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)

(1) Adult postprandial rats were given a continuous, intravenous infusion of 15N-labelled glutamate, alanine, ammonium chloride and glutamine amide for 6 h. The enrichment in the free hepatic pool was measured for ammonia, glutamine amide, urea, aspartate, glutamate and alanine. (2) Glutamine and glutamate supplied significantly more nitrogen to urea than ammonium chloride or alanine. (3) Glutamate was not a significant source of hepatic ammonia, hence in this situation it is not necessary to impute a major role to glutamate dehydrogenase in hepatic ammoniagenesis for urea synthesis. (4) Glutamine and ammonia, mostly of intestinal origin in the postprandial state, were major precursors of hepatic ammonia. (5) The nitrogen of glutamate and alanine moved to urea primarily through aspartic acid.
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PMID:In vivo metabolism of nitrogen precursors for urea synthesis in the postprandial rat. 290 40

Well coupled mitochondria were isolated from transplantable chicken hepatoma induced by MC-29 virus. The mitochondrial phosphate-dependent and phosphate-independent glutaminase activities were increased compared with those from normal chicken liver. Glutamate dehydrogenase was undetectable in the tumor mitochondria. Oxypolarographic tests showed the following: glutamine oxidation was prominent in the tumor mitochondria and was mediated through an NAD-linked reaction, while mitochondria from the liver showed a feeble glutamine oxidation; glutamine oxidation by tumor mitochondria was inhibited either by aminooxyacetate, inhibitor of transaminases, or prior incubation of mitochondria with DON (6-diazo-5-oxonorleucine), which inhibited mitochondrial glutaminases. Bromofuroate, inhibitor of glutamate dehydrogenase, had little or no effect; and glutamate oxidation was also inhibited by aminooxyacetate, while it was not affected by DON. These findings clearly show a high glutamate oxidation activity in the hepatoma and indicate that the product of glutamine hydrolysis, glutamate, is catabolized via transamination in the mitochondria to supply ATP.
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PMID:Prominent glutamine oxidation activity in mitochondria of avian transplantable hepatoma induced by MC-29 virus. 301 1

The literature concerning the metabolism of carbon and nitrogen compounds in ectomycorrhizal associations of trees is reviewed. The absorption and translocation of mineral ions by the mycelia require an energy source and a reductant which are both supplied by respiratory catabolism of carbohydrates produced by the host plant. Photosynthates are also required to generate the carbon skeletons for amino acid and carbohydrate syntheses during the growth of the mycelia. Competition for photosynthates occurs between the fungal cells and the various vegetative sinks in the host tree. The nature of carbon compounds involved in these processes, their routes of metabolism, the mechanisms of control and the partitioning of metabolites between the various sites of utilization are only poorly understood. Both ascomycetous and basidiomycetous ectomycorrhizal fungi synthesize and some, if not all, accumulate mannitol, trehalose and triglycerides. The fungal strains employ the Embden--Meyerhof pathway of glucose catabolism and the key enzymes of the pentose phosphate pathway (6-phosphogluconate dehydrogenase, glucose-6-phosphate dehydrogenase, transaldolase and transketolase). Anaplerotic CO2 fixation, via pyruvate carboxylase and/or phosphoenolpyruvate carboxykinase, provides high pools of amino acids. This process could be important in the recapture and assimilation of respired CO2 in the rhizosphere. The ectomycorrhizas are thought to contain the Embden--Meyerhof pathway, the pentose phosphate pathway and the tricarboxylic acid cycle, which provide the carbon skeletons for the assimilation of ammonia into amino acids. The main route of assimilation of ammonia appears to be through the glutamine synthetase-glutamate synthase cycle in the ectomycorrhizas. Glutamate dehydrogenase plays a minor role in this process. Glutamate dehydrogenase and glutamine synthetase are present in free-living ectomycorrhizal fungi and they participate in the assimilation of ammonia and the synthesis of amino acids through the glutamate dehydrogenase/glutamine synthetase sequence. In both in vitro cultures of fungi and ectomycorrhizas, the assimilated nitrogen accumulates in glutamine. Glutamine, but also ammonia, are thought to be exported from the fungal tissues to the host cells. Studies on the metabolism of ectomycorrhizas and ectomycorrhizal fungi have focused on the metabolic pathways and compounds which accumulate in the symbiotic tissues. Studies on regulation of the overall process, and the control of enzyme activity in particular, are still fragmentary.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Carbon and nitrogen metabolism in ectomycorrhizal fungi and ectomycorrhizas. 312 Jul 92

Glutamate dehydrogenase and carbamoyl phosphate synthase-I were localized in rat liver by immunogold procedures, using monoclonal and polyclonal antibodies. As expected, there was extensive labeling in mitochondria. Label was also found in lysosomal autophagic vacuoles. When autophagy was stimulated by in vivo administration of the anti-microtubular agent vinblastine we found that: (a) carbamoyl phosphate synthase-I and glutamate dehydrogenase could be found in mitochondria within autophagic vacuoles; (b) the carbamoyl phosphate synthase-I and glutamate dehydrogenase content of the mitochondria sequestered into autophagic vacuoles is the same as that of the nearby "free" mitochondria; and (c) in the whole liver, autophagic vacuoles contain c. 1.5 times more glutamate dehydrogenase than carbamoyl phosphate synthase-I, in contrast to mitochondria which have c. three times more carbamoyl phosphate synthase-I than glutamate dehydrogenase. The latter finding could explain, at least partially, the difference in half-lives of these enzymes.
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PMID:Autophagy of mitochondria in rat liver assessed by immunogold procedures. 317 Nov 66

