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)

A protease from Tetrahymena pyriformis inactivated eight of nine commercially available enzymes tested, including lactate deyhdrogenase, isocitrate dehydrogenase (TPN-specific), glucose-6 phosphate dehydrogenase, D-amino acid oxidase, fumarase, pyruvate kinase, hexokinase, and citrate synthase. Urate oxidase was not inactivated. Inactivation occurred at neutral pH, was prevented by inhibitors of the protease, and followed first order kinetics. In those cases tested, inactivation was enhanced by mercaptoethanol. Most of the enzyme-inactivating activity was due to a protease of molecular weight 25,000 that eluted from DEAE-Sephadex at 0.3 M KCl. A second protease of this molecular weight, which was not retained by the gel, inactivated only isocitrate dehydrogenase and D-amino acid oxidase. These two proteases could also be distinguished by temperature and inhibitor sensitivity. Two other protease peaks obtained by DEAE-Sephadex chromatography had little or no no enzyme inactivating activity, while another attacked only D-amino acid oxidase. At least six of the enzymes could be protected from proteolytic inactivation by various ligands. Isocitrates dehydrogenase was protected by isocitrate, TPN, or TPNH, glucose-6-dehydrogenase by glucose-6-P or TPN, pyruvate kinase by phosphoenolypyruvate or ADP, hexokinase by glucose, and fumarase by a mixture of fumarate and malate. Lactate dehdrogenase was not protected by either of its substrates of coenzymes. Citrate synthase was probably protected by oxalacetate. Our data suggest that the protease or proteases discussed here may participate in the inactivation or degradation of a least some enzymes in Tetrahymena. Since the inactivation occurs at neutral pH, this process could be regulated by variations in the cellular levels of substrates, coenzymes, or allosteric regulators resulting form changes in growth conditions or growth state. Such a mechanism would permit the selective retention of enzymes of metabolically active pathways.
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PMID:Enzyme inactivation by a cellular neutral protease: enzyme specificity, effects of ligands on inactivation, and implications for the regulation of enzyme degradation. 1 68

Blood serum of oncologic patients due to immunoglobulin involved in its composition, activates glycolysis in the soluble fraction of muscles when using starch, glycogen and glucose as substrates. The activation is registered under both aerobic and anaerobic conditions. When elucidating the immunoglobulin effect in a glycolytic chain under aerobic conditions it is shown that its activating effect in the incomplete incubation system is manifested with such glycolysis substrates as fructose-6-phosphate and 2-phosphoglyceric acid. Glycolysis activation with serum is insignificant or absent at all with the presence of glucose-6-phosphate, fructose-1,6-diphosphate, 3-phosphoglyceric aldehide, 3-phosphoglyceric acid, phosphoenolpyruvic acid, sodium pyruvate. Immunoglobulin isolated from the blood serum of oncologic patients does not affect the activity of purified preparations of hexokinase, glycerinaldehydephosphate dehydrogenase, lactate dehydrogenase under aerobic and anaerobic conditions. When using the air as a gas medium lactate dehydrogenase is activated by immunoglobulin. Lactate dehydrogenase activity under aerobic and anaerobic conditions is essentially lower than in the case when the air serves as a gas medium.
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PMID:[Peculiarities of the action of protein positively reacting in the sedimentation test for cancer on the activity of glycolytic enzymes]. 92 7

In this study we compare the specific activities and isoenzyme patterns of five enzymes--phosphoglucose isomerase, phosphoglucomutase, hexokinase, lactate dehydrogenase, and alkaline phosphatase--in term placenta with the analogous enzymes in a clone of choriocarcinoma cells grown in culture. Phosphoglucose isomerase, phosphoglucomutase, and lactate dehydrogenase specific activities of the choriocarcinoma did not differ by more than two or three times from the mean activities of the comparable enzymes in placenta; the specific activity of hexokinase in the choriocarcinoma amounted to 14 per cent of the mean value for placenta. In contrast, the mean specific activity of heat-stable alkaline phosphatase in the choriocarcinoma amounted to only 1 per cent of the mean value for placenta. By growing the cells in 5-bromodeoxyuridine, 20 mug per milliliter, we were able to increase alkaline phosphatase activity to 68 per cent of the mean value for placenta. For both extracts, phosphoglucose isomerase zymograms were similar and phosphoglucomutase zymograms were similar. The hexokinase zymogram of term placenta showed two isoenzymes which stained more intensely with 0.5 mM. glucose than with 0.1M glucose. A hexokinase isoenzyme was observed in zymograms of both extracts which stained more intensely with 0.1M glucose than with 0.5 mM glucose. Lactate dehydrogenase exhibited an extra isoenzyme in the choriocarcinoma extract. When the cells were cultivated in medium containing 5 mug per milliliter of 5-bromodeoxyuridine, the induced phosphatase in the cell line was electrophoretically similar to placental phosphatase. At higher concentrations of 5-bromodeoxyuridine, the most anodal isoenzyme was 0.5 cm. slower in mobility than the comparable placental isoenzyme.
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PMID:Enzymes of normal and malignant trophoblast: phosphoglucose isomerase, phosphoglucomutase, hexokinase, lactate dehydrogenase, and alkaline phosphatase. 111 69

