rate of aerobic and anaerobic lactate production by Ehrlich ascites tumor cells has been investigated. The rate of oxygen consumption decreases exponentially with the increase of Lonidamine concentration, with maximal inhibition occurring at 0.40 mM Lonidamine. The rate of aerobic lactate production is inhibited to the same extent as is the oxygen consumption. However, the maximum effect is observed at 0.12 mM Lonidamine, and the decrease is linear with Lonidamine concentration. Anaerobic lactate production is more sensitive to Lonidamine, and complete inhibition can be observed by raising the concentration to 0.6 mM. The possibility that the decrease observed in lactate production was secondary to the inhibition of sodium- and potassium-containing adenosinetriphosphatase was excluded, because the drug has no effect on this enzyme. Mitochondrial adenosinetriphosphatase was not affected. Lonidamine was, however, shown to inhibit the activity of mitochondrially bound hexokinase to approximately the same extent as it inhibited aerobic glycolysis (approximately 70%). It is concluded that inhibition of the glycolysis of Ehrlich ascites tumor cells by Lonidamine results from an effect of the drug on the mitochondrially bound hexokinase.
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PMID:Effect of lonidamine on the energy metabolism of Ehrlich ascites tumor cells. 730 82


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