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)

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

It is shown in experiments is vivo that development of experimental metabolic alkalosis in rats is followed by changes in redox processes in the eye retina and tunic. For the first two months of the experiment the number of sulphydryl group decreases, while that of disulphide ones of water-soluble proteins and low-molecular compounds increases. The amount of oxidized metabolites of glycolysis and of a cycle of tricarboxylic acids (pyruvate, oxaloacetate, alpha-ketoglutarate) increases relative to the reduced ones (lactate, isocitrate, malate), as well as activities of hexokinase, pyruvate kinase, NAD-dependent malate dehydrogenase, while activities of fructose diphosphatase, glucoso-6-phosphate dehydrogenase, glutathione peroxidase and glutathione reductase fall. The content of malonic dialdehyde increases. 90 days later disorders of certain compensatory mechanisms of the metabolic system of alkalosis regulation probably occurred in the eye retina and tunic tissues: hexokinase and pyruvate kinase activity fell to the control values, while that of NAD-dependent malate dehydrogenase--below the control level; the content of lactate increased. Activity of glutathione-dependent enzymes remained low and the amount of malonic dialdehyde grew much more than in the previous terms.
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PMID:[Redox processes in the retina and tunic tissues of the rat eye in experimental alkalosis]. 144 Sep 68

A comparative biochemical study on some enzymes of glycogenolysis, glycolysis and the hexose monophosphate shunt pathway in various fractions (cyst wall, cyst fluid and zoites) of the sarcocysts of Sarcocystis fusiformis from the oesophageal muscles of naturally infected Indian water buffalo (Bubalus bubalis) was carried out. The pattern and the magnitude of enzymic activity differed markedly in these fractions. Phosphorylase, hexokinase, aldolase and pyruvate kinase showed their highest levels of activity in the zoites fractions, whereas lactate dehydrogenase was the highest in cyst fluid. Alcohol dehydrogenases were non-detectable. Glucose 6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase were localized in the cyst wall only. Zoites were considered to be the most active metabolic sites for glucose breakdown.
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PMID:Some glucose metabolic enzymes in various fractions of sarcocysts of Sarcocystis fusiformis of buffalo (Bubalus bubalis). 144 Nov 91

Erythrocytes from young type I diabetic patients (n = 11), incubated in their plasma in anaerobic conditions, exhibited higher glucose consumption than cells from controls (n = 11). This increased metabolic activity is believed to reflect erythrocyte alterations dependent on the degree of metabolic control, as glucose consumption was significantly correlated to glycosylated haemoglobin (HbA1) and to glucose levels (P < 0.05 and P < 0.01 respectively). Red cell hexokinase (HK) and pyruvate kinase (PK) activities were similar in both groups whereas phosphofructokinase (PFK) activity was slightly higher in patients' cells (P < 0.05). No difference was found between patients and controls for red cell ATP and 2.3 diphosphoglycerate (2.3 DPG) levels. However, the concentrations of these glycolytic products seem also closely related to the glucose homeostasis in diabetes. Indeed, within the diabetic group, ATP levels showed a negative relationship with glucose level (P < 0.05) and 2.3 DPG a positive relationship with HbA1 (P < 0.05). In conclusion, higher glycolytic activity is present in young diabetic red cells. This activity as well as ATP and 2.3 DPG levels are related to the degree of short- or long-term diabetic control. These findings stress the importance of a careful metabolic control to avoid haematological disturbances.
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PMID:Erythrocyte metabolic alterations in type I diabetes: relationship to metabolic control. 144 91

