Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.1.1 (hexokinase)
 5,274 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A pathway from glucose via sorbitol bypasses the control points of hexokinase and phosphofructokinase in glucose metabolism. It also may produce glycerol, linking the bypass to lipid synthesis. Utilization of this bypass is favored by a plentiful supply of glucose--hence, conditions under which glycolysis also is active. The bypass further involves oxidation of NADPH, so the pentose phosphate pathway and the bypass are mutually facilitative. Possible consequences in different organs under normal and pathological, especially diabetic, conditions are detailed. Enzymes with related structures (for example, sorbitol dehydrogenase and alcohol dehydrogenase, and possibly, aldehyde reductase and aldose reductase, respectively) are linked functionally by this scheme. Some enzymes of the bypass also feature in glycolysis (aldolase and alcohol dehydrogenase), and these enzymes, with the reductases involved, are proteins known to occur in different classes or multiple isozyme forms. Two of the enzymes (aldolase and alcohol dehydrogenase) both involve classes with and without a catalytic metal (zinc). The existence of parallel pathways and the occurrence of similar enzymic steps in one pathway may help to explain the abundance and multiplicity of enzymes such as reductases, aldolases, and alcohol dehydrogenases.
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PMID:Enzyme relationships in a sorbitol pathway that bypasses glycolysis and pentose phosphates in glucose metabolism. 640 81

The inhibition of glycolysis by 2,3-dinitrilo-1,4-dithia-9,10-antraquinone (DDA) in Ehrlich ascites carcinoma (EAC) cells as well as in the investigated respiratory and fermentative strains of yeasts was found to be the result of inactivation of thiol enzymes of this pathway. Increasing concentration of DDA caused, in EAC cells, marked inhibition of hexokinase (HK), phosphofructokinase (PFK) and practically total inhibition of glyceraldehyde-3-phosphate dehydrogenase (GAPDH). These three enzymes, as well as alcohol dehydrogenase (ADH) were also inactivated by DDA in yeasts. DDA inhibited the biosynthetic processes as measured by following the rate of [14C]adenine and [14C)]valine incorporation into TCA-precipitable fractions proportionally to the degree of glucose consumption by EAC or the yeast cells.
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PMID:Effect of 2,3-dinitrilo-1,4-dithia-9,10-antraquinone on Ehrlich ascites carcinoma and yeast cells. 699 Nov 41

Protease B [EC 3.4.22.9] was purified from baker's yeast by plasmolysis of yeast, acid activation, acid precipitation, and column chromatographies on QAE-Sephadex, SP-Sephadex, D-tryptophan methyl ester-Sepharose 4B and Sephadex G-100. The purified enzyme was inhibited by phenylmethylsulfonyl fluoride and sulfhydryl-blocking reagents. Chymostatin and antipain at extremely low concentrations (1 micro M) inhibited the protease B. The effects of the enzyme on various yeast enzymes were examined by measuring their inactivation. The enzyme inactivated 6-phosphogluconate dehydrogenase [EC 1.1.1.44] and uricase [EC 1.7.3.3], but not malate dehydrogenase [EC 1.1.1.37], alcohol dehydrogenase [EC 1.1.1.1], glutamate dehydrogenase [EC 1.4.1.3], glucose-6-phosphate dehydrogenase [EC 1.1.1.49] or hexokinase [EC 2.7.1.1].
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PMID:Purification and characterization of yeast protease B. 699 57

