Gene/Protein Disease Symptom Drug Enzyme Compound
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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)

Human glucose 6-phosphate dehydrogenase associated with NADPH was efficiently bound with agarose-bound NADP, whereas the enzyme associated with NADP was poorly bound with agarose-bound NADP. After the elimination of haemoglobin from haemolyzate by treatment with DEAE-cellulose, the enzyme was converted into the NADPH-bound form and was applied on an affinity column. The enzyme was specifically eluted from the column by NADP in the elution buffer. A homogeneous enzyme preparation was obtained in high yield.
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PMID:Purification of human red cell glucose 6-phosphate dehydrogenase by affinity chromatography. 0 Apr 16

Glucose-6-phosphate dehydrogenase from intact pea chloroplasts is partially membrane bound and inactivated upon illumination. The inhibitory effect of light can be abolished by addition of methylviologen. Kinetic experiments with glucose-6-phosphate dehydrogenase reveal that, in the dark, the enzyme activity is strongly inhibited by the accumulation of NADPH. The inhibition of NADPH can be reversed by the addition of excess NADP+. The non-Michaelis-Menten-type kinetics suggest that the enzyme is stringently regulated by the ratio of NADPH to NADP+ plus NADPH, i.e., the "reduction charge". These observations seem to indicate that in the light the inhibition of glucose-6-phosphate dehydrogenase is due to a high reduction charge, whereas in the dark the enzyme is controlled by the metabolic demand for reducing equivalents.
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PMID:The regulation of glucose-6-phosphate dehydrogenase in chloroplasts. 0 47

The steady state kinetics of pig liver glucose-6-phosphate dehydrogenase is consistent with an ordered, sequential mechanism in which NADP is bound first and NADPH released last. Kia is 9.0 muM, Ka is 4.8 muM, and Kb is 36 muM. Glucosamine 6-phosphate, a substrate analogue and competitive inhibitor, is used to help rule out a possible random mechanism. ADP is seen to form a complex with the free form of the enzyme whereas ATP forms a complex with both the free and E-NADP forms of the enzyme. The KI for the E-ADP complex is 1.9 mM, while the Ki values for the E-ATP and E-NADP-ATP complexes are 7.2 and 4.5 mM, respectively.
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PMID:A kinetic study of glucose-6-phosphate dehydrogenase. 0 40

1. Chlorophyll (ide) formation from protochlorophyll (ide) that is normally inactive was demonstrated in etioplast membranes isolated from maize and barlley plants, the process being dependent on intermittent illumination and the addition of NADPH. 2. The addition of NADPH to the membranes was shown to result in the conversion of inactive protochlorophyll (ide) absorbing at about 630 nm into a form(s) with light-absorption maxima at about 640 and 652 nm, both of which disappear when chlorophyll (ide) is formed on illumination. 3. The temperature-dependence of the activation process and its response to a variety of reagents were examined. From these, the conclusion is drawn that -SH groups are involved in the activation but in the active complex these are unavailable for reaction with -SH reagents. 4. Evidence is presented for the occurrence of glucose 6-phosphate dehydrogenase activity within etioplasts and the suggestion is made that the oxidative pentose phosphate pathway can provide the NADPH required for chlorophyll biosynthesis during the early stages of greening.
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PMID:Characterization of the terminal stages of chlorophyll (ide) synthesis in etioplast membrane preparations. 0 98

A mild oxidative stimulation of the hexose monophosphate pathway of human glucose-6-phosphate dehydrogenase (EC 1.1.1.49)-deficient erythrocytes (Mediterranean variant) causes a significant drop in NADPH. These results, other than to confirm that glucose-6-phosphate dehydrogenase deficiency is a product deficiency disorder, demonstrate that under oxidative stimulation glutathione reductase may become functionally impaired and GSSG cannot be reduced at a sufficient rate.
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PMID:NADP+ and NADPH in glucose-6-phosphate dehydrogenase-deficient erythrocytes under oxidative stimulation. 0 94

