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PubMed1999

The location of active site opening and closing events in the prehydride transfer phase of the oxidative deamination reaction catalyzed by bovine liver glutamate dehydrogenase using a novel pH jump approach.

A pH jump approach has been developed and used to locate the opening and closing events occurring in the time course of the beef liver glutamate dehydrogenase catalyzed reaction. A comparison of the pH jump results, the resolved component time courses, and the 340 nm fluorescence signal suggests the existence and location on the reaction time course of a previously unreported prehydride transfer complex.

Animals↗
PubMedDate not supplied

Fluorescence polarization studies on the binding between glutamate dehydrogenase and cytoplasmic aspartate aminotransferase.

Polarization of fluorescence measurements on aspartate aminotransferase (from pig heart cytosol) labeled with fluorescein isothiocyanate have been used to detect the formation of a soluble complex of this protein wich glutamate dehydrogenase from bovine liver. The binding of the labeled transaminase to dehydrogenase is detectable at catalytic concentrations of the enzymes.

Animals↗
PubMed2006

The relationship between haematological indices, serum gamma-glutamyl transferase and glutamate dehydrogenase, visual hepatic damage and worm burden in cattle infected with Fasciola gigantica.

The association between visual hepatic damage, burden of Fasciola gigantica, serum levels of gamma glutamyl transferase (GGT) and glutamate dehydrogenase (GLDH) is described from an abattoir study of 70 cattle in the Philippines. In another abattoir study of 60 cattle, the relationship between burden of F. gigantica and haematological indices was investigated. The degree of visual hepatic damage and burden of F. gigantica were significantly positively related to levels of GGT and GLDH. Red blood cell counts and packed cell volume were significantly inversely related to worm burden, but animals compensated for reduced numbers of red blood cells by increasing red cell haemoglobin content.

Animals↗
PubMed1977

Nicotinamide adenine dinucleotide-specific glutamate dehydrogenase of Neurospora. VII. Isolation and sequences of three large cyanogen bromide peptides.

The isolation and sequences of three peptides of large size from a cyanogen bromide digest of the NAD-specific glutamate dehydrogenase of Neurospora crassa are reported. These three peptides comprise 86, 117, and 134 residues, respectively, and represent approximately 30% of the estimated 1030 residues in the peptide chain.

Amino Acid Sequence↗
PubMed1993

Three human glutamate dehydrogenase genes (GLUD1, GLUDP2, and GLUDP3) are located on chromosome 10q, but are not closely physically linked.

Yeast artificial chromosomes (YACs) of 340 and 370 kb that contain the functional human glutamate dehydrogenase gene (GLUD1) and the pseudogene GLUDP2, respectively, were isolated. These genes were not physically linked to each other nor to any other sequences homologous to the exons of GLUD1. No additional GLUD sequences were found within at least 70 kb of the 5' and 175 kb of the 3' end of GLUD1 or 150 kb of either end of GLUDP2. By in situ hybridization, GLUD1 was located at 10q23.3, GLUDP2 at 10q11.2, and another pseudogene of the GLUD gene family, GLUDP3, at 10q22.1. DNA fragments of these three genes showed cross-hybridization to the loci assigned to the other two genes, but not to any other chromosomal locus. Thus, these three genes are located at distinct positions on chromosome 10q.

Base Sequence↗
PubMed1998

Plasma aspartate aminotransferase (AST), glutamate dehydrogenase (GLDH) and gamma-glutamyl transpeptidase (GGT) activities in water buffaloes with experimental subclinical fasciolosis.

The effect of chronic Fasciola hepatica infection on the activity of plasma aspartate aminotransferase (AST), glutamate dehydrogenase (GLDH) and gamma-glutamyl transpeptidase (GGT) was investigated in water buffaloes dosed daily with 60 F. hepatica metacercariae over 20 days. Experimental fluke infection caused no clinical signs but provoked an increase in plasma level of IgG directed against F. hepatica from 4 weeks after infection. There was a significant increase in plasma AST from 6 weeks post-infection. Maximal values were reached at 14 weeks and remained significantly elevated by 23 weeks. Plasma GLDH was significantly elevated from 6 to 21 weeks post-infection. Significant increases in plasma GGT occurred from 8 to 26 weeks post-infection, reaching maximal values at 15 weeks. This study shows that plasma enzyme activities may be useful in studies of fluke-induced liver damage in water buffaloes.

Animals↗
PubMed1997

The glutamate dehydrogenase, E74 and putative actin gene loci in the Drosophila montium subgroup. Chromosomal homologies among the montium species and D. melanogaster.

