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)

Keeping constant cellular magnesium an A 23 187 mediated moderate calcium loading of human red cells causes isoosmotic cell shrinkage, potassium efflux, slight decrease of cellular pH, ATP depletion connected with an increase of AMP, ADP and Pi and enhanced lactic acid formation. The calcium loading and accompanying effects can be abolished by EGTA or by extracellular magnesium, the latter kept more than two orders of magnitude above that of calcium which was 30 micrometer. Inhibition of the (Mg2+ + Ca2+)-dependent ATPase by ruthenium red or lanthanum decreases the calcium stimulated lactic acid formation after a lag phase. However, the ATP depletion proceeds faster and is much more pronounced under these conditions. (Mg+2 + Na+ +K+)-dependent ATPase, hexokinase, phosphofructokinase and cell shrinkage are ruled out, too, as mediators of the ATP depletion. This suggests that an unknown ATP consuming reaction, apparently not being related to the calcium pump, causes the calcium induced ATP depletion.
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PMID:Relations between ion shifting, ATP depletion and lactic acid formation in human red cells during moderate calcium loading using the ionophore A 23187. 33 40

1. A dose-dependent activation of phosphorylase and consumption of ATP was observed in isolated hepatocytes incubated in the presence of fructose; histone kinase and phosphorylase kinase activities were unchanged at doses of this sugar that were fully effective on phosphorylase. The activation of phosphorylase by fructose was also observed in cells incubated in a Ca2+-free medium as well as in the livers of rats in vivo. 2. In a liver high-speed supernatant, fructose, tagatose and sorbose stimulated the activity of phosphorylase kinase; this effect was dependent on the presence of K+ ions, which are required for the activity of fructokinase; it was accompanied by the transformation of ATP into ADP. In the presence of hexokinase, glucose also stimulated phosphorylase kinase, both in an Na+ or a K+ medium. 3. The activities of partially purified muscle or liver phosphorylase kinase were unchanged in the presence of fructose. 4. Some properties of liver phosphorylase kinase are described, including a high molecular weight and an inhibition at ATP/Mg ratios above 0.5, as well as an effect of ATP concentration on the hysteretic behaviour of this enzyme. 5. The effect of fructose on the activation of phosphorylase is discussed in relation to the comsumption of ATP.
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PMID:Mechanism of activation of glycogen phosphorylase by fructose in the liver. Stimulation of phosphorylase kinase related to the consumption of adenosine triphosphate. 43 71

Brain hexokinase (ATP:D-hexose-6-phosphotransferase, EC 2.7.1.1) binds selectively to the outer membrane of rat liver mitochondria but not to inner mitochondrial or microsomal membranes nor to the plasma membrane of human erythrocytes. A protein having subunit molecular weight of 31,000, determined by sodium dodecyl sulfate-gel electrophoresis, has been highly purified from the outer mitochondrial membrane by repetitive solubilization with octyl-beta-D-glucopyranoside followed by reconstitution into membranous vesicles when the detergent is removed by dialysis. When incorporated into lipid vesicles, the protein confers the ability to bind brain hexokinase in a Glc-6-P-sensitive manner as is seen with the intact outer mitochondrial membrane. Hexokinase binding ability and the 31,000 subunit molecular weight protein co-sediment during sucrose density gradient centrifugation. Both hexokinase binding ability and the 31,000 subunit molecular weight protein are resistant to protease treatment of the intact outer mitochondrial membrane while other membrane proteins are extensively degraded. It is concluded that this protein, designated the hexokinase-binding protein (HBP), is an integral membrane protein responsible for the selective binding of hexokinase by the outer mitochondrial membrane.
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PMID:Purification of a hexokinase-binding protein from the outer mitochondrial membrane. 44 25

