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Query: EC:1.1.1.49 (glucose-6-phosphate dehydrogenase)
 7,794 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A number of derivatives of NADP(H) were tested with respect to their effectiveness in interacting with tetrameric glucose 6-phosphate dehydrogenase (G6PD) retaining only the fraction of "structural" coenzyme (4 moles NADP). Interaction was probed by two parameters: a) increased thermostability of G6PD activity, measured as the difference in the corresponding transition temperature (Tm) of samples containing and lacking the NADP derivatives, respectively; b) competitive inhibition toward NADP, expressed a Ki values. Protection afforded by the various effectors against thermal denaturation decreased in the following order: NADPH, NADP, PADP-ribose, adenosine 2',5'-P2. Other NADP derivatives, including 2',3' cyclic NADP, NMN, NMNH, nicotinamide, adenosine 2'-P, were uneffective in respect to this property. The kinetically measured affinity was the greatest for NADPH and decreased progressively for the following effectors: PADP-ribose, NADP, NMNH, PADP-glycolaldehyde, adenosine 2',5'-P2, PADP-ribitol, adenosine 2'-P. Nicotinamide and NMN were uneffective on NADP binding. These data show that the adenosine moiety of NADP is more critically involved than the nicotinamide portion in the interaction with human G6PD.
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PMID:Human erythrocyte glucose 6-phosphate dehydrogenase. Influence of coenzyme derivatives on thermostability and kinetic properties. 23 15

Glutathione reductase plays an important role in protecting hemoglobin, red cell enzymes, and biological cell membranes against oxidative damage by increasing the level of reduced glutathone (GSSGR) in the process of aerobic glycolysis. The enzyme deficiency may result in mild to moderately severe hemolytic anemia upon exposure to certain drugs or chemicals. However, hereditary deficiency of the enzyme is extremely rare. Recent studies on glutathione reductase in the red cell have shown more insight in the understanding of red cell metabolism and interactions with other enzymes, especially glucose-6-phosphate dehydrogenase (G-6-PD). Glutathione reducatase in serum may be a source of error in any clinical laboratory test in which an enzyme activity is determined indirectly by measuring the change in reduced nicotinamide-adenine dinucleotide (NADH) or reduced nicotinamide adenine dinucleotide phosphate (NADPH) absorbance. Glutathione reductase levels are reduced in banked blood when citrate-phosphate-dextrose (CPD) is used as a preservative. Reviewed is the role of glutathione reductase in the metabolism of the red cell and its clinical implication and usefulness.
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PMID:Glutathione reductase in the red blood cells. 62 27

An improved procedure is reported for the histochemical localization of glucose-6-phosphate dehydrogenase in fresh-frozen sections of animal and plant tissues. Used in this procedure are an incubation medium and an inert high-molecular-weight polyvinyl alcohol as a stabilizer to check enzyme diffusion. The incubation medium consists of 10 mg each of nicotinamide adenine dinucleotide phosphate and nitroblue tetrazolium chloride and 60 mg of glucose-6-phosphate per 20 ml of 22% polyvinyl alcohol solution in 0.2 M Tris-maleate buffer, pH 7.2. Use of this medium has given consistent results with the tissues tested. Because the use of an electron-transfer agent in the incubation medium often resulted in enzyme diffusion, its use in glucose-6-phosphate dehydrogenase localization is considered undersirable. Incubation time of 15 to 30 min for animal tissue and 20 to 45 min for plant tissue of 37degreesC was found to be optimal for producing the characteristic blue formazan at the reaction sites.
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PMID:An improved method for the histochemical localization of glucose-6-phoshate dehydrogenase in animal and plant tissues. 83 60

