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)

Parts of the primary structure of the NAD-specific glutamate dehydrogenase [L-glutamate:NAD oxidoreductase (deaminating), EC 1.4.1.2] from Neurospora crassa are presented. Segments of the sequence representing 886 unique amino-acid residues have been determined; the largest contains 267 residues. There are only short regions of possible homology between this enzyme and the glutamate dehydrogenases of bovine liver or the NADP-specific enzyme of Neurospora. The large size of the subunit (116,000 molecular weight) of the NAD-specific glutamate dehydrogenase is unusual when compared to other known dehydrogenases.
Proc Natl Acad Sci U S A 1975 Dec
PMID:Partial amino-acid sequence of NAD-specific glutamate dehydrogenase of Neurospora crassa. 17 80

Electron micrographs from intraplasmatic inclusion bodies of human hepatocytes are described; these paracrystallic aggregations consist of helically arranged filaments. All the observed periodic structures within these bodies can be indicated as originating from the same compound by the use of the Frauenhofer diffraction pattern. Concerning the genesis of these characteristically structured bodies two possibilities are discussed: 1. A special polymeric form of fibrinogen and fibrin built up in vivo. 2. Polymerization of a monomeric enzyme, for example, glutamate dehydrogenase, to paracrystallic bodies by fixation-dependent cross-linkages.
Virchows Arch A Pathol Anat Histol 1975 Dec 29
PMID:[Paracrystallic, intraplasmatic inclusion bodies in human hepatocytes: a structural analytic study (author's transl)]. 17 59

A procedure has been developed for isolating nicotinamide adenine dinucleotide phosphate-specific glutamate dehydrogenase (am) mutants of Neurospora. Physiological, genetic, and enzymatic tests show that the new mutants are am alleles. Reconstruction tests and analysis of the new alleles show that the procedure yields a broad spectrum of lesions at the am locus. The isolation of am mutants by this technique appears to be related to the effect of am mutants on the control of the general permease.
J Bacteriol 1977 Dec
PMID:Direct selective procedure for isolating Neurospora mutants defective in nicotinamide adenine dinucleotide phosphate-specific glutamate dehydrogenase. 20 Jun 2

Ammonia is known to inhibit the steady-state rate of oxidation of L-glutamate catalyzed by glutamate dehydrogenase. We reported previously [Brown, A., Colen, A. H., & Fisher, H. F. (1978) Biochemistry 17, 2031] kinetic evidence supporting the formation in the initial rapid phase of a complex which is composed of enzyme, reduced coenzyme, alpha-ketoglutarate, and ammonia. We show here that the effects of ammonia on the steady-state reaction can be correlated with transient-state kinetic effects related to the concentration of that ammonia-containing complex. These results indicate the existence of alternate reaction pathways which become important at high ammonia concentrations. These new pathways provide an additional route for the release of NADPH from the enzyme surface. The expanded mechanism shows that the noncompetitive product inhibition by ammonia can occur without the simultaneous presence of ammonia and L-glutamate on the enzyme. This mechanism also accommodates the observed substrate inhibition by L-glutamate.
Biochemistry 1979 Dec 25
PMID:Effect of ammonia on the glutamate dehydrogenase catalyzed oxidative deamination of L-glutamate. The steady state. 51 77

1. The concentration of HCO3- (independent of any change of pH) exerts different effects on glutamine metabolism in rat kidney-cortex tubules, hepatocytes and enterocytes.2. In kidney tubules HCO3- (10.5-50 MM) has no effect on glutaminase (EC 3.5.1.2), whereas glutamate dehydrogenase (EC 1.4.1.3) is inhibited as HCO3- concentration is increased. The result is that flux through the entire glutamate-to-glucose pathway is inhibited by increasing HCO3- concentrations. A large proportion (more than 30%) of the glutamine removed undergoes complete oxidation. 3. In hepatocytes, and to a smaller extent in enterocytes, HCO3- is an accelerator of glutaminase. Synthesis of glucose and urea from glutamine in hepatocytes increases as HCO3- concentration is increased. Calculations show that fumarate, formed via aspartate aminotransferase and arginino-succinate lyase, is the precursor of the glucose. There is no complete oxidation of the carbon skeleton of glutamine in hepatocytes. 4. Leucine at near-physiological concentrations (0.1-1 mM) is an accelerator of glutaminase in hepatocytes, but not in kidney tubules or in enterocytes. 5. The results are discussed in relation to regulation of acid/base balance in vivo.
Biochem J 1979 Dec 15
PMID:A role for bicarbonate in the regulation of mammalian glutamine metabolism. 54 52

This communication describes the isolation and characterization of mutants of Rhizobium trifolii which can induce nitrogenase activity in defined liquid medium. Two procedures were used for the isolation of these mutants from R. trifolii strain DT-6: (1) following chemical mutagenesis, slow growing mutants were selected which were unable to utilize NH+4 as sole source of nitrogen; (2) as spontaneous mutants resistant to the glutamate analogue L-methionine-DL-sulfoximine. Mutants (DT-71, DT-125) isolated by these procedures induced nitrogenase activity in the free-living state, whereas the parent strain lacked this property. Induction of nitrogenase activity in these mutants occurred during the late exponential phase of growth when the rate of protein synthesis was decreasing. The addition of NH+4 to a medium containing glutamate as the nitrogen-source resulted in a 50--70% reduction (repression?) of nitrogenase activity; in contrast, the rate of protein synthesis or the rate of respiration was not influenced by exogenous NH+4. Biochemical analysis showed that these mutants (strains DT-71 and DT-125) have defects in both nitrogen and carbon metabolism. The levels of glutamate synthase (both NADP+ -and NAD+ -dependent activities) and glutamate dehydrogenase (NAD+-dependent activity) were markedly lower. In addition, the mutants were found to have no detectable ribitol dehydrogenase or beta-galactosidase activity. These findings are discussed in relation to a mechanism of regulation of symbiotic nitrogen fixation.
Biochim Biophys Acta 1977 Dec 22
PMID:Regulation of nitrogen fixation in Rhizobium spp. Isolation of mutants of Rhizobium trifolii which induce nitrogenase activity. 58 92

