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)

In an attempt to evaluate early signs of placental insufficiency, the functional state of placental and chorionic mitochondria was studied in 62 pregnant women. The group included 18 women who decided to terminate pregnancy at 8-10 weeks of gestation, 13 women with normal delivery at term, 16 women who had miscarriages at 10-12 weeks of gestation, and 15 women who had miscarriages at 18-26 weeks of gestation. Functional state of mitochondria was estimated by oxygen consumption in the absence and presence of the acceptor system (hexokinase-glucose-adenosine diphosphate). Succinic and alpha-ketoglutaric acids were used as oxidation substrates. During normal pregnancy the rate of succinic acid oxidation in the absence of acceptor system (free respiration) was 12.1 and 11.8 microA 02/mg at 8-10 weeks and at term, respectively; the rate of oxygen consumption during oxidation of alpha-ketoglutarate was 7.6 and 6.2 microA 02/mg, respectively. The rate of oxygen consumption in the presence of acceptor system (coupled respiration) was 18.1 and 16.5 microA 02/mg for succinic acid and 14.4 and 11.2 microA 02/mg for alpha-ketoglutaric acid, respectively. Spontaneous miscarriage was characterized by significant decrease in the rate of oxygen consumption. Free respiration at 8-10 and 18-26 weeks was 8.6 and 63 microA 02/mg, respectively, for succinic acid and 6.8 and 5.9 microA 02/mg for alpha-ketoglutaric acid, respectively. Coupled respiration at 8-10 and 18-26 weeks was 11.2 and 5.7 for succinic acid and 9.5 and 6.5 microA 02/mg for alpha-ketoglutaric acid, respectively. These findings indicated that spontaneous miscarriage was preceded by inhibition of oxidative phosphorylation. It was suggested that functional impairment of placenta can be corrected by administration of preparations containing thiol group (cysteine).
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PMID:[Characteristics of the functional state of the placental mitochondria in interrupted pregnancy]. 337 22

The response of hypertrophied soleus and plantaris muscle of rats to endurance training was studied. Hypertrophy was produced by bilateral extirpation of the gastrocnemius muscle. A 13-wk training program of treadmill running initiated 30 days after removal of the gastrocnemius muscle accentuated (P less than 0.01) the hypertrophy. Succinate dehydrogenase activities of the enlarged muscles of sedentary rats were similar to those of normal animals, as were the increases associated with training. Phosphorylase and hexokinase activities were unaltered as a result of the experimental perturbations. Rates of glycogen depletion during exercise were lower (P less than 0.01) in the liver and soleus and plantaris muscles of endurance-trained animals. No difference existed in the rate of glycogen depletion of normal and hypertrophied muscle within the sedentary or trained groups. These data demonstrate that extensively hypertrophied muscle responds to training and exercise in a manner similar to that of normal muscle.
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PMID:Adaptive response of hypertrophied skeletal muscle to endurance training. 403 May 55

The antitumour antibiotic, adriamycin, inhibited oxidative phosphorylation in freshly prepared mitochondria from the heart, liver and kidney of the rat. It abolished respiratory control and stimulated ATPase activity. Succinate oxidation by heart mitochondria was extremely sensitive to the drug when hexokinase was present in the reaction medium. The sensitive site has been identified to lie in the region between the succinate dehydrogenase flavoprotein and ubiquinone of the respiratory chain.
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PMID:Inhibition of mitochondrial oxidative phosphorylation by adriamycin. 621 26

