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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)

Glucose-6-phosphate dehydrogenase (G6PD); EC 1.1.1.49 from thirty-six unrelated Spanish males was partially purified from blood, and the variants were characterized biochemically and electrophoretically according to the methods recommended by the world Health Organization. Subjects were from multiple geographic regions within Spain, and all suffered from hemolytic anemia, either acute (34 cases) or chronic nonspherocytic (2 cases). Almost all the variants studied presented residual erythrocyte G6PD activity ranging from 0 to 10% of normal, and five different mutants were responsible for the deficient phenotype. Three variants were similar to others previously described: G6PD Mediterranean (11 cases), G6PD Athens-like (3 cases), and G6PD Union (2 cases). The remaining variants were different from the numerous variants already reported and have been considered as new mutants. Provisionally they are called G6PD Betica (19 cases) and G6PD Menorca (1 case). The present study constitutes the first attempt to characterize the deficient G6PD variants found in Spain and supplies new data on the relationship between molecular characteristics of deficient variants and their clinical manifestations. The most important findings can be summarized as follows: (1) The Spanish population is characterized by an important heterogeneity in G6PD deficiency. (2) Although G6PD Mediterranean is very frequent, it presents a relatively high degree of polymorphism. (3) Favism has been observed associated with all kinds of variants described here. (4) G6PD Betica, which is the most frequent variant found in subjects of Southern Spanish origin, has been observed associated with favism in all cases except one.
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PMID:Heterogeneity of "Mediterranean type" glucose-6-phosphate dehydrogenase (G6PD) deficiency in Spain and description of two new variants associated with favism. 710 52

Glucose-6-phosphate dehydrogenase (D-glucose-6-phosphate:NADPH+ 1-oxidoreductase, EC 1.1.1.49) and 6-phosphogluconate dehydrogenase (6-phospho-D-gluconate:NADP+ 2-oxidoreductase, EC 1.1.1943) have been purified from methanol-grown Pseudomonas C. Glucose-6-phosphate dehydrogenase exhibits activity with either NADP+ or NAD+ as coenzymes, V NADP+ = 0.96 V NAD+.Km values of 22, 290, and 250 microns are obtained for NADP+, NAD+ and glucose 6-phosphate (NADP+ as the coenzyme), respectively. ATP inhibits Glc-6P dehydrogenase activity with NAD+ as coenzyme and to a less extent the activity with DANP+. In the presence of MgCl2, ATP inhibition of Blc-6P dehydrogeanse activity is abolished. 6-Phosphogluconate dehydrogenase has a dual specificity for both NADP+ or NAD+ as coenzymes, V NADP+ = 1.66 V NAD+.Km values of 20, 500 and 100 microns are obtained for NADP+, NAD+ and 6-phosphogluconate (NADP+ as the coenzyme), respectively. With NAD+ as the coenzyme ATP inhibits 6-phosphogluconate dehydrogeanse activity, while with NADP+ as the coenzyme, activity was less affected. The possible role of these enzymes in the metabolism of one-carbon (C1)-compounds in Pseudomonas C is discussed and compared with other methylotrophic microorganisms.
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PMID:Purification and properties of glucose-6-phosphate dehydrogenase (NADP+/NAD+) and 6-phosphogluconate dehydrogenase (NADP+/NAD+) from methanol-grown Pseudomonas C. 735 Sep 9

Isoenzymes of glucose-6-phosphate dehydrogenase and hexokinase from red cells of newborn infants were analysed by isoelectric focusing in polyacrylamide gel after partial purification. The pattern of isoenzyme distribution was compared with that of erythrocytes from adults. Glucose-6-phosphate dehydrogenase isoenzyme distribution was identical between erythrocytes from newborn infants and adults. Erythrocytic hexokinase isoenzymes patterns were different between newborn infants and adults. Erythrocytes from adults contain a hexokinase isoenzyme which has the same isoelectric point as rat liver hexokinase isoenzyme I (pH 6 . 01). This isoenzyme is lacking in red cells from newborn infants. Isoenzymes with the isoelectric properties of rat liver isoenzyme II (pH 5 . 48) were not detectable in red cells from adults, nor from newborn infants. The occurrence of an isoenzyme III in red cells remained unclear, because only a faint staining was observed in the corresponding region of erythrocytic gels. Preliminary results revealed a fetal type of hexokinase isoenzyme distribution in infants with an age of 10 months. This indicates that regulation of the synthesis of Hb F and of fetal hexokinase isoenzymes is not correlated.
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PMID:Isoelectric focusing of hexokinase and glucose-6-phosphate dehydrogenase isoenzymes in erythrocytes of newborn infants and adults. 743 31

