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)

l-Glutamate uptake, thiourea uptake, and methylammonium uptake and the intracellular ammonium concentration were measured in wild-type and mutant cells of Aspergillus nidulans held in various concentrations of ammonium and urea. The levels of l-glutamate uptake, thiourea uptake, nitrate reductase, and hypoxanthine dehydrogenase activity are determined by the extracellular ammonium concentration. The level of methylammonium uptake is determined by the intracellular ammonium concentration. The uptake and enzyme characteristics of the ammonium-derepressed mutants, meaA8, meaB6, DER3, amrA1, xprD1, and gdhA1, are described. The gdhA mutants lack normal nicotinamide adenine dinucleotide phosphate-glutamate dehydrogenase (NADP-GDH) activity and are derepressed with respect to both external and internal ammonium. The other mutant classes are derepressed only with respect to external ammonium. The mutants meaA8, DER3, amrA1, and xprD1 have low levels of one or more of the l-glutamate, thiourea, and methylammonium uptake systems. A model for ammonium regulation in A. nidulans is put forward which suggests: (i) NADP-GDH located in the cell membrane complexes with extracellular ammonium. This first regulatory complex determines the level of l-glutamate uptake, thiourea uptake, nitrate reductase, and xanthine dehydrogenase by repression or inhibition, or both. (ii) NADP-GDH also complexes with intracellular ammonium. This second and different form of regulatory complex determines the level of methylammonium uptake by repression or inhibition, or both.
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PMID:Ammonium regulation in Aspergillus nidulans. 414 65

Ammonia assimilation has been investigated in four strains of Saccharomyces cerevisiae by measuring, at intervals throughout the growth cycle, the activities of several enzymes concerned with inorganic ammonia assimilation. Enzyme activities in extracts of cells were compared after growth in complete and defined media. The effect of shift from growth in a complete to growth in a defined medium (and the reverse) was also determined. The absence of aspartase (EC 4.3.1.1, l-aspartate-ammonia lyase) activity, the low specific activities of alanine dehydrogenase, glutamine synthetase [EC 6.3.1.2, l-glutamate-ammonia ligase (ADP)], and the marked increase in activity of the nicotinamide adenine dinucleotide phosphate-linked glutamate dehydrogenase (NADP-GDH) [EC 1.4.1.4, l-glutamate:NADP-oxidoreductase (deaminating)] during the early stages of growth support the conclusion that yeasts assimilate ammonia primarily via glutamate. The NADP-GDH showed a rapid increase in activity just before the initiation of exponential growth, reached a maximum at the mid-exponential stage, and then gradually declined in activity in the stationary phase. The NADP-GDH reached a higher level of activity when the yeasts were grown on the defined medium as compared with complete medium. The nicotinamide adenine dinucleotide-linked glutamate dehydrogenase (NAD-GDH) [EC 1.4.1.2, l-glutamate:NAD-oxidoreductase (deaminating)] showed only slight increases in activity during the exponential phase of growth. There was an inverse relationship in that the NADP-GDH increased in activity as the NAD-GDH decreased. The NAD-GDH activity was higher after growth on the complete medium. The glutamate-oxaloacetate transaminase (EC 2.6.1.1. l-aspartate:2-oxoglutarate aminotransferase) activity rose and fell in parallel with the NADP-GDH, although its specific activity was somewhat lower. Although other ammonia-assimilatory enzymes were demonstrable, it seems unlikely that their combined activities could account for the remainder of the ammonia-assimilatory capacity not accounted for by the NADP-GDH. The ability of aspartate to serve as effectively as glutamate as the sole source of nitrogen for the growth of yeast apparently resides in their ability to utilize aspartate for amino acid biosynthesis via transamination.
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PMID:Inorganic nitrogen assimilation in yeasts: alteration in enzyme activities associated with changes in cultural conditions and growth phase. 440 Apr 14

Ammonium ions were incorporated into L-glutamate and alpha-ketoglutarate in epimastigote forms of Trypanosoma cruzi through the following enzymatic systems: NADPH and NADH-dependent glutamate dehydrogenase, NADPH-dependent glutamate synthase, L-glutamine synthetase and NADH-dependent glutamate synthase in order of decreasing specific activity (mumoles of product formed/min/mg protein). The pH optima and Km's for the glutamate dehydrogenase system were determined. Disc electrophoresis showed the presence of cathodic bands of GDH activity, which were highly dependent on NADP+.
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PMID:Incorporation of ammonium in amino acids by Trypanosoma cruzi. 610 92