DNA-specific sequences from an enzyme-coding gene (glutamate dehydrogenase, gdh), a regulatory protein-coding gene (E74) and genes of the actin family were mapped by in situ hybridization on the polytene chromosomes of six species representative of the geographical distribution of the Drosophila montium subgroup of the melanogaster species group. In all species studied, one hybridization signal was detected for the gdh and E74 genes, and seven signals for the actin genes. The distribution of the actin-related loci in five montium species is similar to that of the other Drosophila species studied so far, although they present an extra signal. This distribution differs in the sixth montium species studied, D. kikkawai. Taking into account the present results, as well as previous data obtained mainly by in situ hybridizations, homologies among the polytene chromosomes of the montium subgroup species, as well as between these species and D. melanogaster, were also established.

Actins↗
PubMed1999

Pressure-induced thermostabilization of glutamate dehydrogenase from the hyperthermophile Pyrococcus furiosus.

In this paper, elevated pressures up to 750 atm (1 atm = 101 kPa) were found to have a strong stabilizing effect on two extremely thermophilic glutamate dehydrogenases (GDHs): the native enzyme from the hyperthermophile Pyrococcus furiosus (Pf), and a recombinant GDH mutant containing an extra tetrapeptide at the C-terminus (rGDHt). The presence of the tetrapeptide greatly destabilized the recombinant mutant at ambient pressure; however, the destabilizing effect was largely reversed by the application of pressure. Electron spin resonance (ESR) spectroscopy of a spin-label attached to the terminal cysteine of rGDHt revealed a high degree of mobility, suggesting that destabilization is due to weakened intersubunit ion-pair interactions induced by thermal fluctuations of the tetrapeptide. For both enzymes, the stabilizing effect of pressure increased with temperature as well as pressure, reaching 36-fold for rGDHt at 105 degrees C and 750 atm, the largest pressure-induced thermostabilization of an enzyme reported to date. Stabilization of both native GDH and rGDHt was also achieved by adding glycerol. Based on the kinetics of thermal inactivation and the known effects of glycerol on protein structure, a mechanism of pressure-induced thermostabilization is proposed.

Electron Spin Resonance Spectroscopy↗
PubMed1994

PCR-mediated cloning and sequencing of the gene encoding glutamate dehydrogenase from the archaeon Sulfolobus shibatae: identification of putative amino-acid signatures for extremophilic adaptation.

Highly degenerate oligodeoxyribonucleotides (oligos) were used to PCR amplify the most conserved region of the glutamate dehydrogenase (GDH)-encoding gene from the extreme thermophilic archaeon, Sulfolobus shibatae. The amplified fragment was cloned and sequenced, and then used as a homologous probe to clone a genomic restriction fragment containing the near-complete gdhA gene. The deduced amino acid (aa) sequence shows a very high degree of similarity with the aa sequence previously determined by direct sequencing of the purified enzyme from Sulfolobus solfataricus [Maras et al., Eur. J. Biochem. 203 (1992) 81-87]. The introduction of this new sequence into our GDH phylogenetic trees [Benachenhou-Lahfa et al., J. Mol. Evol. 35 (1993) 335-346] showed that it is a new member of hexameric GDH family II, and did not modify the topology of the trees. Comparison of the primary structures of extremophilic GDH enzymes (halophilic, thermophilic and hyperthermophilic) with those of their non-halophilic and mesophilic counterparts in this family II led us to identify a few aa changes which seem to be specific either to hyperthermophilic or halophilic adaptation.

Adaptation, Physiological↗
PubMed2003

pH-responsive stabilization of glutamate dehydrogenase mRNA in LLC-PK1-F+ cells.

During chronic metabolic acidosis, the adaptive increase in rat renal ammoniagenesis is sustained, in part, by increased expression of mitochondrial glutaminase (GA) and glutamate dehydrogenase (GDH) enzymes. The increase in GA activity results from the pH-responsive stabilization of GA mRNA. The 3'-untranslated region (3'-UTR) of GA mRNA contains a direct repeat of an eight-base AU-rich element (ARE) that binds zeta-crystallin/NADPH:quinone reductase (zeta-crystallin) with high affinity and functions as a pH-response element. RNA EMSAs established that zeta-crystallin also binds to the full-length 3'-UTR of GDH mRNA. This region contains four eight-base sequences that are 88% identical to one of the two GA AREs. Direct binding assays and competition studies indicate that the two individual eight-base AREs from GA mRNA and the four individual GDH sequences bind zeta-crystallin with different affinities. Insertion of the 3'-UTR of GDH cDNA into a beta-globin expression vector (pbetaG) produced a chimeric mRNA that was stabilized when LLC-PK1-F+ cells were transferred to acidic medium. A pH-responsive stabilization was also observed using a betaG construct that contained only the single GDH4 ARE and a destabilizing element from phosphoenolpyruvate carboxykinase mRNA. Therefore, during acidosis, the pH-responsive stabilization of GDH mRNA may be accomplished by the same mechanism that affects an increase in GA mRNA.