Renal clear cell tubules and clear/acidophilic cell tumors were induced in male Sprague-Dawley rats by 7 weeks oral administration (stop model) of N-nitrosomorpholine (NNM) at a concentration of 12 mg/100 ml in the drinking water. Twelve, 23 and 34 weeks after withdrawal of NNM serial cryostat sections of the kidneys were histochemically analyzed for the following parameters: glucose transporter proteins (GLUT1, GLUT2), glycogen content and the activities of glycogen synthase (SYN), glycogen phosphorylase (PHO), glucose-6-phosphatase (G6Pase), glucose-6-phosphate dehydrogenase (G6PDH), hexokinase (HK), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), pyruvate kinase (PK), succinate dehydrogenase (SDH), malate dehydrogenase (MDH), alkaline phosphatase (ALP), acid phosphatase (ACP) and gamma-glutamyltransferase (GGT). Clear cell (glycogenotic) tubules first appeared at 23 weeks, and clear/acidophilic cell tumors at 34 weeks after withdrawal of the carcinogen. G6Pase, ALP, GGT and GLUT2 were absent in clear cell tubules, clear/acidophilic cell tubules, and clear/acidophilic cell tumors indicating a sequential origin of all these types of lesions from the collecting duct system, in line with previous morphological findings. In comparison to the collecting duct epithelium, glycogenotic tubules demonstrated an increased activity of PHO and reduced activities of glycolytic and mitochondrial enzymes, which were accompanied by a strongly reduced expression of GLUT1. Moderately increased activities of glycolytic and mitochondrial enzymes were observed in the clear cells of clear/acidophilic cell tubules and tumors compared with those in glycogenotic tubules. They had slightly increased activities of the glycolytic enzymes GAPDH and PK compared with normal collecting duct epithelium, while most of them were nearly lacking in GLUT1. Our findings suggest that glycogen storage is not due to an increased uptake of glucose from the blood, but results from a disturbance in intracellular flux of metabolites. The development of clear cell tubules from the normal collecting duct epithelium is accompanied by a markedly decreased expression of GLUT1 along with a reduction in glycolytic and mitochondrial enzymes. This reduction of enzyme activities is replaced by an increase in enzyme activities in clear/acidophilic cell tumors indicating a fundamental shift in carbohydrate metabolism during progression from preneoplastic to neoplastic lesions.
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PMID:Sequential changes in glycogen content, expression of glucose transporters and enzymic patterns during development of clear/acidophilic cell tumors in rat kidney. 147 41

Current models based on the analysis of linear metabolic pathways at steady-state predict that large increases over wild type in the activity of one enzyme will not alter an organism's fitness. This prediction is tested at steps in a highly branched pathway under two conditions known to alter steady-state: heat shock and nitrogen starvation. Saccharomyces cerevisiae transformants overproducing 1 of 4 enzymes in glycolysis (hexokinase B, phosphoglucose isomerase, phosphofructokinase, or pyruvate kinase) were subjected to heat shock in both exponential and stationary phases of growth. In neither phase does enzyme overexpression alter heat shock sensitivity. When starved for nitrogen in acetate medium, transformants overproducing hexokinase, phosphoglucose isomerase, and phosphofructokinase sporulate at the same rate and with the same frequency as cells harbouring only the plasmid vector. Current models therefore correctly predict the relationship between activity and components of fitness for 3 of 4 enzymes. By contrast, cells overexpressing pyruvate kinase sporulate poorly. This defect is not observed among cells transformed with a plasmid containing a Tn5 disrupted copy of the PYK gene. These findings are consistent with reports that implicate the PYK locus in yeast cell cycle control and suggest that it may be challenging to model relations between fitness and activity for multifunctional proteins.
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PMID:Regulation of fitness in yeast overexpressing glycolytic enzymes: responses to heat shock and nitrogen starvation. 151 66

The effects of sodium orthovanadate (0.6 mg/ml in drinking water) on hexokinase isozymes, pyruvate kinase and malic enzyme in liver and kidney of control and alloxan diabetic rats were studied and compared. Vanadate treatment of diabetic rats normalized hyperglycemia and almost completely restored the differentially altered enzyme profile of liver (a tissue that underutilizes glucose in diabetes) and kidney (a tissue that overutilizes glucose during diabetes). Vanadate therapy, however, could not restore the depressed plasma insulin level of diabetic rats. The study clearly indicates that vanadate can effectively normalize many metabolic abnormalities even at a low insulin level in both insulin-dependent and -independent tissues of diabetic rats.
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PMID:Effects of vanadate on glycolytic enzymes and malic enzyme in insulin-dependent and -independent tissues of diabetic rats. 152 51