Glucose-6-phosphate dehydrogenase activity was measured quantitatively in isolated cortical fractions of the nephron in sodium-depleted and sodium-loaded rabbits. The samples consisted of isolated fractions of macula densa, proximal convoluted tubule, distal convoluted tubule and glomerulus. In sodium-depleted rabbits enzyme activity was identical to that of normal rabbits. In sodium-loaded rabbits a significant decrease in enzyme activity was found in the macula densa and proximal convoluted tubule. However, using conventional histochemical incubation methods semiquantitative estimation of glucose-6-phosphate dehydrogenase showed a slight decrease in enzyme activity in the macula densa and distal convoluted tubule, and a slight increase in the proximal convoluted tubule during sodium-depletion. During sodium-load a pronounced decrease in enzyme activity was seen in the macula densa and distal convoluted tubule. These results show that semiquantitative histochemical evaluation of changes in enzyme activity is less reliable than the more precise quantitative method especially when there are only slight changes in enzyme activity. Only where there were marked changes in histochemical enzyme activity might the results of quantitative and semiquantitative methods be in accord.
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PMID:Quantitation of glucose-6-phosphate dehydrogenase activity in cortical fractions of the nephron in sodium-depleted and sodium-loaded rabbits. 744 Feb 60

Glucose-6-phosphate dehydrogenase is inactivated slowly by reaction with sugars (glycation), a process thought to be important in the development of diabetic complications. A major protein from the ocular lens, alpha-crystallin. which exhibits some chaperone-like properties, protects against this inactivation. The well-known molecular chaperone GroEL (chaperonin 60 from Escherichia coli) also protects. On a molar basis, alpha-crystallin is better than GroEL at protecting against glycation-induced inactivation of glucose-6-phosphate dehydrogenase. The relative amounts of enzyme/chaperone indicate that each molecule of alpha-crystallin binds two molecules of the damaged enzyme. This supports the view that alpha-crystallin has a chaperone-like structure as well as a chaperone-like function.
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PMID:Molecular chaperones protect against glycation-induced inactivation of glucose-6-phosphate dehydrogenase. 762 68

Glucose-6-phosphate dehydrogenase activity was studied in the brain of the cichlid fish Oreochromis mossambicus during early ontogenetic development. In general a slight but continuous decrease in enzyme activity was found (9.5 +/- 0.5 nmol substrate cleaved per mg protein and per min at developmental stage 13 [= 1 day post hatch at 28 degrees C] to a value of 7.9 +/- 0.6 in adult brain). In order to investigate the possible influence of altered gravity during early ontogenetic brain development, fish larvae were exposed to an increased acceleration of three times earth gravity (3 g) or to functional weightlessness in a fast-rotating clinostat for 7 days. A significant increase of brain G6PDH activity of approx. 15% was found after exposure to hyper gravity, whereas a significant decrease of the enzyme activity, approximately 10%, was detected following functional weightlessness in respect to the corresponding 1 g controls. Analyses concerning the regain of normal control enzyme activity of the larvae revealed dramatic fluctuations within the first 5 h after exposure to an increased acceleration of 3 g. Thereafter, between day 1 and day 3 after exposure, brain glucose-6-phosphate dehydrogenase decreased slowly. At day 3 after exposure no further differences of the hyper-g larvae compared to the controls were found. Only slight changes in total brain glucose-6-phosphate dehydrogenase activity occur during ontogenetic development of cichlid fish. This suggests that a more or less constant enzyme activity is important during brain development, but is reacting very sensitively to changes in the environmental factor gravity.
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PMID:Development and altered gravity dependent changes in glucose-6-phosphate dehydrogenase activity in the brain of the cichlid fish Oreochromis mossambicus. 767 Mar 61