3' Untranslated Regions↗
PubMed1993

Evolution of glutamate dehydrogenase genes: evidence for two paralogous protein families and unusual branching patterns of the archaebacteria in the universal tree of life.

The existence of two families of genes coding for hexameric glutamate dehydrogenases has been deduced from the alignment of 21 primary sequences and the determination of the percentages of similarity between each pair of proteins. Each family could also be characterized by specific motifs. One family (Family I) was composed of gdh genes from six eubacteria and six lower eukaryotes (the primitive protozoan Giardia lamblia, the green alga Chlorella sorokiniana, and several fungi and yeasts). The other one (Family II) was composed of gdh genes from two eubacteria, two archaebacteria, and five higher eukaryotes (vertebrates). Reconstruction of phylogenetic trees using several parsimony and distance methods confirmed the existence of these two families. Therefore, these results reinforced our previously proposed hypothesis that two close but already different gdh genes were present in the last common ancestor to the three Ur-kingdoms (eubacteria, archaebacteria, and eukaryotes). The branching order of the different species of Family I was found to be the same whatever the method of tree reconstruction although it varied slightly according the region analyzed. Similarly, the topological positions of eubacteria and eukaryotes of Family II were independent of the method used. However, the branching of the two archaebacteria in Family II appeared to be unexpected: (1) the thermoacidophilic Sulfolobus solfataricus was found clustered with the two eubacteria of this family both in parsimony and distance trees, a situation not predicted by either one of the contradictory trees recently proposed; and (2) the branching of the halophilic Halobacterium salinarium varied according to the method of tree construction: it was closer to the eubacteria in the maximum parsimony tree and to eukaryotes in distance trees. Therefore, whatever the actual position of the halophilic species, archaebacteria did not appear to be monophyletic in these gdh gene trees. This result questions the firmness of the presently accepted interpretation of previous protein trees which were supposed to root unambiguously the universal tree of life and place the archaebacteria in this tree.

Algorithms↗
PubMed2002

Glutamate dehydrogenase activity: a major criterion for the selection of flavour-producing lactic acid bacteria strains.

Lactic acid bacteria (LAB) have the enzyme potential to transform amino acids into aroma compounds that contribute greatly to cheese flavour. Generally, amino acid conversion by LAB is limited by their low production of alpha-ketoglutarate since this alpha-ketoacid is essential for the first step of the conversion. Indeed, we have demonstrated that adding exogenous alpha-ketoglutarate to cheese curd, as well as using a genetically modified L. lactis strain capable of producing alpha-ketoglutarate from glutamate, greatly increased the conversion of amino acid to potent aroma compounds in cheese. Here we report the presence of glutamate dehydrogenase (GDH) activity required for the conversion of glutamate to alpha-ketoglutarate in several 'natural' LAB strains, commonly used in cheese manufacturing. Moreover, we show that the ability of LAB to produce aroma compounds from amino acids is closely related to their GDH activity. Therefore, GDH activity appears to be a major criterion for the selection of flavour-producing LAB strains, which could be used as a starter or as an adjunct to intensify flavour formation in some cheeses.

Amino Acids↗
PubMedDate not supplied

[Relationship between the glutamine synthetase and glutamate dehydrogenase pathways of detoxification of exogenous ammonia in fish].

Regularities of adaptation reactions of detoxication of exogenic ammonium in fish have been established. Under the pre-threshold level of the toxicant concentration level (0.05 mg/l) the function of the detoxication process is performed at the level of glutamine synthetase reaction mainly catalyzed by the enzyme cytoplasmatic form. The inhibition of both mitochondrial and cytoplasmic forms of the carp muscle glutamine synthetase by the mixed type was revealed under the effect of over-threshold concentrations of ammonium (0.1 mg/l). At the same time activity of NADP-glutamate dehydrogenase increases 2-4 times in the mitochondria and practically 10 times in the cell cytoplasm of the fish muscles and liver. The established regularity is considered as the adaptation of hydrobionts to the changes of ecological conditions of dwelling.

Ammonia↗
PubMed1969

Chemical modification of glutamate dehydrogenase by 2,4,6-trinitrobenzenesulphonic acid.

