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)

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 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

Newborn rabbits have mainly brown or multilocular fat tissue. The activity of G-6-PDH shows a prenatal decrease. The G-6-PDH activity is clearly lower in postnatal as compared to the fetal period. This is due to the minor role of fatty acid synthesis with reduced fat storage during this time. The high capacity of glycolysis becomes apparent by the high activity of hexokinase and lactate dehydrogenase. The activity of both enzymes, however, shows only slight postnatal changes, so that HK and LDH in contrast to pyruvate kinase in the postnatal period apparently have no regulatory effect. The altogether high activity of the NADP specific isocitrate dehydrogenase indicates the high turnover rates in the Krebs cycle and suggests the adjustment of the metabolism to a high energy turnover.
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PMID:[Activities of various enzymes in brown fat tissue of rabbits in the pre- and post-natal period]. 711 50

The effect of DL alpha-lipoic acid on the nephrotoxic potential of gentamicin was examined. Intraperitoneal injection of gentamicin (100 mg/kg/day) to rats resulted in decreased activity of the glycolytic enzymes-hexokinase, phosphoglucoisomerase, aldolase and lactate dehydrogenase. The two gluconeogenic enzymes--glucose-6-phosphatase and fructose-1,6-diphosphatase, the transmembrane enzymes namely the Na+, K(+)-ATPase, Ca(2+)-ATPase, Mg(2+)-ATPase and the brushborder enzyme alkaline phosphatase, also showed decreased activities. This decrease in the activities of ATPases and alkaline phosphatase suggests basolateral and brush border membrane damage. Decreased activity of the TCA cycle enzymes isocitrate dehydrogenase (ICDH), succinate dehydrogenase (SDH) and malate dehydrogenase (MDH), suggests a loss in mitochondrial integrity. These biochemical disturbances were effectively counteracted by lipoic acid administration. Lipoic acid administration by gastric intubation at two different concentrations (10 mg and 25 mg/kg/day) brought about an increase in the activity of the glycolytic enzymes, ATPases and the TCA cycle enzymes. The gluconeogenic enzymes however showed a further decrease in their activities at both the concentrations of lipoic acid administered. These observations shed light on the nephroprotective action of lipoic acid against experimental aminoglycoside toxicity and the protection afforded at 25 mg/kg/day of lipoic acid was noted to be higher than that at 10 mg level.
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PMID:Role of DL alpha-lipoic acid in gentamicin induced nephrotoxicity. 765 73

The structure of the isocitrate dehydrogenase (IDH) complex with bound alpha-ketoglutarate, Ca2+, and NADPH was solved at 2.7-A resolution. The alpha-ketoglutarate binds in the active site at the same position and orientation as isocitrate, with a difference between the two bound molecules of about 0.8 A. The Ca2+ metal is coordinated by alpha-ketoglutarate, three conserved aspartate residues, and a pair of water molecules. The largest motion in the active site relative to the isocitrate enzyme complex is observed for tyrosine 160, which originally forms a hydrogen bond to the labile carboxyl group of isocitrate and moves to form a new hydrogen bond to Asp 307 in the complex with alpha-ketoglutarate. This triggers a number of significant movements among several short loops and adjoining secondary structural elements in the enzyme, most of which participate in dimer stabilization and formation of the active-site cleft. These rearrangements are similar to the ligand-binding-induced movements observed in globins and insulin and serve as a model for an enzymatic mechanism which involves local shifts of secondary structural elements during turnover, rather than large-scale domain closures or loop transitions induced by substrate binding such as those observed in hexokinase or triosephosphate isomerase.
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PMID:Structure of isocitrate dehydrogenase with alpha-ketoglutarate at 2.7-A resolution: conformational changes induced by decarboxylation of isocitrate. 836 1