The energy metabolism of the English E-CMO strain of contagious equine metritis bacterium was studied in whole cells and cell extracts. This bacterium appears to have an active Krebs cycle and probably obtains energy by oxidative phosphorylation since glycolysis and the hexose monophosphate pathways appear to be absent. These conclusions are based on the findings that [U-14C]glucose incorporation by this bacterium is below the level of detection, and that respiration is stimulated by Krebs cycle intermediates (i.e., malate, citrate, and succinate), but not by glucose, fructose, maltose, or sucrose. Furthermore, support comes from the fact that enzymes generally associated with the Krebs cycle and electron transport (i.e., malate dehydrogenase, succinate dehydrogenase, isocitrate dehydrogenase, fumarate hydratase, malate dehydrogenase [decarboxylating], cytochrome oxidase, superoxide dismutase, NADH dehydrogenase, and catalase) were detected. Those enzymes normally associated with glycolysis and the hexose monophosphate pathways (i.e., hexokinase, glucose 6-phosphate dehydrogenase, fructose biphosphate aldolase, glycerol 3-phosphate dehydrogenase, phosphoenolpyruvate carboxykinase, pyruvate kinase, phosphate acetyl transferase, acetate kinase, alcohol dehydrogenase, and lactate dehydrogenase) were below the level of detection.
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PMID:Energy metabolism of the contagious equine metritis bacterium. 708 71

The positively charged photosensitizer toluidine blue (TB) can induce loss of clonogenicity in Kluyveromyces marxianus. Previous studies have revealed that, as a consequence of the localization of this dye at the cell surface, photodynamic action results in extensive damage at the level of the plasma membrane. In this paper, a study is reported on the effect of photodynamic treatment with TB on intracellular enzymes. It is shown that treatment with TB and light resulted in the inhibition of alcohol dehydrogenase, cytochrome c oxidase, glyceraldehyde-3-phosphate dehydrogenase and hexokinase. Photodynamic treatment also lowered the ATP levels. The ATP levels could be partially restored in the presence of glucose but not with ethanol. Toluidine blue binding experiments revealed that photodynamic treatment caused a rapid increase in the amount of cell-associated dye. Moreover, it also appeared that this treatment decreased the binding of TB to the cell surface. It is concluded that TB enters the cell during the first minutes of illumination, whereafter intracellular enzymes are inactivated. The data indicate that photodynamic damage of intracellular sites contributes to the loss of viability.
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PMID:Intracellular damage in yeast cells caused by photodynamic treatment with toluidine blue. 789 97

Glucose-repressed growth of Saccharomyces cerevisiae was analysed in a nitrogen-limited continuous culture at different dilution rates (D). The glucose consumption of the yeast decreased from 3.4 g g-1 h-1 to 3.0 g g-1 h-1 when D was decreased from 0.3 h-1 to 0.15 h-1. No transcripts of the SUC2 and HXK1 genes, encoding, respectively, invertase and hexokinase isoenzyme 1, could be detected. Because both genes are regulated by glucose repression at the transcriptional level, this confirmed that the culture was glucose repressed at every D. During the decrease in D, no change in the activities or mRNA levels of key enzymes in carbon metabolism was observed, except for alcohol dehydrogenases I and II and phosphoglucomutase. These enzymes increased in activity and/or mRNA level when D was decreased, which was also observed in glucose- and galactose-limited continuous cultures. This demonstrates that the expression levels of alcohol dehydrogenases I and II, and also phosphoglucomutase, are coupled to the growth rate of the organism. A comparison between the alcohol dehydrogenase II activity in glucose- and nitrogen-limited continuous cultures demonstrated that the growth rate contributes as much to repression of alcohol dehydrogenase II activity as does glucose. Both the glucose consumption and the activity of the glycolytic enzymes were relatively constant when D was decreased and, as a consequence, the concentrations of intracellular metabolites remained constant. A slight decrease in the glucose 6-phosphate concentration was observed, which could be caused by the slight decrease in glucose consumption at low D values.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:A nitrogen-limited, glucose-repressed, continuous culture of Saccharomyces cerevisiae. 801 81

