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

---

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

The enzyme activities of cultured early erythroid progenitor cells (burst-forming unit erythroid, BFU-E) were measured and were compared with the activities of mature erythrocytes. The enzyme activity of acetylcholinesterase was not detectable in the erythroblasts. The ratios of phosphofructokinase and glutathione peroxidase were low due to low enzyme activities in both the erythroblasts and erythrocytes. The ratios of triose phosphate isomerase, phosphoglycerate kinase, and adenylate kinase were low due to high enzyme activities in both the erythroblasts and erythrocytes. The ratios of hexokinase, glucose phosphate isomerase, monophosphoglyceromutase, pyruvate kinase, and adenosine deaminase were high due to high enzyme activities in the erythroblasts. The isozyme of erythroblast hexokinase was of the prototype isozyme I, while pyruvate kinase was predominantly of the prototype M2, with two hybrid isozymes to the anodal side by electrophoresis. These facts suggest that there is a greatly different metabolic pattern during the maturation of the erythroid cells.
...
PMID:Enzyme activities of cultured erythroblasts. 403 55

The storage lesion which limits the shelf life of human blood in blood banking is associated with a metabolic loss of 2,3-diphosphoglycerate and ATP. This metabolic loss is driven by intracellular ATPase which are usually considered to include the ion pumps and the reactions which maintain the discoid shape of the human erythrocyte. Under the acidic conditions of blood storage, the energy-yielding reactions of the glycolytic pathway are restricted at the hexokinase and phosphofructokinase steps. We show here that under such circumstances the enzyme of the diphosphoglycerate shunt, diphosphoglycerate mutase/phosphatase and the glycolytic enzyme phosphoglycerate kinase can form a futile cycle with ATPase activity. This ATPase activity responds to 2-phosphoglycolate which is known to activate both diphosphoglycerate mutase and diphosphoglycerate phosphatase reactions. When the enzymes of the futile cycle are combined with the enzymes of the lower glycolytic pathway in a reconstitution experiment designed to represent conditions within the stored erythrocyte, the futile cycle does provide an ATPase activity which results in the metabolic loss of 2,3-diphosphoglycerate. An isotope incorporation experiment demonstrates that the futile cycle is active in glucose-depleted erythrocytes.
...
PMID:A futile cycle in erythrocyte glycolysis. 406 53

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.
...
PMID:Control of glycolysis in cerebral cortex slices. 422 84

Previous studies have shown a marked effect of very high levels of copper on red cell glucose-6-phosphate dehydrogenase and glutathione. When the effect of more nearly physiological levels of copper were studied, red cell hexokinase, phosphofructokinase, phosphoglyceric kinase, pyruvate kinase, and 6-phosphogluconate dehydrogenase were found to be inhibited. Inhibition was observed both when copper was added directly to hemolysates or when hemolysates were prepared from red cells from whole blood which had been incubated with copper and washed. The inhibition of red cell enzymes by copper was completely reversed by the addition of EDTA.
...
PMID:The effect of copper on red cell enzyme activities. 425 5

Human platelets were separated by desity-centrifugation into heavy and light populations. Heavy platelets have an average volume approximately twofold greater than light platelets, and have previously been shown to be young platelets. All 11 enzymes of the Embden-Meyerhof pathway plus the five related enzymes: phosphoglucomutase, glucose-6-P dehydrogenase, 6-P-gluconic dehydrogenase, alpha-glycerol-P dehydrogenase, and glutathione reductase (TPNH) were examined in cell lysates from total, heavy, and light platelet populations. Apparent Km for individual enzymes were measured in a total platelet population. Empirical V(max) of the individual enzymes were measured in total, heavy, and light platelet populations. The three apparent rate-limiting enzymes for glycolysis were hexokinase, phosphofructokinase, and glyceraldehyde-3-P dehydrogenase. Heavy platelets contained approximately twofold greater enzyme activity (per gram wet weight) than light platelets for 7 of the 16 enzymes measured: hexokinase, phosphohexoisomerase, phosphofructokinase, glyceraldehyde-3-P dehydrogenase, phosphoglycerokinase, lactic dehydrogenase, and phosphoglucomutase. Heavy platelets also contained 1.9-fold greater reduced glutathione (GSH), 1.7-fold greater DPNH, and 1.2-fold greater TPNH than light platelets. Heavy platelets contained 1.8-fold less lipid peroxidation products (malonyl aldehyde equivalents) than light platelets and were 2.4-fold more resistant to lipid peroxidation catalyzed by 0.1 mM FeCl(3). Sterile incubation of heavy platelets, in vitro for 17 hr, resulted in a significant loss of enzyme activity for the "elevated" seven enzymes when compared with the remainder. Reducing agents such as GSH (0.1 mM), ascorbic acid (0.1 mM), and dithiothreitol (0.01 mM), when added to the incubation mixture, significantly reduced the in vitro loss of activity. In vitro incubation was also associated with a significant loss of GSH and DPNH and a 1.8-fold increase in lipid peroxidation products.
...
PMID:Heterogeneity of human platelets. V. Differences in glycolytic and related enzymes with possible relation to platelet age. 426 50