1. Modification with 2,4,6-trinitrobenzenesulphonic acid was studied for its effect on the structure, activity and response to regulatory effectors of ox liver glutamate dehydrogenase. 2. The modification affected amino groups only, and the relative reactivities of the amino groups of the enzyme are described. 3. A biphasic inactivation of the enzyme was observed and analysis of the course of inactivation and of modification showed that the rapid reaction of one amino group/subunit leads to loss of 80% of the enzymic activity. 4. NADH retarded the inactivation by 2,4,6-trinitrobenzenesulphonic acid, the protection increasing with NADH concentration. This, together with the previous observation, suggests that the rapidly reacting group is essential for the activity of the enzyme. 5. The effects of modification on the optical-rotatory-dispersion and sedimentation behaviour of the enzyme were studied. 6. The enzyme's response to the allosteric effector GTP was rapidly lost on modification, whereas its response to ADP was unaffected. Comparison of the inactivation and desensitization suggests that the reactive amino group is essential for both activity and GTP response, and that only a completely unmodified enzyme oligomer responds fully to GTP. 7. The merits of chemical-modification studies of large enzymes are discussed critically in connexion with the interpretation of these results.

Adenine Nucleotides↗
PubMed1986

Isolation and identification of cysteinyl peptide labeled by 6- [( 4-bromo-2,3-dioxobutyl)thio]-6-deaminoadenosine 5'-diphosphate in the reduced diphosphopyridine nucleotide inhibitory site of glutamate dehydrogenase.

6-[(4-Bromo-2,3-dioxobutyl)thio]-6-deaminoadenosine 5'-diphosphate (6-BDB-TADP) has been shown to react at the reduced diphosphopyridine nucleotide (DPNH) inhibitory site of bovine liver glutamate dehydrogenase with incorporation of 1 mol of reagent/mol of enzyme subunit [Batra, S. P., & Colman, R. F. (1984) Biochemistry 23, 4940-4946]. The modified enzyme had lost one of the six free sulfhydryl groups per enzyme subunit as detected by 5,5'-dithiobis(2-nitrobenzoate). In the unmodified enzyme digested with trypsin, six cysteinyl peptides labeled with [14C]iodoacetic acid were detected by high-performance liquid chromatography (HPLC), whereas only five were observed in the 6-BDB-TADP-modified enzyme. A cysteinyl peptide has been isolated from modified enzyme digested with trypsin and chymotrypsin. Purification of the nucleotidyl peptide was accomplished by chromatography on phenyl boronate-agarose, followed by gel filtration on Sephadex G-25 and Bio-Gel P-4 in 50 mM ammonium bicarbonate, pH 8.0. The modified peptides were finally purified by HPLC on a C18 column using 0.1% trifluoroacetic acid with an acetonitrile gradient. By comparison of the amino acid composition and N-terminal residue of the isolated peptide with the known amino acid sequence of the enzyme, the peptide in the DPNH inhibitory site labeled by 6-BDB-TADP has been identified as the 19-membered fragment from Glu-311 to Lys-329. A unique residue, Cys-319, was identified as the reactive amino acid within the DPNH inhibitory site.

Adenosine Diphosphate↗
PubMed2001

Novel missense mutations outside the allosteric domain of glutamate dehydrogenase are prevalent in European patients with the congenital hyperinsulinism-hyperammonemia syndrome.

The hyperinsulinism-hyperammonemia syndrome (HHS) has been shown to result from 'gain-of-function' mutations of the glutamate dehydrogenase (GlDH) gene, GLUD1. In the original report, all mutations were found in a narrow range of 27 base pairs within exons 11 and 12 which predicted an effect on the presumed allosteric domain of the enzyme and all these mutations were associated by a diminished inhibitory effect of guanosine triphosphate (GTP) on GlDH activity. We have investigated 14 patients from seven European families with mild hyperinsulinism. In four families, more than one member was affected. In eight cases hyperammonemia was documented, and eight cases had signs of significant leucine sensitivity. In one of the families, a novel heterozygous missense mutation in exon 6 [c.833C>T (R221C)] was detected, and in all other cases from six unrelated families the novel heterozygous missense mutation c.978G>A (R269H) was found in exon 7. When GIDH activity was measured in lymphocytes isolated from affected patients, both mutations were shown to result in a normal basal activity but a diminished sensitivity to GTP. It is the first time that this effect is reported for mutations located in the presumed catalytic site and outside the GTP allosteric domain of the enzyme. The observation of the high prevalence of the exon 7 mutation both in familial and sporadic cases of HHS suggests a mutation hot spot and justifies a mutation screening for this novel mutation by mismatch PCR-based restriction enzyme digestion in patients with hyperinsulinism.

Adolescent↗
PubMed1991

[Glutamate dehydrogenase activity in the pancreatic tissue in acute experimental pancreatitis and under the action of sodium thiosulphate].

It has been established that the development of acute pancreatitis is accompanied by the reduced activity of glutamate dehydrogenase in the mitochondrial fraction of pancreas, pronounced in the focus of tissue necrosis and less expressed in the reactive inflammation focus. Besides this in the pancreas redistribution of enzyme, activity in the subcellular organelles takes place and enzyme activity emerges in the cytosol and further--in the blood and peritoneum liquid. Sodium thiosulfate has a marked correlation effect.

Acute Disease↗