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)

The Embden-Meyerhof (EM) or Entner-Doudoroff (ED) pathways of sugar degradation were analyzed in representative species of the hyperthermophilic archaeal genera Thermococcus, Desulfurococcus, Thermoproteus, and Sulfolobus, and in the hyperthermophilic (eu)bacterial genus Thermotoga. The analyses included (1) determination of 13C-labeling patterns by 1H- and 13C-NMR spectroscopy of fermentation products derived from pyruvate after fermentation of specifically 13C-labeled glucose by cell suspensions, (2) identification of intermediates of sugar degradation after conversion of 14C-labeled glucose by cell extracts, and (3) measurements of enzyme activities in cell extracts. Thermococcus celer and Thermococcus litoralis fermented 13C-glucose to acetate and alanine via a modified EM pathway (100%). This modification involves ADP-dependent hexokinase, 6-phosphofructokinase, and glyceraldehyde-3-phosphate:ferredoxin oxidoreductase (GAP:FdOR). Desulfurococcus amylolyticus fermented 13C-glucose to acetate via a modified EM pathway in which GAP:FdOR replaces GAP-DH/phosphoglycerate kinase. Thermoproteus tenax fermented 13C-glucose to low amounts of acetate and alanine via simultaneous operation of the EM pathway (85%) and the ED pathway (15%). Aerobic Sulfolobus acidocaldarius fermented 13C-labeled glucose to low amounts of acetate and alanine exclusively via the ED pathway. The anaerobic (eu)bacterium Thermotoga maritima fermented 13C-glucose to acetate and lactate via the EM pathway (85%) and the ED pathway (15%). Cell extracts contained glucose-6-phosphate dehydrogenase and 2-keto-3-deoxy-6-phosphogluconate aldolase, key enzymes of the conventional phosphorylated ED pathway, and, as reported previously, all enzymes of the conventional EM pathway. In conclusion, glucose was degraded by hyperthermophilic archaea to pyruvate either via modified EM pathways with different types of hexose kinases and GAP-oxidizing enzymes, by the nonphosphorylated ED pathway, or by a combination of both pathways. In contrast, glucose catabolism in the hyperthermophilic (eu)bacterium Thermotoga involves the conventional forms of the EM and ED pathways. The data are in accordance with various previous reports.
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PMID:Comparative analysis of Embden-Meyerhof and Entner-Doudoroff glycolytic pathways in hyperthermophilic archaea and the bacterium Thermotoga. 907 22

1,1'-dimethylferricinium (DMFe+), a stable and pH-insensitive blue dye, was prepared via enzymatic oxidation of a 1,1'dimethyl-ferrocene (DMFe):2-hydroxypropyl-beta-cyclodextrin (HPCD) water-soluble inclusion complex, using bilirubin oxidase immobilized onto porous aminopropyl glass beads via glutaraldehyde activation. In the presence of glucose, DMFe+ was reduced to DMFe by reacting with the reduced glucose oxidase (FADH2), and the absorbance decrease was followed at 650 nm. In acetate pH 5.2 buffer, the response to glucose in blood serum was nonlinear, especially in the low concentration range, because of a competition for the reduced glucose oxidase between the DMFe+ dye and oxygen. At this pH, endogenous ceruloplasmin was also observed to oxidize residual DMFe (16%) in the dye preparation, causing an increase in absorbance at 650 nm. An assay protocol was then developed using maleate buffer, pH 6.5, to overcome these interferences as well as mutarotation of alpha-D-glucose. The results obtained for glucose in the blood serum samples agreed well with those of the reference hexokinase/glucose-6-phosphate dehydrogenase method.
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PMID:An improved enzymatic assay for glucose determination in blood serum using a 1,1'-dimethylferricinium dye. 910 Mar 58

D-mannoheptulose, but not its hexaacetate ester, inhibits, in a competitive manner, D-glucose phosphorylation by either purified beef heart hexokinase or crude parotid gland homogenates. Yet, D-mannoheptulose hexaacetate, but neither the unesterified heptose nor acetate or its methyl ester, inhibits D-[5-3H]glucose utilization and D-[U-14C]glucose conversion to 14CO2 and 14C-labelled acidic metabolites and amino acids in intact isolated parotid cells. It is proposed, therefore, that D-mannoheptulose hexaacetate crosses efficiently the plasma membrane of parotid cells and, after intracellular hydrolysis, allows inhibition of D-glucose phosphorylation by the unesterified heptose. The ester of D-mannoheptulose could thus represent a useful tool to inhibit hexose phosphorylation and interfere with cell growth in cells otherwise resistant to the heptose.
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PMID:Esterification of D-mannoheptulose confers to the heptose inhibitory action on D-glucose metabolism in parotid cells. 955 24

