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 gene (GDH1) coding for the NADP-linked glutamate dehydrogenase system (NADP-GDH) has been cloned from Saccharomyces cerevisiae strain. Cells being transformed by the NADP-GDH gene on a 2 micron bared vector (pCYG4) plasmid confering 11-fold higher level on expressed GDH activity over the wild-type cells. The behavior of these cells was investigated under chemostatic growth with a carbon rate-limiting nutrient. Specific growth rates of cells carrying plasmid pCYG4 were found to be slightly slower than wild type cells. Furthermore, the NADP-GDH activity increases proportionally with the dilution rate. In addition, oscillations in the NADP-GDH activity, especially at a dilution rate up to 0.15/h, are probably consequential on the appearance of a changing mixed population (cells with and without plasmids).
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PMID:Studies on Saccharomyces cerevisiae under carbon-limiting growth transformed with plasmid pCYG4 that carries the gene for NADP-GDH. 215 63

We have constructed a series of deletions in the 5' non-coding sequences of the cloned Neurospora crassa am gene which specifies NADP specific glutamate dehydrogenase. All of the deletions begin at -4.4 kb with respect to the am transcription start site and extend for various distances toward the am gene. Using vectors with a truncated fragment of the am gene, we introduced these deletions into the chromosome upstream of am by transformation. Analysis of glutamate dehydrogenase expression in strains with the deletion mutations confirmed that there are two upstream regulatory sequences (URS) that control the expression of the am gene. The more distal of these elements (URSam beta) has been limited to the 157 bp between -1924 and -2081 with respect to the start of am transcription. The proximal element (URSam alpha) was limited to the 97 bp between -1296 and -1393. The DNA sequence of the entire region was determined. Within the sequences that contain the URS elements several regions of homology with yeast UAS sequences were found. Gel mobility assays with DNA fragments containing the URS elements indicated that sequences in both elements are bound by nuclear proteins from Neurospora. The interaction of these proteins and the DNA fragments was found to be specific.
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PMID:Nucleotide sequence and nuclear protein binding of the two regulatory sequences upstream of the am (GDH) gene in Neurospora. 216 25

We report here that the gdhA gene of Escherichia coli, which encodes the NADP-specific glutamate dehydrogenase, is located at 38.6 min on the map. We have confirmed this location by showing linkage with three Tn10 insertions that are linked to the aroD, pheS, and ansA loci, by complementation by a restriction-mapped lambda clone, and by showing correspondence between the restriction maps of the chromosome and the cloned and sequenced gdhA gene.
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PMID:The gdhA gene is located at 38.6 minutes on the Escherichia coli map. 217 Mar 42

Selected aspects of the metabolism of Plasmodium falciparum are reviewed, but conclusions based on the study of other species of plasmodia are intentionally not included since these may not be applicable. The parasites increase glucose consumption 50-100 fold as compared to uninfected red cells; most of the glucose is metabolized to lactic acid. The parasite contains a complete set of glycolytic enzymes. Some enzymes such a hexokinase, enolase and pyruvate kinase are vastly increased over corresponding levels in uninfected red cells. However, the pathway for synthesizing 2,3-diphosphoglycerate (2,3-DPG) is absent. Parasitized red cells show a decline in the concentration of 2,3-DPG which may function as an inhibitor for certain essential enzyme pathways. Pentose shunt activity is increased in absolute terms, but as a percent of total glucose consumption, there is a decrease during parasite infection of the red cell. The parasite contains a gene for G6PD and can produce a small quantity of parasite-encoded enzyme. It is not clear if the production of this enzyme can be up-regulated in G6PG deficient host red cells. The NADPH normally produced by the pentose shunt can be obtained from other parasite pathways (such as glutamate dehydrogenase). NADPH may subserve additional needs in the infected red cell such as driving diribonucleotide reductase activity--a rate limiting enzyme in DNA synthesis. The role of NADPH in protecting the parasite-red cell system against oxidative stress (via glutathione reduction) remains controversial. Parasitized red cells contain about 10 times more NAD(H) than uninfected red cells, but the NADP(H) content is unchanged.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Plasmodium falciparum carbohydrate metabolism: a connection between host cell and parasite. 225 22

Premeiotic inactivation of duplicated sequences (the RIP phenomenon of Selker et al.) was studied by tetrad analysis using ectopic copies of am+ (coding for NADP-specific glutamate dehydrogenase) and a missense allele am3, coding for a distinctive form of the enzyme, at the normal locus. In duplication crosses either both gene copies were inactivated or neither. Two inactivated am3 derivatives were shown to have undergone methylation and numerous base-pair changes, reflected in losses and gains of restriction sites, but without sequence rearrangement. Cutting at restriction sites within the disrupted sequences was incomplete but became almost complete following growth in the presence of 5-azacytidine. In a triplication cross in which one parent carried two unlinked ectopic gene copies together with am3 at the normal locus, premeiotic inactivation, when it occurred, tended to affect two of the three copies in any one ascus, but there were a few asci in which all three were inactivated.
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PMID:Premeiotic disruption of duplicated and triplicated copies of the Neurospora crassa am (glutamate dehydrogenase) gene. 252 44