1. We have developed a procedure for preparing resealed red cell ghosts that contain ADP but very little ATP. 2. The procedure involves (i) lysis of the cells in a very large volume of lysing solution, (ii) resuspension of the ghosts in a small volume, (iii) the incorporation into the ghosts, before they are resealed, of the adenylate kinase inhibitor P1,P5-di(adenosine-5'-)pentaphosphate (AP5A) and of hexokinase, and (iv) the removal of traces of ATP, formed by residual adenylate kinase activity, by the addition of glucose. 3. Measurements of sodium efflux from ghosts prepared in this way show that sodium-sodium exchange through the sodium pump does not occur in the absence of ATP even if ADP is present. 4. The beta:gamma imido analogue of ATP (AMP.PNP), which is incapable of phosphorylating sodium, potassium-ATPase, cannot replace ATP in supporting sodium-sodium exchange. 5. These findings support the hypothesis that the outward movement of sodium ions through the sodium pump is associated with the transfer of a phosphoryl group from ATP to the enzyme, and that the inward movement of sodium ions through the pump is associated with the return of a phosphoryl group from the phosphoenzyme to ADP.
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PMID:Sodium-sodium exchange through the sodium pump: the roles of ATP and ADP. 53 26

Several glycolytic enzymes were observed to have between 40-90% of their activities associated with the particulate fractions of lysed nerve endings. The enzymes showing high particulate activity in lysed nerve endings were hexokinase (EC 2.7.1.1), aldolase (EC 4.1.2.13), glucosephosphate isomerase (EC 5.3.1.9), phosphofructokinase (EC 2.7.1.11), glyceraldehyde-phosphate dehydrogenase (EC 1.2.1.12), pyruvate kinase (EC 2.7.1.40) and lactate dehydrogenase (EC 1.1.27). With the exception of phosphofructokinase, 80% or more of the particle associated activity of each enzyme was solubilized by salt treatment indicating the association with particles was ionic. Sub-fractionation of lysed nerve endings showed hexokinase and fumarase (EC 4.2.1.2) had the highest specific activity in the same fractions which is consistent with observations indicating that hexokinase is associated with mitochondria. The other glycolytic zymes having high particulate activity, aldolase, glucosephosphate isomerase, phosphofructokinase, glyceraldehyde-phosphate dehydrogenase, pyruvate kinase and lactate dehydrogenase, showed enrichment in fractions containing synaptosomal membranes, i.e. the fractions having highest specific activity of acetylcholinesterase (EC 3.1.1.7) and (Na+ + K+)-ATPase (EC 3.6.1.3).
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PMID:Association of glycolytic enzymes with particulate fractions from nerve endings. 62 35

1. The development of the total rat brain creatine kinase was studied in brain homogenates. Until approx. 14-15 days after birth, the activity remains less than one-third that of the adult activity (207+/-6 units/g wet wt. s.d.; n=3). Over the next 10 days the activity increases markedly to the adult value and thereafter remains essentially constant. 2. In the adult brain, approx. 5% (11.9+/-2.2 units/g wet wt. s.d.; n=5) of the total creatine kinase is associated with the mitochondrial fraction. This creatine kinase could not be solubilized by sodium acetate solutions of up to 0.8m concentration, whereas 66% of the hexokinase associated with brain mitochondria was released under these conditions. 3. Rat brain mitochondria incubated in the presence of various concentrations of creatine (1, 5 and 10mm) and ADP (100mum) synthesized phosphocreatine at rates of approx. 4.5, 11 and 17.5nmol/min per mg of mitochondrial protein. Atractyloside (50mum) or oligomycin (1.5mug/mg of mitochondrial protein) completely inhibited the synthesis of phosphocreatine. 4. The apparent K(m) and V(max.) values of the mitochondrially bound rat brain creatine kinase were determined in both directions. The V(max.) in the direction of phosphocreatine synthesis is 237nmol/min per mg of mitochondrial protein, with an apparent K(m) for creatine of 1.67mm and for MgATP(2-) of 0.1mm, and in the reverse direction V(max.) is 489nmol/min per mg of mitochondrial protein, with an apparent K(m) for phosphocreatine of 0.4mm and for MgADP(-) of 27mum. 5. The results are discussed with reference to the role that the mitochondrially bound creatine kinase may play in the development of brain energy metabolism.
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PMID:Studies on the mitochondrially bound form of rat brain creatine kinase. 62 73

