PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “GLUTAMATE DEHYDROGENASE”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 703 records · Page 39Linked to original sources
PubMed1988

Glutamate dehydrogenase (GDH) deficiency in different types of progressive hereditary cerebellar ataxia.

Leukocyte glutamate dehydrogenase (GDH) was studied in 29 patients affected by progressive cerebellar ataxia (PCA) and in 20 healthy controls. Eight GDH-deficient patients, with GDH activity 2 SD below mean value of controls, were identified. GDH deficiency did not identify a subgroup of PCA by characteristic pattern of inheritance and/or age of onset of disease. However, the GDH-deficient patients presented more neurological signs than non-GDH-deficient patients. A significant correlation was observed between GDH deficiency and the presence of extrapyramidal signs, supranuclear palsy, absence of osteotendineal reflexes and neurogenic electromyographical findings.

Adolescent↗
PubMed1969

1-Anilinonaphthalene-8-sulphonate, a fluorescent conformational probe for glutamate dehydrogenase.

1. The interaction of 1-anilinonaphthalene-8-sulphonate with ox liver glutamate dehydrogenase was examined. 2. The fluorescence of the dye is enhanced 100-fold on binding. 3. A further enhancement is observed when NADH and GTP are added to the enzyme. 4. By using this property of the dye to measure conformational equilibria in the enzyme the effects of coenzyme, inhibitors, enzyme concentration, ionic strength and pH on the allosteric transitions were studied. 5. GTP and NADH interact with the enzyme in a heterotropic manner. 6. The rate of the structural transition brought about by GTP and NADH is biphasic with half-lives of 34 and 200msec. 7. The relation of these observations to regulatory mechanisms is discussed.

Aniline Compounds↗
PubMed1976

Mutants of Aspergillus nidulans lacking nicotinamide adenine dinucleotide-specific glutamate dehydrogenase.

Ten mutants of Aspergillus nidulans lacking nicotinamide adenine dinucleotide-specific glutamate dehydrogenase (NAD-GDH) have been isolated, and their mutations (gdhB1 through gdhB10) have been shown to lie in the gdhB gene. In addition, a temperature-sensitive gdhB mutant (gdhB11) has been isolated. A revertant (designated R-5) of the mutant gdhB1 bears an additional lesion in the gdhB gene and has altered NAD-GDH activity with altered Km values for ammonia or ammonium ions and for alpha-ketoglutarate. These results suggest that gdhB specifies a structural component for NAD-GDH. The growth characteristics of gdhB mutants indicate the routes by which amino acids are utilized as nitrogen and carbon energy sources. The properties are described of the double mutants bearing the mutations gdhB1 and gdhA1 or tamA119, which have low NADP-GDH activity.

Amino Acids↗
PubMedDate not supplied

Full-time course studies of bovine liver glutamate dehydrogenase. Simulation of inhibition by pyridoxal-5'-phosphate.

Inhibition of bovine liver glutamate dehydrogenase by pyridoxal-5'-phosphate was studied by measuring the full time course of the oxidation of NADPH. Progress curves were determined before and after incubation of the enzyme with PLP in the presence of saturating concentrations of alpha-ketoglutarate and ammonium ion, at pH 7.4 and 25 degrees C. The data were fitted to the integrated Michaelis-Menten equation and an inhibition model derived. According to the model, PLP inhibits the enzyme non-competitively, by reversible formation of the complexes E--PLP and E--PLP--NADPH; the oxidation of NADPH is also inhibited by NADP+. After incubation with PLP, the dissociation constants of E--NADPH and E--NADP+ (Km and Kp) show a very definite decrease, while the maximum rate of oxidation (Vm) is increased. The inhibition constants for PLP were also computed.

Animals↗
PubMed1993

Glutamate dehydrogenase deficiency in Machado-Joseph disease.

We studied the activity of glutamate dehydrogenase (GDH) in leukocytes from 23 patients with dominantly inherited ataxia. All the patients were assessed with a rating scale for ataxias and met the clinical criteria for the diagnosis of Machado-Joseph disease. The mean age of onset of symptoms was 37.8, SD 13.4 years and the duration of the disease was 7.4, SD 4.9. Leukocyte GDH activity was significantly decreased (p < 0.001) when compared to 20 normal controls. These data extend previous reports indicating that a GDH deficiency is present in peripheral tissues from some patients with spinocerebellar degenerations. Furthermore, this study suggests that a genetic deficiency of GDH may underlie some forms of dominant ataxias; this deficiency may be marked in patients with Machado-Joseph disease and is not specific for any type of multiple system atrophy.

