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)

Glucose uptake by whole-cell suspensions of the obligate anaerobe Bacteroides thetaiotaomicron was two- to fourfold higher under aerobic conditions than during incubation under atmospheres of N(2) or H(2) gas. The O(2)-stimulated uptake activity was lost rapidly (>70% in 5 h) when cell suspensions were incubated aerobically, but this loss was prevented by the addition of crude catalase. Catalase had no apparent effect on cell viability during these incubations. Glucose uptake activity was strongly inhibited by a 10-fold excess of mannose or galactose but not by methyl-alpha-d-glucoside, fructose, or lactose. Both glucose and mannose were rapidly incorporated into polyglucose after uptake. The O(2)-stimulated glucose uptake was not inhibited by cyanide, azide, 2,4-dinitrophenol, or 2-N-heptyl-4-hydroxyquinoline-N-oxide. However, p-chloromercuribenzoate, menadione, and sodium fluoride inhibited uptake by 88, 67, and 55%, respectively. All attempts to detect phosphoenolpyruvate-phosphotransferase activity for glucose, methyl-alpha-d-glucoside, and 2-deoxyglucose were negative. The bacteria contained hexokinase activity and a complete glycolytic Embden-Meyerhof pathway.
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PMID:Uptake and incorporation of glucose and mannose by whole cells of Bacteroides thetaiotaomicron. 7 63

A long-term administration of retinol in a dose exceeding 15-fold the diurnal requirement to rats weighing 170-200 g provoked a diminution of the erythrocytes resistance to an acid hemolytic, an intensified uptake of glucose, and increased activity of glycolytic enzymes (hexokinase, aldolase, phosphohexoisomerase), accumulation of lactate, along with changes in the redox enzymes activity, suppression of the catalase and intensification of peroxidase activity. The content of microergic nucleotides and electrolites (Na+ and K+) remained unchanged.
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PMID:[Effect of long-term vitamin A administration on the acid fastness and biochemical properties of erythrocytes]. 96 79

Phytomonas sp. isolated from Euphorbia characias was adapted to SDM-79 medium. Cells isolated in the early stationary phase of growth were analyzed for their capacity to utilize plant carbohydrates for their energy requirements. The cellulose-degrading enzymes amylase, amylomaltase, invertase, carboxymethylcellulase, and the pectin-degrading enzymes polygalacturonase and oligo-D-galactosiduronate lyase were present in Phytomonas sp. and were all, except for amylomaltase, excreted into the external medium. Glucose, fructose and mannose served as the major energy substrates. Catabolism of carbohydrates occurred mainly via aerobic glycolysis according to the Embden-Meyerhof pathway, of which all the enzymes were detected. Likewise, the end-products of glycolysis, acetate and pyruvate, glycerol, succinate and ethanol were detected in the culture medium, as were the enzymes responsible for their production. Mitochondria were incapable of oxidizing succinate, 2-oxoglutarate, pyruvate, malate and proline, but had a high capacity to oxidize glycerol 3-phosphate. This oxidation was completely inhibited by salicylhydroxamic acid. No cytochromes could be detected either in intact mitochondria or in sub-mitochondrial particles. Mitochondrial respiration was not inhibited by antimycin, azide or cyanide. The glycolytic enzymes, from hexokinase to phosphoglycerate kinase, and the enzymes glycerol kinase, glycerol-3-phosphate dehydrogenase, phosphoenolpyruvate carboxykinase, malate dehydrogenase and adenylate kinase, were all associated with glycosomes that had a buoyant density of about 1.24 g cm-1 in sucrose. Cytochemical staining revealed the presence of catalase in these organelles. The cytosolic enzyme pyruvate kinase was activated by fructose 2,6-bisphosphate, typical of all other pyruvate kinases from Kinetoplastida. The energy metabolism of the plant parasite Phytomonas sp. isolated from E. characias resembled that of the bloodstream form of the mammalian parasite Trypanosoma brucei.
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PMID:Characterization of carbohydrate metabolism and demonstration of glycosomes in a Phytomonas sp. isolated from Euphorbia characias. 143 59

