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 activities of the proline-specific permease (PUT4) and the general amino acid permease (GAP1) of Saccharomyces cerevisiae vary 70- to 140-fold in response to the nitrogen source of the growth medium. The PUT4 and GAP1 permease activities are regulated by control of synthesis and control of activity. These permeases are irreversibly inactivated by addition of ammonia or glutamine, lowering the activity to that found during steady-state growth on these nitrogen sources. Mutants altered in the regulation of the PUT4 permease (Per-) have been isolated. The mutations in these strains are pleiotropic and affect many other permeases, but have no direct effect on various cytoplasmic enzymes involved in nitrogen assimilation. In strains having one class of mutations (per1), ammonia inactivation of the PUT4 and GAP1 permeases did not occur, whereas glutamate and glutamine inactivation did. Thus, there appear to be two independent inactivation systems, one responding to ammonia and one responding to glutamate (or a metabolite of glutamate). The mutations were found to be nuclear and recessive. The inactivation systems are constitutive and do not require transport of the effector molecules per se, apparently operating on the inside of the cytoplasmic membrane. The ammonia inactivation was found not to require a functional glutamate dehydrogenase (NADP). These mutants were used to show that ammonia exerts control of arginase synthesis largely by inducer exclusion. This may be the primary mode of nitrogen regulation for most nitrogen-regulated enzymes of S. cerevisiae.
Mol Cell Biol 1983 Apr
PMID:Ammonia regulation of amino acid permeases in Saccharomyces cerevisiae. 634 42

Trypanosoma (Schizotrypanum) cruzi epimastigotes (EP stock) grown in complex LIT medium rapidly consume the glucose present but, under aerobic conditions, continue growth in its absence with the concomitant excretion of ammonia, suggesting the utilization of amino acids for energy production. A search for metabolic pathways responsible for amino acid oxidation led to the detection of a NAD+-dependent glutamate dehydrogenase (L-glutamate:NAD+ oxidoreductase, E.C.1.4.1.2) which is different from an NADP+-dependent enzyme previously reported. The enzyme has been partially purified and its kinetic and regulatory properties studied in both directions of the reaction. Km values were 3.6 mM for alpha-ketoglutarate, 0.170 mM for NADH and 16 mM for NH+4, Vmax = 0.67 mumol min-1/mg-1 protein for aminative reduction; Km values were 23.5 mM for L-glutamate and 2.9 mM for NAD+, Vmax = 0.02 mumol min-1 mg-1 protein for deaminative oxidation, Tris buffer, pH 7.6. The enzyme is strongly inhibited by ATP, GTP, ADP and GDP (50% inhibition at 0.75 mM ATP, 3 mM MgCl2). S-Acetyl-CoA is also a potent inhibitor of the enzyme. The results demonstrate the presence of a specific pathway for the oxidation of amino acids, which is tightly regulated by the energy charge and the Krebs cycle activity in T. cruzi epimastigotes.
Mol Biochem Parasitol 1984 Apr
PMID:Regulation of energy metabolism in Trypanosoma (Schizotrypanum) cruzi epimastigotes. II. NAD+-dependent glutamate dehydrogenase. 637 48

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.
J Mol Cell Cardiol 1984 Apr
PMID:Glutamic dehydrogenase from rat heart mitochondria. I. Purification and physical properties including molecular weight determination. 672 19

Glutamic dehydrogenase purified from rat heart mitochondria has been characterized with regard to its substrate kinetics and the influence of nucleotides and potassium phosphate on its kinetic properties. The enzyme had characteristics similar to liver mitochondrial glutamic dehydrogenase. These included several double reciprocal plots which were biphasic, indicating homotropic interaction; inhibition by GTP, which was overcome by ADP and phosphate; and activity with both NAD(H) and NADP(H). There were a number of significant differences however, in the specific kinetic properties of heart mitochondrial glutamic dehydrogenase. The Vmax of reductive amination was four-fold greater with NADH than with NADPH. The maximum rate of oxidative deamination was ten-fold greater with NAD compared to NADP. The differences also included: saturating levels of NADH and NADPH were stimulatory rather than inhibitory; ammonia was stimulatory at millimolar levels; NADP and alpha-ketoglutarate were both inhibitory at saturating levels; and ADP increased reductive amination 30% at lower levels of NADH but inhibited at higher (stimulatory) levels of NADH.
J Mol Cell Cardiol 1984 Apr
PMID:Glutamic dehydrogenase from rat heart mitochondria. II. Kinetic characteristics. 672 20

Half-of-the-sites reactivity in oligomeric enzymes has generally been accepted as evidence for structural asymmetry between subunits. However, we show that the symmetric two-state allosteric model [Monod, J., Wyman, J., & Changeux, J.-P. (1965) J. Mol. Biol. 12, 88-118] is quantitatively consistent with half-of-the-sites reactivity data for several hexameric and tetrameric enzymes. Specifically, the time courses for both the modification and the inactivation of glutamate dehydrogenase by glutamyl alpha-chloromethyl ketone and uridine diphosphoglucose dehydrogenase by 5-(iodoacetamidoethyl)aminonaphthalene-1-sulfonic acid are fit with just five parameters for each enzyme-modifier pair. In the case of glyceraldehyde-3-phosphate dehydrogenase, the time courses for modification of the yeast enzyme by iodoacetic acid and the rabbit-muscle enzyme by 3,3,3-trifluorobromoacetone are fit with the same model, and parameter values from these fits are used to generate theoretical inactivation curves which are found to agree well with the experimentally measured inactivation. We conclude that half-of-the-sites reactivity, if it is not an artifact of residual heterogeneity, could be a kinetic phenomenon related to metastability of partially modified states of a symmetric oligomer and that asymmetry between subunits should therefore not necessarily be inferred from such behavior. If similar metastability occurs in substrate binding, it may play a significant role in mechanism of catalysis and control. In such cases, the virtual inaccessibility of the substrate binding equilibrium would preclude conventional quasi-equilibrium models for the enzyme kinetics.
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PMID:Molecular symmetry and metastable states of enzymes exhibiting half-of-the-sites reactivity. 702 97

