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)

Cytochalasin A at 10-20 mug/ml inhibits growth and sugar uptake by Saccharomyces strain 1016. The effects of cytochalasin A in intact cells were completely prevented when 1 mM cysteine or dithiothreitol was added along with cytochalasin A, but were not eliminated by thiols added after inhibition had occurred. Purified yeast hexokinase, glucose-6-P dehydrogenase, phosphofructokinase and aldolase were not sensitive to cytochalasin A (20 mug/ml). Glyceraldehyde-3-P dehydrogenase was strongly inhibited by cytochalasin A (5 mug/ml); activity was promptly restored by thiols. Anaerobic glycolysis was inhibited by cytochalasin A or by iodoacetate; unlike iodoacetate, cytochalasin A did not cause accumulation of sugar phosphates. In contrast, cytochalasin A, but not iodoacetate, inhibited isolated membrane-bound ATPases. Cytochalasin A is a sulfhydryl-reactive agent and has membrane-related effects (adenosine triphosphatase) which may well be the basis of its interference with energy-dependent uptake of solutes.
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PMID:Action of cytochalasin A, a sulfhydryl-reactive agent, on sugar metabolism and membrane-bound adenosine triphosphatase of yeast. 12 88

ATP and citrate, the well known inhibitors of phosphofructokinase (ATP: D-fructose 6-phosphate 1-phosphotransferase, EC 2.7.1.11), were found to inhibit the activities of the multiple forms of phosphoglucomutase (alpha-D-glucose 1,6-bisphosphate: alpha-D-glucose 1-phosphate phosphotransferase, EC 2.7.5.1) from rat muscle and adipose tissue. This inhibition could be reversed by an increase in the glucose 1,6-bisphosphate (Glc-1,6-P2) concentration. Other known activators (deinhibitors) of phosphofructokinase, viz. cyclic AMP, AMP, ADP or Pi, had no direct deinhibitory action on the ATP or citrate inhibited multiple phosphoglucomutases. Cyclic AMP and AMP, could however lead indirectly to deinhibition of the phosphoglucomutases, by activating phosphofructokinase which catalyzes the ATP-dependent phosphorylation of glucose 1-phosphate to form Glc-1,6-P2, the la-ter then released the multiple phosphoglucomutases from ATP or citrate inhibition. The Glc-1,6-P2 was also found to exert a selective inhibitory effect on hexokinase (ATP: D-hexose 6-phosphotransferase, EC 2.7.1.1) type II, the predominant form in skeletal muscle. This selective inhibition by Glc-1,6-P2 was demonstrated on the multiple hexokinases which were resolved by cellogel electrophoresis or isolated by chromatography on DEAE-cellulose. Based on the in vitro studies it is suggested that during periods of highly active epinephrine-induced glycogenolysis in muscle, the Glc-1,6-P2, produced by the cyclic AMP-stimulated reaction of phosphofructokinase with glucose 1-phosphate, will release the phosphoglucomutases from ATP or citrate inhibition, and will depress the activity of muscle type II hexokinase.
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PMID:Complementarity in the regulation of phosphoglucomutase, phosphofructokinase and hexokinase; the role of glucose 1,6-bisphosphate. 12 9

The control theory of steady states, previously presented for linear enzymatic systems (Heinrich and Rapoport, 1974) is extended to nonlinear systems. On the basis of three theorems a new procedure for the calculation of the control strength and of the control matrix is developed. The theory is applied to the extended model of glycolysis of erythrocytes, which includes also ATP-consuming processes. Also in this model the glycolytic flux is mainly controlled by the hexokinase-phosphofructokinase-system. The control strengths of the pyruvate kinase and of the enzymes of the 2.3 P2G-bypass are negligibly small. The control strength of the ATPase is negative, i.e. an activation of this enzyme leads to a decrease of the flux. For transition states of multienzyme systems definitions are given for the mean time required for the transition of the metabolites and for the "transient control" of enzymes. Enzymes with a pronounced influence on the transition time are called time-limiting enzymes. Enzymes which excert strong control on the time-dependent processes may have little influence under steady state conditions and vice versa. The transition times of ATP have been calculated for transient states of glycolysis.
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PMID:Mathematical analysis of multienzyme systems. II. Steady state and transient control. 12 16