Adolescent↗
PubMed2002

The Antarctic Psychrobacter sp. TAD1 has two cold-active glutamate dehydrogenases with different cofactor specificities. Characterisation of the NAD+-dependent enzyme.

Psychrobacter sp. TAD1 is a psychrotolerant bacterium from Antarctic frozen continental water that grows from 2 to 25 degrees C with optimal growth rate at 20 degrees C. The new isolate contains two glutamate dehydrogenases (GDH), differing in their cofactor specificities, subunit sizes and arrangements, and thermal properties. NADP+-dependent GDH is a hexamer of 47 kDa subunits and it is comparable to other hexameric GDHs of family-I from bacteria and lower eukaria. The NAD+-dependent enzyme, described in this communication, has a subunit weight of 160 kDa and belongs to the novel class of GDHs with large size subunits. The enzyme is a dimer; this oligomeric arrangement has not been reported previously for GDH. Both enzymes have an apparent optimum temperature for activity of approximately 20 degrees C, but their cold activities and thermal labilities are different. The NAD+-dependent enzyme is more cold active: at 10 C it retains 50% of its maximal activity, compared with 10% for the NADP+-dependent enzyme. The NADP+-dependent enzyme is more heat stable, losing only 10% activity after heating for 30 min, compared with 95% for the NAD+-dependent enzyme. It is concluded that in Psychrobacter sp. TAD1 not only does NAD+-dependent GDH have a novel subunit molecular weight and arrangement, but that its polypeptide chains are folded differently from those of NADP+-dependent GDH, providing different cold-active properties to the two enzymes.

Adaptation, Physiological↗
PubMed1995

Isolation and characterization of a cDNA that encodes maize glutamate dehydrogenase.

A full-length cDNA clone, pMGDH1, encoding maize NADH-glutamate dehydrogenase (NADH-GDH) was isolated from a maize root cDNA library. The identity of the cDNA was established by the coincidence of the structure of the purified protein with that inferred from the nucleotide sequence of the cDNA. pMGDH1 had a cDNA insert of 1,638 bp and the open reading frame encoded 411 amino acid residues. The deduced amino acid sequence was similar to putative partial sequences of GDHs from higher plants and to the sequences of GDHs from organisms as diverse as mammals and bacteria. The NH2-terminal sequence deduced from the open reading frame had a typical structure that is associated with the import of proteins into the mitochondrial matrix. The cDNA hybridized to an RNA of about 1.6 kb. This transcript was more abundant in roots than in leaves and was localized in the bundle sheath cells in leaf tissues. Analysis of genomic DNA by Southern hybridization suggested the existence of gene(s) for another NADH-GDH subunit(s).

Amino Acid Sequence↗
PubMed1998

The NADP+-linked glutamate dehydrogenase from Trypanosoma cruzi: sequence, genomic organization and expression.

NADP-linked glutamate dehydrogenase (NADP+-GluDH, EC 1.4.1.4) has been purified to homogeneity from epimastigotes of Trypanosoma cruzi by an improved procedure, and the amino acid sequences of 11 internal peptides obtained by digestion with trypsin, endopeptidase Lys-C, endopeptidase Arg-C or CNBr have been obtained. Using oligonucleotide primers synthesized according to the amino acid sequence of the N-terminus of the mature enzyme and to the nucleotide sequence of a clone corresponding to the C-terminus, obtained by immunological screening of an expression library, two complete open reading frames (TcGluDH1 and TcGluDH2) were isolated and sequenced. The sequences obtained are most similar to that of the NADP+-GluDH of Escherichia coli (70-72% identity), and less similar (50-56%) to those of lower eukaryotes. Using TcGluDH1 as a probe, evidence for the presence of several genes and developmental regulation of the expression of NADP+-GluDH in different parasite stages was obtained. TcGluDH1 encodes an enzymically active protein, since its expression in E. coli resulted in the production of a GluDH activity with kinetic parameters similar to those of the natural enzyme.