The effect of estradiol-17 beta on the activities of glycolytic enzymes from female rat brain was studied. The following enzymes were examined: hexokinase (HK, EC 2.7.1.1), phosphofructokinase (PFK, EC 2.7.1.11), aldolase (EC 4.1.2.13), glyceraldehyde-3-phosphate dehydrogenase (EC 1.2.1.12), phosphoglycerate kinase (EC 2.7.2.3), phosphoglycerate mutase (EC 2.7.5.3), enolase (EC 4.2.1.11) and pyruvate kinase (PK, EC 2.7.1.40). The activities of HK (soluble and membrane-bound), PFK and PK were increased after 4 h of hormone treatment, while the others remained constant. The changes in activity were not seen in the presence of actinomycin D. The significant rise of the activities of the key glycolytic enzymes was also observed in the cell culture of mouse neuroblastoma C1300 treated with hormone. Only three of the studied isozymes, namely, HKII, B4 and K4 were found to be estradiol-sensitive for HK, PFK and PK, respectively. The results obtained suggest that rat brain glycolysis regulation by estradiol is carried out in neurons due to definite isozymes induction.
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PMID:Rat brain glycolysis regulation by estradiol-17 beta. 153 2

The effects of calcium antagonists nimodipine, nicardipine and flunarizine on lactate production and specific activities of some enzymes regulating glycolytic flux have been evaluated in synaptosomes isolated from rat whole brain and submitted to in vitro chemical hypoxia induced by rotenone, an inhibitor of mitochondrial respiration. The following enzymes have been tested; hexokinase (ATP: D-hexose-6-phosphotransferase, EC2.7.1.1), phosphofructokinase (ATP: D-fructose-6-phosphate 1-phosphotransferase, EC 2.7.1.11) and pyruvate kinase (ATP: pyruvate 2-O-phosphotransferase, EC 2.7.1.40). The results show that rotenone increases by about eight times the production of lactate; nicardipine and nimodipine, starting from a concentration of 10(-4) M, were able to counteract the rotenone-induced stimulation of glycolysis, but flunarizine was without effect. The dihydropyridines but not flunarizine decreased the maximum activity of phosphofructokinase. This effect was already detectable at a concentration of 10(-5) M. Neither hexokinase nor pyruvate kinase were affected by any of the drugs studied.
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PMID:Effects of calcium antagonists on glycolysis of rat brain synaptosomes. 153 11

The B-CK isozyme of cytoplasmic creatine kinase is localized distinctly in the terminal web region of the intestinal epithelial cell brush border (Keller and Gordon: Cell Motil. Cytoskeleton 19:169-179, 1991). Experiments were performed to determine whether this CK is energetically coupled to the myosin II that is present in the circumferential ring and interrootlet structural domains of the brush border terminal web. In isolated brush borders, ATP-dependent circumferential ring contraction and interrootlet myosin solubilization were supported either by an exogenous PEP-pyruvate kinase-based ATP-regeneration system (PEP-PK) or by the addition of phosphocreatine to the endogenous B-CK-based ATP-regeneration system (PCr-B-CK). Addition of an exogenous hexokinase-glucose ATP-hydrolysis system (HK-G) effectively blocked both contraction and myosin solubilization in the PEP-PK assay. In contrast, HK-G had no significant effect on PCr-B-CK-supported brush border contraction, although it did inhibit interrootlet myosin solubilization. Thus, when high-energy phosphate is supplied as phosphocreatine, brush border B-CK imparts to the circumferential ring myosin a selective energetic advantage over other ATPases. These results suggest that myosin and B-CK are functionally coupled in the brush border circumferential ring, where they might comprise one end of an energy circuit that supplies energy for contraction, but that colocalization of CK with myosin in the brush border interrootlet domain is insufficient to establish functional coupling.
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PMID:Functional coupling to brush border creatine kinase imparts a selective energetic advantage to contractile ring myosin in intestinal epithelial cells. 153 84


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