Glutamate dehydrogenase (L-glutamate:NAD+ oxidoreductase (deaminating); EC 1.4.1.2) has been purified from Peptostreptococcus asaccharolyticus in a single step using dye-ligand chromatography. The enzyme (GDH) was present in high yields and was stabilized in crude extracts. A subunit molecular weight of 49000 +/- 500 was determined by SDS polyacrylamide gel electrophoresis and six bands were obtained after cross-linking the subunits with dimethyl suberimidate. This bacterial GDH was predominantly NAD+-linked, but was able to utilize both NADP+ and NADPH at 4% of the rates with NAD+ and NADH, respectively. An investigation of the amino acid specificity revealed some similarities with GDH from mammalian sources and some clear differences. The values of apparent Km for the substrates ammonia, 2-oxoglutarate, NADH, NAD+ and glutamate were 18.4, 0.82, 0.066, 0.031 and 6 mM, respectively. The P. asaccharolyticus GDH was not regulated by purine nucleotides, but was subject to strong inhibition with increasing ionic strength.
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PMID:Characterization of Peptostreptococcus asaccharolyticus glutamate dehydrogenase purified by dye-ligand chromatography. 650 34

Glutamic dehydrogenase extracted with tris buffer from fresh freeze-thawed rat heart mitochondria was purified by ammonium sulphate fractionation, affinity chromatography on GTP agarose, hydroxyapatite chromatography and concentration using a molecular sieve. The final specific activity is 80 units/mg protein. Thin gel SDS electrophoresis of the purified enzyme preparation after reduction with dithiothreitol shows a major band with a molecular weight of 38 000 Daltons. Two minor bands are also present. Sucrose density gradient centrifugation reveals a molecular weight of 230 000 Daltons for unreduced mitochondrial GDH activity. By gel filtration rat heart mitochondrial glutamic dehydrogenase has a major peak at 230 000 Daltons, a minor peak at 300 000 Daltons and some larger molecular weight species. Rat liver mitochondrial glutamic dehydrogenase has a minor peak at 230 000, a major peak at 300 000 and some larger molecular weight species. The rat liver mitochondrial glutamic dehydrogenase predominance at 300 000 is unchanged by incubation, extraction and purification with rat heart mitochondria. The purified GDH is stable frozen at -10 degrees C in tris-HCl buffer with EDTA. It loses activity at 4 degrees C especially when stored in 0.2 M phosphate buffer. It also loses activity when dialyzed for 24 h. This loss of activity is not completely prevented by adding nucleotides to the buffer (AMP or ADP) but is decreased by their presence.
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PMID:Glutamic dehydrogenase from rat heart mitochondria. I. Purification and physical properties including molecular weight determination. 672 19

1. The acute oral LD50 and chronic LC50 toxicity values for ethylene dibromide (EDB) were estimated for japanese quail. 2. Single sub-acute oral and intraperitoneal doses of EDB (1/2 LD50) and chronic oral doses of EDB (1/3 LC50) were administered to quail in order to characterise the sub-lethal effects of EDB residues. 3. At 24 h after sub-acute dosing, relative liver weight, plasma aspartate aminotransferase (AT) [EC 2.6.1.1] and L-iditol (sorbitol) dehydrogenase (SDH) [EC 1.1.1.14] were elevated and decreases were found in hepatic total lipid, total protein, AT and glutamic dehydrogenase (NAD (P)+) (GDH) and plasma cholinesterase (ChE) [EC 3.1.1.8] and total lipid. 4. Following chronic administration, elevations in relative liver weight, plasma ChE and total lipid, haemoglobin and haematocrit were found and hepatic AT, GDH and total lipid were decreased. 5. The changes in hepatic and plasma enzymes and constituents are discussed in relation to possible biphasic effects resulting from EDB exposure.
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PMID:A study on the toxicity and the biochemical effects of ethylene dibromide in the Japanese quail. 702 16

Serum glutamate dehydrogenase (EC 1.4.1.3.) activity was measured in 73 hospital patients who had a history of chronic alcohol abuse and who all had a liver biopsy performed. High levels of serum GDH activity occurred in those patients with recent excess alcohol consumption independently of the underlying liver histology, and did not discriminate between those patients with and those without alcoholic hepatitis.
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PMID:Serum glutamate dehydrogenase is not a reliable marker of liver cell necrosis in alcoholics. 706 13