Amino Acid Sequence↗
PubMed1996

The existence of a hexameric intermediate with molten-globule-like properties in the thermal denaturation of bovine-liver glutamate dehydrogenase.

We have studied the thermal denaturation of hexameric beef-liver glutamate dehydrogenase by itself and in the presence of ADP and guanidine-HCl by a variety of techniques. In differential scanning calorimetry studies, the observed melting temperature and total enthalpy of denaturation show no dependence on protein concentration, but do show significant dependence on the scan rate. This suggests that the overall denaturation process is irreversible and kinetically controlled. Isothermal unfolding kinetics from spectrophotometry confirm this result. The size of the protein, as shown by quasi-elastic light scattering measurements, does not change during the denaturation process. We interpret these results in terms of the following model: N6 reversible N'6-->6U(-->F) where N6 and N'6 are, respectively, the native hexamer and a hexameric, highly folded high-enthalpy species, U is the unfolded monomer and F is some final aggregated state. The kinetic intermediate, N'6, possesses the properties of one definition of a molten globule, having a very high enthalpy and a hexameric compact structured form. This "molten globule" is an obligatory intermediate in the unfolding pathway of the protein. The stabilization of the protein by ADP is due to the modulation of the high-enthalpy two-state predenaturational E reversible E' transition, resulting in the lowering of the energy of the native state of the protein.

Adenosine Diphosphate↗
PubMed1999

Purification and characterization of glutamate dehydrogenase as another isoprotein binding to the membrane of rough endoplasmic reticulum.

Glutamate dehydrogenase (GDH) was purified from rough endoplasmic reticulum (RER) in rat liver using anion-exchange and affinity chromatography. As GDH has been known as an enzyme that exists mainly in the matrix of mitochondria, the properties of purified GDH were compared with those of mitochondrial GDH. The GDH activity in 0. 1% Triton X-100-treated RER subcellular fraction was nearly the same as intact RER, whereas that of the mitochondrial fraction increased by 50% after the detergent treatment. In kinetic values, in addition, mitochondrial GDH had a higher K(m) value for NADP(+) than NAD(+), whereas the K(m) value for NAD(+) was higher than that for NADP(+) in the case of GDH of RER, which showed a difference in specificity to cofactors. Moreover, when two GDH isoproteins were incubated at 42 degrees C or treated with trypsin, GDH from RER was more stable against heat inactivation and less susceptible to proteolysis than mitochondrial GDH in both cases. In addition, GDH of RER had at least five amino acids different from mitochondrial GDH when sequences of N-terminal and several internal peptide fragments were analyzed. These results showed that GDH of RER is another isoprotein of GDH, of whose properties are different from those of mitochondrial GDH.

Amino Acid Sequence↗
PubMed1992

Purification and some properties of glutamate dehydrogenase and glutamine synthetase from Paracoccus denitrificans.

The purification and some properties of NADP-dependent glutamate dehydrogenase (GDH) and glutamine synthetase (GS) from the facultatively anaerobic Gram-negative bacterium Paracoccus denitrificans were investigated. The enzymes were purified to homogeneity using a procedure which involved affinity chromatography on Blue Sepharose CL-6B as the major purification step. The recoveries in the purification of GDH and GS were 28% and 64%, respectively. The specific activity of purified GDH was 183 nkat (mg protein)-1 (deaminating reaction). GDH was composed of subunits of molecular mass 47 kDa and the native enzyme was either a tetramer or hexamer. The apparent Km values for L-glutamate, NADP, 2-oxoglutarate, NADPH and ammonia were 1.5 mM, 5.9 microM, 0.47 microM, 12.5 microM and 14 mM, respectively. The specific activity of purified GS was 1125 nkat (mg protein)-1 (transferase reaction). The molecular mass of native GS was 570 kDa; it was composed of 12 subunits of molecular mass 50.1 kDa. The apparent Km values for L-glutamine and hydroxylamine in the transferase reaction were 2.1 and 2.4 mM, respectively; those of ammonia, L-glutamate and ATP in the biosynthetic reaction were 0.03, 1 and 0.17 mM, respectively. After the adenylylation of GS, the Km for L-glutamine and L-glutamate increased and reached the values of 8.0 and 27 mM, respectively. The effects of the changes in GS activity on the ammonia metabolism of Paracoccus denitrificans are discussed.