Procyclic culture forms of Trypanosoma brucei stock 427 have been screened for the presence of enzymes involved in glycolysis, mitochondrial energy metabolism and threonine degradation. The enzyme activities in the procyclics were compared with those of the blood stream forms. The specific activities of glycolytic enzymes represented 30-70% of the respective levels in the blood stream form, except for hexokinase which was 25-fold reduced. Cell fractionation showed that the enzymes involved in the early sequence of the glycolytic pathway, i.e. from hexokinase to phosphoglycerate kinase, and the enzymes NAD+-linked glycerol-3-phosphate dehydrogenase and glycerol kinase were all present in glycosomes equilibrating at a density of 1.23 g/cm3 in sucrose gradients. Malate dehydrogenase was 8-fold more active in procyclics than in bloodstream forms. This increase in activity was the result of the appearance of malate dehydrogenase in the glycosomes of the procyclics, in addition to mitochondrial and cell-sap activities which were present in both stages of the life cycle. Glycosomes contained part of the adenylate kinase activity, which was also associated with the mitochondrion. Succinate dehydrogenase and sn-glycerol-3-phosphate dehydrogenase, together with oligomycin-sensitive ATPase, were located in the mitochondrion which had a density in sucrose ranging from 1.16 to 1.18 g/cm3. This organelle also contained L-threonine 3-dehydrogenase and carnitine acetyltransferase, two enzymes involved in threonine catabolism. The latter two enzymes had activities which were, respectively, 15-and 13-fold higher in the procyclics than in the bloodstream form. Mitochondrial sn-glycerol-3-phosphate dehydrogenase was decreased 4-fold.
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PMID:Localization of malate dehydrogenase, adenylate kinase and glycolytic enzymes in glycosomes and the threonine pathway in the mitochondrion of cultured procyclic trypomastigotes of Trypanosoma brucei. 680 9

The effect of dissolved oxygen concentration on the metabolism of glucose in Pseudomonas aeruginosa was studied with chemostat cultures using both single-step and gradual transitions from either ammonium or glucose limitation to oxygen limitation and studying transient and steady states. The pathway of glucose metabolism was regulated by the availability of oxygen. The organism responded to oxygen limitation by adjusting its metabolism of glucose from the extracellular direct oxidative pathway, which produces gluconate and 2-oxogluconate, to the intracellular phosphorylative route. This change was a consequence of decreased activities of glucose dehydrogenase and gluconate dehydrogenase and of the transport systems for gluconate and 2-oxogluconate, and an increased activity of glucose transport, while relatively high activities of hexokinase and glucose-6-phosphate dehydrogenase were maintained. Citrate synthase, isocitrate dehydrogenase and malate dehydrogenase activities responded to changes in dissolved oxygen concentration rather than to changes in the glucose or ammonium concentrations. The effect of oxygen limitation on the oxo-acid dehydrogenases and aconitase was probably due, wholly or in part, to repression by glucose consequent upon the increase in residual glucose concentration. Succinate dehydrogenase was repressed by an increase in ammonium concentration under an oxygen limitation.
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PMID:The role of oxygen in the regulation of glucose metabolism, transport and the tricarboxylic acid cycle in Pseudomonas aeruginosa. 708 92

The monomethyl ester of succinic acid (SME) was recently found to protect pancreatic islet B-cells against the impairment of glucose-stimulated insulin release caused by either glucopenia or starvation. The possible metabolic determinants of such a protective action are now scrutinized. After 180 min preincubation at 2.8 mM D-glucose in the presence of SME (10 mM), the oxidation of D-[U-14C]glucose, relative to either the utilization of D-[5-3H]glucose or the generation of 14C-labeled acidic metabolites, was higher than that after preincubation in the absence of SME and became close to that otherwise found after preincubation at 16.7 mM D-glucose. Likewise, after 3 days of culture at a low concentration of D-glucose (2.8 mM), the presence of SME in the culture medium tended to increase the subsequent oxidation of D-[6-14C]glucose and utilization of D-[5-3H]glucose. These two variables increased as a function of the concentration of D-glucose in the culture medium, this coinciding with a modest increase in hexokinase activity and a more pronounced increase in glucokinase activity. The presence of SME in the culture medium failed, however, to exert any obvious effect upon the respiration of the islets, suggesting that the protective action of the ester against glucopenia may also involve variables distinct from the metabolism of either endogenous or exogenous nutrients. Likewise, the fact that SME infusion to starved rats prevents the impairment of glucose-induced insulin release otherwise attributable to starvation may involve enzymatic determinants, such as a less severe decrease in glucokinase activity, metabolic variables, such as a greater relative increase in D-[U-14C]glucose oxidation relative to D-[5-3H]glucose utilization in response to a rise in extracellular D-glucose concentration, and other factors yet to be identified that participate in the secretory sequence at a site distal to those metabolic events triggered by D-glucose in the islet cells.
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PMID:Protective action of succinic acid monomethyl ester against the impairment of glucose-stimulated insulin release caused by glucopenia or starvation: metabolic determinants. 785 80

