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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)

We have measured, by a sensitive cycling assay, the concentration of bound and unbound dinucleotides in normal and glucose-6-phosphate dehydrogenase (G6PD)-deficient erythrocytes. Measurement of free NADP in ultrafiltrates confirms that in normal erythrocytes almost all NADP is bound to cytosolic proteins. In glucose-6-phosphate dehydrogenase-deficient erythrocytes unbound NADP is significantly higher than in normal red cells and the NADP+/NADPH ratio is largely in favor of the oxidized form. In normal and glucose-6-phosphate dehydrogenase-deficient erythrocytes essentially all NAD (bound and unbound) is in the oxidized state. About 50% of the total amount of NAD (NAD+ + NADH) is free in the cytosol, with a NAD+/NADH ratio greater than 100.
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PMID:Bound and unbound pyridine dinucleotides in normal and glucose-6-phosphate dehydrogenase-deficient erythrocytes. 204 59

Interpretation of enzymatic data requires consideration of the food intake of each animal studied. Food intake and body mass gain are closely correlated in rapidly growing animals. Direct measurement of food intake by individual fish within a school is nearly impossible. We examined the relationship between growth and liver enzyme activity as a means of inferring the food intake of individual fish within a school. Trout, identified by passive integrated transponder implants, were fed either 0, 0.3, 1, or 2% body mass/d to produce a wide range of growth rates. The activities of five enzymes, predominantly localized in liver, were measured. Results showed that, although the magnitude of response differed, increases in total liver activities of all five enzymes measured were linearly related to growth. Hexokinase (EC 2.7.1.1) increased at a rate below, and beta-D-glucose:NAD(P)+1-oxidoreductase (EC 1.1.1.47) increased at a rate equivalent to, observed increases in total liver mass. Malic enzyme (EC 1.1.1.40), glucose-6-phosphate dehydrogenase (EC 1.1.1.49) and 6-phosphogluconate dehydrogenase (EC 1.1.1.44) showed preferential increases in activity as food intake increased. Correlation of enzyme activities measured in fish fed restricted rations with either growth or nominal feeding rate showed that growth of individual fish was more closely related to liver enzyme activities than nominal feeding rate.
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PMID:Relationship between growth and selected liver enzyme activities of individual rainbow trout. 205 Dec 29

The activity of human myocardial enzymes in sudden coronary death (SCD) was quantitatively histochemically examined. The activity of succinate dehydrogenase (SDH), lactate dehydrogenase (LDH), beta-oxybutyrate dehydrogenase (beta-OBDH), alpha-glycerolphosphate dehydrogenase (alpha-GPDH), NAD-diaphorase (NAD-ase), and glucose-6-phosphate dehydrogenase (G-6-PDH) was measured on prompt autopsies (up to 3 hours of death onset). beta-OBDH and LDH showed an increase in activity in the myocardium from the subjects who had suddenly died from coronary heart disease without evident changes in the heart. In SCD in the presence of small cardiosclerosis, the activity of the enzymes characterizing the major processes of energy generation was also enhanced, which was caused by moderately severe myocardial hypertrophy. In the myocardium from the subjects who had died from coronary heart disease in the presence of large postinfarction cardiosclerosis, the activity of the enzymes was directly related to the degree of myocardial hypertrophy and the signs of chronic heart failure. As myocardial hypertrophy progressed, the enzymatic activity rose, but there were signs of chronic heart failure, it fell. The findings suggest that the changes in myocardial enzymatic activity in SCD are heterogeneous and associated with the type of prior abnormalities in the cardiovascular system.
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PMID:[Disorders of myocardial metabolism in sudden coronary death in the presence of coronary atherosclerosis: findings of quantitative histoenzymologic studies]. 221 37

Glucose-6-phosphate dehydrogenase (EC 1.1.1.49) has been purified from methanol grown Pseudomonas W6 by a simple procedure involving dye-ligand affinity chromatography on Cibacronblue F3G-A-Sephadex and Procion Red HE-3B-Sepharose. The purification procedure yielded a homogeneous enzyme with (1) high specific activity of 390 and 500 units/mg with NADP and NAD, respectively, and (2) low concentrations of contaminating activities. The molecular mass of the native enzyme was estimated to be 123 +/- 5 kDa. For the polypeptide chain after SDS denaturation a molecular mass of about 61 kDa was calculated. The kinetic behaviour of glucose-6-phosphate dehydrogenase exhibiting activity with either NADP or NAD was studied with respect to the substrate and coenzyme affinities and to ATP inhibition of enzyme activity. The applicability of prepared glucose-6-phosphate dehydrogenase as an auxiliary enzyme in clinical tests is discussed.
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PMID:Purification and characterization of glucose-6-phosphate dehydrogenase from Pseudomonas W6. 228 62

