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:1.4.3.11 (glutamate dehydrogenase)
4,437 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Streptococcus bovis JB1 cells energized with glucose transported glutamine at a rate of 7 nmol/mg of protein per min at a pH of 5.0 to 7.5; sodium had little effect on the transport rate. Because valinomycin-treated cells loaded with K and diluted into Na (pH 6.5) to create an artificial delta psi took up little glutamine, it appeared that transport was driven by phosphate-bond energy rather than proton motive force. The kinetics of glutamine transport by glucose-energized cells were biphasic, and it appeared that facilitated diffusion was also involved, particularly at high glutamine concentrations. Glucose-depleted cultures took up glutamine and produced ammonia, but the rate of transport per unit of glutamine (V/S) by nonenergized cells was at least 1,000-fold less than the V/S by glucose-energized cells. Glutamine was converted to pyroglutamate and ammonia by a pathway that did not involve a glutaminase reaction or glutamate production. No ammonia production from pyroglutamate was detected. S. bovis was unable to take up glutamate, but intracellular glutamate concentrations were as high as 7 mM. Glutamate was produced from ammonia via a glutamate dehydrogenase reaction. Cells contained high concentrations of 2-oxoglutarate and NADPH that inhibited glutamate deamination and favored glutamate formation. Since the carbon skeleton of glutamine was lost as pyroglutamate, glutamate formation occurred at the expense of glucose. Arginine deamination is often used as a taxonomic tool in classifying streptococci, and it had generally been assumed that other amino acids could not be fermented. To our knowledge, this is the first report of glutamine conversion to pyroglutamate and ammonia in streptococci.
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PMID:Transport of glutamine by Streptococcus bovis and conversion of glutamine to pyroglutamic acid and ammonia. 272 40

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

We have designed a new kinetic assay for estimating Factor XIII in plasma. Plasma fibrinogen is removed by treatment with bentonite (colloidal aluminum silicate) before measurement. During the lag phase, Factor XIII is transformed by thrombin and Ca2+ into active transglutaminase (EC 2.3.2.13), which attaches the substrate ethylamine to a glutamine residue in acetylated, dephosphorylated beta-casein. During the reaction, ammonia is released, which can be continuously monitored in an NADPH-dependent indicator reaction catalyzed by glutamate dehydrogenase (EC 1.4.1.4). We determined the optimal concentrations of substrate and activator and found that, to eliminate the clottable fibrinogen from the plasma samples, bentonite treatment was more advantageous than the traditional heat treatment. Results by the method correlate well with those by the most widely used amine incorporation and immunoinhibition assays for Factor XIII. We established a reference interval of 12.1-22.7 U/L; at optimal conditions, the variance of the method was less than 3% within this range. The method has several theoretical and practical advantages over traditional determinations of Factor XIII.
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PMID:Kinetic determination of blood coagulation Factor XIII in plasma. 285

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

Activity of enzymes participating in metabolism of glutamate and content of nicotinamide nucleotides was studied in rat liver tissue within 24 hrs after intramuscular administration of alpha-tocopheryl acetate at doses of 30 mg and 300 mg per kg of body mass. Excess of the vitamin was responsible for a decrease in the ratio NAD+/NADH in cytosol, for stimulation of glutamate dehydrogenase reaction, for a decrease of aspartate aminotransferase activity in mitochondria and of alanine aminotransferase activity in cytosol as well as for an increase of NADPH content.
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PMID:[Effect of alpha-tocopherol on glutamic acid metabolism and nicotinamide coenzyme levels in hepatocytes]. 287 84

Pathways of ammonia assimilation into glutamic acid and alanine in Bacillus polymyxa were investigated by 15N NMR spectroscopy in combination with measurements of the specific activities of glutamate dehydrogenase, glutamine synthetase, glutamate synthetase, alanine dehydrogenase, and glutamic-alanine transaminase. Ammonia was found to be assimilated into glutamic acid predominantly by NADPH-dependent glutamate dehydrogenase with a Km of 2.9 mM for NH4+ not only in ammonia-grown cells but also in nitrate-grown and nitrogen-fixing cells in which the intracellular NH4+ concentrations were 11.2, 1.04, and 1.5 mM, respectively. In ammonia-grown cells, the specific activity of alanine dehydrogenase was higher than that of glutamic-alanine transaminase, but the glutamate dehydrogenase/glutamic-alanine transaminase pathway was found to be the major pathway of 15NH4+ assimilation into [15N]alanine. The in vitro specific activities of glutamate dehydrogenase and glutamine synthetase, which represent the rates of synthesis of glutamic acid and glutamine, respectively, in the presence of enzyme-saturating concentrations of substrates and coenzymes are compared with the in vivo rates of biosynthesis of [15N]glutamic acid and [alpha,gamma-15N]glutamine observed by NMR, and implications of the results for factors limiting the rates of their biosynthesis in ammonia- and nitrate-grown cells are discussed.
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PMID:Ammonia assimilation in Bacillus polymyxa. 15N NMR and enzymatic studies. 288 2