During oil deposition in developing seeds of Arabidopsis, photosynthate is imported in the form of carbohydrates into the embryo and converted to triacylglycerols. To identify genes essential for this process and to investigate the molecular basis for the developmental regulation of oil accumulation, mutants producing wrinkled, incompletely filled seeds were isolated. A novel mutant locus, wrinkled1 (wri1), which maps to the bottom of chromosome 3 and causes an 80% reduction in seed oil content, was identified. Wild-type and homozygous wri1 mutant plantlets or mature plants were indistinguishable. However, developing homozygous wri1 seeds were impaired in the incorporation of sucrose and glucose into triacylglycerols, but incorporated pyruvate and acetate at an increased rate. Because the activities of several glycolytic enzymes, in particular hexokinase and pyrophosphate-dependent phosphofructokinase, are reduced in developing homozygous wri1 seeds, it is suggested that WRI1 is involved in the developmental regulation of carbohydrate metabolism during seed filling.
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PMID:wrinkled1: A novel, low-seed-oil mutant of Arabidopsis with a deficiency in the seed-specific regulation of carbohydrate metabolism. 973 29

Oxidative damage, through increased production of free radicals, is believed to be involved in UV-induced cataractogenesis (eye lens opacification). The possibility of UVB radiation causing damage to important lenticular enzymes was assessed by irradiating 3 months old rat lenses (in RPMI-1640 medium) at 300 nm (100 microWcm(-2)) for 24 h, in the absence and presence of ascorbic acid, alpha-tocopherol acetate and beta-carotene. UVB irradiation resulted in decreased activities of hexokinase, glucose-6-phosphate dehydrogenase, aldose reductase, and Na, K- ATPase by 42, 40, 44 and 57% respectively. While endopeptidase activity (229%) and lipid peroxidation (156%) were increased, isocitrate dehydrogenase activity was not altered on irradiation. In the presence of externally added ascorbic acid, tocopherol and beta-carotene (separately) to the medium, the changes in enzyme activities (except endopeptidase) and increased lipid peroxidation, due to UVB exposure, were prevented. These results suggest that UVB radiation exerts oxidative damage on lens enzymes and antioxidants were protective against this damage.
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PMID:Protection against UVB inactivation (in vitro) of rat lens enzymes by natural antioxidants. 1039 Nov 22

Lead is known to be a potent inhibitor of many enzymes working in the brain, thus possibly inducing functional problems in the brain under pathophysiological conditions. Among such enzymes are those involved in glucose metabolism and energy production. We investigated the inhibitory effects of low-level lead on brain hexokinase (HK), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), pyruvate kinase (PK) and pyruvate dehydrogenase complex (PDHc) with rat brain homogenate. PDHc was distinctively inhibited when low-dose lead acetate was added last of all (IC50 = 5 microM) to the reaction mixture. The other enzymes were completely resistant to 5 microM of lead acetate. When the homogenate was preincubated with lead acetate HK was dramatically inhibited by low-level lead acetate (1-5 microM), in a manner dependent on both preincubation time and lead concentration. However, the inhibitory effect was abolished by coincubation with its substrates, glucose or ATP. The results suggest that exposure to low levels of lead may increase the risk of cerebral hypometabolism caused by direct inhibition of specific glucose-utilizing enzymes. In this context, lead might be regarded as a risk factor in the abnormal glucose metabolism seen in some kinds of neurodegenerative disorders such as sporadic Alzheimer's disease.
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PMID:Effects of low-level lead on glycolytic enzymes and pyruvate dehydrogenase of rat brain in vitro: relevance to sporadic Alzheimer's disease? 1082 44

Acetate kinase, an enzyme widely distributed in the Bacteria and Archaea domains, catalyzes the phosphorylation of acetate. We have determined the three-dimensional structure of Methanosarcina thermophila acetate kinase bound to ADP through crystallography. As we previously predicted, acetate kinase contains a core fold that is topologically identical to that of the ADP-binding domains of glycerol kinase, hexokinase, the 70-kDa heat shock cognate (Hsc70), and actin. Numerous charged active-site residues are conserved within acetate kinases, but few are conserved within the phosphotransferase superfamily. The identity of the points of insertion of polypeptide segments into the core fold of the superfamily members indicates that the insertions existed in the common ancestor of the phosphotransferases. Another remarkable shared feature is the unusual, epsilon conformation of the residue that directly precedes a conserved glycine residue (Gly-331 in acetate kinase) that binds the alpha-phosphate of ADP. Structural, biochemical, and geochemical considerations indicate that an acetate kinase may be the ancestral enzyme of the ASKHA (acetate and sugar kinases/Hsc70/actin) superfamily of phosphotransferases.
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PMID:Urkinase: structure of acetate kinase, a member of the ASKHA superfamily of phosphotransferases. 1113 63

