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)

Bioluminescent methods are widely used for the assay of the co-factors, NADH and ATP. Although the bioluminescent method is highly sensitive, the enzymes used are unstable and expensive. Therefore a chemiluminescent method would be valuable in clinical routine assay. We have developed a chemiluminescent method for the assay of NADH using the 1-methoxy-5-methylphenazinium methyl sulphate (1-MPMS)/isoluminol(IL)/microperoxidase(m-POD) system. In order to increase the sensitivity of this method, enzymatic cycling system was coupled to the chemiluminescent assay of NADH. Alcohol dehydrogenase and malate dehydrogenase were used as the cycling enzyme. The standard curve was obtained in the range from 3 X 10(-14) to 5 X 10(-12) mol/assay. The detection limit of NADH was 30 fmol/assay which was comparable to that of the bioluminescent method using bacterial luciferase. Two chemiluminescent methods for the assay of ATP have been developed. Method 1 is the system using hexokinase/G6PDH and 1-PMS/IL/m-POD, and method 2 is the system based on the enzymatic cycling reaction of ATP using hexokinase/pyruvate kinase. Method 2 is 1000/fold more sensitive than the method 1. The detection limit of ATP was 10 fmol/assay.
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PMID:Chemiluminescent assay of co-factors. 280 Dec 32

A microassay method sensitive enough to analyze the enzyme activities in one oocyte was developed using enzymatic cycling for amplifying the reaction product to 10,000 fold. An oil-well technique was applied in the assay for achieving the reaction in the medium as small as 1.0 to 5.0 microliter. Immature Wistar rats were superovulated by PMS-hCG administration. Oocytes were collected by the puncture of the follicle and the flushing of the tube. They were freeze-dried after washing to remove cumulus cells. The dry weight was about 50ng on a quartz fiber fishpole balance. The activity of hexokinase was 1.75 +/- 0.14 picomol/oocyte/hr corresponding to one-tenth of the ovarian homogenate as control, indicating low capacity of glucose utilization in the oocyte. The activities of G6PD, LDH, and MDH were 8.41 +/- 0.34, 35.7 +/- 2.89. 11.1 +/- 2.5 picomol/oocyte/min, respectively. High activity of G6PD suggests the pentose phosphate shunt concerned with steroidogenesis is active in the oocyte. HCG increased the activities of hexokinase and MDH and decreased that of G6PD. The activity of LDH remained unchanged.
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PMID:[Study of energy metabolism in the oocyte by cycling method]. 717 80

A novel concept for a dual-enzyme-based microbiosensor for the detection of adenosine-5'-triphosphate (ATP) was developed. The employed enzymes pyrroloquinoline quinone-dependent glucose dehydrogenase (PQQ-GDH) and hexokinase were entrapped, using pH-shift-induced precipitation of electrodeposition paint (EDP) at platinum microelectrodes (diameter of 25 microm). PQQ-GDH is known showing a superior activity for glucose conversion at the relevant conditions (low oxygen concentration) for ATP detection in targeted biomedical studies. For immobilizing the two enzymes PQQ-GDH and hexokinase, the deposition conditions of EDP Resydrol AY498w/35WA were adapted to ensure high immobilization rates. Prior to ATP sensing, the conversion of glucose, which is the co-substrate for both enzymatic reactions, was optimized. Optimization was targeted towards ATP measurements in biomedical environments by optimizing the PQQ-GDH sensor for glucose. Therefore, different mediators were tested regarding their electron transfer rate and their compatibility with the enzyme: free-diffusing N-methylphenazonium methyl sulfate (PMS) and ferrocenemethanol, and an immobilized chromium hexacyanoferrate layer at platinum electrode. Free-diffusing ferrocenemethanol reveals high sensitivity towards glucose of 1.5 +/- 0.4 nA/mM. In a next step, hexokinase was co-entrapped in the polymer film resulting in a sensitivity of up to 290 pA/microM.
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PMID:Developmental aspects of amperometric ATP biosensors based on entrapped enzymes. 1977 27