The behavior of enzyme activities, substrates and metabolites of glycosis as well as of the pentose phosphate shunt following local irradiation (250 to 6000 R surface dose) is biochemically investigated in the guinea-pig's myocardium. During irradiation, an activation of phosphorylase-a is going on while the total phosphorylase content remains unchanged. Enzyme activities of hexokinase and phosphofructokinase are increased in dependence on dosage as well as time. The glycogen content is being reduced; tissular concentration of the metabolites glucose-1-phosphate, glucose-6-phosphate, glyceraldehyde-3-phosphate, glycerol-3-phosphate, and pyruvate increases following irradiation; the content of fructose-1,6-diphosphate, dihydroxyacetonephosphate, and lactate is decreased. The activity of glucose-6-phosphate dehydrogenas is slightly inhibited, whereas 6-phosphogluconate-dehydrogenase remains unaffected.
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PMID:[Studies on the effect of radiation on electrolyte changes and metabolism of the myocardium. V. Changes in enzyme activities and glycolysis metabloites due to radiation]. 12 7

We decribed the preparation of adenine 1-oxide nucleotides by oxidation of the natural compounds with monopermaleic acid in aqueous solutions at neutral pH, with an overall yield after chromatographic purification between 75 and 80%. If irradiated, the adenine 1-oxide nucleotides undergo a photochemical rearrangement reaction, the main photoproducts in aqueous solution at alkaline pH being the corresponding isoguanine nucleotides. The modified ring vibration pattern of the 1-oxide analogues as well as the 13C chemical shift indicate a loss of aromaticity as compared to the natural compounds. Coupling constant measurements show that the dihedral angle between the 31POC and OC13C planes is around 180degree, i.e., trans, as in the natural adenine nucleotides. The modified adenine nucleotides were tested as potential substrates and/or inhibitors of mitochondrial processes, as substrates of varous phosphotransferases from mitochondria or cytosol, and as allosteric effectors in the reactions catalyzed by glutamate dehydrogenase and phosphofructokinase. Although the adenine 1-oxide nucleotides are not recognized by the translocase system of the inner mitochondrial membrane, they are good substrates for mitochondrial phosphotransferases located in the intermembrane space. Similarly, they participate in the phosphoryl group transfer reactions catalyzed by pyruvate kinase, phosphofructokinase, and hexokinase. As allosteric effectors, the modified nucleotides are less active than the natural compounds, probably because of a lower binding capacity to the allosteric sites of the regulatory enzymes.
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PMID:Structural and enzymatic properties of adenine 1-oxide nucleotides. 12 77

Clinical and hematological studies were performed on ten homozygous and seven heterozytous individuals with pyruvate kinase deficiency, aged between 2 and 71 years. Five of the homozygotes were splenectomized. With the exception of a decreased enzyme activity between 41 and 55 per cent and minor changes in their red cell metabolism the heterozygotes showed no abnormal results. In the homozygotes the following results could be demonstrated: 1. Pyruvate kinase activity was decreased to 11 to 35 per cent of normal enzyme activity. 2. There is no relation between the severity of hemolysis and the degree of the enzyme defect. 3. The reticulocyte counts correlated inversely with the hemoglobin concentrations. 4. There is a close correlation between the activities of hexokinase, phosphofructokinase, glucose-6-phosphate dehydrogenase and glutamate oxalacetate transaminase on the one side and reticulocyte counts on the other. 5. Adenosine triphosphate or adenosine reduced the increased autohemolysis in all cases. 6. Following splenectomy, anemia was less pronounced than before. Splenectomized patients did not need further transfusions, though hemolysis persisted.
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PMID:[Pyruvate kinase deficiency. I. Clinical and hematological observations (author's transl)]. 12 93

The regularities for changes were established in activity of hexokinase, glucokinase, glucosephosphate-isomerase, phosphofructokinase and glucose-6-phosphate dehydrogenaseduring the early development of loach (Misgurnus fossilis). It was found that a 30-minute incubation of fertilized loach eggs in the lactate or fumarate solutions decreases the glucokinase activity in the embryos of 3, 6, 9, 12, 15, 18 and 24 hours of their development, while the inhibitory effect of glucose on the enzyme activity is pronounced only after 18 and 24 hours of the development. A significant increase in the hexokinase and glucose-6-phosphate dehydrogenase activities under the above-mentioned conditions is observed only under the effect of glucose 9 and 6 and 9 hours, respectively, after fertilization. The glucose phosphate isomerase and phosphofructokinase activites under the effect of used compounds undergo no changes during the primary stages of embryogenesis.
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PMID:[Enzymes of glycolysis and pentosephosphate shunt during early embryogenesis of the loach and the effect of glucose, lactate and fumarate on fertilized oocytes]. 12 65