Groups of Sprague-Dawley rats were exposed to ozone for either 8 or 24 hours a day for 7 consecutive days to evaluate morphologic changes of the respiratory system. Three levels of exposure (0.2, 0.5, and 0.8 p.p.m. of O3) were selected to simulate moderate to severe episodes of oxidant pollution in urban environments. Morphologic evaluation included light, scanning electron, and transmission electron microscopy. Biochemical parameters which were examined included succinate oxidase, glucose-6-phosphate dehydrogenase, and nicotinamide adenine dinucleotide phosphate-cytochrome c reductase activities. The results indicated that (1) exposure to concentrations as low as 0.2 p.p.m. for 7 days induced pulmonary damage; (2) there was a dose-dependent pulmonary response to the three levels of ozone which was quantitated by alterations in biochemical marker enzyme activities and observed morphologically; (3) proportionate differences were not observed in morphologic characteristics of the lesions or detected in biochemical parameters between rats exposed continuously for 7 days and those exposed intermittently for 8 hours a day for 7 consecutive days; (4) alterations in surface height and granularity of the cytoplasmic luminal projection of Clara cells were subtle changes which were dose-dependent, occurring even at the lowest ozone concentration, and best detected by scanning electron microscopy; (5) alveolar macrophage accumulation within proximal alveoli of alveolar ducts was the most readily detectable morphologic indicator of pulmonary damage; and (6) although the brunt of ozone damage was borne by the centriacinar region, there was damage to cilia and increased ciliogenesis occurring in the trachea and larger conducting airways following exposure of 0.5 and 0.8 p.p.m. of ozone.
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PMID:Pulmonary responses of rats to ambient levels of ozone: effects of 7-day intermittent or continuous exposure. 93 66

Various metabolic changes were observed in male hamsters fed vitamin B-12-deficient diets with or without supplements of cobalt, methionine, and a previously untested cobalt-free pseudovitamin B-12. The effects observed after 31 weeks of consuming the vitamin B-12-deficient diets included a marked increase in the urinary excretion of both methylmalonic acid and formiminoglutamic acid, slight increases in red blood cell mean corpuscular volume, and higher tissue levels of glutathione and activities of glutathione reductase and glucose-6-phosphate dehydrogenase. Vitamin B-12 in the diet prevented these changes, as did inorganic cobalt. The cobalt-free pseudovitamin B-12 showed no vitamin B-12 activity, neither did it have any potent antagonistic effect. Methionine supplementation reversed some of the metabolic changes. Addition of inorganic cobalt to the diet resulted in a significant increase in tissue stores of vitamin B-12.
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PMID:Metabolic changes in golden hamsters fed vitamin B-12-deficient diets. 124 94

In vitro alterations induced by a 10 micrograms/ml and 50 micrograms/ml dose each of thiophenate and fenbendazole on the absorptive surfaces of Haemonchus contortus (Nematoda: Trichostrongylidae) were studied. The most significant changes were induced in the gut epithelium. Alkaline phosphatase and adenosine triphosphatase activities were decreased, succinic dehydrogenase activity was increased, while acid phosphatase and glucose-6-phosphatase were completely lost from the intestinal epithelium after treatment with either of the drugs. A stimulatory effect of these two anthelmintics was observe on lactic dehydrogenase and reduced nicotinamide adenine dinucleotide diaphorase distribution. Thiophenate caused an increase in the activities of glutamate dehydrogenase (GDH), glucose-6-phosphate dehydrogenase (G-6-PD) and nonspecific esterases and a decrease in reduced nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-D) activity. Fenbendazole treatment led to the inhibition of GDH, while G-6-PD, NADPH-D, cytochrome oxidase, monoamine oxidase and nonspecific esterase activity remained unaltered in the epithelium.
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PMID:Histoenzymic effects of thiophenate and fenbendazole on the absorptive surfaces of Haemonchus contortus. 133 82

The lipogenic capacity of omental adipose tissue and liver was measured in vitro from samples obtained at slaughter from 33 young male goats. The animals were slaughtered either on the day of weaning (d 0) or 2, 14, or 56 d after weaning. Ages at weaning were 4 wk (early weaning) or 6 or 8 wk (late weaning). Blood samples from the jugular vein were taken before slaughter to measure the concentrations of plasma glucose and nonesterified fatty acids. There was a 30% decrease in glucose concentration after weaning. Nonesterified fatty acid concentration increased fourfold between d 0 and 2 after weaning. By d 14 after weaning, nonesterified fatty acids returned to basal concentration. The lipoprotein lipase (LPL) activity of adipose tissue declined markedly (90%) on d 2 after weaning. Lipoprotein lipase activity returned to preweaning values by d 56 after weaning in those goats that had ad libitum access to feed. In adipose tissue, nicotinamide adenine dinucleotide phosphate (NADP)-malate dehydrogenase activity fell by only 17% by d 2 after weaning and to 63% by d 14 after weaning. Lipoprotein lipase activity was closely related to metabolizable energy intake the day before slaughter. Acetyl-coenzyme A carboxylase activity was low in adipose tissue and it increased only slightly by d 56 after weaning. The data indicated that LPL played a preponderant role in the restoration of lipid stores after weaning. High NADP-malate dehydrogenase activity together with a high concentration of plasma glucose by d 56 after weaning suggested that this enzyme activity could be enhanced by high glucose availability in goat kids. Activities of lipase, acetyl-coenzyme A carboxylase, NADP-malate dehydrogenase, and glucose-6-phosphate dehydrogenase in liver were essentially unaffected by weaning. The extent and rapidity of change of lipogenic enzymes of goat kids was much more pronounced in adipose tissue than in liver.
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PMID:Changes in activities of lipogenic enzymes in adipose tissue and liver of growing goats. 136 29

