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)

We developed a quantitative histochemical assay for measurement of local glutamate concentrations in cryostat sections of rat liver. Deamination of glutamate by glutamate dehydrogenase (GDH) was coupled to the production of formazan and formazan precipitation was used for colorimetric visualization. The method was tested and validated with gelatin model sections with known glutamate concentrations. Calibration graphs showed linear relationships with high correlation coefficients (> 96%) between glutamate concentrations or section thickness and absorbance values. The method was reproducible, with a constant percentage of 60 +/- 5% of glutamate being converted in gelatin model sections containing glutamate concentrations of 2 mM and higher. Glutamate concentrations were estimated in periportal, intermediate, and pericentral zones of liver lobules that contain low, intermediate, and high GDH activity, respectively. In fed adult male rat livers, periportal zones contained the highest concentrations of glutamate (approximately 14 mM) and intermediate and pericentral zones approximately 13 and 9 mM, respectively. On starvation, glutamate concentrations increased only in the small rim of pericentral cells that express glutamine synthetase, to approximately 15 mM. In livers of fetal and newborn rats, glutamate was homogeneously distributed, with a concentration of approximately 5 mM. In suckling rat liver, distribution of glutamate was still homogeneous but the concentration was increased to approximately 8 mM. These glutamate distribution patterns were in agreement with those detected immunohistochemically.
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PMID:In situ measurement of glutamate concentrations in the periportal, intermediate, and pericentral zones of rat liver. 928 9

The nucleotide sequence of the gene encoding the glucose-regulated protein 78 (GRP78) of Neurospora crassa was determined. The ORF codes for a protein of 662 amino acids (72 kDa) and belongs to the heat shock protein 70 (hsp70) gene family, which is characterized by three HSP70 'signature sequences'. The grp78 gene contains 5 introns. The protein carries the ER retention signal HDEL at its carboxy terminus and is most homologous to the KAR2/GRP78 protein of Saccharomyces cerevisiae (78%) and to KAR2/BiP of Yarrowia lipolytica (76%). The expression of grp78 is constitutive and can be enhanced by starvation, treatment with tunicamycin, the calcium ionophore A23187 or elevated temperatures (40 degrees C). An uninterrupted ORF was found on the reverse cDNA strand of grp78. The putative peptide shows 47% homology to the NAD-specific glutamate dehydrogenase of Achlya klebsiana.
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PMID:Molecular analysis of a glucose-regulated gene (grp78) of Neurospora crassa. 954 20

In fish, metabolic changes and qualitative responses during different nutritional situations are highly controversial in the scientific literature, and for this reason the objective of this work has been to probe deeper into the adaptive behaviour of two important amino acid-metabolising enzymes, glutamate dehydrogenase (GDH) and alanine aminotransferase (AAT) of liver and kidney in trout. In the present study, we examined the long-term effects of endogenous or exogenous proteins--generated, respectively, by a prolonged starvation or by feeding a high-protein diet--on the kinetics of liver and kidney GDH and AAT. Feeding on a high-protein diet significantly increased the liver (100%) and kidney (49%) GDH Vmax and catalytic efficiency; the same kinetic parameters of AAT increased by 65% only in the liver enzyme, without changing the Km and activity ratio values. Starvation registered a significant increase of both enzymes, Vmax and catalytic efficiency in the liver, but activity was unaltered in the kidney. In addition, no significant changes were found in the Km or activity ratio. All enzyme kinetics showed a Michaelian behaviour without any evidence of sigmoidicity. The experimental results show strong adaptive responses in the kinetic behaviour of the enzymes of both tissues. With the exception of renal AAT, the remainder of the enzymes presented a marked influence in their kinetic parameters by an excess of protein. The results are discussed in terms of the possible adaptive role of enzyme kinetics to amino acid availability.
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PMID:Long-term nutritional effects on the primary liver and kidney metabolism in rainbow trout. Adaptive response to starvation and a high-protein, carbohydrate-free diet on glutamate dehydrogenase and alanine aminotransferase kinetics. 967 61

The glutamine metabolism was studied in glucose-starved and glucose-sufficient hybridoma and Sp2/0-Ag14 myeloma cells. Glucose starvation was attained by cultivating the hybridoma cells with fructose instead of glucose, and the myeloma cells with a low initial glucose concentration which was rapidly exhausted. Glutamine used in the experiments was labeled with 15N, either in the amine or in the amide position. The fate of the label was monitored by 1H/15N NMR analysis of released 15NH+4 and 15N-alanine. Thus, NH+4 formed via glutaminase (GLNase) could be distinguished from NH+4 formed via glutamate dehydrogenase (GDH). In the glucose-sufficient cells a small but measurable amount of 15NH+4 released by GDH could be detected in both cell lines (0.75 and 0.31 micromole/10(6) cells for hybridoma and myeloma cells, respectively). The uptake of glutamine and the total production of NH+4 was significantly increased in both fructose-grown hybridoma and glucose-starved myeloma cells, as compared to the glucose-sufficient cells. The increased NH+4 production was due to an increased throughput via GLNase (1.6 -1.9-fold in the hybridoma, and 2.7-fold in the myeloma cell line) and an even further increased metabolism via GDH (4.8-7.9-fold in the hybridoma cells, and 3.1-fold in the myeloma cells). The data indicate that both GLNase and GDH are down-regulated when glucose is in excess, but up-regulated in glucose-starved cells. It was calculated that the maximum potential ATP production from glutamine could increase by 35-40 % in the fructose-grown hybridoma cells, mainly due to the increased metabolism via GDH.
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PMID:Elevated glutamate dehydrogenase flux in glucose-deprived hybridoma and myeloma cells: evidence from 1H/15N NMR. 1009 57