1. Time-curves of insulin effects on energy-producing systems in different cellular compartments of rat diaphragm muscle have revealed: (a) a rapid (within minutes) and transient stimulatory effect of insulin on cytoskeletal phosphofructokinase and aldolase and mitochondrial hexokinase. (b) A slower and consistent stimulatory effect on glucose 1,6-bisphosphate level, with concomitant gradual activation of cytosolic phosphofructokinase. Fructose 2,6-bisphosphate levels were not changed by insulin. (c) Lactate concentration correlated with the stimulation of cytoskeletal and cytosolic glycolysis. 2. Calmodulin antagonists, trifluoperazine or CGS 9343B, prevented all these effects of insulin. 3. These results suggest that cytoskeletal glycolysis and mitochondrial oxidation are the source of ATP for the rapid actions of insulin, whereas cytosolic glycolysis is the source of ATP for the slow actions of insulin. Calmodulin is involved in all these effects of insulin.
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PMID:Sequence of insulin effects on cytoskeletal and cytosolic phosphofructokinase, mitochondrial hexokinase, glucose 1,6-bisphosphate and fructose 2,6-bisphosphate levels, and the antagonistic action of calmodulin inhibitors, in diaphragm muscle. 139 93

Spirochaeta thermophila RI 19.B1 (DSM 6192) fermented glucose to lactate, acetate, CO2, and H2 with concomitant formation of cell material. The cell dry mass yield was 20.0 g/mol of glucose. From the fermentation balance data and knowledge of the fermentation pathway, a YATP of 9.22 g of dry mass per mol of ATP was calculated for pH-uncontrolled batch-culture growth on glucose in a mineral medium. Measurement of enzyme activities in glucose-grown cells revealed that glucose was taken up by a permease and then subjected to ATP-dependent phosphorylation by a hexokinase. Glucose-6-phosphate was further metabolized to pyruvate through the Embden-Meyerhof-Parnas pathway. The phosphoryl donor for phosphofructokinase activity was PPi rather than ATP. This was also found for the type strain of S. thermophila, Z-1203 (DSM 6578). PPi was probably formed by pyrophosphoroclastic cleavage of ATP, with recovery of the resultant AMP by the activity of adenylate kinase. All other measured kinase activities utilized ATP as the phosphoryl donor. Pyruvate was further metabolized to acetyl coenzyme A with concomitant production of H2 and CO2 by pyruvate synthase. Lactate was also produced from pyruvate by a fructose-1,6-diphosphate-insensitive lactate dehydrogenase. Evidence was obtained for the transfer of reducing equivalents from the glycolytic pathway to hydrogenase to produce H2. No formate dehydrogenase or significant ethanol-producing enzyme activities were detected.
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PMID:Glucose catabolism by Spirochaeta thermophila RI 19.B1. 155 64

Energy metabolism of malaria parasites was investigated in P. berghei infected red blood cells of rat. Although Plasmodia contain mitochondria most of their ATP is formed by glycolysis. Lactate formation is two orders of magnitude higher than in noninfected erythrocytes. The coupling of respiration and glycolysis is very loose, a Pasteur-effect was not found. The key enzymes of glycolysis hexokinase and phosphofructokinase have been partially purified and kinetically characterized. The kinetic properties of both enzymes significantly differ from those of erythrocytes. They are less efficiently inhibited and PFK is activated only by PEP, Fru6P and Pi. The high rate of glycolytic proton formation in Plasmodia inhibits the PFK and thus the anaerobic energy metabolism of the host cell but not that of the parasite. Nevertheless the ATP concentrations in the host and the parasite compartment were found to be nearly identical. This supports the assumption that the parasites make ATP available to their host cell, probably by an adenine nucleotide translocator.
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PMID:Regulation of the energy metabolism of Plasmodium berghei. 214 51

In epithelial cells isolated from rat small intestine and incubated in the presence of 1 mM glucose, streptozotocin-induced diabetes reduced, by 46 and 29%, respectively, the rates of both glucose utilization and L-lactate formation. These effects were accompanied by a significant decrease of enterocyte fructose 2,6-bisphosphate concentration (about 50%) and of the glycolytic flux through the reaction catalyzed by 6-phosphofructo 1-kinase. The diminution of enterocyte fructose 2,6-bisphosphate levels caused by diabetes occurred in spite of an increase of hexose 6-phosphate concentration, and was associated with a reduction in the amount of active form of 6-phosphofructo 2-kinase; total activity of this enzyme was not significantly modified. Diabetes also caused an acceleration in the rate of 3-O-methyl-D-(14C) glucose uptake and increased hexokinase activity in enterocytes. Lactate dehydrogenase, pyruvate kinase and 6-phosphofructo 1-kinase activities were not found to be significantly different in epithelial cells isolated from control or diabetic animals. Our results indicate that a reduction of the glycolytic flux in enterocytes could collaborate to increase intestinal glucose absorption in the diabetic state.
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PMID:Effect of streptozotocin diabetes on the glycolytic flux and on fructose 2,6-bisphosphate levels in isolated rat enterocytes. 216 51