This paper describes an ultramicro method for achieving enzyme assays. Enzyme saturating concentrations of substrate, coenzyme when appropriate, and running buffer were mixed and used to fill a deactivated fused-silica capillary in a capillary zone electrophoresis apparatus. The enzyme glucose-6-phosphate dehydrogenase was injected by either electrophoresis or siphoning and mixed with the reagents in the capillary by electrophoretic mixing. Enzyme activity was assayed by electrophoresing the product, reduced nicotinamide adenine dinucleotide phosphate, to the detector where it was detected at 340 nm. Under constant potential, the transport velocity of enzyme and the product was generally different. This caused product to be separated from the enzyme after it was formed. Because product formation was much faster than the rate of enzyme-product separation, product accumulated. The amount of accumulated product was inversely related to operating potential. In the extreme case, the operating potential was zero. Zero potential assays were generally carried out by electrophoresing the enzyme partially through the capillary and then switching to zero potential. This capillary was left at zero potential for several minutes to allow additional product to accumulate. After this additional amplification step, potential was again applied and the product transported to the detector. Product formed under constant potential appears as a broad peak with a flat plateau. When the voltage is switched to zero at intermediate migration distance, a peak will be observed on top of this plateau. Either the eight of the plateau or the area of the peak may be used to determine enzyme concentration. The lower limit of detection was 4.6.10(-17) mol of glucose-6-phosphate dehydrogenase.
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PMID:Ultramicro enzyme assays in a capillary electrophoretic system. 143 25

Alcohol dehydrogenase (ADH) and glucose-6-phosphate dehydrogenase (G6PDH) activities of cetyltrimethylammonium bromide permeabilized baker's yeast whole cells were employed to prepare reduced nicotinamide nucleotides NADH and NADPH from their corresponding oxidised forms. Both NADH and NADPH were found to be stable in the presence of permeabilized cells under the conditions of preparation. No dephosphorylation of NADP+ to NAD+ or of NADPH to NADH was found. Reduction is complete and the prepared NADH and NADPH are chromatographically pure. Since readily available Baker's yeast cells were used instead of expensive isolated enzyme the method described here is simple, economical, and easy to scale up.
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PMID:Preparation of NADH/NADPH using cetyltrimethylammonium bromide permeabilized baker's yeast cells. 177 72

Erythrocyte glucose-6-phosphate dehydrogenase (G6PD) was characterized in blood samples of 94 male subjects in Sudan having deficient and non-deficient electrophoretic variants. They comprised 44 GdB, 17 GdA, 19 GdB-, 11 GdA- and 3 nondeficient (GdKhartoum) variants. Biochemical characteristics including enzyme activity, electrophoretic mobility, Km for glucose-6-phosphate (G6P) and nicotinamide adenine dinucleotide phosphate (NADP), heat stability and pH optimum of all the common and deficient variants were consistent with the reported characteristics of these variants. The GdKhartoum variant had 90% mobility in TEB buffer and 100% in phosphate buffer, 120% activity, Km of 130 +/- 49 microns for G6P and 0.8 +/- 0.2 microns for NADP, lowered thermostability and an optimum pH of 7.6. This variant was not inhibited by 15 mM maleic acid, 10 mM iodoacetate and dehydro-iso-androsterone. All other variants were inhibited by dehydro-iso-androsterone but uninhibited by maleic acid and iodoacetate.
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PMID:Characterization of glucose-6-phosphate dehydrogenase variants in the Sudan--including GdKhartoum, a hyperactive slow variant. 182 77


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