Seven female and three male common wombats (Vombatus ursinus) collected from forested areas of Victoria (Australia) over a 10 mo period, 10 April 1997 to 22 February 1998 had at least 30% of their skin affected by severe hyperkeratotic sarcoptic mange. Mangy wombats were grazing during the day, could be readily approached, were in poor body condition, and lacked subcutaneous fat. The anterolateral surface of the body was most heavily parasitised with Sarcoptes scabiei var wombati followed by the posterolateral surface, the dorsal region between the ears, the ears, ventral abdomen, medial aspect of the legs, axillary and inguinal areas, and the dorsal midline. Larvae were the most prevalent life-cycle stage followed by eggs, nymphs, females, and males. Mite numbers and the severity of clinical signs, namely thickness of scale crust and the degree of alopecia, were correlated and were symmetrical on each side of the body. Fissuring of crust and skin only occurred when scale crust was present. Bacterial infections occurred in three of 10 wombats within lymph nodes or the pleural cavity. Lymphoid depletion did not occur in lymph nodes or spleens and prescapular lymph nodes contained a greater amount of nuclear debris in germinal centres than non-mangy wombats. Seven wombats had fatty change in their livers. Gonads of mature wombats were not active or had minimal activity. Significant histopathological changes were not seen in the gastrointestinal tract, kidney, brain, myocardium, spleen, thyroid, reproductive tract, and gonads. Hematocrit, mean corpuscular volume, mean corpuscular hemoglobin, and concentrations of hemoglobin, lymphocytes, calcium, glucose, creatinine, total solids, total protein, albumin determined both colormetrically and electrophoretically, and globulins were significantly lower and concentrations of neutrophils, monocytes, phosphorus, urea, glutamate dehydrogenase, aspartate aminotransferase and creatine kinase were significantly higher in mangy versus captive wombats. Concentrations of erythrocytes, mean corpuscular hemoglobin, leucocytes, band neutrophils, eosinophils, nucleated erythrocytes, sodium, potassium, chloride, total bilirubin, alkaline phosphatase, and gamma glutamyltransferase for mangy wombats were not significantly different from that reported for captive wombats. Hematological and pathological changes in mangy wombats were consistent with anemia, inflammation, and changes seen with starvation.
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PMID:Distribution of life cycle stages of Sarcoptes scabiei var wombati and effects of severe mange on common wombats in Victoria. 1057 22

It has been shown recently that glutamine is taken up by the mouse kidney in vivo. However, knowledge about the fate of this amino acid and the regulation of its metabolism in the mouse kidney remains poor. Given the physiological and pathophysiological importance of renal glutamine metabolism and the increasing use of genetically modified mice in biological research, we have conducted a study to characterize glutamine metabolism in the mouse kidney. Proximal tubules isolated from fed and 48 h-starved mice and then incubated with a physiological concentration of glutamine, removed this amino acid and produced ammonium ions at similar rates. In agreement with this observation, activities of the ammoniagenic enzymes, glutaminase and glutamate dehydrogenase, were not different in the renal cortex of fed and starved mice, but the glutamate dehydrogenase mRNA level was elevated 4.5-fold in the renal cortex from starved mice. In contrast, glucose production from glutamine was greatly stimulated whereas the glutamine carbon removed, that was presumably completely oxidized in tubules from fed mice, was virtually suppressed in tubules from starved animals. In accordance with the starvation-induced stimulation of glutamine gluconeogenesis, the activities and mRNA levels of glucose-6-phosphatase, and especially of phosphoenolpyruvate carboxykinase, but not of fructose-1,6-bisphosphatase, were increased in the renal cortex of starved mice. On the basis of our in vitro results, the elevated urinary excretion of ammonium ions observed in starved mice probably reflected an increased transport of these ions into the urine at the expense of those released into the renal veins rather than a stimulation of renal ammoniagenesis.
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PMID:Effect of starvation on glutamine ammoniagenesis and gluconeogenesis in isolated mouse kidney tubules. 1216 89