Electrophoresis, Polyacrylamide Gel↗
PubMed1997

Characterization and expression of NAD(H)-dependent glutamate dehydrogenase genes in Arabidopsis.

Two distinct cDNA clones encoding NAD(H)-dependent glutamate dehydrogenase (NAD[H]-GDH) in Arabidopsis thaliana were identified and sequenced. The genes corresponding to these cDNA clones were designated GDH1 and GDH2. Analysis of the deduced amino acid sequences suggest that both gene products contain putative mitochondrial transit polypeptides and NAD(H)- and alpha-ketoglutarate-binding domains. Subcellular fractionation confirmed the mitochondrial location of the NAD(H)-GDH isoenzymes. In addition, a putative EF-hand loop, shown to be associated with Ca2+ binding, was identified in the GDH2 gene product but not in the GDH1 gene product. GDH1 encodes a 43.0-kD polypeptide, designated alpha, and GDH2 encodes a 42.5-kD polypeptide, designated beta. The two subunits combine in different ratios to form seven NAD(H)-GDH isoenzymes. The slowest-migrating isoenzyme in a native gel, GDH1, is a homohexamer composed of alpha subunits, and the fastest-migrating isoenzyme, GDH7, is a homohexamer composed of beta subunits. GDH isoenzymes 2 through 6 are heterohexamers composed of different ratios of alpha and beta subunits. NAD(H)-GDH isoenzyme patterns varied among different plant organs and in leaves of plants irrigated with different nitrogen sources or subjected to darkness for 4 d. Conversely, there were little or no measurable changes in isoenzyme patterns in roots of plants treated with different nitrogen sources. In most instances, changes in isoenzyme patterns were correlated with relative differences in the level of alpha and beta subunits. Likewise, the relative difference in the level of alpha or beta subunits was correlated with changes in the level of GDH1 or GDH2 transcript detected in each sample, suggesting that NAD(H)-GDH activity is controlled at least in part at the transcriptional level.

Amino Acid Sequence↗
PubMed1976

Inhibition of glutamate dehydrogenase and malate dehydrogenases by palmitoyl coenzyme A.

In extension of a previous study with yeast glucose-6-P dehydrogenase (Kawaguchi, A., and Bloch, K. (1974) J. Biol. Chem. 249, 5793-5800), the structural changes accompanying the inhibition of glutamate dehydrogenase and several malate dehydrogenases by palmitoyl-CoA and by sodium dodecyl sulfate have been investigated. Palmitoyl-CoA converts liver glutamate dehydrogenase to enzymatically inactive dimeric subunits (Mr = 1.2 X 10(5)) and tightly binds to the dissociated enzyme. Removal of the inhibitor from the palmitoyl-CoA-dimer complex fails to regenerate enzyme activity. The Ki values for palmitoyl-CoA inhibition of malate dehydrogenases (oxalacetate reduction) are, for the enzyme from pig heart mitochondria, 1.8 muM, 500 muM from pig heart supernatant, and 10 muM from chicken heart supernatant. These inhibitions are readily reversible. Palmitoyl-CoA does not alter the quaternary structure of any of the malate dehydrogenases and binds only weakly to these enzymes. Mitochondrial malate dehydrogenase assayed in the direction malate to oxalacetate is much less sensitive to palmitoyl-CoA, with Ki values of 50 muM at pH 10 and greater than 50 muM at pH 7.4. While the differences in palmitoyl-CoA sensitivity in the forward and backward reactions catalyzed by mitochondrial dehydrogenase are unexplained, a physiological rationale for these differential effects is offered. Sodium dodecyl sulfate dissociates the various dehydrogenases to monomeric subunits in contrast to the more selective effects of palmitoyl-CoA.

Animals↗
PubMed2005

Regulation of glutamate level in rat brain through activation of glutamate dehydrogenase by Corydalis ternata.

