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)

Fed and fasted rats were injected with L-tryptophan (12.5 mg/100 g body weight) and the specific activities of L-glutamic: NAD oxidoreductase (deaminating) (EC 1.4.1.2) (GDH), L-aspartic-2-ketoglutaric aminotransferase (EC 2.6.1.1) (GOT) and L-alanine-2-ketoglutaric aminotransferase (EC 2.6.1.2) (GPT) from hepatic mitochondria and cytosol were compared. L-tryptophan results in a decrease of mitochondrial GDH activity by 22% and of cytosolic GPT and GOT by 42% and 38% respectively in the liver of fasted rats. Xanthurenate is a potent inhibitor of purified extramitochondrial GPT, whereas anthranilate and quinolinate are less potent inhibitors. L-tryptophan, 5-OH-tryptophan and indole exert a slight inhibition. Kynurenine, 5-OH-tryptamine, tryptamine, picolinic acid, nicotinic acid and indoloacetic acid do not show any inhibition of GPT. It is suggested that L-tryptophan injection inhibits extramitochondrial GPT by its transformation to xanthurenate and anthranilate.
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PMID:Effect of L-tryptophan injection in rats on some enzymes of amino acid metabolism in liver. I. In vitro studies of the effect of L-tryptophan and its metabolites on the extramitochondrial L-alanine: 2-ketoglutaric aminotransferase. 722 74

A procedure for purification of glutamate dehydrogenase (GDH; L-glutamate NAD(P) oxidoreductase, EC 1.4.1.3) from beef brain has been developed. The enzyme preparation obtained has the specific activity of 6.7 units per mg of protein (192-fold enhance with a 30% yield of total activity of the homogenate). In some of its physico-chemical properties (pH optimum of catalyzed reactions, molecular weight, subunit structure, thermal stability) the brain GDH is identical to the enzyme from beef liver. The Km values for most of the coenzymes and substrates for the enzyme studied do not exceed those for beef liver enzyme more than 1,5--2-fold. The only exception is the Km value for glutamate, which in the case of brain GDH is 4 times less than that for the liver enzyme. The results obtained suggest that upon interaction with NAD the brain GDH reveals a relatively higher affinity for L-glutamate and L-ketoglutarate as compared to the liver enzyme.
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PMID:[Purification and some physico-chemical properties of glutamate dehydrogenase from beef brain]. 738 66

NAD-specific glutamate dehydrogenase [L-glutamate: NAD+ oxidoreductase (deaminating) EC 1.4.1.2] from Medicago sativa constitutes organ-specific patterns of isoenzymes. The isoenzyme-patterns of seeds (GDH-I) and roots (GDH-II) were purified 1520-fold and 92-fold, respectively. All isoenzymes of both patterns remain stable throughout the purification procedures. Isoenzyme a7, the only isoenzyme common to both patterns was isolated from the GDH-I pattern. The three enzyme preparations were found to be identical in pH optima, substrate specificity and general kinetic properties. A comparative kinetic analysis revealed no pronounced differences between the various kinetic constants evaluated for the three enzyme preparations. Furthermore an identical order of substrate binding and product release could be established. Both initial rate measurements and product inhibition studies are consistent with an ordered ternary-binary kinetic mechanism. The results suggest that tissue-specific enzyme multiplicity of plant glutamate dehydrogenase is not related to differences in general or kinetic properties.
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PMID:Glutamate dehydrogenase from Medicago sativa L., purification and comparative kinetic studies of the organ-specific multiple forms. 740 65

Urea-induced effects in clostridial glutamate dehydrogenase (GDH, EC 1.4.1.2) were studied by spectrophotometry, circular dichroism, FPLC, affinity chromatography and PAGE. Denaturation of enzyme occurred over a narrow range of urea concentrations (2.5-3.5 M), accompanied by inactivation of enzyme with a similar rate constant. The contribution of instantaneous inhibition by urea was also ascertained. FPLC studies of urea-treated GDH gave no evidence for dissociated oligomeric fragments of the hexamer in the presence of subdenaturing concentrations of urea. Likewise a mixture of fully 5,5'-dithiobis-(2-nitrobenzoic acid)-modified GDH hexamers and unmodified enzyme in 2 M urea failed to give rise to hybrid molecules. Exposure of unmodified GDH to high concentrations of urea led to the dissociation of hexamers to denatured monomers followed by association to form non-specific high-M(r) aggregates. This conclusion was confirmed by native gradient PAGE experiments. Various specific ligands stabilized the enzyme against urea-induced inactivation, succinate and 2-oxoglutarate being particularly effective. This protection of the native state was enhanced in ternary complexes, and the complex most resistant to urea-induced inactivation was the productive ternary complex GDH-NADH-2-oxoglutarate. Native gradient PAGE experiments indicate that these protecting ligands preserve the native hexameric structure of GDH.
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PMID:Urea-induced inactivation and denaturation of clostridial glutamate dehydrogenase: the absence of stable dimeric or trimeric intermediates. 748 49