High hexokinase activity was not related to glucose repression in Candida utilis IGC 3092. The addition of Cibacron Blue 3G-A to growing cells in batch culture led to a permanent in vivo hexokinase inactivation, decreased growth rate and inhibited alcohol dehydrogenase. Hexokinase inactivation up to 90% did not alleviate glucose repression of alpha-glucosidase, as has been described for Saccharomyces cerevisiae and other yeasts. Moreover, when cells were physiologically derepressed by growing them in a chemostat at low glucose concentrations, the highest hexokinase activity was shown by the derepressed cells, and decreased as repression increased. Thus, in our strain of C. utilis, hexokinase activity was inversely proportional to glucose repression.
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PMID:The inactivation of hexokinase activity does not prevent glucose repression in Candida utilis. 859 74

In this paper, we demonstrate the ability of liquid-liquid partition chromatography (LLPC) to detect conformational alterations occurring in well-characterized enzymes. The conformational changes induced in dehydrogenases such as alcohol dehydrogenase (ADH), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), lactate dehydrogenases (LDH) and malate dehydrogenase (MDH) upon binding of ligand(s) were detectable by LLPC. The ligand-dependent equilibrium between two forms of citrate synthase (CS), glutamate-oxaloacetate transaminase (GOT), hexokinase (HK) and 3-phosphoglycerate kinase (PGK) could also be demonstrated. Furthermore, different conformational forms of some of the apoenzymes could also be detected and separated by LLPC. The results obtained here are discussed in relation to those obtained by other methods.
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PMID:Enzyme conformational alterations detected by partition column chromatography. 879 88

The presence of 14 enzymes was investigated using purified spores of the microsporidian Nosema grylli from fat body of the crickets Gryllus bimaculatus. Glucose 6-phosphate dehydrogenase (EC 1.1.1.49), phosphoglucomutase (EC 5.4.2.2), phosphoglucose isomerase (EC 5.3.1.9), fructose 6-phosphate kinase (EC 2.7.1.11), aldolase (EC 4.1.2.13), 3-phosophoglycerate kinase (EC 2.7.2.3), pyruvate kinase (EC 2.7.1.40) and glycerol 3-phosphate dehydrogenase (EC 1.1.1.8) were detected with activities of 15 +/- 1, 7 +/- 1, 1,549 +/- 255, 10 +/- 1, 5 +/- 1, 16 +/- 4, 6 +/- 1 and 16 +/- 2 nmol/min mg protein, respectively. Hexokinase (EC 2.7.1.1), NAD-dependent malate dehydrogenase (EC 1.1.1.37), malic enzyme (EC 1.1.1.40), lactate dehydrogenase (EC 1.1.1.27), alcohol dehydrogenase (EC 1.1.1.1) and succinate dehydrogenase (EC 1.3.99.1) were not detectable. These results suggest the catabolism of carbohydrates in microsporidia occurs via the Embden-Meyerhof pathway. Glycerol 3-phosphate dehydrogenase may reoxidize NADH which is produced by glyceraldehyde 3-phosphate dehydrogenase in glycolysis.
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PMID:Activities of enzymes of carbohydrate and energy metabolism of the spores of the microsporidian, Nosema grylli. 918 13

A new analytical approach has been applied to the determination and characterization of mercury-accessible -SH groups in pure native protein samples (ovalbumin, hemoglobin, glyceraldehyde-3-phosphate dehydrogenase, aldolase, pyruvate kinase, hexokinase, lactate dehydrogenase, alcohol dehydrogenase, creatine phosphokinase, lysozyme, and cytochrome c). The method is based on the selective reduction of Hg(II) in the presence of Hg(II)-thiol complexes with alkaline sodium tetrahydroborate, to give Hg(0) in a continuous flow reaction system coupled with atomic fluorescence spectrometric (AFS) detection. The method is fast and specific and allows one to work with nanomole amounts of a single protein without any preliminary incubation and without any separation of Hg(II) from thiol-complexed mercury. The meaning of the results obtained in the determination of the accessible -SH groups in native proteins by using chemical probes is discussed.
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PMID:Application of mercury cold vapor atomic fluorescence spectrometry to the characterization of mercury-accessible -SH groups in native proteins. 1052 12


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