Stereospecificities are reported for seven dehydrogenases from Acholeplasma laidlawii, an organism from an evolutionarily distinct branch of life which has not previously been studied from a stereochemical point of view. Three of the activities examined (alcohol dehydrogenase, lactate dehydrogenase, and alanine dehydrogenase) catalyze the transfer of the pro-R (A) hydrogen from NADH. Four other activities (3-hydroxy-3-methylglutaryl-CoA reductase, glyceraldehyde-3-phosphate dehydrogenase, glucose-6-phosphate dehydrogenase, and NADH oxidase) catalyze the transfer of the pro-S (B) hydrogen from NAD(P)H. The stereospecificity of hydroxymethylglutaryl-CoA reductase is notable because it is the opposite of that of hydroxymethylglutaryl-CoA reductases from yeast and rat. These data are used to derive the simplest historical model capable of explaining available experimental facts.
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PMID:The stereospecificities of seven dehydrogenases from Acholeplasma laidlawii. The simplest historical model that explains dehydrogenase stereospecificity. 236 93

Vanadate dimer and tetramer inhibit glucose-6-phosphate dehydrogenase from Leuconostoc mesenteroides. The inhibition by a vanadate mixture containing vanadate monomer, dimer, tetramer, and pentamer was determined by measuring the rates of glucose 6-phosphate oxidation and reduction of NAD (or NADP) catalyzed by glucose-6-phosphate dehydrogenase. The inhibition by vanadate is competitive with respect to NAD or NADP and noncompetitive (a mixed type) with respect to glucose 6-phosphate (G6P) when NAD or NADP are cofactors. This inhibition pattern varies from that observed with phosphate and thus suggests vanadate interacts differently than a phosphate analogue with the enzyme. 51V NMR spectroscopy was used to directly correlate the inhibition of vanadate solutions to the vanadate dimer and/or tetramer, respectively. The activity of the vanadate oligomer varied depending on the cofactor and which substrate was being varied. The vanadate dimer was the major inhibiting species with respect to NADP. This is in contrast to the vanadate tetramer, which was the major inhibiting species with respect to G6P and with respect to NAD. The inhibition by vanadate when G6P was varied was weak. The competitive inhibition pattern with respect to NAD and NADP suggests the possibility that vanadate oligomers may also inhibit catalysis of other NAD- or NADP-requiring dehydrogenases. Significant concentrations of vanadate dimer and tetramer are only found at fairly high vanadate concentrations, so these species are not likely to represent vanadium species present under normal physiological conditions. It is however possible the vanadate dimer and/or tetramer represent toxic vanadate species.
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PMID:Vanadate dimer and tetramer both inhibit glucose-6-phosphate dehydrogenase from Leuconostoc mesenteroides. 239 7

Estrogens and LH are necessary among other assays for ovulation diagnostic and ovarian monitoring during stimulations. They can be both measured with a method based on a bioluminescent reaction. This method measures, with a standard luminometer, the reduced NAD produced and accumulated by the reaction of two dehydrogenase enzymes: the estradiol dehydrogenase for direct assay of estrogens (estrone + estradiol), the glucose-6-phosphate dehydrogenase for gonadotrophin determination. These techniques can be applied to all biological fluids. They are simple and straightforward, do not need extraction and can be automated. Urinary assays are very useful in clinical practice to appreciate ovarian function, either during a spontaneous cycle or under stimulation, and are mandatory to decide the timing of hCG injection. The reported studies can be listed as follows: determination of preovulatory LH rise (LH greater than 10 Ul/g of creatinine) prior to embryo transfer after cryopreservation and thawing, detection of LH surges during ovarian stimulation, either premature surges causing premature luteinization, either normal surges when follicular maturation is adequate (296 cycles), confirmation of pituitary desensitization when using GnRH agonists (43 cycles), study of the initial stimulatory effect of GnRH agonists (13 patients). This effect can be responsible for the inadequate results obtained with the so-called "short protocol" in this experience when compared with the "long protocol" in the author's experience with compared with the "long protocol" (8 p. cent pregnancy rate per stimulation cycle versus 20 p. cent respectively, intrafollicular LH in 129 follicular fluids (86 with GnRH agonists and 43 without) has no correlation with the fecundability of the ovum. These results lead to extend bioluminescent techniques to the study of other parameters, and in particular FSH.
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PMID:[Use of a technic of bioluminescence for determining estrogens and LH during static and dynamic study of the ovary]. 250 49

