Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:1.4.1.2 (glutamate dehydrogenase)
4,380 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Yeast cells growing on mineral medium plus ammonia and glucose contained high levels of nicotinamide adenine dinucleotide phosphate-dependent glutamate dehydrogenase activity, as measured in crude extracts. After suspension of cells in fresh medium lacking glucose, there was a loss of the glutamate dehydrogenase activity. Loss of activity was inhibited by 2,4-dinitrophenol, sodium azide, iodoacetic acid, and cycloheximide. The enzyme activity was restored when glucose was added back to the medium, and this recovery was fully prevented in the presence of cycloheximide.
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PMID:Effect of glucose starvation on the nicotinamide adenine dinucleotide phosphate-dependent glutamate dehydrogenase of yeast. 2 40

The nicotinamide adenine dinucleotide phosphate-dependent glutamate dehydrogenase (NADP-GDH) from the food yeast Candida utilis was found to be rapidly inactivated when cultures were starved of a carbon source. The addition of glutamate or alanine to the starvation medium stimulated the rate of inactivation. Loss of enzyme activity was irreversible since the reappearance of enzyme activity, following the addition of glucose to carbon-starved cultures, was blocked by cycloheximide. A specific rabbit antibody was prepared against the NADP-GDH from C. utilis and used to quantitate the enzyme during inactivation promoted by carbon starvation. The amount of precipitable antigenic material paralleled the rapid decrease of enzyme activity observed after transition of cells from NH(4) (+)-glucose to glutamate medium. No additional small-molecular-weight protein was precipitated by the antibody as a result of the inactivation, suggesting that the enzyme is considerably altered during the primary steps of the inactivation process. Analysis by immunoprecipitation of the reappearance of enzyme activity after enzyme inactivation showed that increase of NADP-GDH activity was almost totally due to de novo synthesis, ruling out the possibility that enzyme activity modulation is achieved by reversible covalent modification. Enzyme degradation was also measured during steady-state growth and other changes in nitrogen and carbon status of the culture media. In all instances so far estimated, the enzyme was found to be very stable and not normally subject to high rates of degradation. Therefore, the possibility that inactivation was caused by a change in the ratio of synthesis to degradation can be excluded.
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PMID:Evidence for the degradation of nicotinamide adenine dinucleotide phosphate-dependent glutamate dehydrogenase of Candida utilis during rapid enzyme inactivation. 2 41

The reaction of glutamate dehydrogenase with two different stable nitroxides (spin labels) is reported. The two compounds contain a carbonyl and an iodoacetamide group as their reactive parts. The carbonyl compound inactivates the enzyme by the formation of a 1:1 covalent complex after NaBH4 reduction of an intermediate Schiff's base. Evidence indicates that the enzyme is modified at lysine-126 in the active site. The electron spin resonance (ESR) spectrum of spin-labeled enzyme indicates a high degree of immobilization of the nitroxide. The binding of reduced coenzyme NADPH is reflected by a change (immobilization) of the ESR spectrum. Nuclear relaxation of bound substrate, oxidized coenzyme, and inhibitor by the paramagnetic group is observed. This shows the existence of a binding site for these compounds close to the active site. The distances of selected protons of the binding ligands to the nitroxide are calculated. The iodoacetamide spin label reacts with several groups, one of which is not a sulfhydryl. The reaction of this particular group causes inactivation of the enzyme. Protection against this inactivation could be achieved with certain ligands. Only enzyme that was spin labeled without such protection caused paramagnetic relaxation of bound substrate and coenzyme.
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PMID:Electron spin resonance and nuclear relaxation studies on spin-labeled glutamate dehydrogenase. 2 62

From the cell-free extract of fodder yeast Candida tropicalis NADP-specific glutamate dehydrogenase was isolated and partially purified (75-fold) by means of fractional precipitation by ammonium sulphate and ion-exchange chromatography on DEAE-cellulose. The preparation was investigated with the aid of polyacrylamide gel electrophoresis. Kinetic characteristics of the enzyme in the cell-free extract and partially purified preparation were derived.
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PMID:[Purification and properties of the NADP-specific glutamate dehydrogenase of Candida tropicalis feed yeasts]. 2 41

The constitution and control by the inorganic nitrogen source of glutamate dehydrogenases of some unicellular green algae have been studied. The Ankistrodesmus braunii and Scenedesmus obliquus cells contain two different glutamate dehydrogenases, one of which is NADP-specific, the other is active with both NAD and NADP. Their synthesis does not depend on the nitrogen source. The activity of NADP-specific glutamate dehydrogenase increases sharply during nitrogen starvation. In Chlorella pyrenoidosa 82 and Ch. ellipsoidea only one constitutive double specific glutamate dehydrogenase is observed. Its activity does not change depending on the nitrogen nutrition conditions. In the cells of the thermophylic Chlorella strain Chlorella sp. K. ammomium induces a de novo synthesis of NADP-specific glutamate dehydrogenase in addition to the constitutive double specific glutamate dehydrogenase. Thus, the algae tested contain constitutive double specific glutamate dehydrogenase. The NADP-specific enzyme is absent in two Chlorella strains, is constitutive in A. braunii and S. obliquus, and is ammonium-inducible in three thermophylic Chlorella strains.
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PMID:[Glutamate dehydrogenases of unicellular green algae: effects of nitrate and ammonium in vivo]. 2 79

