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)

The relationship between nitrogen assimilation, metabolism and aflatoxin formation has been investigated in a toxigenic and a non-toxigenic strain of Aspergillus parasiticus. Ammonia from the medium is mainly assimilated via NADP-requiring glutamate dehydrogenase. During growth NAD-requiring glutamate dehydrogenase followed an inverse pattern of activity with respect to NADP glutamate dehydrogenase. Alpha-ketoglutarate, the product of NAD glutamate dehydrogenase, stimulated acetate incorporation into aflatoxins. Glutamine synthetase, ornithine transcarbamylase, both utilizing glutamate as substrate were assayed under different growth conditions. An important regulatory role for glutamine synthetase is suggested. The metabolic route of asparagine utilization was also investigated. Both the known pathways, glutamate oxaloacetate transaminase and glutamate pyruvate transaminase are operative simultaneously.
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PMID:Nitrogen metabolism in Aspergillus parasiticus NRRL 3240 and A. flavus NRRL 3537 in relation to aflatoxin production. 287 96

Glutamate dehydrogenase (aminating) and glutamine synthetase activities were assayed in Mycobacterium smegmatis following growth on various carbon and nitrogen sources. The activities (expressed as nmoles product formed/min/mg crude extract protein) of these two enzymes were higher in crude extracts from glucose-grown cells than in glycerol- or fructose-grown cells. In the presence of succinate, pyruvate, fumarate or acetate in the growth medium, both these enzyme activities were lower than those in citrate-grown cells. The glutamate dehydrogenase (GDH) activity was the same in asparagine and glutamine-grown cells. Ammonium chloride, alanine or glutamic acid, when used as nitrogen source, resulted in low GDH activity as compared to asparagine-grown cells. Glutamine synthetase activity was considerably lower (2-4 fold) when the cells were grown on alanine, glutamine, glutamic acid or ammonium chloride as the nitrogen source than those in asparagine-grown cells. Glutamate and ammonium chloride, when present in the growth medium, repressed both glutamate dehydrogenase and glutamine synthetase, though the degree of repression was small. The results suggest that only a weak transcriptional control operates for these enzyme activities in M. smegmatis.
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PMID:Changes in the enzyme activities involved in nitrogen assimilation in Mycobacterium smegmatis under various growth conditions. 289 60

Anaesthetized rats were given an i.v. overload of 200 mmoles of ammonium acetate. Plasma ammonium levels were not altered for up to 20 minutes after the end of the infusion. The load of ammonium, however, increased the overall non-protein nitrogen content of circulating plasma, as for the increase in urea and amino acids (alanine, phenylalanine, aspartate + asparagine and glutamate + glutamine). The activities of glutamine synthetase was found increased in liver, muscle and kidney; and glutamate dehydrogenase increased in liver and decreased in muscle and kidney. Adenylate deaminase decreased in all the studied tissues. The fast enzyme and plasma metabolite adaptations to ammonium overload were all in the sense of favoring the incorporation of ammonium into amino acids (later into urea) as well as to avoid their deamination, thus effectively removing the excess ammonium from the bloodstream.
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PMID:Rapid detoxification of infused ammonium by the anesthetized rat. 290 36

The metabolism of L-leucine in pancreatic islets is reviewed. Regulatory sites may involve the transport and intracellular distribution of L-leucine, its transamination as modulated by the availability of 2-keto acids, the activity of branched-chain 2 keto acid dehydrogenase and the further catabolism of isovaleryl coenzyme A. Emphasis is also placed on the activation of glutamate dehydrogenase by L-leucine, its interference with the utilization of endogenous nutrients and the reciprocal effects of L-leucine and either L-glutamine or L-asparagine upon their respective metabolism. The relevance of L-leucine metabolism to its insulinotropic action is underlined.
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PMID:Branched-chain amino and keto acid metabolism in pancreatic islets. 354 3

