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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)

Two new kinetic analyses for mammalian hexokinases are presented, which permit one to study the regulation of these enzymes by product inhibition. One method uses the pyruvate kinase-coupled assay and the other the glucose-6-phosphate dehydrogenase-coupled assay. Both methods give simple linear plots, which indicate that the magnesium-ATP complex overcomes the glucose 6-phosphate inhibition competitively, but by atypical kinetics. A new regulation coefficient (Kr) was defined and it was shown that, with both assay methods, the reciprocals of the slopes of the simple linear plots are proportional to Kr.[Mg.ATP].NADP, but not NAD, was found to be a powerful inhibitor of pig heart hexokinase.
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PMID:Two kinetic methods to study the regulation of mammalian hexokinases. 272 60

The ovaries of 84 ground squirrels (C. Citellus L.) were studied during the four seasons of the year. The ovarian atretic follicles were examined by histological methods and by electron microscopy. The histoenzyme activities of NAD.H2-tetrazolium reductase, glucose-6-phosphate dehydrogenase, and 3 beta-hydroxy-delta 5-steroid dehydrogenase were photometrically demonstrated. The steroid-producing atretic follicles were mainly described as they reached their highest enzyme activity during the lactation period in April. The atresia of the primordial and primary follicles was manifested by disappearance of the oocyte and preservation of the granulose cells surrounded by basal lamina. Atresia of follicles with two oocytes was a typical process for the ground squirrel. Later on the oocytes and the granulose cells around it disappeared. The remaining part of the follicle continued its development and reached maturity. Atresia was observed mainly in March, April, and May.
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PMID:Seasonal changes of the ovarian atretic follicles of the ground squirrel (Citellus citellus L.). 276 86

The genetic structure of two Chukot Evens subpopulations (314 individuals) for electrophoretic protein systems and taste sensitivity to PTC was studied. 17 of the 39 loci were polymorphic (43.59%). The following systems were completely monomorphic: diaphorase NAD H (Dia); glucose-6-phosphate dehydrogenase (G-6-PD); glutamatoxalate transaminase (GOT); carbonic anhydrase (Ca-1); catalase (Ct), lactate dehydrogenase (loci LDH-A and LDH-B); leucine aminopeptidase (Lap); malate dehydrogenase (MDH); purine nucleoside phosphorylase (PNP); superoxide phosphorylase (PNP); superoxide dismutase (SOD); phosphoglucomutase-2 (PGM2); cholinesterase (locus E1); red cell esterase (4 loci); albumin (Alb); hemoglobin (Hb A and B); ceruloplasmin (Cp); and blood, gren, using the standard method. The following systems were polymorphic: red cell acid phosphatase (AcP); phosphoglucomutase-1 (PGM1); 6-phosphogluconate dehydrogenase (PGD); glutamatepyruvate transaminase (GPT); glyoxalase-1 (GLO-1); esterase (EsD); adenilatkinase (AK); alkaline phosphatase (Pp); cholinesterase (locus E2); haptoglobin (Hp); transferrin (Tf); group-specific component (Gc) and ABO, MN, Lewis, P blood groups and taste sensitivity to PTC. The following allele frequencies for polymorphic loci have been detected: AKI = 0.994; GLO = 1I = 0.082; GPT1 = 0.653; AcPA = 0.400; AcPB = 0.599; AcPC = 0.001; PGDA = 0.944; PGM1(1) = 0.906; EsD1 = 0.897; E2+ = 0.048; HpI = 0.394; GcI = 0,919; Tfc = 0.987; r(O) = 0.669; p(A) = 0.184; q(B) = 0.146; M = 0.711; Le = 0.411; P1+ = 0.521; t = 0.295. The genetic structure of Chukot Evens population is significantly nearer to that of the other ethnic groups of the North-East, in comparison with the genetic structure of Evenks of the Middle Siberia.
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PMID:[Genetic structure of the populations of native inhabitants in the northeastern USSR. V. The Chukot Evens]. 293 99