1. This study investigated the effects of fructose and 2-deoxyglucose on the uptake and release of phosphate from everted intestinal sacs of mice. 2. Both the sugars significantly decreased the release of phosphate without affecting the uptake. 3. Succinate and fumarate were able to partially reverse the inhibition of phosphate release exerted by fructose but not that exerted by 2-deoxyglucose. 4. Pre-loading with mannoheptulose, a known inhibitor of hexokinase, improved the release of phosphate in the presence of either of these sugars. 5. Adrenaline, known to inhibit phosphorylation of 2-deoxyglucose, reduced the inhibition exerted by this sugar on phosphate release. 6. These results indicate that the inhibition of phosphate release caused by these sugars may be due to the trapping of free phosphate during their metabolism in the gut wall.
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PMID:Does phosphorylation affect transport of inorganic phosphate? 815 54

Chronic electrical stimulation of skeletal muscle at 10 Hz induces fast-to-slow fiber type transformation. Does a lower aggregate amount of activity lead to a less complete transformation, or does it produce the same transformation over a longer time course? We examined this question by subjecting adult rabbit tibialis anterior and extensor digitorum longus muscles to continuous stimulation at 2.5 Hz for 2-12 wk. Most of the fibers acquired the histochemical and immunocytochemical characteristics of type 2A, not type 1, fibers. There was a corresponding rise in oxidative activity, but this was accompanied by a marked decline in anaerobic glycolysis. The activities of hexokinase and 3-oxoacid CoA-transferase stopped increasing after 2 wk, glutamate oxaloacetate transaminase after 4 wk, and beta-hydroxyacyl-CoA dehydrogenase after 6 wk of stimulation. Succinate dehydrogenase, citrate synthase, lactate dehydrogenase, and creatine phosphokinase continued to change up to 12 wk of stimulation. Changes in enzyme activity were not as rapid or as marked as those observed for stimulation at 10 Hz, and none showed the typical two-phase response of oxidative enzyme activities to stimulation at 10 Hz. The latter may therefore be dependent on induction of type 1 myosin isoforms.
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PMID:Induction of a fast-oxidative phenotype by chronic muscle stimulation: histochemical and metabolic studies. 877 59

Utilization of the tricarboxylic acid (TCA) cycle intermediates, L-malic acid and succinic acid, by the yeast Pachysolen tannophilus is repressed in the presence of glucose. Strains of P. tannophilus containing mutations in two hexokinases and a glucokinase were characterized for growth on glucose plus L-malic acid or succinic acid. Increased specific utilization rates of malic acid and succinic acid in the presence of glucose were observed in mutants containing a lesion in hexokinase A, an enzyme associated with catabolite repression. Such derepressed mutants may have application in winemaking in which utilization of a major grape acid, L-malic acid, is often desirable for acidity reduction.
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PMID:Derepressed utilization of L-malic acid and succinic acid by mutants of Pachysolen tannophilus. 924 68

Rats were fasted for 48 h, but infused with either NaCl or the sodium salt of monoethyl succinic acid (EMS), both delivered at a rate of 80 mumol/g body weight per day. The infusion of EMS, as compared to NaCl, failed to affect paraovarian adipose tissue or liver weight, liver or muscle glycogen, and insulinemia. It accentuated the starvation-induced fall in body weight, and decreased both liver and muscle protein content. Nevertheless, the succinate ester increased plasma D-glucose concentration, delayed the rise in ketonemia, maintained a higher glucokinase/hexokinase activity ratio in liver and pancreatic islets, and allowed for a more efficient stimulation of insulin release by D-glucose or 2-ketoisocaproate in isolated pancreatic islets. These findings indicate that monoethyl succinate displays a significant nutritional value when infused in starved rats.
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PMID:Nutritional value of succinic acid monoethyl ester in starvation. 926 86


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