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)

The interaction of CrADP, an exchange-inert paramagnetic analogue of Mg-ADP, with yeast hexokinase has been studied by measuring the effects of CrADP on the longitudinal nuclear relaxation rate (1/T1) of the protons of water and the protons and phosphorus atom of enzyme-bound glucose-6-P. The paramagnetic effect of CrADP on 1/T1 of water protons is enhanced upon complexation with the enzyme. Titrations measuring this paramagnetic effect at several enzyme concentrations in the presence of glucose-6-P yielded a characteristic enhancement factor for 1/T1 of water protons and the dissociation constant of CrADP from the ternary enzyme . ADPCr . glucose-6-P complex. The latter value (2 mM) is similar to that obtained from kinetic inhibition studies (Danenberg and Cleland [1975]. Biochemistry. 14:28). The presence of glucose-6-P increased the enhancement of the water relaxation rate by enzyme-bound CrADP, suggesting the formation of an enzyme . CrADP . glucose-6-P complex. The existence of such a complex was confirmed by the observation of a paramagnetic effect of enzyme-bound CrADP on the l/T1 of the 31P-nucleus and protons of enzyme-bound glucose-6-P. From the paramagnetic effects of enzyme-bound CrADP on the relaxation rates of the 31P-nucleus and the carbon-bound protons of glucose-6-P in the enzyme . ADPCr . glucose-6-P complex, using the correlation time of approximately 0.7 ns, determined from the magnetic field-dependence of 1/T1 of water protons over the range 24.3-360 MHz, a Cr3+ to phosphorus distance of 6.6 +/- 0.7 A and Cr3+ to alpha- and beta-anomeric proton distances of 8.9 and 9.7 A were calculated. These results imply the absence of a direct coordination of the phosphoryl group of glucose-6-P by the nucleotide-bound metal on hexokinase but indicate van der Waals contact between a phosphoryl oxygen of glucose-6-P and the hydration sphere of the nucleotide-bound metal. The distances are consistent with a model that assumes molecular contact between the phosphorus of glucose-6-P and a beta-phosphoryl oxygen of ADP suggesting an associative phosphoryl transfer. Because after phosphorylation of ADP, the metal ion is coordinated to the transferred phosphoryl group, the overall migration of the phosphoryl group during the phosphoryl transfer is approximately 3.6 A toward the nucleotide-bound metal. Little or no catalysis of phosphoryl transfer from glucose-6-P to alpha, beta-bidentate or beta-monodentate CrADP ( less than or equal to 0.05% of the rate found with MgADP) occurred in the presence of hexokinase, as monitored by glucose formation in a coupled assay system using glucose oxidase and peroxidase. The ability of beta, gamma-bidentate CrATP to act as a substrate (Danenberg and Cleland [1975].
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PMID:Magnetic resonance studies of the spatial arrangement of glucose-6-phosphate and chromium (III)-adenosine diphosphate at the catalytic site of hexokinase. 23 78

We assessed the analytical performance of the co-immobilized hexokinase (EC 2.7.1.1) and glucose-6-phosphate dehydrogenase (EC 1.1.1.49) method for D-glucose analysis on the Technicon SMAC. The enzyme-containing coils were usable for one month, or 12 000 tests. Bilirubin, hemoglobin, lipemia, creatinine, uric acid, citric acid, and ascorbic acid did not interfere. Results with this method were compared to those by the National Glucose Reference Method. The upper limits of the total error estimate (a combination of random and systematic errors) were 76, 74, and 125 mg/liter at concentrations of 500, 1200, and 3000 mg/liter, respectively. The error estimates were less than allowable errors based on medical usefulness; thus the method was judged to perform acceptably with respect to the Reference Method. We also present performance data for the routine SMAC glucose oxidase (EC 1.1.3.4)/Peroxidase (EC 1.11.1.7) 3-methyl-2-benzothianolinone hydrazone-N,N-dimethylaniline method, the direct hexokinase method with the Du Pont aca, and the glucose oxidase oxygen-rate method with the Beckman Glucose Analyzer.
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PMID:Evaluation of the co-immobilized hexokinase/glucose-6-phosphate dehydrogenase method for glucose, as adapted to the Technicon SMAC. 65 1

Studies are reported on the reaction kinetics of the glucose assay according to Trinder which involves the specific oxidation of glucose by glucose oxidase and the determination of the hydrogen peroxide released by means of phenol and 4-aminophenazone in the presence of peroxidase. The results have been used to develop a general kinetic fixed-time method for the analysis of glucose in whole blood and serum. The single reagent method has been adapted to the ENI GEMSAEC centrifugal analyzer and to the Abbott ABA-100 analyzer. The procedures exhibited excellent precision and the results correlated well with those obtained by the hexokinase method, Linearity was achieved from 3 to 64 mmol/1 glucose for the GEMSAEC method, and from 3 to 33 mmol/1 glucose for the ABA-100 method. Reagent or sample blank corrections were not necessary. There were no interferences from various drugs, hemoglobin, bilirubin, or lipemia.
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PMID:Kinetic enzymatic method for automated determination of glucose in blood and serum. 83 60

