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)

Neurospora crassa wild-type is almost unable to grow on glutamine as sole nitrogen and carbon source but a GDH-; GS +/- double mutant strain, lacking NADP-dependent glutamate dehydrogenase and partially lacking glutamine synthetase did grow. Under these conditions, the double mutant had a higher chemical energy content than the wild-type. Enzyme assays and labelling experiments with glutamine indicated that in the double mutant glutamine was degraded to ammonium and to carbon skeletons by glutamate synthase, the catabolic (NADH-dependent) glutamate dehydrogenase and the glutamine transaminase-omega-amidase pathway.
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PMID:Glutamine assimilation pathways in Neurospora crassa growing on glutamine as sole nitrogen and carbon source. 257 59

Both glutamate synthase (GOGAT) and glutamate dehydrogenase (GDH) are involved in glutamate synthesis in Streptomyces coelicolor. The highest levels of GDH were seen in extracts of cells grown with high levels of ammonium as the nitrogen source. GOGAT activity was reduced two- to threefold in extracts of cells grown with good sources of glutamate. S. coelicolor mutants deficient in GOGAT (Glt-) required glutamate for growth with L-alanine, asparagine, arginine, or histidine as the nitrogen source but grew like wild-type cells when ammonium, glutamine, or aspartate was the nitrogen source. The glt mutations were tightly linked to hisA1. Mutants deficient in both GOGAT and GDH (Gdh-) required glutamate for growth in all media. The gdh-5 mutation was mapped to the left region of the S. coelicolor chromosomal map, between proA1 and uraA1.
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PMID:Glutamate synthesis in Streptomyces coelicolor. 270 9

Rats were fed a standard diet or the standard diet supplemented with ammonium acetate (20% w/w) for up to 100 days. The effect of the ingestion of the high-ammonium diet on some aspects of nitrogen metabolism in rats was studied. Ammonia levels in blood increased approximately 3-fold; in brain, liver and muscle the increases were 36, 34 and 50%, respectively. Urea levels in blood and urea excretion increased approximately 2-fold. There was no increase of carbamyl phosphate synthase. Liver glutamine synthase activity increased by 58% and glutamate dehydrogenase by 40%, whereas glutaminase was not affected. Glutamine content in brain was twice that of controls. This new animal model to study hyperammonemia offers several advantages over others: it is simpler, is bloodless, requires no animal manipulation and permits long-term studies.
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PMID:A simple animal model of hyperammonemia. 275 49

Sixteen independent Azorhizobium sesbaniae ORS571 vector insertion (Vi) mutants defective in ammonium assimilation (Asm-) were selected; genomic DNA sequences flanking the insertion endpoints were cloned directly. Resulting recombinant plasmids were used to identify, by hybridization, corresponding wild-type DNA sequences from an A. sesbaniae lambda EMBL3 genomic library (lambda Asm phages). All 16 Asm- Vi mutants physically mapped to a single genomic locus. Plasmid subclones of recombinant phage lambda Asm152 were able to complement both Escherichia coli gltB and A. sesbaniae Asm- Vi mutants; NADPH-glutamate synthase activity was detected in all such strains complemented to Asm+. Heterologous and homologous complementations required both A. sesbaniae gltA+ and (inferred) gltB+ genes. Eleven A. sesbaniae Asm- Vi mutants mapped to a 4-kilobase-pair (kbp) DNA region that exhibited homology with Bacillus subtilis gltA+. In E. coli maxicell labeling experiments, this 4-kbp DNA region encoded a 165-kilodalton polypeptide that was inferred to be the product of the A. sesbaniae gltA+ gene (glutaminase NADPH-dependent L-glutamate synthase subunit). Site-directed Tn5-lacZ mutagenesis of a glt plasmid subclone identified a region that bisected this locus into (at least) two cistrons. Because the remaining five A. sesbaniae Asm- mutants mapped to a 1.5-kbp region adjacent to gltA+, these mutants probably define a single gltB+ gene (glutamate dehydrogenase NADPH-dependent L-glutamate synthase subunit); this region did not exhibit homology with the B. subtilis gltB+ gene.
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PMID:Characterization of the Azorhizobium sesbaniae ORS571 genomic locus encoding NADPH-glutamate synthase. 283 Feb 30

Evidence for the participation of the glutamine transaminase-omega-amidase pathway in the utilization of glutamine in Neurospora crassa was obtained. Its participation is indicated by the in vitro activities of glutamine transaminase and omega-amidase, the in vivo accumulation of alpha-ketoglutaramate when an inhibitor of transamidases is present, and the inhibition by aminooxyacetic acid and 6-diazo-5-oxo-L-norleucine of the ammonium excreted in the presence of glutamine by a mutant strain that lacks glutamate dehydrogenase and glutamate synthase.
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PMID:Omega-amidase pathway in the degradation of glutamine in Neurospora crassa. 285 67