A highly sensitive chemiluminescent assay for NAD(P)H have been developed. The principle of the method is as follows; NAD(P)H reduces molecular oxygen to superoxide anion (O2-) and hydrogen peroxide (H2O2) in the presence of 1-methoxy-5-methylphenazinium methyl sulphate (1-MPMS) as electron mediator. The produced O2- and H2O2 can be measured by chemiluminescent reaction using isoluminol (IL) and microperoxidase (m-POD). A linear relationship between chemiluminescence intensity and NAD(P)H concentration (log/log) was obtained ranged from 10(-9) mol/l to 10(-5) mol/l. This chemiluminescent reaction has been coupled to the assay of glucose-6-phosphate dehydrogenase (G6PDH), beta-D-galactosidase (beta-Gal) and alkaline phosphatase (ALP). The detection limits of G6PDH, beta-Gal and ALP were 10(-18) mol, 10(-20) mol and 10(-18) mol per assay, respectively. The chemiluminescent assay of these enzymes applied to chemiluminescent enzyme immunoassay for 17 alpha-hydroxy-progesterone and DNA hybridization assay using these enzymes as label.
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PMID:Chemiluminescent assay of various enzyme activities and its application to enzyme immunoassays. 250 34

Alcohol dehydrogenase (Adh) (alcohol:NAD+ oxidoreductase, EC 1.1.1.1) gene frequencies and ethanol tolerance in Drosophila melanogaster are known to exhibit long-range latitudinal variations on different continents; this has led to the argument that the clines are adaptive. Accordingly, tropical populations are characterized both by a low frequency of Adh-F and by a low ethanol tolerance. In the urban area of Brazzaville (Congo) under an equatorial African climate, an original genetic structure of local populations has been found: Adh-F frequency varies from 3% to 90% when countryside and brewery populations are compared. This variation is accompanied by an increase of ethanol tolerance (from 6% to 13% alcohol). Such differences, which have remained stable for the past 3 years, were observed between collection sites less than 1 km apart. Two other enzyme loci exhibited a correlated variation with Adh-F--i.e., an increase of the S allele of glycerol-3-phosphate dehydrogenase (NAD+) (sn-glycerol-3-phosphate:NAD+ 2-oxidoreductase, EC 1.1.1.8) and of the F allele of glucose-6-phosphate dehydrogenase (D-glucose-6-phosphate:NADP+ 1-oxidoreductase, EC 1.1.1.49). Such observations suggest very strong selective pressures exerted by environmental ethanol that oppose the gene flow due to adult dispersal between contiguous habitats. A functional relationship between the polymorphisms of the three enzyme loci seems likely, and a metabolic interaction involving NAD and NADP cofactors is proposed.
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PMID:Short-range genetic structure of Drosophila melanogaster populations in an Afrotropical urban area and its significance. 251 Jan 64

An assay system for creatine kinase using microtiter plates and a plate reader that records absorbancies at 405 nM has been devised. The system is an adaptation of well-established assays that couple creatine kinase with the reactions catalyzed by hexokinase and glucose-6-phosphate dehydrogenase (G6PDH), to give a measurable increase in reduced pyridine nucleotide quantitated by absorbance at 340 nM. Two features of this system are modified for reading at 405 nM: (i) The thioamido derivative of NAD is used because its reduced form exhibits a substantial increase in absorbance at 405 nM, the most commonly available wavelength on microplate readers; and (ii) glucose-6-phosphate dehydrogenase from Leuconostoc mesenteroides is used because it can reduce either NAD or NADP (unlike most other G6PDH enzymes, which require NADP), thus making it unnecessary to use the more expensive thio-NADP. The rate of thio-NAD reduction is linear with enzyme concentration and time over a 20-fold range of concentrations of purified creatine kinase, and the assay also works well with myogenic cells allowed to grow and differentiate in the 96-well plate in which the assay is performed. This system offers considerable savings in cells, time, and material in studies of muscle cell differentiation, for which creatine kinase levels are frequently measured. It also provides a potential method for the convenient and economical measurement of activities of many other enzymes that can be coupled to reduction of thio-NAD.
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PMID:Assay of creatine kinase in microtiter plates using thio-NAD to allow monitoring at 405 nM. 261 Mar 56


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