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)

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

A new method for the assay of maltase and sucrase is reported. The method makes use of mutarotase, hexokinase and glucose 6-phosphate dehydrogenase as ancillary enzymes. The reaction is linear at least up to a delta E/min of 0.13.
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PMID:A new continuous optical assay for maltase and sucrase. 130 54

We propose the following scheme for cerebral uptake and overall metabolism of glucose in vivo: that brain selects from two pools of glucose anomers in arterial blood, that it takes up excess glucose, that glucose enters the brain tissue as glucose-6-phosphate through the actions of mutarotase and hexokinase, that some glucose-6-phosphate becomes metabolized to CO2 and some becomes incorporated into brain carbon pools, and that excess glucose-6-phosphate leaves brain through glucose-6-phosphatase and mutarotase activities. This results from our observations in arterio-venous studies for the determination of cerebral metabolism in humans in vivo that the cerebral uptake of [14C]glucose often appeared to differ from that of unlabeled glucose. With rapidly falling arterial radioactivity, unlabeled glucose uptake was more than [14C]glucose. With rising arterial radioactivity, [14C]glucose extraction exceeded unlabeled glucose. Studies with [14C]glucose-6-phosphate suggested that glucose-6-phosphatase in brain removes excess substrate by dephosphorylation. However, when arterial [14C]glucose increased slowly, [14C]glucose uptake varied considerably and the data resembled human cerebral metabolism of glucose anomers. An experiment employing [13C]glucose and NMR provided further support for our proposed scheme.
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PMID:Evidence for the cerebral uptake in vivo from two pools of glucose and the role of glucose-6-phosphatase in removing excess substrate from brain. 298 20

A study of the reverse reaction of rat brain hexokinase (ATP:D-hexose 6-phosphotransferase, EC 2.7.1.1) has been performed using a photometric method based on a mutarotase-glucose oxidase-peroxidase-chromogen system to trap and visualize glucose, plus a glycerol kinase-glycerol system to trap ATP. Glucose 6-phosphate or 2-deoxyglucose 6-phosphate were used as phosphoryl donors at different concentrations of ADP. Variation of glucose 6-phosphate concentrations resulted in a biphasic curve from which apparent Km and Ki values of ca. 0.2 mM were calculated. In contrast, variation of 2-deoxyglucose 6-phosphate concentrations resulted in Michaelian kinetics with an apparent Km of 2 mM. The Km value for MgADP was 16 mM irrespective of the nature and concentration of the hexose 6-phosphate substrate. These results are fully consistent with an allosteric site for glucose 6-phosphate as an explanation for the inhibition of animal hexokinases by glucose 6-P and further indicate that the maximal rate is the parameter affected. From these observations and previous knowledge, the possible occurrence in animal hexokinases of a regulatory site for ATP to account for the competition between glucose 6-phosphate and ATP in the forward reaction is postulated.
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PMID:Allosteric inhibition of brain hexokinase by glucose 6-phosphate in the reverse reaction. 400 67