Ultraviolet (UV) radiation is one of the major risk factors of cataract (loss of eye-lens transparency). The influence of UVB radiation (300 nm; 100 microW cm-2) on the activity and apparent kinetic constants (Km and Vmax) of rat lens hexokinase (HK;EC 2.7.1.1), phosphofructokinase (PFK; EC 2.7.1.11), isocitrate dehydrogenase (ICDH; EC 1.1.1.41) and malate dehydrogenase (MDH; EC 1.1.1.37) of energy metabolism has been investigated by irradiating the lens homogenate of three- and 12-month-old rats. In the three-month-old group specific activities of HK and PFK are reduced by 56 and 43%, respectively, and there is no change in ICDH and MDH activities after a 24 h exposure. On the other hand, in the 12-month-old group the decreases are 72, 71, 24 and 16% for HK, PFK, ICDH and MDH, respectively. UVB irradiation increases the apparent Km of HK and PFK (in both age groups), whereas the Km of ICDH and MDH is not altered. While the decrease in Vmax of these enzymes due to UVB exposure is only marginal in three-month-old rats, it is more pronounced (significant) in 12-month-old rats. A similar decrease in enzyme activities of HK and PFK is also observed upon UVB exposure of the intact rat lens. The photoinduced changes in energy metabolism may in turn have a bearing on lens transparency, particularly at an older age.
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PMID:UVB irradiation alters the activities and kinetic properties of the enzymes of energy metabolism in rat lens during aging. 949 95

Extraction and isoenzyme analysis of four isolates of Arthrobotrys including A. musiformis, A. robusta and A. conoides were conducted. Among the 14 enzymes studied by starch gel electrophoresis, using morpholine-citrate as gel/electrode buffer, the following nine enzymes showed interpretable banding patterns: alpha-esterase, fumarase, hexokinase, isocitrate dehydrogenase, leucine aminopeptidase, malate dehydrogenase, 6-phosphogluconate dehydrogenase, phosphoglucomutase and phosphoglucoisomerase. All isolates studied displayed typical isoenzyme phenotypes for each species. Two isolates of A. conoides differed in their alpha-isoesterase banding patterns, but no differences were observed for the other enzymes. The assay was satisfactory for enzyme extraction and resolution of Arthrobotrys and could be used in future taxonomic and genetic studies of this organism.
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PMID:Isoenzyme analysis of Arthrobotrys, a nematode-trapping fungus. 949 29

As part of the development of structured models for the metabolism of myeloma cells in suspension culture, a study was made of the subcellular localization of key enzymes of glucose and glutamine metabolism. Steady state chemostat cultures of the mouse myeloma SP2/0-Ag14 were used as a reproducible source of biomass. Homogenates of the cells, obtained via mechanical disruption, were separated into a mitochondrial and a cytosolic fraction via differential centrifugation. The following conclusions are drawn: (1) approximately one fifth of the hexokinase activity of cell-free homogenates is associated with the mitochondria; (2) a malate-aspartate shuttle may operate for oxidation of cytosolic NADH, as indicated by high levels of malate dehydrogenase and aspartate aminotransferase in both particulate and soluble fractions; (3) the pentose phosphate pathway and isocitrate dehydrogenase may contribute to the provision of cytosolic NADPH; (4) phosphoenolpyruvate carboxykinase and pyruvate kinase, which are present in high activities, are exclusively cytosolic and probably play a key role in glutamine metabolism; (5) oxidation of glutamine via these enzymes leads to the formation of pyruvate that enters the same pool as pyruvate generated by glycolysis. As a result, lactate and alanine formation can occur from both glucose and glutamine.
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PMID:Subcellular localization of enzyme activities in chemostat-grown murine myeloma cells. 965 Feb 85

Hyperglycemic effect of cassava diet in presence of varying amounts of protein has been carried out. The rats fed a low protein high cyanide diet showed an increase in the blood glucose and a decrease in the liver glycogen. The activity of glycogen phosphorylase, glucose 6-phosphatase and phosphoglucomutase showed higher levels in the liver of low protein high cyanide group compared to the control group. Also, the activity of hexokinase, and isocitrate dehydrogenase activity in the liver of high cyanide low protein were significantly low. The results suggests that cassava diet with the low protein can induce hyperglycemia.
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PMID:Hyperglycemic effect of low protein cassava diet. 975 64

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


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