Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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 damaging effects of ADP/Fe/NADPH-induced lipid peroxidation were studied on the enzymes and membranes of rat liver mitochondria. Succinate, an inhibitor of mitochondrial lipid peroxidation, prevented or delayed most of the damage caused by the peroxidation on different mitochondrial structures and functions. There were marked abnormalities on the electrophoretic pattern of mitochondrial proteins during the course of lipid peroxidation. The disappearance of particular polypeptide bands and the accumulation of high-molecular-weight aggregates could be observed. Succinate was found to delay these effects. As a consequence of lipid peroxidation the succinate oxidase activity of mitochondria was decreased. The succinate dehydrogenase enzyme and the component(s) of the respiratory chain were inactivated. Succinate prevented the inactivation of succinate dehydrogenase but did not protect the other components of terminal oxidation chain. From the matrix enzymes the glutamate dehydrogenase retained its full activity but the NADP-linked isocitrate dehydrogenase was inactivated. The mitochondrial membranes became permeable to large protein molecules. Succinate prevented the inactivation of isocitrate dehydrogenase and delayed the release of protein molecules from mitochondria.
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PMID:Effect of succinate on mitochondrial lipid peroxidation. 2. The protective effect of succinate against functional and structural changes induced by lipid peroxidation. 303 29

Cell-free extracts of proteolytic strains of Clostridium botulinum types A, B and F (group I) were found to have unusually high specific activities of NAD+-dependent L-glutamate dehydrogenase (NAD-GDH). In comparison, nonproteolytic strains of types B, E and F (group II) had low specific activities. The enzyme was purified 131-fold from C. botulinum 113B to a final specific activity of greater than 1,092 mumol x min-1 x mg protein-1. The enzyme is a hexamer of a polypeptide of Mr = 42,500, and the native molecular weight is 250,800. The apparent Km values for substrates were 5.3 mM for glutamate and 0.028 mM for NAD+ in the deamination reaction, and 7.2 mM for alpha-ketoglutarate, 243 mM for NH4+ and 0.028 mM for NADH in the reverse reaction. NADP+ did not serve as a hydrogen acceptor for the enzyme. Activity in the animation direction was inhibited by fumarate, oxalacetate, aspartate, glutamate and glutamine. The results suggest that GDH is important in group I (proteolytic) C. botulinum to generate alpha-ketoglutarate as a substrate for transamination reactions. We have also found that the high activity decreases significantly when cells are exposed to sodium chloride. Therefore GDH probably has several important physiological roles in group I proteolytic C. botulinum.
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PMID:Purification, properties, and metabolic roles of NAD+-glutamate dehydrogenase in Clostridium botulinum 113B. 306 71

The concentration-dependent association-dissociation tendency of purified bovine liver and rat liver glutamic dehydrogenase (GDH) has been demonstrated by high-performance liquid chromatographic gel filtration. In the concentration range of 100 to 1.0 micrograms bovine GDH/ml molecular species ranged from dimer and unimer to subunimeric forms. The dissociation process of the unimeric hexapeptide, consisting of six polypeptide chains, to the subunimeric tripeptide, consisting of three polypeptide chains, was irreversible without added ionic support, but reversible with added ionic support. In dilute Tris-HCl bovine liver GDH was dispersed to subunimeric sizes. Increasing the ionic strength in 20 mM phosphate as the mobile phase increased dissociation to a subunimeric tripeptide while sustaining as much as 80% of its activity. Activity of a eluting subunimer was verified by the inclusion of reaction substrates (NAD and glutamute) in the mobile phase and quantification of reaction products (NADH) in chromatograms. Gel filtration of GDH in the presence of GTP with NADH rendered a subunimeric tripeptide, largely independent of ionic strength or GDH concentration. Rat liver GDH, differing from bovine liver GDH, was dissociated by gel filtration to an active tripeptide independent of ionic or buffer conditions.
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PMID:Association-dissociation studies of bovine and rat liver glutamic dehydrogenase by high-performance liquid chromatography gel filtration. 317 32

