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)

We adapted the p-hydroxybenzoic acid hydrazide procedure for serum glucose for use with the Technicon SMA 12/60 AutoAnalyzer. Like the o-toluidine method, this method is based on a general carbohydrate reaction except that it occurs in a mildly alkaline medium and the intense yellow color formed is measured at 400 nm. Advantages of this reagent over o-toluidine include lower cost, less toxicity, and higher purity. Aside from those carbohydrates that are present in serum in insignificant quantities, there are no interferences from various physiological compounds or drugs (hypoglycemic agents) found either in normal persons or diabetics. Within-run and day-to-day values had coefficients of variation of 1.39% and 3.44%, respectively; recoveries ranged from 100 to 102% (mean, 101%). Comparative data showed excellent agreement with the hexokinase (r equals 0.998; y equals 0.950x + 5.91) and glucose oxidase (r equals 0.996; y equals 0.986x + 5.34) enzymatic ("true") glucose methods, and with the o-toluidine procedure (r equals 0.998; y equals 0.979x + 3.14).
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PMID:P-Hydroxybenzoic acid hydrazide procedure for serum glucose adapted to the Technicon "SMA 12/60," and compared with other glucose methods. 0 94

Small-bore ("Autozyme") tubes with immobilized enzymes at the inner wall have been developed and studied for application in the Technicon "SMAC" high-speed continuous-flow biochemical analyzer. Tubes coated with glucose oxidase (D-glucose:oxygen oxidoreductase, EC 1.1.3.4) have been prepared for the assay of glucose, with colorimetric assay of the hydrogen peroxide produced; tubes coated with glycerol kinase (ATP:glycerol phosphotransferase, EC 2.7.1.30) for the enzymatic assay of triglycerides; tubes coated with hexokinase (ATP:D-hexose-6-phosphotransferase, EC 2.7.1.1) and glucose-6-phosphate dehydrogenase (D-glucose-6-phosphate:NAD+ oxidoreductase EC 1.1.1.49) for the measurement of ATP, an intermediate product in assays for creatine kinase. With use of 10-15 cm lengths of Autozyme tube and SMAC hydraulics (150 samples per hour), assay sensitivity and carryover were similar to values for the corresponding free-enzyme methods. These immobilized enzymes were sufficiently stable for one to eight weeks of continuous use before replacemnt. We conclude that suitable bound-enzyme tubes can replace either single or multiple free-enzyme reagents in many continuous-flow assays at high sampling rates.
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PMID:Continuous-flow analysis for glucose, triglycerides, and ATP with immobilized enzymes in tubular form. 1 65

An automated kinetic assay for the determination of glucose in blood is described. The method employs the enzyme glucose dehydrogenase in the presence of mutarotase, with nicotinamide adenine dinucleotide as hydrogen acceptor. The analytical parameters of the method are determined and the flexibility of the method in relation to sample volume and sensitivity is discussed. Finally, the method is compared with automated glucose oxidase and hexokinase procedures.
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PMID:A rapid kinetic assay for glucose using glucose dehydrogenase. 3 97

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

The BIOSTATOR Systems have an on-line glucose analyzer for use with whole blood. This analyzer utilizes a novel enzyme (glucose oxidase) membrane configuration and an electrochemical cell to measure the H2O2 generated. The analyzer response is fast, accurate, precise, stable, and linearly related to the blood glucose concentration over the full range of clinical interest. Extensive correlation studies have been completed to show the agreement between this analyzer and the U.S. Food and Drug Administration's recommended hexokinase-glucose-6-phosphate dehydrogenase procedure. In addition, studies on potentially interfering substance and the differences in whole blood and plasma glucose levels have been completed.
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PMID:Evaluation of the BIOSTATOR systems glucose analyzer. 29 37