Human saliva was incubated with human enamel powder, and the lactoperoxidase activity of the saliva was measured before and after incubation. Liquidphase lactoperoxidase activity was reduced in direct proportion to the weight of enamel powder added. Lactoperoxidase molecules were adsorbed to the enamel surface in an enzymatically active conformation, and this enamel-bound lactoperoxidase activity was also measured. The adsorption of lactoperoxidase was irreversible and produced at least a 40% increase in the concentration of lactoperoxidase in the enamel surface phase as compared with its concentration in the liquid phase. Enamel-bound lactoperoxidase, as well as the free enzyme, was capable of inactivating the key glycolytic enzyme hexokinase. The implications of the adsorption phenomenon for bacterial colonization are discussed.
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PMID:Enzyme activity of salivary lactoperoxidase adsorbed to human enamel. 88 9

We describe a novel fluorometric technique for simple, rapid, and economical assay of glucose by use of immobilized glucose oxidase and peroxidase. A cylindrical magnetic stirrer was specially designed to hold the immobilized enzymes firmly and to allow the reaction minzymic transformation quickly. Blood plasma can be assayed directly with no pretreatment. Ascrobic acid, uric acid, and creatinine in concenctrations of 0.25, 0.25, and 0.2 g/liter, respectively, did not interfere. The linearity of the assay was extended to 4.0 g of glucose concentrations. Results by our technique and by the otoluidine or hexokinase methods agreed well. The immobilized enzymes are stable for several months and can be used for several hundred highly accurate and reproducible assays.
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PMID:Measurement of glucose in plasma, with use of immobilized glucose oxidase and peroxidase. 94 48

A long-term administration of retinol in a dose exceeding 15-fold the diurnal requirement to rats weighing 170-200 g provoked a diminution of the erythrocytes resistance to an acid hemolytic, an intensified uptake of glucose, and increased activity of glycolytic enzymes (hexokinase, aldolase, phosphohexoisomerase), accumulation of lactate, along with changes in the redox enzymes activity, suppression of the catalase and intensification of peroxidase activity. The content of microergic nucleotides and electrolites (Na+ and K+) remained unchanged.
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PMID:[Effect of long-term vitamin A administration on the acid fastness and biochemical properties of erythrocytes]. 96 79

Acetaminophen, p-aminophenol, and oxyphenbutazone interfere with the glucose oxidase/peroxidase method for glucose. Structurally related compounds that lack a free phenolic hydroxyl group (acetanilide, aniline, and phenylbutazone) do not interfere. During the analytical procedure acetaminophen is consumed. One mole of acetaminophen leads to an apparent loss of four moles of glucose. The hexokinase/glucose-6-phosphate dehydrogenase method (Boehringer Hexokinase method) is not affected by these substances.
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PMID:Interference by acetaminophen in the glucose oxidase-peroxidase method for blood glucose determination. 97 21

A new glucose dehydrogenase preparation has been used to determine the glucose concentration in serum or plasma with the GEMSAEC(ENI) analyzer. The reaction is sufficiently linear to be suitable for a kinetic determination. A sample volume of 15 mul or less is needed, and 14 determinations can be done simultaneously within 160 s (the time needed for loading the samples and reagents into the distribution disc plus a reaction time of 70 s). The reaction is linear up to 300 mg of glucose per 100 ml, but with special computer software linearity could be extended to 1 g of glucose per 100 ml. Day-to-day and within-day precision have been tested with a number of different sera and standards. Accuracy has been checked by comparing the results with those obtained by the hexokinase and the glucose oxidase/peroxidase methods. A better agreement was found with the hexokinase method. The proposed procedure has the advantage of involving only one enzymatic step and of directly measuring reduced coenzyme formation at 340 nm.
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PMID:Kinetic determination of glucose with the GEMSAEC (ENI) centrifugal analyzer by the glucose dehydrogenase reaction, and comparison with two commonly used procedures. 115 1

We evaluated a slight modification of the automated oxidase/peroxidase method for glucose determination in blood with use of 4-aminophenazone [J. Clin. Pathol. 22, 246 (1969)]. Nonsugar reducing substances did not interfere, except for ascorbic acid in very high concentrations. Lipemic sera gave slightly lower values. Values for reproducibility, specificity, and sensitivity were closer to such values for the hexokinase method than was the case for some other commonly used methods.
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PMID:Evaluation of an automated glucose-oxidase procedure. 115 24

Trinder's method for glucose has nearly all the attributes of an ideal automated colorimetric glucose oxidase procedure. The chemicals used in the color reaction with peroxidase are readily available, the solutions are stable and can be prepared by the user, the method is highly specific and largely free of interferences, the sensitivity can be adjusted by the user to cover a wide range of glucose concentrations, and the reagents are not hazardous. We found very good agreement between results by this method and by the hexokinase and Beckman Glucose Analyzer methods. The method has been modified and adapted to the AutoAnalyzer I and SMA 6/60 (Technicon) with manifolds that give very little interaction between specimens. A study of the method by the simplex technique revealed that the glucose oxidase activity in the reagent is the most critical variable.
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PMID:Evaluation of Trinder's glucose oxidase method for measuring glucose in serum and urine. 123 63


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