The Glucose-Controlled Insulin Infusion System (Biostator) is a modular, computerized, feedback control system for dynamic control of blood glucose concentrations in diabetics. This on-line glucose analyzer for use with whole blood utilizes a novel enzyme (glucose oxidase)-membrane configuration and an electrochemical cell to measure the H202 generated. The analyzer exhibits both short- and long-range stability, and instrument response and analyte concentration are linearly related over the full range of clinical interest. The response is fast, accurate, and precise, and permits determination of blood glucose within 2 min from the moment the blood leaves the patient. Correlation studies were completed to show the agreement between the Biostator Glucose Analyzer and the FDA's recommended hexokinase/glucose-6-phosphate dehydrogenase procedure on whole blood (e.g., average per cent recovered for 11 concentrations between 250 and 900 mg/liter was: hexokinase, 95.6%, Biostator Analyzer, 95.9%; bias and SDd, respectively, at low, normal, and high glucose values were: 12 and 41 mg/liter at the 500 mg/liter level; 4 and 52 mg/liter at the 1000 mg/liter level, and 4 and 128 mg/liter at the 4000 mg/liter level). No appreciable interference is observed with above-normal concentrations of bilirubin, uric acid, creatinine, sodium salicylate, or dextran. Platelet adhesion, which tends to decrease the useful life of the membrane, has been significantly decreased.
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PMID:Development and evaluation of a glucose analyzer for a glucose controlled insulin infusion system ((Biostator). 67 60

There was a close correlation between the hexokinase-glucose-6-phosphate-dehydrogenase method and reflomat/Reflotest-glucose on capillary blood samples without addition of glycolysis-inhibitors. The relative deviations were less than 10% over the entire range. In systematic studies set up to determine the influence of sodium fluoride and sodium monoiodo-acetate on the reflomat/Reflotest glucose system it was demonstrated that sodium monoiodo-acetate can be used when determining glucose with reflomat/Reflotest glucose, while sodium fluoride produced false values with this system.
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PMID:[Results of using the reflomat for determining glucose concentration, and the influence of glycolysis inhibitors on Reflotest-glucose (author's transl)]. 72 78

The Reflomat System for rapid estimation of plasma or blood glucose concentration has been evaluated. The System gave a linear response throughout its analytical range and the recovery of glucose added to glucose-free plasma was 97-105%. Addition of sodium fluoride to plasma produced a 7-15% reduction in the estimated glucose concentration. Plasma glucose concentration estimated with the Reflomat agreed closely with results of a glucose oxidase and a hexokinase based method, and blood glucose concentration measured with the Reflomat agreed well with results of a glucose oxidase method.
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PMID:An assessment of a reflectance meter system for measurement of plasma or blood glucose in the clinic or side ward. 85 27

Blood serum of oncologic patients due to immunoglobulin involved in its composition, activates glycolysis in the soluble fraction of muscles when using starch, glycogen and glucose as substrates. The activation is registered under both aerobic and anaerobic conditions. When elucidating the immunoglobulin effect in a glycolytic chain under aerobic conditions it is shown that its activating effect in the incomplete incubation system is manifested with such glycolysis substrates as fructose-6-phosphate and 2-phosphoglyceric acid. Glycolysis activation with serum is insignificant or absent at all with the presence of glucose-6-phosphate, fructose-1,6-diphosphate, 3-phosphoglyceric aldehide, 3-phosphoglyceric acid, phosphoenolpyruvic acid, sodium pyruvate. Immunoglobulin isolated from the blood serum of oncologic patients does not affect the activity of purified preparations of hexokinase, glycerinaldehydephosphate dehydrogenase, lactate dehydrogenase under aerobic and anaerobic conditions. When using the air as a gas medium lactate dehydrogenase is activated by immunoglobulin. Lactate dehydrogenase activity under aerobic and anaerobic conditions is essentially lower than in the case when the air serves as a gas medium.
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PMID:[Peculiarities of the action of protein positively reacting in the sedimentation test for cancer on the activity of glycolytic enzymes]. 92 7


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