When treated with protopine and alkalized extracts of the tuber of Corydalis ternata for one year, significant decrease in glutamate level and increase in glutamate dehydrogenase (GDH) activity was observed in rat brains. The expression of GDH between the two groups remained unchanged as determined by Western and Northern blot analysis, suggesting a post-translational regulation of GDH activity in alkalized extracts treated rat brains. The stimulatory effects of alkalized extracts and protopine on the GDH activity was further examined in vitro with two types of human GDH isozymes, hGDH1 (house-keeping GDH) and hGDH2 (nerve-specific GDH). Alkalized extracts and protopine activated the human GDH isozymes up to 4.8-fold. hGDH2 (nerve- specific GDH) was more sensitively affected by 1 mM ADP than hGDH1 (house-keeping GDH) on the activation by alkalized extracts. Studies with cassette mutagenesis at ADP-binding site showed that hGDH2 was more sensitively regulated by ADP than hGDH1 on the activation by Corydalis ternata. Our results suggest that prolonged exposure to Corydalis ternata may be one of the ways to regulate glutamate concentration in brain through the activation of GDH.

Animals↗
PubMed1999

Chemical rescue of the catalytically disabled clostridial glutamate dehydrogenase mutant D165S by fluoride ion.

The catalytically disabled Asp165-->Ser mutant of clostridial glutamate dehydrogenase shows 100000-fold less activity than the wild-type (WT) enzyme in a standard glutamate oxidation assay and 1000-fold less activity in the reductive-amination reaction. The large reduction in the rate has been attributed to removal of the negative charge and the postulated proton-donor capacity of the aspartate carboxyl group. However, fluoride ion (1 M NaF) causes a 1000-fold activation of the mutant enzyme while simultaneously inhibiting WT activity by 20-fold in the forward reaction. For the reverse reaction, F- (1 M) activates the mutant 4-fold and inhibits WT activity to approx. 64%. The net result when 1 M F- is present is a decrease in the WT:mutant activity ratio from 100000 to 5 for the forward reaction. None of the other halides tested, nor NO3(-), CHCOO- or HCOO-, give comparable activation. Re-activation took 15-30 s under assay conditions, suggesting the possibility of conformational change; CD spectroscopy, however, provided no evidence of a substantial change and kinetics of modification using 5,5'-dithiobis(2-nitrobenzoic acid) suggested only subtle structural rearrangement. This phenomenon is discussed in the light of available information about the structure of the mutant enzyme. It is suggested that the F- ion provides a fixed negative charge at the position of the missing aspartate carboxyl group. Therefore, this appears to be an example of 'chemical rescue'.

Catalysis↗
PubMed2004

Nutritional value of a corn containing a glutamate dehydrogenase gene for growing pigs.

Eight female PIC Line 42 pigs (initial BW = 47.5 +/- 1.8 kg) were used in a two-period switchback design (n = 4 per treatment per period) to evaluate the nutritional difference between a genetically modified corn and a similar nontransgenic corn. The genetically altered corn (gdhA+) contained a glutamate dehydrogenase gene isolated from Escherichia coli. The non-transgenic corn was the same variety lacking the transgenic cassette, grown at the same two locations. Pigs were surgically fitted with steered ileocecal valve cannulas for collection of ileal digesta. Diets were made up of primarily one of the two corn sources. Dietary AA profiles were adjusted using crystalline AA to match Illinois Ideal Protein Ratios. Pigs were limit-fed at 8% of metabolic body weight (BW0.75) in two equal feedings at 0600 and 1800 daily throughout the experiment. The study consisted of two 15-d periods. Each period consisted of a 7-d acclimation period, a 3-d total collection of feces and urine, two 12-h ileal collections, and a 3-d adjustment period between ileal collections to ensure adequate hydration. Crude protein, leucine, methionine, alanine, aspartic acid, glutamic acid, and tyrosine concentrations were greater (P < 0.05) in the gdhA+ corn than in the nontransgenic variety. The presence of the gene did not alter (P > 0.17) BW gain. Similarly, DM digestibility, fecal N excretion (grams per day), apparent total-tract N digestibility, N balance, net protein utilization, and N retained as percentages of absorbed were not affected (P > or = 0.32) by the gene modification. Apparent ileal AA digestibility values did not differ (P > 0.31) between the two dietary treatments. Results of this study suggest corn that contains the E coli. gene for glutamate dehydrogenase was nutritionally equivalent to the unaltered variety.

Animal Feed↗