When ammonia was removed from Chlorella sorokiniana cells, which contain an ammonium-inducible nicotinamide adenine dinucleotide phosphate-specific glutamate dehydrogenase (NADP-GDH), the activity of this enzyme decayed with a half-life of approximately 8 min. By use of rocket immunoelectrophoresis, indirect immunoprecipitation, and indirect immunoadsorption (coupled with pulse-chase experiments with 35S-labeled sulfate), the rapid initial loss in activity was shown to be due to enzyme inactivation rather than degradation of NADP-GDH antigen. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of immunoprecipitates obtained with anti-NADP-GDH immunoglobulin G showed that enzyme inactivation is accompanied by the conversion of enzyme subunits (Mr = 59,000) to a protein with a molecular weight of 118,000. Because this protein was stable during boiling and in the presence of sodium dodecyl sulfate and high concentrations of mercaptoethanol or dithiothreitol, it was tentatively assumed to be a covalently linked dimer of enzyme subunits. Pulse-chase experiments showed that total NADP-GDH antigen was subject to rapid degradation (t 1/2 = 88 min) in induced cells, and the same degradation rate was maintained after removal of ammonia from induced cells.
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PMID:Turnover of ammonium-inducible glutamate dehydrogenase during induction and its rapid inactivation after removal of inducer from Chlorella sorokiniana cells. 720 42

By use of a rocket immunoelectrophoresis-activity stain procedure, it was shown that catalytic activity of an ammonium-inducible nicotinamide adenine dinucleotide phosphate-specific glutamate dehydrogenase (NADP-GDH) was accompanied by a coincident increase in enzyme antigen during the cell cycle of preinduced synchronous Chlorella sorokiniana cells growing in the continuous presence of ammonia. Between the fourth and fifth hours of the G-1 phase of the cell cycle, a three- to fourfold increase in linear accumulation of enzyme antigen was observed. Pulse-chase studies with [35S]sulfate, coupled with a specific indirect immunoadsorption procedure for enzyme antigen, showed that NADP-GDH antigen undergoes continuous degradation (i.e., a half-life of 88 to 110 min) during its linear pattern of accumulation during the cell cycle. The apparent half-life of the enzyme increased by approximately 23% of the 4.5-h positive rate change in antigen accumulation during the cell cycle. This increase in half-life is insufficient in itself to account for the large change in rate of NADP-GDH antigen accumulation. The data from immunoelectrophoresis, pulse-chase, and initial 35S incorporation rate experiments taken together support the inference that changes in the rate of NADP-GDH synthesis are primarily responsible for the accumulation patterns of NADP-GDH activity during the C. sorokiniana cell cycle.
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PMID:Regulation of accumulation of ammonium-inducible glutamate dehydrogenase catalytic activity and antigen during the cell cycle of fully induced, synchronous Chlorella sorokiniana cells. 721 11

The cells of Chlorella sorokiniana cultured in nitrate medium contain no detectable catalytic activity of an ammonium-inducible nicotinamide adenine dinucleotide phosphate-specific glutamate dehydrogenase (NADP-GDH). However, several lines of experimental evidence indicated that the NADP-GDH messenger ribonucleic acid was present at high levels and was being translated in uninduced cells. First, binding studies with 125I-labeled anti-NADP-GDH immunoglobulin G and total polysomes isolated from uninduced and induced cells showed that NADP-GDH subunits were being synthesized on polysomes from both types of cells. Second, when polyadenylic acid-containing ribonucleic acid was extracted from polysomes from uninduced and induced cells and placed into a messenger ribonucleic acid-dependent in vitro translation system, NADP-GDH subunits were synthesized from the ribonucleic acid from both sources. Third, when ammonia was added to uninduced cells, NADP-GDH antigen accumulated without an apparent induction lag. Fourth, by use of a specific immunoprecipitation procedure coupled to pulse-chase studies with [35S]sulfate, it was shown that the NADP-GDH subunits are rapidly synthesized, covalently modified, and then degraded in uninduced cells.
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PMID:Evidence for messenger ribonucleic acid of an ammonium-inducible glutamate dehydrogenase and synthesis, covalent modification, and degradation of enzyme subunits in uninduced Chlorella sorokiniana cells. 721 12


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