2-Keto-3-fluoroglutaric acid prepared by acid hydrolysis of its diethyl ester is stable, as the free acid in aqueous solution at pH 2, and can be stored at -20 degrees C for several years. Both enantiomers are reduced by NADH in the presence of glutamate dehydrogenase (EC 1.4.1.2) to the two diastereomers of 3-fluoro-L-glutamate, which are stable at neutral pH and at high pH unless heated. 2-Keto-3-fluoroglutarate exists in solution almost entirely as a hydrate both at low and neutral pH. Both enantiomers of ketofluoroglutarate react with the pyridoxamine forms of aspartate, alanine and 4-aminobutyrate transaminases to give fluoride release. 2 mol of cosubstrate amino acid react for each mol of ketofluoroglutarate (KFG) when starting from the pyridoxamine form of the enzyme: 2 RCHNH2COOH + KFG + H2O----F- + NH4+ + glutamate + 2 RCOCOOH. Both diastereomers of fluoroglutamate are decarboxylated by glutamate decarboxylase (EC 4.1.1.15) with fluoride release: KFG + H2O----CO2 + F- + HCOCH2CH2COOH. By contrast, only one isomer of fluoroglutamate will react with the pyridoxal form of glutamate-oxalacetate transaminase to give fluoride release: HOOCCHNH2CHFCH2COOH + H2O----4F- + NH4+ + HOOCCOCH2CH2COOH. The enzymatic decarboxylation of 3-fluoroisocitrate produces only one enantiomer of ketofluoroglutarate, which is reduced to threo (2R,3R)-3-fluoroglutamate by NADH and glutamate dehydrogenase: [2R,3S]-HOOCCH(OH)CF(COOH)CH2COOH + NADP+----[3R]-KFG + CO2 + NADPH + H+. The proton, 13C, and 19F-NMR parameters of ketofluoroglutarate and the two fluoroglutamate diastereomers are presented. These molecules are useful probes of enzymatic mechanisms thought to involve carbanion intermediates.
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PMID:2-Keto-3-fluoroglutarate: a useful mechanistic probe of 2-keto-glutarate-dependent enzyme systems. 289 78

In experiments on 18 sheep with a differentiated nitrogen intake (3.7, 6.2 and 21 g N/day), it was found that different enzyme activities--glutamate dehydrogenase (GDH) (NADH- and NADPH-dependent) and glutamine synthetase (GS)--of bacteria adhering to the rumen wall and to food particles and the rumen fluid bacteria altered in correlation to the nitrogen intake. With a nitrogen intake of 3.7-6.2 g/day there was a significant increase, and of 6.2-21 g/day a decrease, in NADH- and NADPH-dependent GDH activity in the three given bacterial fractions, with the exception of NADPH-dependent GDH activity of the rumen fluid bacteria of sheep given 3.7-6.2 g N/day, in which the difference was nonsignificant. GS activity was significantly higher only in adherent rumen wall bacteria in the presence of a nitrogen intake of 3.7-6.2-21 g/day. The results show that the effect of the nitrogen intake on the given enzyme activities is strongest in the case of bacteria adhering to the rumen wall. The high GS activity and low GDH activities in these bacteria during lower nitrogen intakes (3.7 g/day) as well as lower rumen ammonia concentration (2.39 +/- 0.98 mmol.l-1) indicate that bacteria adhering to the rumen wall utilize ammonia at an increased rate by means of CS catalyzed reactions. Reduced GDH activity in the presence of a high nitrogen intake (21 g/day) and the relatively high rumen ammonia concentration (36.63 +/- 5.28 mmol.l-1) indicate that ammonia inhibits this enzyme in the rumen bacteria in question.
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PMID:Glutamate dehydrogenase and glutamine synthetase activity of the bacteria of the sheep's rumen after different nitrogen intake. 289 17


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