Birds have evolved alternate physiologic strategies to contend with dehydration, starvation, malnutrition, and reproduction. Basic anatomic and functional differences between birds and mammals impact clinical chemistry values and their evaluation. Interpretation of the results of standard biochemical analyses, including BUN, alanine aminotransferase, aspartate aminotransferase, creatine kinase, gamma glutamyltransferase, bilirubin, ammonia, alkaline phosphatase, cholesterol, bile acids, glucose, albumin, globulins, calcium, phosphorus, prealbumin (transthyretin), fibrinogen, iron, and ferritin, is reviewed and discussed in relation to these physiological differences. The use and interpretation of alternative analytes appropriate for avian species, such as uric acid, biliverdin, glutamate dehydrogenase, and galactose clearance, also are reviewed. Normal avian urine and appropriate use of urinalysis, an integral part of laboratory diagnosis in mammalian species that frequently is omitted from avian diagnostic protocols, is discussed.
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PMID:Clinical chemistry of companion avian species: a review. 1218 2

The nucleotide sequences reported in this paper have been submitted to the GenBank(R)/EBI Nucleotide Sequence Databases with accession numbers AF462037 (glutamine synthetase) and AF462032 (glutamate synthase). Nitrogen retrieval and assimilation by symbiotic ectomycorrhizal fungi is thought to play a central role in the mutualistic interaction between these organisms and their plant hosts. Here we report on the molecular characterization of the key N-assimilation enzyme glutamine synthetase from the mycorrhizal ascomycete Tuber borchii (TbGS). TbGS displayed a strong positive co-operativity ( n =1.7+/-0.29) and an unusually high S(0.5) value (54+/-16 mM; S(0.5) is the substrate concentration value at which v =(1/2) V (max)) for glutamate, and a correspondingly low sensitivity towards inhibition by the glutamate analogue herbicide phosphinothricin. The TbGS mRNA, which is encoded by a single-copy gene in the Tuber genome, was up-regulated in N-starved mycelia and returned to basal levels upon resupplementation of various forms of N, the most effective of which was nitrate. Both responses were accompanied by parallel variations of TbGS protein amount and glutamine synthetase activity, thus indicating that TbGS levels are primarily controlled at the pre-translational level. As revealed by a comparative analysis of the TbGS mRNA and of the mRNAs for the metabolically related enzymes glutamate dehydrogenase and glutamate synthase, TbGS is not only the sole messenger that positively responds to N starvation, but also the most abundant under N-limiting conditions. A similar, but even more discriminating expression pattern, with practically undetectable glutamate dehydrogenase mRNA levels, was observed in fruitbodies. The TbGS mRNA was also found to be expressed in symbiosis-engaged hyphae, with distinctively higher hybridization signals in hyphae that were penetrating among and within root cells.
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PMID:Distinctive properties and expression profiles of glutamine synthetase from a plant symbiotic fungus. 1268 51

The metabolic, biochemical and molecular events occurring in the different leaf stages along the main axis of tobacco (Nicotiana tabacum) plants grown either on a nitrogen-rich medium, on a medium containing ammonium as sole nitrogen source or on a nitrogen-depleted medium, are presented. This study shows that the highest induction of cytosolic glutamine synthetase (GS1) protein and transcript occurs when nitrogen remobilization is maximal as the result of nitrogen starvation, whereas both glutamate dehydrogenase (GDH) transcript and activity remain at a very low level. In contrast, GDH is highly induced when plants are grown on ammonium as sole nitrogen source, a physiological situation during which leaf protein nitrogen remobilization is limited. It is therefore concluded that GDH does not play a direct role during the process of nitrogen remobilization but is rather induced following a built up of ammonium provided externally or released as the result of protein hydrolysis during natural leaf senescence.
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PMID:New insights towards the function of glutamate dehydrogenase revealed during source-sink transition of tobacco (Nicotiana tabacum) plants grown under different nitrogen regimes. 1503 56

We undertook the study of the use of glutamine (Gln) as the source of carbon and energy by Rhizobium etli. Tn5-induced mutagenesis allowed us to identify several genes required for Gln utilization, including those coding for two broad-range amino acid transporters and a glutamate dehydrogenase. The isolated mutants were characterized by the analysis of their capacity i) to grow on different media, ii) to transport Gln (uptake assays), and iii) to utilize Gln as the C energy source (CO2 production from Gln). We show that Gln is degraded through the citric acid cycle and that its utilization as the sole C source is related to a change in the bacterial cell shape (from bacillary to coccoid form) and a high susceptibility to a thiol oxidative insult. Both these data and the analysis of ntr-dependent promoters suggested that Gln-grown bacteria are under a condition of C starvation and N sufficiency, and as expected, the addition of glucose counteracted the morphological change and increased both the bacterial growth rate and their resistance to oxidative stress. Finally, a nodulation analysis indicates that the genes involved in Gln transport and degradation are dispensable for the bacterial ability to induce and invade developing nodules, whereas those involved in gluconeogenesis and nucleotide biosynthesis are strictly required.
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PMID:Glutamine utilization by Rhizobium etli. 1524 66


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