An improved synthesis of the 8-(6-aminohexyl)amino derivative of NADP+ is described for use in affinity chromatography. The binding of glutamate dehydrogenase isolated from halobacterium of the Dead Sea on a column of Sepharose linked to this NADP+ derivative could be drastically enhanced by addition of sulfate (1M) and provided a tool for partially purifying the enzyme from a crude extract. A similar finding is reported for glucose-6-phosphate dehydrogenase in crude extracts of Escherichia coli. The effects are shown to be biospecific, suggesting that the strength of the interaction between protein and immobilized coenzymes is a function of the sulfate concentration.
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PMID:Sulfate-mediated affinity chromatography on NADP+-Sepharose of glutamate dehydrogenase from halophilic bacteria and of glucose-6-phosphate dehydrogenase from Escherichia coli. 2 66

Iodoacetyldiethylstilbestrol was used as an affinity label to alkylate the estrogen binding site of bovine liver glutamate dehydrogenase. This reagent induced inactivation and alkylation of the enzyme. The non-alkylating analogues diethylstilbestrol and estradiol protected the enzyme towards alkylation. The apparent constant of alkylation was of the order of magnitude of I50 for the allosteric inhibition by diethylstilbestrol. These two results suggest that alkylation occurred at the estrogen binding site. The stoichiometry of alkylation was between one and two, depending on the experimental conditions. When the stoichiometry was found to be less than or equal to 1, 90% of the label was bound on cystein residues, 70% of which was carried by cysteine-89, a cysteine residue which is known to be inacessible to iodoacetamide in phosphate buffer in the same conditions of temperature and pH.
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PMID:Affinity labelling of the estrogen binding site of glutamate dehydrogenase with iodoacetyldiethylstilbestrol. Selective alkylation of cysteine-89. 2 68

The nicotinamide adenine dinucleotide phosphate-specific glutamate dehydrogenase (NADP-GDH) of Chlorella sorokiniana was purified 260-fold to electrophoretic homogeneity in six steps. Depending on the techniques used, the native enzyme appeared to have a molecular weight of 290,000 or 410,000 and to be composed of five to seven identical subunits with a molecular weight of 58,000. The amino acid composition of this enzyme was shown to differ considerably from that of the NAD-GDH in this organism. The NH2-terminal amino acid was unavailable to dansylation. All six cysteines in the native enzyme were in the free sulfhydryl form. The pH optima for the aminating and deaminating reactions were 7.2 and 9.2, respectively. The Km values for NH4+, alpha-ketoglutarate, NADPH, L-glutamate, and NADP+ were 68, 12, 0.13, and 0.038 mM, respectively. At low substrate concentrations, no cooperativity was seen; however, severe inhibition of enzyme activity was observed at high alpha-ketoglutarate concentrations. Nucleotides did not affect enzyme activity. Antiserum produced in rabbits to the subunits of the enzyme yielded a single precipitin band with the purified enzyme in Ouchterlony double-diffusion analysis. Immunoelectrophoresis was used to confirm the purity of the enzyme and also to quantify the amount of enzyme antigen. These studies indicate that the NADPH-GDH and NAD-GDH isozymes are distinct molecular species in this organism.
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PMID:Purification and properties of the inducible nicotinamide adenine dinucleotide phosphate-specific glutamate dehydrogenase from Chlorella sorokiniana. 2 61

When synchronous cells of the eucaryotic microorganism Chlorella sorokiniana growing in nitrate medium were challenged to synthesize an ammonium-inducible nicotinamide adenine dinucleotide phosphate-specific glutamate dehydrogenase (NADP-GDH) at frequent intervals during the cell cycle the initial rate of induction (i.e., enzyme potential) of this enzyme increased in an approximately linear manner until the period of DNA replication (i.e., S phase). During the S phase, NADP-GDH potential exhibited a positive rate change proportional to the step increase in DNA level. The timing of this rate change was insensitive to large changes in cellular growth rate. This rate change could be blocked within the first cell cycle by specific inhibition of DNA replication with 2'-deoxyadenosine. The approximately linear increase in NADP-GDH potential and also of total cellular protein observed before and after the S phase is proposed to be a result of the increasing photosynthetic capacity of the cell during the cell cycle.
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PMID:Regulation of initial rate of induction of nicotinamide adenine dinucleotide phosphate-specific glutamate dehydrogenase during the cell cycle of synchronous Chlorella. 2 62

The symbiotic, nitrogen-fixing bacterium Rhizobium sp. 32H1 is a specialized ammonium producer during symbiosis. However, during free-living growth, Rhizobium 32H1 assimilates ammonium very poorly. Two pathways of ammonium assimilation exist in enteric bacteria. One is mediated by glutamate dehydrogenase, and the other is mediated by glutamine synthetase-glutamate synthase. The former pathway is altogether inoperative in Rhizobium 32H1; the latter pathway operates at a slow rate and is under strict negative control by ammonium itself. Rhizobium 32H1 glutamine synthetase activity is modulated by both repression-derepression and reversible adenylylation. For a biochemical process lacking an alternative pathway, such a regulatory pattern exacerbates the very process. This suggests that Rhizobium 32H1 restricts its own ammonium assimilation to maximize the contribution of fixed nitrogen to the host plant during symbiosis.
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PMID:Control of ammonium assimilation in Rhizobium 32H1. 2 98


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