The usefulness of blood enzyme determinations as markers of liver necrosis was tested in 100 alcoholics who underwent biopsy during clinical investigation. Mean values of glutamate dehydrogenase (GDH), serum aspartate and alanine transferase (SGOT and SGPT), ornithine carbamoyltransferase (OCT), and gamma-glutamyltranspeptidase (gamma-GTP) tended to rise with increasing liver cell necrosis, though values of SGOT, SGPT, OCT, and gamma-GTP showed considerable overlap between the 32 patients with histologically proved hepatitis and the 68 without. By contrast, GDH values showed virtually no overlap between patients with and without hepatitis, and a value of two and a half times the normal value discriminated between the two groups. Because of its easy determination and its reliable reflection of liver cell necrosis the GDH concentration should be estimated routinely in alcoholic patients.
Br Med J 1977 Dec 10
PMID:Glutamate dehydrogenase: a reliable marker of liver cell necrosis in the alcoholic. 58 7

1. The pathway of glutamate metabolism in non-synaptic rat brain mitochondria was investigated by measuring glutamate, aspartate and ammonia concentrations and oxygen uptakes in mitochondria metabolizing glutamate or glutamine under various conditions. 2. Brain mitochondria metabolizing 10mm-glutamate in the absence of malate produce aspartate at 15nmol/min per mg of protein, but no detectable ammonia. If amino-oxyacetate is added, the aspartate production is decreased by 80% and ammonia production is now observed at a rate of 6.3nmol/min per mg of protein. 3. Brain mitochondria metabolizing glutamate at various concentrations (0-10mm) in the presence of 2.5mm-malate produce aspartate at rates that are almost stoicheiometric with glutamate disappearance, with no detectable ammonia production. In the presence of amino-oxyacetate, although the rate of aspartate production is decreased by 75%, ammonia production is only just detectable (0.3nmol/min per mg of protein). 4. Brain mitochondria metabolizing 10mm-glutamine and 2.5mm-malate in States 3 and 4 were studied by using glutamine as a source of intramitochondrial glutamate without the involvement of mitochondrial translocases. The ammonia production due to the oxidative deamination of glutamate produced from the glutamine was estimated as 1nmol/min per mg of protein in State 3 and 3nmol/min per mg of protein in State 4. 5. Brain mitochondria metabolizing 10mm-glutamine in the presence of 1mm-amino-oxyacetate under State-3 conditions in the presence or absence of 2.5mm-malate showed no detectable aspartate production. In both cases, however, over the first 5min, ammonia production from the oxidative deamination of glutamate was 21-27nmol/min per mg of protein, but then decreased to approx. 1-1.5nmol/min per mg. 6. It is concluded that the oxidative deamination of glutamate by glutamate dehydrogenase is not a major route of metabolism of glutamate from either exogenous or endogenous (glutamine) sources in rat brain mitochondria.
Biochem J 1977 Dec 15
PMID:The pathway of glutamate metabolism in rat brain mitochondria. 60 50

The initial rate of incorporation of [15N]alanine into the 6-amino group of the adenine nucleotides in rat hepatocytes was about one-eighteenth of the rate of incorporation into urea. Thus the purine nucleotide cycle cannot provide most of the ammonia needed in urea synthesis for the carbamoyl phosphate synthase reaction (EC 2.7.2.5). On the other hand, contrary to the view expressed by McGivan & Chappell [(1975) FEBS Lett. 52, 1--7], the experiments support the view that hepatic glutamate dehydrogenase can supply the required ammonia.
Biochem J 1978 Dec 15
PMID:Sources of ammonia for mammalian urea synthesis. 74 49

1. The effects of lipoate and asparagusate on animal and plant enzymes of the TCA cycle and related metabolic pathways were studied. 2. Lipoate inhibited bovine liver glutamate dehydrogenase [EC 1.4.1.3]. The inhibition may play a role in metabolic regulation. 3. Asparagusate inhibited lipoyl dehydrogenase [EC 1.6.4.3] from asparagus and lettuce competitively with respect to lipoate. Asparagusate had practically no effects on other asparagus enzymes. 4. Asparagusate strongly inhibited lipoyl dehydrogenase, glutamate dehydrogenase, and isocitrate dehydrogenase [EC 1.1.1.42] from animal sources, in competition with the corresponding substrate. 5. Asparagusate and lipoate also inhibited yeast glutamate dehydrogenase. 6. Based upon kinetic studies, the mode of these inhibitions is discussed.
J Biochem 1975 Dec
PMID:Effects of asparagusate and lipoate on enzymes of the tricarboxylic acid cycle and related metabolic pathways. 77 25


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