To obtain information on the route(s) of ammonium assimilation in Streptomyces venezuelae, cell suspensions transferred to fresh medium lacking nitrogen were pulsed with [15N2]ammonium sulphate. Cells and extracellular fluids were examined by nuclear magnetic resonance and amino acid analysis to assess changes in amino acid pools and the disposition of [15N]ammonium. Following addition of [15N]ammonium, glutamate--glutamine pools of low cell density replacement cultures expanded rapidly and became progressively labelled with 15N, whereas the alanine pool size increased much more slowly and became labelled with 15N to a much lesser extent. These results are consistent with the assimilation of ammonium via glutamate dehydrogenase or glutamine synthetase--glutamate synthase rather than alanine dehydrogenase. Under anaerobic conditions, S. venezuelae assimilates ammonium into alanine rather than glutamate--glutamine. Alanine dehydrogenase may thus function as a vehicle to regenerate NAD+ to maintain substrate-level phosphorylation during periods of anaerobiosis.
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PMID:Pathway of ammonium assimilation in Streptomyces venezuelae examined by amino acid analyses and 15N nuclear magnetic resonance spectroscopy. 286 83

Cells of Euglena gracilis Klebs strain z Pringsheim had high NADP-dependent glutamate dehydrogenase activity when grown on glutamate as nitrogen source but activity was completely repressed in cells grown on ammonium (NH4+). A 120-fold purification of NADPH-glutamate dehydrogenase (subunit Mr = 45 000) was achieved from glutamate-grown cells by affinity chromatography on blue Sepharose CL-6B. Antisera raised against the homogeneously pure protein were used to demonstrate that increase in NADPH-glutamate dehydrogenase activity on transfer from NH4+ to glutamate medium resulted from an increase in the amount of protein. Glutamate NH4+-grown cells were labelled with L-[35S]methionine and anti-(NADPH-glutamate dehydrogenase) used to immunoprecipitate the dehydrogenase from cell extracts. NADPH-glutamate dehydrogenase protein was detected in glutamate-grown but not NH4+-grown cells. Anti-(NADPH-glutamate dehydrogenase) was used to detect NADPH-glutamate dehydrogenase resulting from the translation of total polyadenylated RNA from Euglena in a cell-free rabbit reticulocyte lysate system. NADPH-glutamate dehydrogenase mRNA was present in glutamate NH4+-grown cells, there being no apparent difference in mRNA abundance between cells showing a tenfold difference in NADPH-glutamate dehydrogenase specific activity. These results indicate that the synthesis of this dehydrogenase is regulated primarily at the post-transcriptional level.
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PMID:Glutamate dehydrogenase (NADP-dependent) mRNA in relation to enzyme synthesis in Euglena gracilis. Evidence for post-transcriptional control. 286 58

Succinivibrio dextrinosolvens C18 was found to possess glutamine synthetase (GS), urease, glutamate dehydrogenase, and several other nitrogen assimilation enzymes. When grown in continuous culture under ammonia limitation, both GS and urease activities were high and glutamate dehydrogenase activity was low, but the opposite activity pattern was observed for growth in the presence of ample ammonia. The addition of high-level (15 mM) ammonium chloride to ammonia-limited cultures resulted in a rapid loss of GS activity as measured by either the gamma-glutamyl transferase or forward assay method with cells or extracts. No similar activity losses occurred for urease, glutamate dehydrogenase, or pyruvate kinase. The GS activity loss was not prevented by the addition of chloramphenicol and rifampin. The GS activity could be recovered by washing or incubating cells in buffer or by the addition of snake venom phosphodiesterase to cell extracts. Manganese inhibited the GS activity (forward assay) of untreated cells but stimulated the GS activity in ammonia-treated cells. Alanine, glycine, and possibly serine were inhibitory to GS activity. Optimal pH values for GS activity were 7.3 and 7.4 for the forward and gamma-glutamyl transferase assays, respectively. The glutamate dehydrogenase activity was NADPH linked and optimal in the presence of KCl. The data are consistent with an adenylylation-deadenylylation control mechanism for GS activity in S. dextrinosolvens, and the GS pathway is a major route for ammonia assimilation under low environmental ammonia levels. The rapid regulation of the ATP-requiring GS activity may be of ecological importance to this strictly anaerobic ruminal bacterium.
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PMID:Glutamine synthetase activity in the ruminal bacterium Succinivibrio dextrinosolvens. 286 38

Inorganic nitrogen metabolism in the obligate anaerobic thermophiles Chlostridium thermosaccharolyticum and Clostridium thermoautotrophicum differs in several respects. C. thermosaccharolyticum contains a nitrogenase as inferred from NH4+ repressible C2H2 reduction, a glutamine synthetase which is partially repressed by ammonium, very labile glutamate synthase activities with both NADH and NADPH, NADPH-dependent glutamate dehydrogenase, and NH4+-dependent asparagine synthetase. C. thermoautotrophicum contains no nitrogenase, but glutamine synthetase, no glutamate synthase, no glutamate dehydrogenase, but a NADH-dependent alanine dehydrogenase and a NH4+-dependent asparagine synthetase.
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PMID:N2 fixation and NH4+ assimilation in the thermophilic anaerobes Clostridium thermosaccharolyticum and Clostridium thermoautotrophicum. 287 Jun 91

A glutamate auxotroph was obtained in Nostoc muscorum by induced mutagenesis with nitrosoguanidine. The metabolic pathway leading to glutamate synthesis was traced by selecting several enzymes. The strain was found to be lacking glutamate dehydrogenase. Other enzymes, however, were normal in their activity including isocitric dehydrogenase, glutamine synthetase and glutamate synthase. Nitrogen metabolism of the auxotroph and wild type was compared. The strain released exceedingly high amounts of ammonium in the medium.
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PMID:Regulation of glutamate dehydrogenase activity and ammonia production in a nitrogen fixing cyanobacterium. 288 Apr 48


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