Glutamate dehydrogenase was purified from the liver of immature (4-weeks), young (22-weeks) and old (116-weeks) female rats to study the effect of age on this enzyme. From 30 g of liver tissue of each age group, approximately 90-fold purified enzyme was obtained in crystalline form with an average yield of 4% of the original enzyme activity. This 4% enzyme was used extensively for analyzing its age-related properties. The elution profile on a Sephadex G-200 column, molecular weight (53,000 +/- 3,000), ratio of A280/260 (1.8), optimum pH (7.8), optimum temperature (25 degrees C), and Km values for different substrates/coenzymes of the purified enzymes did not show marked age-dependent variations. Similarly, remarkable differences were not observed in the effect of a variety of nucleotides or steroid hormones on the activity of the purified enzymes of the three ages. These findings may suggest that rat liver glutamate dehydrogenase is an unaltered enzyme with advancing age of the animal.
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PMID:Properties of purified liver glutamate dehydrogenase of aging rats. 322 34

In adult rat liver, glutamate dehydrogenase is present in high concentrations around the terminal portal (zone 1) and hepatic (zone 3) veins, whereas its concentration is low in the intermediate zone. Although the size and staining intensity of the periportal glutamate dehydrogenase-positive compartment are less than those of the pericentral compartment, it can expand under appropriate endocrine conditions, leading to a homogeneous distribution. At birth, glutamate dehydrogenase is also homogeneously distributed. Glutamate dehydrogenase disappears from the periportal compartment during the first postnatal week and reappears in that compartment after weaning. These observations indicate an independent regulation of glutamate dehydrogenase levels in the periportal and pericentral zone. The size of the periportal glutamate dehydrogenase-containing zone is appreciably smaller than that of carbamoylphosphate synthetase, whereas the pericentral glutamate dehydrogenase-containing zone is appreciably larger than that of glutamine synthetase. The heterogeneous distribution of glutamate dehydrogenase suggests the possibility that, under normal conditions, deamination of glutamate prevails in the periportal compartment and amination of glutamate in the pericentral compartment.
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PMID:Immunohistochemical localization of glutamate dehydrogenase in rat liver: plasticity of distribution during development and with hormone treatment. 333 69

Glutamate appears to be the neurotransmitter of granule cells, the major neuronal population of the cerebellar cortex. To determine the role of astroglial cells in the synthesis of glutamate, we have measured the specific activity of glutamate dehydrogenase (GDH) in clonal cell lines that might be the in vitro equivalents of the different cerebellum astroglial cell types. In conditions where GDH operates in the direction of glutamate synthesis, the specific activity of GDH measured in the "Golgi-Bergmann"-like clone was 4-6 times higher than in the "velate protoplasmic"- or "fibrous-like" astrocytic clones. These data correlate well with the intense immunoreactivity to GDH in Golgi-Bergmann astrocytes in vivo that has been recently reported.
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PMID:Glutamate dehydrogenase activity is markedly higher in a "Golgi-Bergmann"-like glial clone than in other astroglial cell lines. 333 66

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

Glutamate dehydrogenase (GDH, EC 1.4.1.2) has long been used as a marker for mitochondria in brain and other tissues, despite reports indicating that GDH is also present in nuclei of liver and dorsal root ganglia. To examine whether GDH can be used as a marker to differentiate between mitochondria and nuclei in the brain, we have measured GDH by enzymatic activity and on immunoblots in rat brain mitochondria and nuclei which were highly enriched by density-gradient centrifugation methods. The activity of GDH was enriched in the nuclear fraction as well as in the mitochondrial fraction, while the activities of other "mitochondrial" enzymes (fumarase, NAD-isocitrate dehydrogenase and pyruvate dehydrogenase complex) were enriched only in the mitochondrial fraction. Immunoblots using polyclonal antibodies against bovine liver GDH confirmed the presence of GDH in the rat brain nuclear and mitochondrial fractions. The GDH in these two subcellular fractions had a very similar molecular weight of 56,000 daltons. The mitochondrial and nuclear GDH differed, however, in their susceptibility to solubilization by detergents and salts. The mitochondrial GDH could be solubilized by extraction with low concentrations of detergents (0.1% Triton X-100 and 0.1% Lubrol PX), while the nuclear GDH could be solubilized only by elevated concentrations of detergents (0.3% each) plus KCl (greater than 150 mM). Our results indicate that GDH is present in both nuclei and mitochondria in rat brain. The notion that GDH may serve as a marker for mitochondria needs to be re-evaluated.
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PMID:The subcellular localization of glutamate dehydrogenase (GDH): is GDH a marker for mitochondria in brain? 352 73

A scheme for the quantitative detection of aspartate aminotransferase isoenzymes and multiple forms after electrophoretic separation is described. Glutamate generated from the aminotransferase reaction is quantitated by using the glutamate dehydrogenase/diaphorase-coupled enzyme system to form a formazan dye. Product inhibition of aspartate aminotransferase by oxaloacetate is prevented by including oxaloacetate decarboxylase in the overlay reagent. Results compare favorably with those of an immunochemical precipitation procedure. The method can also be used to detect quantitatively subforms and atypical forms (genetic variants, immunoglobulin-enzyme complexes) of aspartate aminotransferase.
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PMID:Quantitation of aspartate aminotransferase isoenzymes after electrophoretic separation. 357 88


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