We have isolated a series of human liver cDNA clones encoding glutamate dehydrogenase. The cDNA-derived protein sequence specifies a single 558-amino acid long polypeptide including a cleavable signal sequence of 53 amino acids. Blotting analysis of RNA from human, monkey, and rabbit showed that glutamate dehydrogenase mRNA is present in various amounts in all tissues tested. Glutamate dehydrogenase mRNAs are of four sizes and are found in different ratios in different tissues; the predominant ones are approximately 3.5 and approximately 2.9 kilobases. Blot hybridization of human genomic DNA to nonoverlapping cDNA fragments revealed multiple bands, many of which hybridize with two or more probes in a manner inconsistent with the existence of a single GLUD gene. Moreover, two separate 36-base synthetic oligonucleotides corresponding to the coding region hybridize to multiple genomic fragments, confirming the existence of more than one GLUD-related gene in human.
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PMID:Isolation and characterization of cDNA clones encoding human liver glutamate dehydrogenase: evidence for a small gene family. 336 58

Tryptophan room temperature phosphorescence in solution was detected in glutamic dehydrogenase from bovine liver and Escherichia coli with lifetimes of 1.2 and 0.65 s, respectively. Although these enzymes possess three and five tryptophanyl residues per polypeptide chain, respectively, the temperature dependence of the phosphorescence quantum yield estimates that the room temperature emission is due, in either case, to a single residue. Long triplet-state lifetimes and very small rates of O2 quenching indicate that these tryptophanyl side chains are embedded in a highly inflexible internal region of the macromolecule. Aided by sequence homology with dehydrogenases of known structure and theoretical predictions of secondary structure [Wootton, J.C. (1974) Nature (London) 252, 542-546; Brett, M., Chambers, G.K., Holder, A. A., Fincham, J.R.S., & Wootton, J.C. (1976) J. Mol. Biol. 106, 1-22], the phosphorescing tryptophans have been tentatively placed in the catalytic coenzyme binding domain of each enzyme. The particular sensitivity of the triplet-state lifetime in probing local changes in conformation provides a strong indication that within the time window of phosphorescence measurements the six subunits in the hexameric enzymes are equivalent. Furthermore, while in the bovine enzyme this parameter is markedly affected by the interaction with ligands which have a functional role, the constancy of the phosphorescence lifetime at various degrees of polymerization suggests that the association process is not accompanied by important conformational changes in the macromolecule.
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PMID:Characterization of tryptophan environments in glutamate dehydrogenases from temperature-dependent phosphorescence. 366 38

The translational inhibition produced by addition of oxidized glutathione (GSSG) to hemin-containing reticulocyte lysates and the accompanying phosphorylation of the alpha subunit of the polypeptide chain initiation factor eIF-2 can be prevented or reversed by NADPH generators, including glucose 6-phosphate, deoxyglucose 6-phosphate, fructose 6-phosphate, NADPH itself, and also by dithiols, e.g., dithiothreitol, but not by reduced glutathione (GSH) or other monothiols, e.g., 2-mercaptoethanol. The same is true of the inhibition caused by addition of glutamate dehydrogenase, alpha-ketoglutarate, and NH4+, which may be entirely due to NADPH depletion via the reaction.
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PMID:Studies on the activation of the heme-stabilized translational inhibitor of reticulocyte lysates by oxidized glutathione and NADPH depletion. 400 74

