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)

The author reports a modification of the UV method UltraZyme Plus alpha-Amyl Harleco and the adaptation to the Eppendorf Enzymautomat 5010. alpha-amylase acts on an oligosaccharide mixture yielding maltose, which is hydrolysed by alpha-glucosidase. The liberated glucose is determined specifically by the hexokinase/glucose-6-phosphate dehydrogenase (NAD+-dependent) method+ by addition of pyruvate, lactate dehydrogenase and ATP. Thereafter the lactate dehydrogenase reaction is stopped by addition of oxamate and the alpha-amylase activity is measured.
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PMID:[Kinetic determination of alpha-amylase in serum and urine with an oligosaccharide as substrate--modification for a fully mechanized enzyme measuring device (author's transl)]. 9 28

The problems encountered with a coupled enzyme assay for ATP using glucose, hexokinase and glucose-6-phosphate dehydrogenase are discussed and a modification where fructose and glucosephosphate isomerase were substituted for glucose is described. This modified assay was used successfully to measure the ATP synthesized by reversal of the sarcoplasmic reticulum ATPase. ATP synthesized by adenylate kinase contaminating the sarcoplasmic reticulum was easily corrected for by a subtraction procedure.
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PMID:A spectrophotometric assay of ATP synthesized by sarcoplasmic reticulum. 9 39

In previous papers we reported that the earlier peak time (PT) in radiorespiratory during feeding with 3'-methyl-4-(dimethylamino)azobenzene(3'-Me-DAB) is due to activation of the hexose monophosphate (HMP) pathway together with hepatic cell proliferation reflecting the toxic effects of this carcinogen. In this study, we investigated the correlation between the results of radiorespiratory and the levels of enzyme activities of HMP pathway in regenerating rat liver in connection with hepatic cell proliferation. [3H]Thymidine incorporation into rat liver DNA and the activities of hexokinase (HK) and glucose-6-phosphate dehydrogenase(G-6-PD) reached a maximum at the 3rd day after partial hepatectomy. On radiorespirometry using [U-14C] glucose, the peak time (PT) was much earlier at the 2nd to 3rd day after partial hepatectomy. The peak height (PH) decreased to less than 1/2 of the initial level at the 2nd, but began to recover from the 3rd day. The yield value (YV) remained below the initial level for 4 days after the operation.
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PMID:Radiorespirometric analysis of glucose metabolism in the rat during feeding with 3'-methyl-4-(dimethylamino)azobenzene--radiorespirometry after partial hepatectomy. 12 May 61

The R3230AC mammary adenocarcinoma was not dependent on insulin; tumor growth was equal to or greater in diabetic rats than in intact animals. However, tumor growth was reduced when daily doses of insulin were administered. Treatment with estrogen inhibited growth of the R3230AC carcinoma, either in diabetic rats or in intact animals simultaneously treated with insulin. The effects of insulin plus estrogen treatment appeared to be additive in causing inhibition of tumor growth. Tumors from diabetic rats showed few metabolic alterations as reflected by little or no changes in the activities of selected glycolytic enzymes, pyruvate kinase, phosphofructokinase, and hexokinase, nor any striking changes in the activities of glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase, representing the pentose phosphate pathway. A modest reduction in the ratio of utilization of (1-14C)glucose: (6-14C)glucose was seen in vitro by tumors from diabetic rats. It was concluded that insulin, along with estrogen and prolactin, should be considered as a hormonal factor that influences growth of this automonous, hormone-responsive adenocarcinoma.
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PMID:Influence of insulin on estrogen-induced responses in the r3230ac mammary carcinoma. 12 68

The metabolic activity of the red cell glycolytic pathway hexose monophosphate shunt (HMP) with dependent glutathione system was studied in patients with hyperthyroidism (n = 10), hyperlipoproteinemia (n = 16), hypoglycemia (n = 25) and hyperglycemia (n = 23). In uncontrolled diabetics and patients with hyperthyroidism the mean value of glucose phosphate isomerase (GPI), glucose-6-phosphate dehydrogenase (G-6-PD), glutathione reductase (GR) was increased, whereas these enzyme activities were reduced in patients with hypoglycemia. Apart from a few values of hexokinase (HK) which were lower than normal the results in hyperlipoproteinemia patients remained essentially unchanged, including the intermediates such as 2,3-diphosphoglycerate (2,3-DPG), adenosine triphosphate (ATP) and reduced glutathione (GSH). While increased rates of 2,3-DPG and ATP in hypoglycemia patients were obtained, these substrates were markedly reduced in diabetics.
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PMID:Adaptation of red cell enzymes and intermediates in metabolic disorders. 12 51

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

Two reaction intermediates of H-meromyosin (HMM) ATPase [EC 3.6.1.3], E2AT32P, and (see article), were formed by mixing excess HMM with AT32P. Then a large excess of unlabelled ATP was added, and the amount of AT32P liberated from E2AT32P was measured as the difference between the total amount of AT32P in the reaction mixture and the amount of AT32P bound to HMM, obtained by filtering the mixture after adding charcoal to adsorb nucleotides (charcoal-filtration method). The amount of free AT32P was also measured as the amount of glucose-6-32P formed within 15 sec after adding large excesses of hexokinase [EC 2.7.1.1] and glucose to the reaction mixture. The rate constant, k-2, for the step E2ATP yields E plus ATP was calculated at various KCl concentrations from the time-course of liberation of AT32P. The intermediate, (see article), was formed by mixing HMM with AT32P in a molar ratio of 1:2, and the rate constant, k-6, for the step (see article) was also determined by the same procedures used for k-2. In 0.5 M KCl and 2 mM MgCl2 at pH 7.8 and 0 degrees, k-2 and k-6 were 0.002 sec-1 and 0.1 sec-1 or more, respectively. From the rate constants determined in this work and the rate and equilibrium constants which we reported previously, the standard free energy changes (kcal/mole) for formation of various reaction intermediates in the reaction of HMM ATPase in 0.5 M KCl and 2 mM MgCl2 at pH 7.8 and 0 degrees were calculated to be as follows: (see article).
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PMID:Standard free energy changes for formation of various intermediates in the reaction of H-meromyosin ATPase. 12 76

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 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

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


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