Quantitative histochemical assays of several enzymes (succinic, lactic, beta-hydroxybutyrate, alpha-glycerophosphate, and glucose-6-phosphate dehydrogenases, NAD diaphorase, and phosphorylase) in the myocardium of persons who had died suddenly with postinfarctional cardiosclerosis have failed to reveal any changes specific for this patient group. Direct correlations were established between the enzyme activities assayed, on the one hand, and the extent of myocardial hypertrophy and the signs of chronic heart failure, on the other. The activities of beta-hydroxybutyrate dehydrogenase and glucose-6-phosphate dehydrogenase, which are involved in fatty acid utilization and in the pentose phosphate pathway, were elevated in cases of moderate hypertrophy, as were those of all redox enzymes in cases of strongly marked hypertrophy, although they were reduced in cases with signs of chronic cardiac failure despite the presence of considerable myocardial hypertrophy. Areas of acute myocardial ischemia were discovered in 45% of the cases.
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PMID:[Histochemical study of the enzyme activity of the myocardium of sudden death victims with postinfarct cardiosclerosis]. 296 Feb 98

The structural gene (zwf) for Leuconostoc mesenteroides glucose-6-phosphate dehydrogenase has been cloned into Escherichia coli on pBR322 by selecting for complementation of a zwf mutation of E. coli which eliminates glucose-6-phosphate dehydrogenase. The gene has been subcloned on a 3.4-kilobase DNA segment. The encoded glucose-6-phosphate dehydrogenase displays the dual nucleotide specificity (reacting with NAD and NADP) of the L. mesenteroides enzyme and has a subunit Mr of 55,000. A second gene encoding protein of subunit Mr 24,000 is also encoded on the 3.4-kilobase DNA segment. The genes have been located by the analysis of deletions and insertions generated in vitro and by transcriptional mapping with a promoterless chloramphenicol acetyl transferase cartridge inserted at different sites in the 3.4-kilobase fragment.
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PMID:Expression of the gene for NAD-dependent glucose-6-phosphate dehydrogenase from Leuconostoc mesenteroides cloned in Escherichia coli K-12. 302 77

Within the uterine glands, the following enzymes were demonstrated by histochemical methods after 30, 58, 80, 100, and 110 d of pregnancy, respectively: beta-N-acetyl-hexosaminidase, beta-galactosidase, beta-glucuronidase, alpha-mannosidase, acid phosphatase, alkaline phosphatase, esterases, cytochrome oxidase, 5-nucleotidase, leucine aminopeptidase, adenosine triphosphatase, diaphorases (NADH, NADPH), glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, succinate dehydrogenase, isocitrate dehydrogenase (NAD, NADP), beta-hydroxybutyrate dehydrogenase, glycero-3-phosphate dehydrogenase, NAD-glycero-3-phosphate dehydrogenase, glutamate dehydrogenase (NAD, NADP), lactate dehydrogenase. The results show that the activities of G-6-PDH, 6-PGDH, and cytochrome oxidase increase within secreting cells during the 2nd half of pregnancy. The activities of the other enzymes remained almost unchanged during the period of investigation. The description of our results distinguishes between gland neck, middle, and distal part of the secretory unit, respectively. In general, the enzyme activities are similar within the middle and distal gland segments, but lower in the epithelia of the neck region. The activity of dehydrogenases was medium to intensive within the middle and distal gland segments, but only low to medium within the neck portion. Of the hydrolases, the acid phosphatase, ATPase, leucine aminopeptidase, and beta-galactosidase demonstrated an intensive activity within activity secreting cells. The enzyme activities of the gland epithelia are compared with these of the uterine surface epithelia and the histochemical results are discussed in context with their significance in histiotrophic nutrition.
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PMID:[Enzyme histochemistry of the pig placenta. III. Histotopics of enzymes in the uterine epithelium]. 309 49