Glucose metabolism by Prevotella intermedia and Prevotella nigrescens were investigated. Glucose increased the anaerobic growth of these bacteria and promoted the accumulation of intracellular polysaccharide. The polysaccharide was confirmed to be glycogen-like glucan by the absorption spectrum of iodinepolysaccharide complex and the sugar composition. The washed cells consumed glucose anaerobically and converted a part of glucose into the metabolic end-products acetate, formate and succinate. The rest of glucose was confirmed to be accumulated as intracellular polysaccharide. The cells grown in the presence of glucose produced acetate, formate and succinate without exogenous glucose along with the consumption of intracellular polysaccharide. The metabolism of glucose and intracellular polysaccharide required bicarbonate. Prevotella cells had hexokinase and a set of the usual enzymes of the Embden-Meyerhof-Parnas pathway except that phosphofructokinase was pyrophosphate-dependent. A series of enzymes, including phosphoenolpyruvate carboxylase, phosphoenolpyruvate carboxykinase, malate dehydrogenase, fumarase and fumarate reductase, was found for succinate formation. Another series of enzymes, pyruvate oxidoreductase, pyruvate formate-lyase, phosphotransacetylase and acetate kinase was found for acetate and formate formation. Glucose 1,6-bisphosphate-dependent phosphoglucomutase and fructose 1,6-bisphosphate-activated UDP-glucose pyrophosphorylase were detected for glycogen synthesis, while glycogen phosphorylase was for glycogen degradation. The capacity of intracellular polysaccharide formation in addition to glucose fermentation could be advantageous for survival in the supragingival area as well as in the subgingival area.
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PMID:Glucose metabolism by Prevotella intermedia and Prevotella nigrescens. 1115 2

The hyperthermophilic, sulfate-reducing archaeon Archaeoglobus fulgidus strain 7324, rather than the type strain VC16, was found to grow on starch and sulfate as energy and carbon source. Fermentation products and enzyme activities were determined in starch-grown cells and compared to those of cells grown on lactate and sulfate. During exponential growth on starch, 1 mol of glucose-equivalent was incompletely oxidized with sulfate to approximately 2 mol acetate, 2 mol CO2 and 1 mol H2S. Starch-grown cells did not contain measurable amounts of the deazaflavin factor F420 (<0.03 nmol/mg protein) and thus did not show the F420-specific green-blue fluorescence. In contrast, lactate (1 mol) was completely oxidized with sulfate to 3 mol CO2 by strain 7324, and lactate-grown cells contained high amounts of F420 (0.6 nmol/mg protein). In extracts of starch-grown cells, the following enzymes of a modified Embden-Meyerhof pathway were detected: ADP-dependent hexokinase (ADP-HK), phosphoglucose isomerase, ADP-dependent 6-phosphofructokinase (ADP-PFK), fructose-1,6-phosphate aldolase, glyceraldehyde-3-phosphate:ferredoxin oxidoreductase (GAP:FdOR), phosphoglycerate mutase, enolase, and pyruvate kinase (PK). Specific activities of ADP-HK, ADP-PFK, GAP:FdOR, and PK were significantly higher in starch-grown cells than in lactate-grown cells, indicating induction of these enzymes during starch catabolism. Pyruvate conversion to acetate involved pyruvate:ferredoxin oxidoreductase and ADP-forming acetyl-CoA synthetase. The findings indicate that the archaeal sulfate reducer A. fulgidus strain 7324 converts starch to acetate via a modified Embden-Meyerhof pathway and acetyl-CoA synthetase (ADP-forming). This is the first report of growth of a sulfate reducer on starch, i.e. on a polymeric sugar.
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PMID:Sugar utilization in the hyperthermophilic, sulfate-reducing archaeon Archaeoglobus fulgidus strain 7324: starch degradation to acetate and CO2 via a modified Embden-Meyerhof pathway and acetyl-CoA synthetase (ADP-forming). 1170 74

In a previous report, we observed an altered proportion of fiber types and a reduction of capillary per fiber ratio in extensor digitorus longus (EDL) and soleus (SOL) muscles of deoxicorticosterone acetate (DOCA)-salt hypertensive rats when compared with controls. The aim of the present study was to ascertain various carbohydrate and lipid enzyme activities and substrates that may be involved in the morphological changes reported. In the SOL muscle of hypertensive rats, glucose, glycogen and triglycerides (TG) levels were increased, citrate synthase (CS) and beta-hydroxy-acyl-CoA dehydrogenase (HAD) activities were reduced, while hexokinase (HK) and lipoprotein lipase (LPL), LPL mass, lactate and free fatty acids (FFA) levels were unchanged. In EDL muscles of hypertensive rats, glycogen levels and LPL mass were higher than in controls, while CS, HAD, HK, and LPL activities and glucose, lactate, FFA and TG levels were unmodified. Serum levels of insulin, TG, cholesterol and FFA were increased while glucose levels were decreased and high-density lipoprotein-cholesterol levels were similar in hypertensive rats when compared with controls. In conclusion, hypertensive rats showed increased glycogen in both EDL and SOL muscles, with hyperinsulinemia and reduced glycemia. Hyperinsulinemia might have been a compensatory response to insulin resistance. The oxidative capacity of SOL muscle was reduced indicating that glucose uptake was conduced via non-oxidative metabolism. TG, FFA and cholesterol were increased in serum and TG in SOL muscle.
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PMID:Metabolic changes in DOCA-salt hypertensive rats. 1191 12


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