The metabolic effects on rat cardiac and skeletal muscle of a strenous program of swimming, of cold acclimation and of isoprenaline treatment (0.3 mg/kg daily for 5 five-day weeks) were compared. Exercised and cold-exposed rats gained less body weight than did controls or isoprenaline-treated rats. In all treated groups the heart and the intercapular brown adipose tissue hypertrophied. The size of the adrenals increased only in isoprenaline-treated animals. Cold-acclimation and physical training increased and isoprenaline treatment reduced or did not affect the activities of succinate dehydrogenase, malate dehydrogenase and citrate synthase of cardiac muscle. In the skeletal muscle all treatments resulted in increased activities of these enzymes. Of the anaerobic enzymes analysed, only the activity of hexokinase increased in response to the treatements used. This increase was the same in cardiac as in skeletal muscle, but it was significantly greater with isoprenaline-treatment than with training or with cold-acclimation. The activities of lactate dehydrogenase and phosphofructokinase did not differ significantly. All treatments improved cold resistance, but only swimming exercise and cold acclimation significantly increased tolerance to exercise. It is concluded that prolonged stimulation of adrenergic beta-receptors by catecholamines is responsible for the metabolic changes observed.
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PMID:Comparison of the effects of physical exercise, cold acclimation and repeated injections of isoprenaline on rat muscle enzymes. 12 87

The activity of carbohydrate metabolism certain enzymes [hexokinase (EC 2.7.1.1.), glucokinase (EC 2.7.1.2), phosphofructokinase (EC 2.7.1.11.1), glucoso-6-phosphate-dehydrogenase (EC 1.1.1.49.)] was studied in the sheep skin when adding vitamin A, sodium sulphate and insulin to the basic ration. The activity of the studied enzymes in the skin was established to be rather high and depend to a considerable extent on feeding, seasonal and hormonal factors. In summer the activity of such enzymes as glucoso-6-phosphate-dehydrogenase and glucokinase decreases, and that of hexokinase, vice versa, increases. Vitamin A alone against a background of the basic ration almost has no effect on the activity of the enzymes, with the exception of phosphofructokinase in certain periods of the experiment. More noticeable shifts in the activity of the enzymes were observed in the case when vitamin A and sodium sulphate were added to the ration of sheep, and also with the injection of insulin. In such cases in the sheep skin there occurs first of all an increase in the activity of glucokinase and glucoso-6-phosphate-dehydrogenase.
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PMID:[Activity of some carbohydrate-metabolizing enzymes in sheep skin]. 13 Jul 4

Specimens of human adipose tissue were cultured for one week with or without the addition of insulin. The basal as well as the noradenaline-stimulated lipolysis were enhanced in the explants cultured with insulin, showing that the long-term effect of the hormone is lipolytic. However, an acute antilipolytic effect of insulin could be demonstrated in these explants in the subsequent short-term incubations. The basal rate of glucose incorporation into the lipids was enhanced in the explants cultured with insulin. When insulin was added in the short-term incubations these explants did not further respond to the hormone while this was the case with the explants cultured without insulin. Thus, it seems that prolonged exposure to insulin leads to a diminished acute effect of the hormone on glucose metabolism. However, the same explants responded to the antilipolytic effect showing that insulin was able to bind itself to the membrane. The activities of hexokinase (HK), glucose-6-phosphage dehydrogenase (G6PDH), pyruvate kinase (PK) and lactate dehydrogenase (LDH) were increased in large fat cells both in freshly excised tissue and in cultured explants. However, the activity of phosphofructokinase (PFK) did not correlate with the cell size. The presence of insulin during the culture period enhanced the activities of G7PDH, PK, and LDH, while this was not found for HK or PFK. The data thus suggest that the metabolic capacity of human fat cells is enhanced by long-term exposure to insulin. Although enzyme induction could be shown for G6PDH, PK and LDH it seems unlikely that this is of importance for the increased rates of glucose metabolism in these explants since the rate-limiting enzymes, HK and PGK, were not increased. Most probably, then, this stimulating effect of insulin is exerted on the membrane and the rate of glucose transport.
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PMID:Human adipose tissue in culture V. Studies on the metabolic effects of insulin. 13 27


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