When modified by 2,2,6,6-tetramethyl-4-oxopiperidine-1-oxyl (TMPO) bovine liver glutamate dehydrogenase (L-glutamate NAD(P) oxidoreductase, E. C. 1.4.1.3) looses its catalytical activity and sensitivity to allosteric inhibitor GTP. The stoicheiometry of the binding of TMPO to glutamate dehydrogenase has been studied--each protomer bound one molecule of TMPO. It is supposed that TMPO reacts with lysine residue located in the enzyme's active center.
Mol Biol (Mosk)
PMID:[Bovine liver glutamate dehydrogenase modified by 2,2,6,6-tetramethyl-4-oxopiperidine-1-oxyl: enzymatic activity and catalytic properties]. 707 Mar 87

The internal amino acid residues of proteins are almost always non-polar since the hydrophobic effect is very important in stabilizing the three-dimensional structure. This fact suggests several new criteria for judging the correctness of structures predicted from sequence data. The dinucleotide binding domain has been used as a test structure for these criteria. The percentage of ionic residues, mutation data, hydrophobicity, dipole moments, and internal preferences of the residues on the interiors of the known dinucleotide binding folds are consistent with expectations. On the other hand, the values of these parameters for predicted domains in glutamate dehydrogenase (Wootton, J.C. (1974) Nature 252, 542--546) and aldolase (Stellwagen, E. (1976) J. Mol. Biol. 106, 903--911) differ significantly from the expected values indicating that these predictions are not entirely correct. The internal residue criteria can then be used to test modifications of the predictions for a better correlation with the internal residue pattern of the domain.
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PMID:Internal residue criteria for predicting three-dimensional protein structures. 737 53

Expression of the Neurospora crassa am (NADP-specific glutamate dehydrogenase) gene is controlled by two upstream enhancer-like elements designated URSam alpha and URSam beta. URSam alpha is localized between - 1.3 and - 1.4 kb with respect to the major transcriptional start site. Deletion of a 90 bp sequence containing this element resulted in the loss of approximately 50% of normal glutamate dehydrogenase expression. Gel mobility shift analysis indicated that a nuclear protein from Neurospora binds in a specific manner to sequences within the 90 bp fragment. We have now used a combination of ion-exchange and affinity chromatography to purify this nuclear protein, which we call Am Alpha Binding protein (AAB). The activity was monitored by gel shift analysis. The protein was purified more than 14,000-fold with a yield of approximately 7%. The purified protein appears as a heteromer on denaturing polyacrylamide gel electrophoresis, with only two strong bands visible in silver-stained preparations. One band has an apparent molecular mass of 40 kDa, the other appears as a doublet with an apparent molecular mass of 30 kDa. DNAse I protection analysis indicated a protected region consisting of 30 bp, which contains a CCAAT pentanucleotide motif. Mutagenesis of the CCAAT motif abolished the binding of AAB to the DNA fragment.
Mol Gen Genet 1995 Nov 27
PMID:Purification of a heteromeric CCAAT binding protein from Neurospora crassa. 750 Sep 55

In rat pancreatic islets, D-glucose in concentrations exceeding 5.6 mM caused a concentration-related decrease of the mitochondrial NADH/NAD+ ratio, as judged from the changes in the islet content of glutamate, NH4+, and 2-ketoglutarate, and assuming that the glutamate dehydrogenase reaction is near equilibrium with the mitochondrial NAD system. The concentration dependency of the response to D-glucose was vastly different in islet and parotid cells, respectively. L-Leucine, 2-ketoisocaproate, BCH (a nonmetabolized but insulinotropic analog of L-leucine) and 3-phenylpyruvate also lowered the mitochondrial NADH/NAD+ ratio. In the presence of D-glucose, the latter ratio was also decreased by NH4+ or the absence of extracellular Ca2+, but dramatically increased by aminooxyacetate. Taking into account prior metabolic findings, the nutrient-induced fall in the mitochondrial redox state is thought to reflect an increased clearance of mitochondrial NADH through both the respiratory chain and malate-aspartate shuttle. The nutrient-induced decrease in the mitochondrial NADH/NAD+ ratio might favor both the circulation of metabolites in the Krebs cycle and the exit of Ca2+ from the mitochondria.
Biochem Mol Med 1995 Jun
PMID:Hexose metabolism in pancreatic islets: regulation of the mitochondrial NADH/NAD+ ratio. 755 20

A clone isolated from a Drosophila auraria heat-shock cDNA library presents two long, antiparallel, coupled (LAC) open reading frames (ORFs). One strand ORF is 1,929 nucleotides long and exhibits great identity (87.5% at the nucleotide level and 94% at the amino acid level) with the hsp70 gene copies of D. melanogaster, while the second strand ORF, in antiparallel in-frame register arrangement, is 1,839 nucleotides long and exhibits 32% identity with a putative, recently identified, NAD(+)-dependent glutamate dehydrogenase (NAD(+)-GDH). The overlap of the two ORFs is 1,824 nucleotides long. Computational analysis shows that this LAC ORF arrangement is conserved in other hsp70 loci in a wide range of organisms, raising questions about possible evolutionary benefits of such a peculiar genomic organization.
J Mol Evol 1995 Oct
PMID:A Drosophila hsp70 gene contains long, antiparallel, coupled open reading frames (LAC ORFs) conserved in homologous loci. 756 28


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