1. The reaction catalysed by glucose 6-phosphate dehydrogenase (D-glucose 6-phosphate-NADP+ oxidoreductase, EC 1.1.1.49) from baker's yeast was studied in 42mM-glycylglycine buffer, pH7.4 at 25 degrees C, by initial-velocity studies and by the use of NADPH as a product inhibitor. 2. The reactions catalysed by both the soluble enzyme and a stable enzyme covalently attached to CNBr-activated Sepharose 4B probably follow an ordered reaction mechanism with NADP+ and NADPH as the leading reactants. 3. The kinetic constants obtained for the soluble enzyme lere: KNADP+m, 19 muM; KNADP+s, 23 muM; KNADPHs, 15 muM. Similar values were obtained for the immobilized enzyme. 4. The assay of the immobilized enzyme was done by using a micro packed-bed recirculation reactor, and the advantages of this technique are discussed.
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PMID:Kinetic mechanism from steady-state kinetics of the reaction catalysed by baker's-yeast glucose 6-phosphate dehydrogenase in solution and covalently attached to sepharose. 0 71

Michaelis-Menten kinetics are observed in studies of highly purified bovine adrenal glucose-6-phosphate dehydrogenase at pH8.0 in 0.1 M bicine. The Km for NADP+ is 3.8 muM and for glucose-6-phosphate, 61 muM. At pH 6.9 Km for NADP+ increases to 6.5 muM. The enzyme is inhibited by NADPH both at pH 6.8 and at 8.0 with a Kip of 2.36 muM at pH 8.0. Inhibition is competitive with respect to both substrates implying that addition of substrates is random ordered. The data are also interpreted in terms of "reducing charge", the mole fraction of coenzyme in the reduced form. This appears to be the major mechanism for regulation of the pentose shunt. D-glucose, oxidized by the enzyme at a very slow rate, is also a competitive inhibitor for the natural substrate with a Ki of 0.29 M. Phosphate is a competitive inhibitor for glucose-6-phosphate oxidation but both phosphate and sulfate accelerate glucose oxidation suggesting a common binding site for the two anions and the phosphate of the natural substrate. While binding of ACTH to our enzyme preparations has been observed, we have not been able, in spite of repeated attempts, to demonstrate augmentation of the activity of the enzyme by the addition of ACTH.
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PMID:Kinetics and control of bovine adrenal glucose-6-phosphate dehydrogenase. 0 67

Placental aldose reductase (EC 1.1.1.21) was incubated with glucose in the presence of [4A-2H] NADPH prepared in the oxidation of [2-2H] isocitrate by isocitrate dehydrogenase (EC 1.1.1.42) or [4B-2H] NADPH prepared in the oxidation of [1-2H] glucose-6-phosphate dehydrogenase (EC 1.1.1.49). The sorbitol formed from [4A-2H] NADPH contained deuterium and from [4B-2H] NADPH it did not. Therefore, aldose reductase in an A-type enzyme.
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PMID:Stereospecificity of the hydrogen transfer catalyzed by human placental aldose reductase. 1 22

The enzymatic properties of a new glucose-6-phosphate dehydrogenase (G-6-PD) variant (G-6-PD Long Prairie) were studied in a white patient with chronic nonspherocytic hemolysis. The red cells were found to have 2.3%-7.7% normal enzymatic activity. The mutant enzyme exhibited marked heat instability, an increased pH optimum, a moderately decreased Km for G-6-P, and increased utilization of 2-deoxyglucose-6-phosphate and deamino NADP. The Km for NADP and Ki for NADPH were both normal. G-6-PD Long Prairie is an interesting new G-6-PD variant that demonstrates that chronic hemolysis can be associated with modestly decreased G-6-PD activity despite normal sensitivity to inhibition by NADPH. Although increased sensitivity to inhibition by NADPH has been postulated to decrease intracellular enzyme activity, resulting in enhanced susceptibility to hemolysis in certain G-6-PD variants with only moderately decreased enzymatic activity, an alternative mechanism of hemolysis, possibly enzyme thermolability, exists in G-6-PD Long Prairie.
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PMID:G-6-PD Long Prairie: a new glucose-6-phosphate dehydrogenase mutant exhibiting normal sensitivity to inhibition by NADPH and accompanied by nonspherocytic hemolytic anemia. 1 46

A new variant of red cell glucose-6-phosphate dehydrogenase (G6PD) has been found in a Caucasian man with congenital non-spherocytic haemolytic anaemia. This variant has reduced activity, increased thermolability, increased Michaelis constants for glucose-6-phosphate and NADP, slightly increased electrophoretic mobility, and a biphasic pH-activity profile. The red cell adenine compounds and ATP, are in normal limits. The increased activity of red cell NADP-glutathione reductase is probably the expression of a mechanism of compensation for the decrease of G6PD and a consequence of the decrease of NADPH.
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PMID:Glucose-6-phosphate dehydrogenase Velletri. 1 70


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