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)

Tissue culture for one or seven days of pancreatic islets isolated from 21-day old fetal rats was found to be associated with a marked increase in the oxidation of L-(U-14C) glutamine by intact islets and in the activity of both alanine-glutamate and aspartate-glutamate transaminases as well as glutamate dehydrogenase in islet homogenates. This coincided with an increase in the relative amount of mitochondrial DNA. The activities of glucose-phosphorylating enzymes (hexokinase and glucokinase), glyceraldehyde-3-phosphate dehydrogenase and lactate dehydrogenase were less markedly increased during the culture period than those of enzymes involved in amino acid catabolism and located, in part at least, in mitochondria. The combined data suggest that the functional maturation of fetal islets during the culture period is associated with and may be attributable to a preferential maturation of their mitochondria.
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PMID:Maturation of fetal rat islet cells in vitro during tissue culture is associated with increased mitochondrial function. 213 6

We assessed our speculation that 2-cyclohexen-1-one (CHX) impairs glucose-induced insulin secretion through inactivation of glucokinase. Treatment of pancreatic islets with CHX at concentrations (0-5 mM) that caused a dose-dependent inactivation of glucokinase activity similarly inhibited glucose-induced insulin secretion. Another glucose-phosphorylating enzyme (hexokinase) in pancreatic islets was little affected by CHX. CHX-induced inactivation of glucokinase was blocked by the presence of its substrates (glucose and mannose) and an inhibitor (N-acetylglucosamine), all of which also protected against the inhibitory effect of the drug on glucose-induced insulin secretion. CHX also impaired insulin secretion induced by D-glyceraldehyde and dimethyl succinate, which are believed to stimulate the release of the hormone by being directly oxidized by glyceraldehyde-3-phosphate dehydrogenase, by entering the midstream of the glycolytic pathway as glyceraldehyde 3-phosphate, or by entering the tricarboxylic acid cycle in mitochondria after intracellular hydrolysis. The inhibitory effect of CHX on glucose-induced insulin secretion, however, was far more marked than that on insulin secretion evoked by D-glyceraldehyde and dimethyl succinate at any CHX concentrations used. Our study revealed that the inhibitory action of CHX on glucose-induced insulin secretion is exerted mainly, but not solely, through inactivation of glucokinase. This conclusion supports the view that glucokinase is a key enzyme in the recognition of glucose as an insulin secretagogue in pancreatic islets.
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PMID:Participation of glucokinase inactivation in inhibition of glucose-induced insulin secretion by 2-cyclohexen-1-one. 221 70

The activities of 6 enzymes involved in carbohydrate metabolism were determined quantitatively in preovulatory oocytes by cytochemical means per individual cell as well as biochemically in cell homogenates. Oocytes were incorporated in a polyacrylamide matrix for appropriate enzyme cytochemical staining. This incorporation preserves the morphology of the cells very well, and the enzymes keep their activity for a considerable period of time. This method could also be used to demonstrate more than one enzyme activity in the same cell. The results obtained by cytochemical means appeared to correlate very well with the biochemical data (P less than 0.005). Glucose 6-phosphate dehydrogenase, the key-enzyme in the pentose phosphate pathway, had very high activity in these preovulatory oocytes, but 6-phosphogluconate dehydrogenase activity was only about 2% of that of glucose 6-phosphate dehydrogenase. The activities of lactate dehydrogenase and to a lesser extent glucose phosphate isomerase and D-glyceraldehyde-3-phosphate dehydrogenase also appeared to be very high, while hexokinase showed a very low activity.
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PMID:A cytochemical method for measuring enzyme activity in individual preovulatory mouse oocytes. 241

Chloroquine at pH 8.0 and 1mM [corrected] concentration inhibits about 30% glucose consumption and ethanol formation in yeast cells. Out of the 11 glycolytic enzymes assayed, phosphoglycerate kinase and pyruvate decarboxylase have been found to be most sensitive to chloroquine. Next sensitive are hexokinase, glyceraldehyde-3-phosphate dehydrogenase and pyruvate kinase. Kinetic studies with the three kinases studied revealed competitive inhibition of chloroquine with ATP (hexokinase, phosphoglycerate kinase) or ADP (pyruvate kinase).
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PMID:Sensitivity of yeast glycolytic enzymes to chloroquine. 284 78

The specific activities of each of the enzymes of the classical pentose phosphate pathway have been determined in both cultured procyclic and bloodstream forms of Trypanosoma brucei. Both forms contained glucose-6-phosphate dehydrogenase (EC 1.1.1.49), 6-phosphogluconolactonase (EC 3.1.1.31), 6-phosphogluconate dehydrogenase (EC 1.1.1.44), ribose-5-phosphate isomerase (EC 5.3.1.6) and transaldolase (EC 2.2.1.2). However, ribulose-5-phosphate 3'-epimerase (EC 5.1.3.1) and transketolase (EC 2.2.1.1) activities were detectable only in procyclic forms. These results clearly demonstrate that both forms of T. brucei can metabolize glucose via the oxidative segment of the classical pentose phosphate pathway in order to produce D-ribose-5-phosphate for the synthesis of nucleic acids and reduced NADP for other synthetic reactions. However, only procyclic forms are capable of using the non-oxidative segment of the classical pentose phosphate pathway to cycle carbon between pentose and hexose phosphates in order to produce D-glyceraldehyde 3-phosphate as a net product of the pathway. Both forms lack the key gluconeogenic enzyme, fructose-bisphosphatase (EC 3.1.3.11). Consequently, neither form should be able to engage in gluconeogenesis nor should procyclic forms be able to return any of the glyceraldehyde 3-phosphate produced in the pentose phosphate pathway to glucose 6-phosphate. This last specific metabolic arrangement and the restriction of all but the terminal steps of glycolysis to the glycosome may be the observations required to explain the presence of distinct cytosolic and glycosomal isoenzymes of glyceraldehyde-3-phosphate dehydrogenase and phosphoglycerate kinase. These same observations also may provide the basis for explaining the presence of cytosolic hexokinase and phosphoglucose isomerase without the presence of any cytosolic phosphofructokinase activity. The key enzymes of the Entner-Doudoroff pathway, 6-phosphogluconate dehydratase (EC 4.2.1.12) and 2-keto-3-deoxy-6-phosphogluconate aldolase (EC 4.1.2.14) were not detected in either procyclic or bloodstream forms of T. brucei.
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PMID:The enzymes of the classical pentose phosphate pathway display differential activities in procyclic and bloodstream forms of Trypanosoma brucei. 292 7