Two mutants carrying different deletions of the IMP2 coding sequence of Saccharomyces cerevisiae, delta T1, which encodes a protein lacking the last 26 C-terminal amino acids, and delta T2, which completely lacks the coding region, were analysed for derepression of glucose-repressible maltose, galactose, raffinose and ethanol utilization pathways in response to glucose limitation. The role of the IMP2 gene product in the regulation of carbon catabolite repressible enzymes maltase, invertase, alcohol dehydrogenase, NAD-dependent glutamate dehydrogenase (NAD-GDH) and L-lactate:ferricytochrome-c oxidoreductase (L-LCR) was also analysed. The IMP2 gene product is required for the rapid glucose derepression of all above-mentioned carbon source utilization pathways and of all the enzymes except for L-LCR. NAD-GDH is regulated by IMP2 in the opposite way and, in fact, this enzyme was released at higher levels in both imp2 mutants than in the wild-type strain. Therefore, the product of IMP2 appears to be involved in positive and negative regulation. Both deletions result in growth and catalytic defects; in some cases partial modification of the gene product yielded more dramatic effects than its complete absence. Moreover, evidence is provided that the IMP2 gene product regulates galactose- and maltose-inducible genes at the transcriptional level and is a positive regulator of maltase, maltose permease and galactose permease gene expression.
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PMID:IMP2, a gene involved in the expression of glucose-repressible genes in Saccharomyces cerevisiae. 749 32

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).
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PMID:Isolation and characterization of a cDNA that encodes maize glutamate dehydrogenase. 755 85

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.
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PMID:A Drosophila hsp70 gene contains long, antiparallel, coupled open reading frames (LAC ORFs) conserved in homologous loci. 756 28

Two soluble forms of novel glutamate dehydrogenase isoproteins, designated GDH I and GDH II, have been purified from bovine brain. GDH I and GDH II were separated on a hydroxyapatite column and eluted by a step gradient at different phosphate concentrations (30 mM and 50 mM for GDH I and GDH II, respectively). The preparations were homogeneous on SDS/PAGE. GDH I and GDH II showed similarity in their molecular sizes and are composed of six identical subunits having a molecular size of 57,500 Da. Differences between the biochemical properties of GDH I and GDH II, such as N-terminal amino acid sequences of intact and tryptic-digested enzymes, kinetic parameters, optimum pH and heat stability, were extensively examined in both reductive amination of alpha-oxoglutarate and oxidative deamination of glutamate. The different effects of ADP on GDH isoproteins were also studied under various conditions. These results indicate that GDH I and GDH II, isolated from bovine brain, are novel and distinct polypeptides.
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PMID:Two soluble forms of glutamate dehydrogenase isoproteins from bovine brain. 758 64

The nicotinamide adenine dinucleotide phosphate (NADP)-dependent glutamate dehydrogenase (NADP-GDH) of Agaricus bisporus, a key enzyme in ammonia assimilation, was purified to apparent electrophoretic homogeneity with 27% recovery of the initial activity. The molecular weight of the native enzyme was 330 kDa. The enzyme is probably a hexamer, composed of identical subunits of 48 kDa. The isoelectric point of the enzyme was found at pH 4.8. The N-terminus appeared to be blocked. The enzyme was specific for NADP(H). The Km-values were 2.1, 3.2, 0.074, 27.0, and 0.117 mM for ammonia, 2-oxoglutarate, NADPH, L-glutamate, and NADP respectively. The pH optima for the amination and deamination reactions were found to be 7.6 and 9.0, respectively. The temperature optimum was 33 degrees C. The effect of several metabolites on the enzyme's activity was tested. Pyruvate, oxaloacetate, ADP, and ATP showed some inhibitory effect. Divalent cations slightly stimulated the aminating reaction. Antibodies raised against the purified enzyme were able to precipitate NADP-GDH activity from a cell-free extract in an anticatalytic immunoprecipitation test. Analysis of a Western blot showed the antibodies to be specific for NADP-GDH.
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PMID:Purification and characterization of NADP-dependent glutamate dehydrogenase from the commercial mushroom Agaricus bisporus. 776 94

The aim of the present study is to compare normal and tumoral pancreatic islet cells in terms of both the activity of selected cytosolic and mitochondrial enzymes participating to nutrient catabolism and the intrinsic properties of FAD-glycerophosphate dehydrogenase. The activity of the glycolytic enzymes hexokinase and lactate dehydrogenase was higher in tumoral (RINm5F) than normal islet cells. The opposite was seen for glutamate decarboxylase, glutamate-oxaloacetate transaminase, glutamate-pyruvate transaminase, glutamate dehydrogenase, 2-ketoglutarate dehydrogenase and FAD-glycerophosphate dehydrogenase (m-GDH). These findings are consistent with the high rates of glycolysis and protein synthesis seen in tumoral islet cells compared with normal islet cells, which favour mitochondrial oxidative events associated with the catabolism of D-glucose and amino acids. The intrinsic catalytic properties of m-GDH were comparable, albeit not identical, in normal and tumoral islet cells. Since a deficiency of m-GDH in pancreatic islets may represent a contributing factor in the pathogenesis of non-insulin-dependent diabetes, it is proposed that RINm5F cells may readily yield sufficient islet m-GDH for purification and further gene cloning.
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PMID:Activity of cytosolic and mitochondrial enzymes participating in nutrient catabolism of normal and tumoral islet cells. 776 86


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