The metabolic effects of beta-(+/-)-2-aminobicyclo-(2.2.1)-heptane-2-carboxylic acid (BCH), a nonmetabolizable analog of leucine and known activator of glutamate dehydrogenase, were studied in hepatocytes isolated from fed and fasted rats. With glutamine as substrate, BCH stimulated in a concentration-dependent manner urea synthesis in both physiological states and glucose formation in hepatocytes from fasted rats. Despite the much higher rates of ureagenesis in the fasted animals, the degree of stimulation by BCH, over 2-fold, was similar. The effect of the drug was specific for glutamine since the rates of urea synthesis from NH4Cl, alanine, and asparagine were essentially unaltered. The stimulation of glutamine catabolism by BCH led to a decrease in the content of intracellular glutamine. The redox states of the mitochondrial and cytosolic nicotinamide adenine dinucleotides remained unaltered. In hepatocytes isolated from fasted rats and incubated with 5 mM glutamine the BCH-induced increases in urea, ammonia, and the amino acids, glutamate, aspartate, and alanine, accounted fully for the 2.4-fold rise in glutamine utilization. The stimulatory effects of BCH and glucagon on the formation of glucose, urea, and 14CO2 from [U-14C]glutamine were additive. Aminooxyacetate, and inhibitor of transaminases, neither blocked glutamine catabolism (as measured by the sum of urea, ammonia, and glutamate) nor prevented its activation by BCH. It is suggested that, in isolated hepatocytes, BCH-induced stimulation of glucose and urea formation from glutamine results from activation of glutaminase by a mechanism which is distinct from that of glucagon.
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PMID:Glutamine metabolism in rat hepatocytes. Stimulation by a nonmetabolizable analog of leucine. 377 24

1. Inhibition of ox liver glutamate dehydrogenase with N-(N'-acetyl-4[(35)S]-sulphamoylphenyl)maleimide (ASPM) is more specific at pH7.3 than at pH6.9. At pH7.3 inhibition accompanies the incorporation at 1 mole of ASPM residues into about 53000g. of protein. 2. Digestion of the modified protein with chymotrypsin and trypsin yields a unique radioactive peptide. 3. Acid hydrolysis of 1 mole of this peptide yields 1 mole of N(in)-succin-2-yl-lysine. The in-amino group of a lysyl residue is thus the site of modification of the protein. 4. The sequence containing the modified lysyl residue is: [Formula: see text] where Asx respresents either aspartic acid or asparagine.
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PMID:A peptide containing a reactive lysyl group from ox liver glutamate dehydrogenase. 578 69

Effects of norepinephrine on gluconeogenesis and ureogenesis from glutamine by hepatocytes from fasted rats were assessed. Comparisons were made to asparagine metabolism and to the effects of NH4Cl and dibutyryl cyclic AMP. With asparagine as substrate, aspartate content was very high but norepinephrine, dibutyryl cyclic AMP, or NH4Cl had little effect on gluconeogenesis or ureogenesis. Metabolism of asparagine could be greatly enhanced by the combination of oleate, ornithine, and NH4Cl. However, even under these conditions, asparatate content remained high, and norepinephrine and dibutyryl cyclic AMP had little influence on glucose or urea synthesis. With glutamine as substrate, aspartate content was much lower, but was greatly elevated by norepinephrine, dibutyryl cyclic AMP, or NH4Cl. Each of these effectors strongly stimulated glucose and urea formation from glutamine. NH4Cl stimulation was accompanied by an increased glutamate and decreased alpha-ketoglutarate content. This suggests the mechanism for NH4Cl stimulation is a near-equilibrium adjustment to ammonia by glutamate dehydrogenase and aspartate aminotransferase rather than a principal involvement of glutaminase. Although both norepinephrine and dibutyryl cyclic AMP lowered alpha-ketoglutarate to the same extent, norepinephrine more rapidly increased aspartate content and led to a smaller accumulation of glutamate than did dibutyryl cyclic AMP. Moreover, only norepinephrine led to a rapid increase in succinyl-CoA concentration. The catecholamine effect could not be explained by specific changes in cytosolic or mitochondrial redox states. The results suggest that alpha-ketoglutarate dehydrogenase is a site of catecholamine action in rat liver. Since purified alpha-ketoglutarate dehydrogenase is known to be Ca2+ stimulated and Ca2+ flux is involved in catecholamine action, these findings also suggest that mitochondrial Ca2+ is elevated by catecholamines.
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PMID:Glutamine metabolism of isolated rat hepatocytes. Evidence for catecholamine activation of alpha-ketoglutarate dehydrogenase. 609 58

