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)

The behavior of cytoplasmic and mitochondrial enzymes has been studied in rat liver at 1, 5, and 24 hr after 60 min of ischemia using histochemical methods. This period of ischemia resulted 24 h after ischemia in liver cell necrosis in about 15% of the volume of the ischemic liver lobes. As early as after 1 hr reperfusion lactate dehydrogenase (LDH, cytoplasm) activity decreased in a certain proportion of the liver parenchymal cells, whereas glutamate dehydrogenase (GDH, mitochondrial matrix) activity started to decrease after 5 hr reperfusion; the activities of mitochondrial membrane enzymes, monoamine oxidase and succinate dehydrogenase, did not decrease before 24 hr of reperfusion. It has been concluded that the early decrease in LDH activity is caused by leakage into the blood and reflects reversible damage; when this decrease is accompanied by a decrease in GDH activity irreversible liver cell damage is assumed. Diminished activity of mitochondrial membrane enzymes, due to leakage and denaturation, is observed when real necrosis can be assessed.
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PMID:Changes in cytoplasmic and mitochondrial enzymes in rat liver after ischemia followed by reperfusion. 367 63

A cold-labile glutamate dehydrogenase (GDH, EC 1.4.1.3) has been purified to homogeneity from the crude extracts of Azospirillum brasilense. The purified enzyme shows a dual coenzyme specificity, and both the NADPH and NADH-dependent activities are equally cold-sensitive. The enzyme is highly specific for the substrates 2-oxoglutarate and glutamate. Kinetic studies with GDH indicate that the enzyme is primarily designed to catalyse the reductive amination of 2-oxoglutarate. The NADP+-linked activity of GDH showed Km values 2.5 X 10(-4) M and 1.0 X 10(-2) M for 2-oxoglutarate and glutamate respectively. NAD+-linked activity of GDH could be demonstrated only for the amination of 2-oxoglutarate but not for the deamination of glutamate. The Lineweaver-Burk plot with ammonia as substrate for NADPH-dependent activity shows a biphasic curve, indicating two apparent Km values (0.38 mM and 100 mM) for ammonia; the same plot for NADH-dependent activity shows only one apparent Km value (66 mM) for ammonia. The NADPH-dependent activity shows an optimum pH from 8.5 to 8.6 in Tris/HCl buffer, whereas in potassium phosphate buffer the activity shows a plateau from pH 8.4 to 10.0. At high pH (greater than 9.5) amino acids in general strongly inhibit the reductive amination reaction by their competition with 2-oxoglutarate for the binding site on GDH. The native enzyme has a Mr = 285000 +/- 20000 and appears to be composed of six identical subunits of Mr = 48000 +/- 2000. The GDH level in A. brasilense is strongly regulated by the nitrogen source in the growth medium.
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PMID:NADPH/NADH-dependent cold-labile glutamate dehydrogenase in Azospirillum brasilense. Purification and properties. 395 1

Photooxidation of bovine liver glutamate dehydrogenase (GDH, EC 1.4.1.3) in the presence of methylene blue at a low light intensity occurs in two stages. At the first stage, the duration of which depends on temperature and dye concentration, a slight activation is observed simultaneously with the oxidation of two histidine residues. At the second stage, the inactivation is concomitant with the oxidation of three histidine and one tryptophan residues. The inactivation is a first order reaction (k = 3,22 X 10(-2) min-1) and is correlated with changes in the circular dichroism spectra. These data testify to the structural role of histidine residues in the GDH molecule. The kinetic behaviour of GDH during its modification with diethylpyrocarbonate (DEP) depends on pH and the reagent concentration. Four histidine residues undergo carbethoxylation at pH 6.0 and 7.5, but the modification rate is much higher at pH 7.5. At low DEP concentrations, a remarkable activation is observed with a simultaneous modification of one histidine residue, which is independent of pH. At high DEP concentrations, a rapid inactivation takes place at pH 7.5. Treatment of the carbethoxylated inactive enzyme with hydroxylamine results in the deacylation of histidine residues without any noticeable reactivation. The data on the combined effect of DEP and pyridoxal-5'-phosphate suggest that GDH inactivation by DEP at pH 7.5 is a result of modification of an essential epsilon-NH2 group of lysine-126.
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PMID:[Structural role of histidine residues in NAD(P)-glutamate dehydrogenase from the bovine liver]. 407 86

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

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


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