The glutamine synthetase and the NADP-specific glutamate dehydrogenase activities of Neurospora crassa were lost in a culture without carbon source only when in the presence of air. Glutamine synthetase was previously reported to be liable to in vitro and in vivo inactivation by activated oxygen species. Here we report that NADP-specific glutamate dehydrogenase was remarkably stable in the presence of activated oxygen species but was rendered susceptible to oxidative inactivation when chelated iron was bound to the enzyme and either ascorbate or H2O2 reacted on the bound iron. This reaction gave rise to further modifications of the enzyme monomers by activated oxygen species, to partial dissociation of the oligomeric structure, and to precipitation and fragmentation of the enzyme. The in vitro oxidation reaction was affected by pH, temperature, and binding to the enzyme of NADPH. Heterogeneity in total charge was observed in the purified and immunoprecipitated enzymes, and the relative amounts of enzyme monomers with different isoelectric points changes with time of the oxidizing reaction.
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PMID:Oxidation of Neurospora crassa NADP-specific glutamate dehydrogenase by activated oxygen species. 253 Feb 8

Ammonia assimilation in Bacillus fastidiosus proceeds via the NADP-dependent glutamate dehydrogenase. The enzyme, purified to homogeneity, is composed of identical subunits with a molecular weight of about 48,000 dalton. Presumably the enzyme is a hexamer. The enzyme is specific for NADP(H). The pH optima for the amination and deamination reactions are 7.7 and 8.6, respectively. The temperature optimum is 60 degrees C. Furthermore, temperature stability and apparent Km values for substrates of both the amination and deamination reactions were determined. Several metabolites were tested for their effect on the enzyme activity. Only malate and fumarate showed some inhibitory effect.
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PMID:Purification and characterization of the NADP-dependent glutamate dehydrogenase from Bacillus fastidiosus. 254 90

Specific in vitro-generated insertion, replacement, and deletion mutations have been integrated near the chromosomal locus of am (NADP-specific glutamate dehydrogenase) of Neurospora crassa. Two approaches have been successful. One approach used am+-containing vectors capable of integrating at any site in the genome. This technique was used to introduce a specific 700 bp insertion near the am locus and to replace chromosomal sequences near am with plasmid DNA. Efficiency was low, however, and many transformants had to be screened to find the desired alterations among the ectopic insertions unless the incoming DNA had a large region of homology with the am region. A second approach increased the efficiency by using vectors containing a truncated am gene, so that prototrophs could arise only by homologous recombination. Overall transformation frequency was reduced relative to the first method, but a large fraction of the transformations involved specific alterations of the am region.
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PMID:Use of transformation to make targeted sequence alterations at the am (GDH) locus of Neurospora. 254 76

The nucleotide sequence of the Aspergillus nidulans gdhA gene encoding NADP linked glutamate dehydrogenase has been determined and Northern blot analysis used to study the regulation of expression of this gene. The gdhA gene is 1485 nucleotides long and, by comparison with the corresponding Neurospora crassa am gene, has two putative introns of 53 nucleotides and a protein encoding region of 1380 nucleotides that codes for an inferred protein of 49.63 kDa which shows regions of homology with glutamate dehydrogenase proteins from a range of organisms. mRNA analysis of wild-type mycelium grown under a variety of conditions shows that: (a) the highest levels are seen with glucose as the carbon source with inorganic nitrogen; and (b) no gdhA mRNA is detectable when cells are transferred to amino acids as sole carbon source, closely matching the observed glutamate dehydrogenase activity levels under identical conditions. The results presented strongly suggest that a good carbon source is a prerequisite for transcription, but the molecular mechanism responsible is unclear.
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PMID:Nucleotide sequence and regulation of expression of the Aspergillus nidulans gdhA gene encoding NADP dependent glutamate dehydrogenase. 255 Jul 58

Streptomyces fradiae has two chromatographically distinct forms of glutamate dehydrogenase (GDH): one GDH utilizes NAD as coenzyme, the other uses NADP. The intracellular level of both GDHs is strongly regulated by the nitrogen source in the growth medium. NADP-dependent GDH was purified to homogeneity from crude extracts of S. fradiae. The Mr of the native enzyme was determined to be 200,000 by size-exclusion high-performance liquid chromatography whereas after sodium dodecyl sulphate-polyacrylamide gel electrophoresis one major band of Mr 49,000 was found, suggesting that the enzyme is a tetramer. The enzyme was highly specific for the substrates 2-oxoglutarate and L-glutamate, and required NADP, which could not be replaced by NAD, as a cofactor. The pH optimum was 9.2 for oxidative deamination of glutamate and 8.4 for reductive amination of 2-oxoglutarate. The Michaelis constants (Km) were 28.6 mM for L-glutamate and 0.12 mM for NADP. Km values for reductive amination were 1.54 mM for 2-oxoglutarate, 0.07 mM for NADPH and 30.8 mM for NH+4. The enzyme activity was significantly reduced by adenine nucleotides, particularly ATP.
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PMID:Purification and properties of NADP-dependent glutamate dehydrogenase from Streptomyces fradiae. 256 88


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