The primary cause of red cell destruction in enzymopathies of anaerobic remains controversial and difficult to investigate especially because the erythrocyte population in enzymopenic patients is largely heterogeneous. We have shown that loading human erythrocytes with monospecific enzyme-inactivating antibodies could be useful in understanding the biochemical modifications occurring in enzymopenic erythrocytes and the mechanisms leading to red cell destruction. Hexokinase-inactivating antibodies were prepared and loaded in human erythrocytes using a procedure of encapsulation based on hypotonic hemolysis, isotonic resealing and reannealing. Red blood cells loaded with anti-hexokinase IgG showed 20 +/- 3% residual hexokinase activity while all other enzymes were normal. Lactate production by these cells was 30% of controls while the amount of glucose metabolized in the hexose monophosphate pathway (HMP) was unchanged under resting conditions. However, in the presence of methylene blue HMP rates were only 12% of controls. Determination of adenine nucleotide levels suggests that the antihexokinase-loaded red blood cells are not able to maintain, in vitro, their ATP level as well as their 2,3-diphosphoglycerate. Osmotic fragility, methemoglobin, and reduced glutathione content were near normal. These and other properties of the antihexokinase-loaded erythrocytes were similar to those found in cases of hexokinase deficiency. When the antibody-loaded erythrocytes were chromatrographed on immobilized Protein A columns 66-70% of cells were retained by the column against 0-10% of controls suggesting that hexokinase inactivation promotes autologous IgG binding. Since the phenomenon is known to be associated with red cell phagocytosis, it could be concluded that in hexokinase deficiency red cells are mainly removed by phagocytosis, and that hemolysis probably occurs in cases of oxidative stress when the production of a large amount of reducing equivalents (NADPH) is needed but not provided by the hexokinase-deficient erythrocytes.
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PMID:Human red blood cell loading with hexokinase-inactivating antibodies. An in vitro model for enzyme deficiencies. 250 71

The effects of beta 1- and beta 1 + beta 2-antagonists on the myocardial adaptation to exercise training were investigated in male Sprague-Dawley rats randomly divided into trained (treadmill, 1 hr/day, 5 days/week for 10 weeks at 27 m/min, 15% grade) without drug (TC), sedentary without drug (SC), trained treated with atenolol (TA) (10 mg/kg body wt, i.p.), trained treated with propranolol (TP, 30 mg/kg body wt, i.p.), and sedentary propranolol. Doses of both beta-antagonists were titrated to decrease the exercise heart rate by 25% compared to the controls. The heart weight and heart/body weight ratio were significantly greater in TC (1.28 +/- 0.07 g (P less than 0.01); 296 +/- 12 mg/100 g body wt (P less than 0.05) respectively) than in SC (1.09 +/- 0.04 g and 268 +/- 11 mg/100 g body wt), or in TP and TA. Myocardial mitochondrial protein was unchanged by training or beta-blockade. Citrate synthase and beta-hydroxyacyl CoA dehydrogenase activities were not altered. Carnitine palmitoyltransferase activity was increased in SP compared to SC. Training increased hexokinase activity only in TC (5.22 +/- 0.12 vs 4.26 +/- 0.23 mumol/min/g wet wt, P less than 0.01). Lactate dehydrogenase activity increased significantly (P less than 0.01) in both TC (383 +/- 14 mumol/min/g wet wt) and TA (372 +/- 14 mumol/min/g wet wt) compared to SC (276 +/- 14 mumol/min/g wet wt), but not in TP versus SP. These data indicate that (1) beta-adrenergic blockade prevents training-induced cardiac hypertrophy; (2) beta-antagonists have little effect on the myocardial oxidative capacity; and (3) while the training induction of myocardial hexokinase is inhibited by both beta 1- and beta 1 + beta 2-antagonists, myocardium may increase its ability to utilize lactate during exercise with training despite beta 1-blockade.
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PMID:Effects of beta 1- and beta 1 + beta 2-antagonists on training-induced myocardial hypertrophy and enzyme adaptation. 289 Mar 50

The activities of the rate-limiting enzymes of glycolytic pathway were measured in various areas of rat brains kept at a temperature of +25 degrees C for various intervals after death by cervical dislocation. Hexokinase shows a substantial decline in activity over a period of 24 h, reaching 41%, 57%, 44%, and 51% of the controls in cerebellum, medulla oblongata and pons, cerebral cortex, and diencephalon, respectively. In the same areas the phosphofructokinase reached 28%, 61%, 60%, and 40% of the zero-time activity, respectively. Lactate dehydrogenase behaves differently in the four areas, with an increase in cerebral cortex and diencephalon and a decrease in cerebellum and medulla oblongata and pons. Pyruvate kinase activity was quite stable over the 24 h period studied. Therefore, the activities of hexokinase and phosphofructokinase in brain tissue were of little value for diagnosis of the time of death.
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PMID:Postmortem activity of the key enzymes of glycolysis. In rat brain regions in relation to time after death. 294 19


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