An in vitro animal model was used to characterize the protective effect of glucose on lenses subjected to oxidative stress. Paired rat lenses were incubated in TC-199 medium for six hours in the presence of an oxidant (0.06 mM H2O2, superoxide produced from 5 mM purine, or hydroxyl radical) and 2 mM glucose (control) or no glucose (experimental). Soluble hexokinase (HK) specific activity and lactate production were measured. 0.06 mM H2O2 inactivates 48% of the hexokinase in the absence of glucose; with glucose present hexokinase activity is reduced only 26%. Control experiments without oxidants show a statistically insignificant difference between hexokinase activities in the 0 and 2 mM groups, suggesting that the changes observed are not simply due to the presence or absence of glucose. Hexosemonophosphate shunt activity increases nearly 2.5-fold in the presence of 0.06 mM H2O2 and 2.0, 4.0 or 5.5 mM glucose. This suggests that the loss of hexokinase (a -SH enzyme) in the presence of H2O2 and 0 mM glucose is due to NADPH production inadequate to offset the oxidative stress on enzyme -SH groups. FPLC analysis suggests that type II HK is more susceptible to oxidative inactivation than type I, and further studies have shown that this inactivation is localized to the capsule/epithelium. Lactate levels were measured and controls (without oxidants) were run, to obtain a baseline value for fresh lenses and assess the contribution of endogenous glucose to lactate production. H2O2 levels in superoxide and hydroxyl radical media were measured, and the protective effects of mannitol and catalase were also determined.
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PMID:The protective effect of glucose on soluble rat lens hexokinase in the presence of oxidative stress. 301 94

Rat lenses treated with greater than 0.06 mM hydrogen peroxide (HP) appeared to sustain epithelial damage, particularly a loss of enzymes including hexokinase, which controls the supply of glucose-6-phosphate. This may account for the lower level of hexose monophosphate shunt activation observed in these lenses. Other alterations include a decrease of lactate production and disturbance to ionic balance. These changes occurred despite HP removal by glutathione reductase/peroxidase system, catalase and other mechanisms. This suggests an inherent weakness for the lens to resist stresses from high levels of HP. Further, competition for NADPH between aldose reductase and glutathione reductase apparently affects the lens's ability to detoxify HP. This implies a role for oxidation in diabetic cataractogenesis.
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PMID:The lens's response to exogenous hydrogen peroxide. 322 97

Photodamage to lens hexokinase has been investigated by exposing the lenses of rat, rabbit and calf eyes to 300 nm irradiation. Hexokinase activity was diminished by 15.9% +/- 5.4 and 23.4% +/- 5.0 upon irradiation of the isolated rat lens for 1 and 2 hours respectively. Irradiation of the whole eye for 2 hours resulted in hexokinase deactivation of 13.6% +/- 5.8 and 19.2% +/- 6.2 for rat and rabbit lens homogenates and 55% +/- 7 for calf lens capsule plus epithelium. Enzyme deactivation was prevented when the isolated lens was irradiated with the vitreous attached. Glucose, catalase or ascorbate added to the medium prior to irradiation, each had a protective effect on hexokinase deactivation. The results are consistent with a mechanism in which photochemical generation of active species of oxygen, via the photosensitizing action of tryptophan photoproducts, plays a significant role in enzyme deactivation.
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PMID:Lens hexokinase deactivation by near-UV irradiation. 335 12