Bovine liver glutamate dehydrogenase (GDH), a hexameric enzyme, undergoes subunit dissociation, denaturation, and inactivation in the presence of guanidine hydrochloride (GdnHCl), depending on the denaturant concentration. The correlation between the enzymatic activity and the molecular state of GDH, and the reconstitution of native hexamer from subunits after the removal of GdnHCl were examined by measuring the enzymatic activity and CD spectrum in the far ultraviolet region. It was found that only the hexameric form of GDH has enzymatic activity, and the reconstitution of the hexamer with full enzymatic activity from the trimeric form which has native polypeptide chain structure can be achieved by the removal of GdnHCl. On the other hand, the recovery of enzymatic activity from the dissociated form in more concentrated GdnHCl solution where unfolding of the polypeptide chain takes place showed an exponential decrease with increasing incubation time in the GdnHCl solution. The time constant for the decay of enzymatic activity with respect to the incubation time was almost the same as that for unfolding of the polypeptide chain (followed by CD spectroscopy). It is suggested on the basis of these experimental results that the failure of reconstitution of GDH hexamer from subunits produced at high denaturant concentration is due to failure in the refolding of the unfolded subunit to the correct three-dimensional structure of the polypeptide chain rather than in the reassociation process from subunits.
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PMID:Denaturation of bovine liver glutamate dehydrogenase by guanidine hydrochloride. Correlation between enzymatic activity and molecular state. 403 Jul 18

1. One mol of diethyl pyrocarbonate will react with one mol of glutamate dehydrogenase polypeptide chains to form one mol of N(1)-carbethoxyhistidine. Reaction is prevented by NADH. 2. The 1:1 complex has an increased specific activity (1.4-2.0-fold). 3. The reason for the activation is discussed. The results are not consistent with NADH dissociation from the enzyme-glutamate-NADH complex being rate-limiting in the steady state measured. 4. The effects of modification on the properties of the enzyme were investigated. The effects of GTP and NAD(+) on the enzyme activity are unaltered by activation. NADH binding is unaltered and there is no apparent change in the molecular weight. However, the activated enzyme can still be further activated by ADP. K(s) for ADP is decreased fivefold.
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PMID:The reaction of a histidine residue in glutamate dehydrogenase with diethyl pyrocarbonate. 435 38

Micrococcus aerogenes grown in media containing glutamate has high levels of glutamate dehydrogenase and alpha-ketoglutarate reductase. The latter enzyme catalyzes the reversible reduction of alpha-ketoglutarate to alpha-hydroxyglutarate in the presence of reduced nicotinamide adenine dinucleotide (NADH). The enzyme has a high specificity for both substrates in either direction and displays Michaelis-Menten kinetics at moderate substrate concentrations. K(m) values of 0.12 to 0.17 mm alpha-ketoglutarate and 0.3 mm NADH for the forward reaction were calculated from data obtained at low substrate concentrations. At high concentrations, this reaction was inhibited by both substrates. The reverse reaction, which proceeded at 0.1 to 0.2 times the rate of the forward reactions, was inhibited by one of the products, alpha-ketoglutarate. K(m) values for the substrates of this reaction were 10 mm for alpha-hydroxyglutarate and 1 mm for nicotinamide adenine dinucleotide. alpha-Ketoglutarate reductase has a molecular weight of 7.5 x 10(4) to 8.2 x 10(4) and is composed of identical polypeptide chains with a molecular weight of 3.6 x 10(4) to 3.8 x 10(4).
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PMID:Purification and properties of alpha-ketoglutarate reductase from Micrococcus aerogenes. 439 93

In Neurospora crassa the assimilation of high and low concentrations of ammonium occurs by two different pathways. When the fungi are growing exponentially on ammonium excess, this compound is fixed by a glutamic dehydrogenase and an octameric glutamine synthetase (GS). The synthesis of this GS polypeptide (beta) is regulated by the nitrogen source present in excess; being higher on glutamate, intermediate on ammonium, and lower on glutamine. When N. crassa is growing in fed-batch ammonium-limited cultures a different polypeptide of GS (alpha), arranged as a tetramer, is synthesized. In both conditions synthesis in vivo correlates with the data obtained with an in vitro translation system primed with N. crassa RNA. This different expression of alpha and beta GS polypeptides was also observed when the cultures were shifted from excess to low nitrogen, and vice versa. By agarose gel electrophoresis in the presence of methylmercury hydroxide, some separation of different mRNAs that direct the in vitro synthesis of alpha and beta GS polypeptides has been accomplished. Data are presented that establish the operation of the tetrameric alpha GS and of glutamate synthase in the assimilation of ammonium in low concentration.
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PMID:Physiology of ammonium assimilation in Neurospora crassa. 612 Sep 27


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