NAD-linked activity of glucose-6-phosphate dehydrogenase from both low-producing and high-producing strains of Streptomyces aureofaciens was inhibited by ATP, ADP, AMP and Pi. The inhibition constants indicate that ADP was the most potent inhibitor. The NADP-linked activity remained unaffected even at relatively high concentrations of these inhibitors. All inhibitions of the NAD-linked activity were competitive with respect to NAD and noncompetitive with respect to glucose-6-phosphate. The results represent a possible new regulatory mechanism of glucose-6-phosphate dehydrogenase from a streptomycete and emphasize its involvement in the regulation of the biosynthesis of tetracyclines.
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PMID:Inhibition studies of glucose-6-phosphate dehydrogenase from tetracycline-producing Streptomyces aureofaciens. 309 56

The levels of ATP, ADP, AMP, NADP, NADPH, NAD, NADH and reduced glutathione were determined in the red blood cells of individuals with glucose-6-phosphate dehydrogenase (G6PD) deficiency, beta-thalassemia (beta-thal) heterozygotes and in a boy carrying both mutations. The results obtained confirmed a reduced concentration of NADPH in G6PD deficiency and showed that with the combination of both diseases, the red blood cell contained practically undetectable levels of NADPH. Assays of some red blood cell enzyme activities known to be markedly influenced by cell age suggested that a younger mean red cell population is present in beta-thal/G6PD deficiency. Thus, the marked oxidative stress caused by beta-thal, that is apparently incompatible with G6PD deficiency, in fact exists, probably because of the residual activity of this enzyme in the younger red cells.
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PMID:Redox and energetic state of red blood cells in G6PD deficiency, heterozygous beta-thalassemia and the combination of both. 309 52

The common approach is developed for isolation of mutants deficient in key enzymes of ribulose monophosphate pathway for formaldehyde oxidation and assimilation by obligate methylotrophic bacteria. The approach is based on total isolation of temperature sensitive mutants and their biochemical characterization. A number of ts- mutants of obligate methylotroph M. flagellatum KT is isolated following nitrosoguanidine induced mutagenesis. The modified screening method was developed and used for identification of mutants deficient in the key enzymes of ribulose monophosphate pathway. The mutant deficient in glucose-6-phosphate dehydrogenase (zwf) was identified. The NAD-dependent activity of glucose-6-phosphate dehydrogenase was not measurable under nonpermissive temperature while the level of NADP-dependent activity was only four-fold less comparing with wild type strain. It was concluded that growth limitation of zwf mutant of M. flagellatum KT (designated T623) at 42 degrees C results from the absence of NAD-dependent activity of glucose-6-phosphate dehydrogenase.
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PMID:[Temperature-sensitive mutant of the obligate methylotroph Methylobacillus flagellatum KT deficient in glucose-6-phosphate dehydrogenase]. 311 3

Content of glucose as well as activities of glyceraldehyde phosphate dehydrogenase (alpha-GPD), glucose-6-phosphate dehydrogenase (G6PD), superoxide dismutase (SOD) and catalase were studied in whole blood, in intact and hemolyzed erythrocytes of 57 volunteers within 120 min after sucrose loading. Direct correlation was found between the activity of the enzymes studied and level of glucose as well as the rate of its utilization in erythrocytes. These data suggest that reduced NAD- and NADP-containing oxidoreductases alpha-GPD and G6PD are donors of H+ used in biosynthesis of H2O2 catalyzed by SOD. Intact and hemolyzed erythrocytes are involved in destruction of H2O2 accompanied by liberation of O2, which reacted with Hb more readily as compared with atmospheric oxygen.
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PMID:[Changes in glyceraldehydephosphate dehydrogenase, glucose-6-phosphate dehydrogenase, superoxide dismutase, and catalase activity in erythrocytes depending upon the rate of glucose utilization]. 321 46


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