Glucose-6-phosphate dehydrogenase (D-glucose-6-phosphate: NADP+ 1-oxidoreductase, EC 1.1.1.49) from Bakers' yeast was immobilized with the highest activity on polyacrylamide beads possessing carboxylic functional groups activated by a water-soluble carbodiimide. The optimal pH values for the catalytic activity of the soluble and the immobilized glucose-6-phosphate dehydrogenase were practically identical, lying between pH 9.0 and 9.2. The optimal temperature for both the soluble and the immobilized enzyme was about 50 degrees C. The apparent Km values of the immobilized enzyme were slightly higher than those of the soluble enzyme. The immobilization improved the stability of the enzyme in the pH range 6.0-9.0 at 45 degrees C. The operational stability of the immobilized glucose-6-phosphate dehydrogenase proved favorable in a column experiment during 37 days of operation.
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PMID:Coenzyme production using immobilized enzymes. III. Immobilization of glucose-6-phosphate dehydrogenase from bakers' yeast. 776 12

This study reports the effects of alloxan induced diabetes on glucose metabolism enzymes viz. Hexokinase, Lactate dehydrogenase, and Glucose-6-phosphate dehydrogenase from discrete brain regions. Enzymes activity was assayed from hypothalamic areas such as medial preoptic area and median eminence-arcuate region which have gonadotropin releasing hormone cell bodies and their terminals, respectively and other brain regions like septum, amygdala, hippocampus, and thalamus. In all the areas studied, induction of diabetes resulted in a significant decrease in particulate bound HK activity, whereas soluble HK, LDH and G6PDH activity showed increase at 3, 8, 15 and 28 days intervals. Insulin treatment of diabetic rats led to recovery in enzyme activity. Blood glucose levels increased significantly after induction of diabetes and recovery was seen after insulin treatment. The present results suggest that altered cerebral glucose metabolism may also be responsible for reproductive failure observed in diabetic rats.
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PMID:Changes in glucose metabolism from discrete regions of rat brain and its relationship to reproductive failure during experimental diabetes. 789 76

Glucose-6-phosphate dehydrogenase (EC 1.1.1.49) was purified from Cryptococcus neoformans, a basidiomyceteous yeast that is an opportunistic pathogen of AIDS patients. The enzyme had a subunit molecular weight of 5 x 10(4), a specific activity of 50 units mg-1, and Km values for NADP and glucose-6-phosphate of 1.6 and 24 microM, respectively. The enzyme catalyzed the dehydrogenation of glucose, in the presence of dimethylsulfoxide, with Km of 5 mM and Vmax 10% of that with glucose-6-phosphate. pH profiles indicated the presence of a group with pKa of 6.6 that is involved in catalysis, and groups with pKas of about 8.8 that are involved in binding of NADP and glucose-6-phosphate. The enzyme was inhibited by NADPH, competitive versus NADP, with Ki of 1 microM, and by zinc ion, competitive versus glucose-6-phosphate, with Ki of 2 microM. Crude enzyme extract catalyzed an appreciable rate of reduction of NADP in the absence of added substrate, a "nothing dehydrogenase" activity. This activity was shown to be due to the presence of glucose-6-phosphate in the crude extract. It was calculated that cells of C. neoformans contain about 25 mumol of glucose-6-phosphate per gram, wet weight.
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PMID:Purification and characterization of glucose-6-phosphate dehydrogenase from Cryptococcus neoformans: identification as "nothing dehydrogenase". 808 Feb 77

1. Glucose-6-phosphate dehydrogenase (G6PDH EC 1.1.1.49) from mouse liver has been purified 1100-fold by extraction, ion-exchange chromatography on DE-52, absorption chromatography on Bio-Gel HTP and gel filtration through sepharose 6 HR 10/30. The purified enzyme showed a single band in silver stained SDS-PAGE. 2. The native and subunit molecular weight were 117 and 31 kDa respectively. 3. The kinetic studies and the patterns obtained from the inhibition by-products suggest that the enzyme follows an ordered sequential kinetic mechanism. 4. The reduced Km values for the substrates favour the operativity of the enzyme. The "fine control" of the enzymatic activity was exerted by the NADPH, whose Ki is several fold lower than the in vivo concentration.
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PMID:Purification, characterization and kinetic mechanism of glucose-6-phosphate dehydrogenase from mouse liver. 817 54


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