1. Parenchymal cells have been prepared from mouse liver by enzymic and mechanical means. 2. The dry weights, protein and DNA contents of these cells have been determined. 3. Mouse liver ;M-' and ;L-type' pyruvate kinases have been prepared free of contamination with each other; their kinetic properties have been examined and a method has been developed for their assay in total liver homogenates. 4. Recoveries of phosphoglycerate kinase, lactate dehydrogenase and phosphofructokinase in enzymically prepared cells indicate that little, if any, cytoplasmic protein is lost during preparation. 5. Parenchymal cells exhibit a very substantial increase in the activity ratio of glucokinase to hexokinase over that in total liver homogenate; in three out of eight experiments, hexokinase activity was undetectable. 6. ;L-type' pyruvate kinase alone occurs in the parenchymal cell. Non-parenchymal cells are characterized by the presence of ;M-type' activity only. 7. Parenchymal cells contain both glucose 6-phosphatase and fructose 1,6-diphosphatase. The non-parenchymal fraction appears to contain fructose 1,6-diphosphatase, but is devoid of glucose 6-phosphatase. 8. No aldolase A was detectable in the whole liver. Aldolase B occurs in both parenchymal and non-parenchymal tissue. 9. Parenchymal cells prepared by mechanical disruption of mouse liver with 20% polyvinyl alcohol exhibit a similar enzyme profile to those prepared enzymically. 10. The methodology involved in the preparation of isolated liver cells is discussed. The importance of the measurement of several parameters as criteria for establishing the viability of parenchymal cells is stressed. 11. The metabolic implications of the results in the present study are discussed.
...
PMID:Glycolytic and gluconeogenic enzyme activities in parenchymal and non-parenchymal cells from mouse liver. 426 95

1. The degradation rates and half-lives of hexokinase, 6-phosphogluconate dehydrogenase, lactate dehydrogenase, pyruvate kinase, glucose 6-phosphate dehydrogenase, phosphoglycerate kinase and aldolase were calculated from measurements of the decline in activities of these enzymes in rat small intestine during starvation. 2. The half-lives of the enzymes are: hexokinase, 5.7h; 6-phosphogluconate dehydrogenase, 7.6h; glucose 6-phosphate dehydrogenase, 6.0h; pyruvate kinase, 8.9h; lactate dehydrogenase, 8.7h; phosphoglycerate kinase, 8.7h; aldolase, 5.1h. 3. The significance of the results is discussed with respect to the regulation of enzyme concentrations in response to changes in diet.
...
PMID:Degradation of glucose-metabolizing enzymes in the rat small intestine during starvation. 472 2

Inhibition of IMP dehydrogenase in AS-30D hepatoma cells in suspension culture resulted in a pronounced and selective reduction of guanine nucleotide pools. Total acid-soluble guanine nucleotides decreased to 40% and the content of GTP and GDP dropped to about 20% of control within 4 h when mycophenolate or ribavirin were used as the inhibitors. Induction of GTP deficiency was associated with a 50% rise in UTP and other uracil nucleotides. Guanosine rapidly reversed both the reduction of guanine nucleotide pools and the elevation of cellular UTP contents. Enzymatic nucleotide analyses in cell and tissue extracts after treatment with ribavirin indicated that ribavirin 5'-triphosphate was an effective substrate for yeast hexokinase, yeast phosphoglycerate kinase, and nucleosidediphosphate kinase from yeast or bovine liver. These results were confirmed in detail by the use of synthetic ribavirin 5'-triphosphate and 5'-diphosphate. The latter nucleotide analog was also a substrate of pyruvate kinase from muscle. Mycophenolate-induced GTP deficiency was associated with an arrest of hepatoma cell growth in suspension culture. Ribavirin, at an equimolar concentration, was much less effective in this respect. None of the two inhibitors had a detectable effect, however, in vivo when guanine or uracil nucleotides were assayed in liver. This indicated that an inhibition of de novo guanylate synthesis in vivo can be compensated by salvage pathway synthesis.
...
PMID:Selective guanosine phosphate deficiency in hepatoma cells induced by inhibitors of IMP dehydrogenase. 610 11

Three enzymes, glycogen phosphorylase, glycogen synthase, and phosphoglucomutase were evaluated in subcellular fractions and in brain regions. Also the development of each of these enzymes was evaluated in whole brain homogenates. Each enzyme increased during the first three weeks of post partum in a manner that is similar to the development of glycolytic enzymes during this period. The specific activity of each enzyme in various subcellular fractions indicated that the enzymes were primarily soluble. Also unlike the glycolytic enzyme phosphoglycerate kinase, the glycogen metabolizing enzymes had a lower specific activity in synaptosomes than in particle free supernatant fractions of homogenates. Regarding regional distribution small (less than twofold) but significant differences were seen between different brain areas. An inverse relationship between the glycogen metabolizing enzymes and hexokinase was observed, that is, regions highest in glycogen synthase and glycogen phosphorylase were lowest in hexokinase and regions highest in hexokinase were lowest in the glycogen metabolizing enzymes.
...
PMID:Glycogen metabolizing enzymes in brain. 621 21

Red cell enzymes, 2,3-diphosphoglycerate (2,3-DPG) and adenosine triphosphate (ATP), were evaluated in a 23-mo-old boy with juvenile chronic myelocytic leukemia (JCML) at the onset of his illness and 6 mo later during the accelerated phase. The activities of the age-dependent red cell enzymes, hexokinase, aldolase, pyruvate kinase, and glucose-6-phosphate dehydrogenase, were elevated, as were the concentrations of red cell 2,3-DPG and ATP, consistent with a young red cell population metabolizing at an increased glycolytic rate. The activities of the non-age-dependent enzymes, glyceraldehyde-3-phosphate dehydrogenase (G3PD), phosphoglycerate kinase, and enolase, were also increased to levels similar to or greater than those observed in term infants. As the illness progressed, the activity of red cell G3PD increased further, and phosphoglucose isomerase activity increased markedly. These results are consistent with the prior suggestion that JCML represents a reversion to "fetal" erythropoiesis.
...
PMID:Fetal erythropoiesis in juvenile chronic myelocytic leukemia. 622 20


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>

---