The role of blastospores in the protection of Aspergillus parasiticus from high levels of aflatoxins was studied. The strain protects itself from aflatoxicity by forming thick-walled blastospores. The formation of blastospores was not observed under conditions of reduced aflatoxin formation, e.g., under zinc and asparagine deficiencies. The germination of blastospores coincided with an increase in the specific activity of glutamate dehydrogenase (NADP) and a simultaneous decrease in the specific aflatoxin production.
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PMID:Role of blastospores in protecting Aspergillus parasiticus NRRL 3240 from high levels of aflatoxins. 713 1

The initial velocity, pH and temperature optima, and Km values of Schizosaccharomyces pombe NADP-glutamate dehydrogenase (NADP-GDH:EC 1.4.1.4) have been determined. NADP-GDH was found to be specific for the substrates used in the reaction mixtures. NADP-GDH activity showed a sigmoidal response to changes in alpha-ketoglutarate concentrations, following Hill kinetics with a coefficient nH = 2. A two-fold and a three-fold increase in activity was found in extracts of cells grown on a medium containing cytosine or histidine as a sole nitrogen source, respectively, relative to the activity found in cells grown on other sole nitrogen sources including ammonium, adenine, arginine, aspartate, asparagine, glutamate, glutamine, leucine, lysine, proline, uridine and urea. Five NADP-GDH-defective mutants were isolated on the basis of no growth on ammonium plus allantoin as sole nitrogen sources. The mutants also failed to grow on allantoin alone but, in contrast, they were phenotypically indistinguishable from the wild-type growing on solid minimal medium with ammonium. Additionally, the mutants were found to grow as wild-type on minimal medium with alanine, arginine, asparagine, aspartate, glutamate, glutamine, leucine, ornithine and proline in the absence or presence of allantoin. In liquid minimal medium with ammonium as sole nitrogen source they had a slower growth than the wild-type. Normal growth was observed in cells grown on alanine, arginine, asparagine, aspartate, glutamate, glutamine, leucine, ornithine and proline. The mutants had undetectable levels of NADP-GDH activity, but retained wild-type levels of NAD-GDH, glutame synthase (GOGAT) and glutamine synthetase (GS).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Biochemical and genetical studies of NADP-specific glutamate dehydrogenase in the fission yeast Schizosaccharomyces pombe. 788 25

A 28.7-kb DNA region containing the gdhA gene of Aspergillus awamori was cloned from a genomic DNA library. A fragment of 2570 nucleotides was sequenced that contained ORF1, of 1380 bp, encoding a protein of 460 amino acids (Mr 49.4 kDa). The encoded protein showed high similarity to the NADP-dependent glutamate dehydrogenases of different organisms. The cloned gene was functional since it complemented two different Aspergillus nidulans gdhA mutants, restoring high levels of NADP-dependent glutamate dehydrogenase to the transformants. The A. awamori gdhA gene was located by pulsed-field gel electrophoresis in a 5.5-Mb band (corresponding to a doublet of chromosomes II and III), and was transcribed as a monocistronic transcript of 1.7 kb. Transcript levels of the gdhA gene were very high during the rapid growth phase and decreased drastically after 48 h of cultivation. Very high expression levels of the gdhA gene were observed in media with ammonium or asparagine as the nitrogen source, whereas glutamic acid repressed transcription of the gdhA gene. These results indicate that expression of the gdhA gene is subject to a strong nitrogen regulation at the transcriptional level.
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PMID:Characterization and nitrogen-source regulation at the transcriptional level of the gdhA gene of Aspergillus awamori encoding an NADP-dependent glutamate dehydrogenase. 968 75


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