The effect of sesquiterpene lactones isolated from Geigeria was tested on three glycolytic enzymes. Phosphofructokinase was inhibited irreversibly by all of the sesquiterpene lactones, with ivalin(III) giving the highest extent of inhibition. Values for the kinetic constants Ki (1.3 mM) and kp (2.2 min-1) were established. Hexokinase and glyceraldehyde-3-phosphate dehydrogenase were also strongly inhibited at 1 mM and 3 mM concentrations of sesquiterpene lactones, respectively. Pre-incubation of ivalin with dithiothreitol decreased its inhibiting effect on phosphofructokinase, hexokinase and glyceraldehyde-3-phosphate dehydrogenase activities. Phosphofructokinase and hexokinase were protected against inhibition by ivalin by their respective substrates, adenosine-5'-triphosphate and glucose.
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PMID:The effect of the sesquiterpene lactones from Geigeria on glycolytic enzymes. 293 49

The intracellular distribution of the glycolytic enzymes hexokinase, glyceraldehyde-3-phosphate dehydrogenase, lactate dehydrogenase and the pyruvate kinase isoenzymes type M1 and type M2 within unfertilized hen eggs was studied. Most of glycolytic enzyme activities were found in the yolk fraction; 8-24% of total glycolytic enzyme activities were found in the vitelline membrane fraction. However, the specific activities of these enzymes in the vitelline membrane fraction are 19-72-fold higher (U/mg protein) and 45-178-fold more concentrated (U/g wet weight) than in the yolk fraction. The study of intracellular localization of pyruvate kinase isoenzymes shows that the blastodisc, latebra and vitelline membrane contain only pyruvate kinase type M2, whereas pyruvate kinase types M1 and M2 are found in the egg yolk. The exclusive occurrence of pyruvate kinase type M2 in the blastodisc is consistent with the concept that this isoenzyme is involved in the cell proliferation. The heterogeneous distribution of the glycolytic enzymes hexokinase, glyceraldehyde-3-phosphate dehydrogenase and lactate dehydrogenase, and the heterogeneous localization of the pyruvate kinase isoenzymes types M1 and M2 indicate that glycolysis is distributed heterogeneously within the unfertilized hen egg cell.
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PMID:Demonstration of a heterogeneous distribution of glycolytic enzymes and of pyruvate kinase isoenzymes types M1 and M2 in unfertilized hen eggs. 294 22

Preincubation with Mipafox and Methamidofos as well as Paraoxon (used as control) did not cause inhibition of hexokinase, phosphofructokinase, glyceraldehyde-3-phosphate dehydrogenase and lactate dehydrogenase. This is in contrast with the inhibition of glycolysis by other neurotoxic compounds (hexacarbons, acrylamide, carbon disulfide).
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PMID:Lack of inhibition of glycolytic enzymes by the neurotoxic organophosphorus compounds mipafox and methamidofos. 296 83

The in vitro effect of acrylamide and its analogues on rat brain glycolytic enzymes was examined to elucidate the biochemical lesions responsible for the pathogenesis of acrylamide-induced neuropathy. All test compounds inhibited glyceraldehyde-3-phosphate dehydrogenase, irrespective of their neurotoxicity, and their inhibitory potency was a linear function of the rate constant with reduced glutathione. Phosphofructokinase was also inhibited by some of the test compounds, independently of their neurotoxicity. The rate-limiting enzymes in glycolysis, hexokinase and pyruvate kinase, were not inhibited by acrylamide.
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PMID:Effect of acrylamide and related compounds on glycolytic enzymes of rat brain. 316 Dec 19

A latex phagocytosis technique was used to prepare relatively pure plasma membranes with inside-out orientation. This method was adapted through a number of modifications in order to evaluate the association of glycolytic enzymes with the cytoplasmic side of the plasma membrane of C6 glial cells. As phosphorylation is strictly coupled with transport in these cells, glycolytic enzymes, especially hexokinase, could metabolize glucose in close vicinity to its transporter. Of the enzymes tested, hexokinase is present in considerable quantities on these membranes (nearly 40% of homogenate specific activity), followed by D-glyceraldehyde-3-phosphate dehydrogenase (10%), pyruvate kinase (8%), and 3-phosphoglycerate kinase (1%). Except for hexokinase, the enzyme pattern presented here is different from that published for other membrane preparations.
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PMID:Association of glycolytic enzymes with the cytoplasmic side of the plasma membrane of glioma cells. 335 18


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