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

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

The long-term stability of glucose in 45 commercial pools of lyophilized quality control serum is evaluated. The pools have been used in conjunction with the Quality Assurance Service (QAS) of the College of American Pathologists by laboratories participating in Regional Quality Control Programs. Directional instability of glucose was detected by at least one analytic method in 69% of the pools studied. Two distinct and opposite directional trends in glucose concentration were found. Increasing concentration of analyte, averaging 4.7 mg/dl per year, were observed with manual and automated glucose oxidase methods and the automated neocuproine procedure in approximately one fourth of pool--method combinations. Decreasing concentrations of glucose, averaging 3.0 mg/dl per year, were found with automated ferricyanide and hexokinase methods and the manual orthotoluidine procedure in approximately one third of pool--method combinations. The results are best explained by postulating that in affected pools there is a gradual diminution of free and bound glucose and/or a shift of glucose from the protein-bound to the free state.
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PMID:Long-term stability of glucose in lyophilized quality control serum. A study utilizing data from the Quality Assurance Service (QAS) Program of the College of American Pathologists. 70 19

To learn whether a single dialysis can acutely improve the intravenous glucose tolerance (i.v.GTT) of chronically dialyzed patients, a standard i.v.GTT was performed on 10 nonobese uremic subjects on maintenance hemodialysis for 27 +/- 9 (mean +/- SEM) mo, and on a control group of 13 normal subjects. The uremic patients were tested first 0.2-17 (range) hr, and then 65-109 hr, from last dialysis. In the uremic sera, plasma glucose was analyzed by 4 methods; 2 reducing (neocopurine and ferricyanide) and 2 enzymatic (hexokinase and glucose oxidase). The reducing methods markedly overestimated plasma glucose concentration because of the presence of nonglucose reducing substances (notably, creatinine). This inteference was significantly cut down by dialysis. A single dialysis, on the other hand, failed to improve the glucose fractional decay rate (KG) computed from the glucose oxidase data (1.69 +/- 0.2%/min before and 1.35 +/- 0.1 after dialysis, versus 1.47 +/- 0.1 of the normal subjects). The same conclusion was derived from the data measured by the other 3 methods of glucose assay. Fasting plasma insulin concentrations were, on average, above normal (5.5 +/- 0.6 muU/ml) both before (12.3 +/- 2.7, p less than 0.05) and after (17.2 +/- 3.5, p less than 0.01) a single dialysis. Likewise, the area under the glucose-induced plasma insulin curve was significantly greater than normal (1.46 +/- 0.21 mU/ml . min) both before (2.26 +/- 0.34, p less than 0.05), and after (2.86 +/- 0.43, p less than 0.01) dialysis. A single dialysis had little effect on either basal or glucose-stimulated insulin release, and no significant difference in the insulinogenic index (insulin area/glucose area) was found between the control and the uremic group in either test. Insulin response was not correlated with KG, whereas it was significantly associated with higher triglyceride levels. Creatinine, urea or methylguanidine did not appear to have any influence on KG, but lower serum potassium levels were significantly associated with poorer i.v.GTT's. Plasma calcium bore a reciprocal relation to the insulinogenic index. Chronically dialyzed subjects show some degree of tissue insulin resistance, which a single dialysis fails to correct. Electrolyte disturbances may play a role in this metabolic derangement.
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PMID:The response to intravenous glucose of patients on maintenance hemodialysis: effects of dialysis. 76 47

A commerical adaptation of Trinder's glucose oxidase procedure for glucose determination was evaluated by regression analysis. Excellent correlation was found between the glucose oxidase procedure and a hexokinase procedure. Good correlation was observed between an AutoAnalyzer I, the SMA 12/60, and a Beckman Glucose Analyzer, all utilizing variations of the glucose oxidase procedure. This combination provides a system that can handle screening, routine, and emergency requests in essentially the same manner and with comparable true glucose results. No interference was found with common anticoagulants and preservatives. Boehringer Mannheim Corporation's kit for glucose determinations appears to be of equivalent quality to the original method as outlined by Trinder and evaluated by others.
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PMID:Evaluation of a glucose oxidase procedure. 82 52


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