Cells of the aerotolerant anaerobe Giardia lamblia respire in the presence of oxygen. Endogenous respiration is stimulated by glucose but not by other carbohydrates and Krebs cycle intermediates. Endogenous and glucose-stimulated respiration are insensitive to cyanide, malonate, and 2,4-dinitrophenol, but are inhibited by atabrin and iodoacetamide. G. lamblia produces ethanol, acetate and CO2 both aerobically and anaerobically either from endogenous reserves or exogenous glucose. Molecular hydrogen is not produced. The following enzyme activities were detected in homogenates: hexokinase, fructose-biphosphate aldolase, pyruvate kinase, phosphoenolpyruvate carboxykinase, malate dehydrogenase, malate dehydrogenase (decarboxylating), pyruvate synthase, acetyl-CoA synthetase, alcohol dehydrogenase (NADP+), NADH dehydrogenase, NADPH dehydrogenase, NADPH oxidoreductase and superoxide dismutase. The enzymes of energy and carbohydrate metabolism are nonsedimentable (109 000 x g for 30 min). Activities of lactate dehydrogenase, hydrogenase, phosphate acetyltransferase, acetate kinase, citrate synthase, succinate dehydrogenase, fumarate hydratase and catalase were below the limits of detection. The results suggest the occurrence of glycolysis, energy production by substrate level phosphorylation and a flavin, iron-sulfur protein mediated electron transport system as well as the absence of cytochrome mediated oxidative phosphorylation and functional Krebs cycle.
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PMID:Energy metabolism of the anaerobic protozoon Giardia lamblia. 610 7

Deciliation of Paramecium tetraurelia by a Ca2+ shock procedure releases a discrete set of proteins which represent about 1% of the total cell protein. Marker enzymes for cytoplasm (hexokinase), endoplasmic reticulum (glucose-6-phosphatase), peroxisomes (catalase), and lysosomes (acid phosphatase) were not released by this treatment. Among the proteins selectively released is a Ca2+-dependent ATPase. This enzyme has a broad substrate specificity which includes GTP, ATP, and UTP, and it can be activated by Ca2+, Sr2+, or Ba2+, but not by Mg2+ or by monovalent cations. The crude enzyme has a specific activity of 2-3 mumol/min per mg; the optimal pH for activity is 7.5. ATPase, GTPase, and UTPase all reside in the same protein, which is inhibited by ruthenium red, is irreversibly denatured at 50 degrees C, and which has a sedimentation coefficient of 8-10 S. This enzyme is compared with other surface-derived ATPases of ciliated protozoans, and its possible roles are discussed.
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PMID:A Ca2+-activated ATPase specifically released by Ca2+ shock from Paramecium tetraurelia. 612 13

The following aspects have been investigated in 10 patients affected by Huntington's disease )HD): --extensive haematological investigations; --red cell enzyme activities and level of the most important glycolytic intermediate compounds; --protein, lipid and carbohydrate composition of the erythrocyte membrane and membrane polarity; --effects of in vitro aging on red cell membranes. Lack of 4.5 protein band in SDS-PAGE and 14-fold decrease in membrane-bound catalase were found in the in vitro aged red cells from the 10 HD patients examined. Na+ + K+ATPase was slightly higher than normal in all the patients. Red cells from 5 out of 8 patients showed a decrease in reduced glutathione and phosphoenolpyruvate levels and/or an increase in hexokinase, glucose-6-phosphate dehydrogenase, pyruvate kinase and glutathione reductase activities. The haematological investigations, the protein lipid and carbohydrate composition of the fresh red cells, the membrane polypeptide aggregates and the membrane polarity evaluated by microspectrofluorometric analysis were normal.
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PMID:Metabolic impairment and membrane abnormality in red cells from Huntington's disease. 644 71

A new and simple enzymatic assay for measuring D-mannose in serum is described. Endogenous glucose is eliminated from serum by use of glucose oxidase (EC 1.1.3.4) and catalase (EC 1.11.1.6). D-Mannose concentration is calculated from the increase in NADH formation after mannosephosphate isomerase (EC 5.3.1.8) is added. This increase is a result of coupling the following series of enzymes: hexokinase (EC 2.7.1.1), glucosephosphate isomerase (EC 5.3.1.9), and glucose-6-phosphate dehydrogenase (EC 1.1.1.49, NAD+-dependent). The study included subjects who were healthy volunteers and patients with suspected or proven fungal infections.
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PMID:Enzymatic determination of D-mannose in serum. 669 39


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