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)

A single administration to rats of cyanamide (60 mg/kg, for 1 hour) was found to decrease the contents of cysteate, serine, glutamate, glycine, alanine, valine, methionine, isoleucine, tyrosine, ethanolamine, ornithine and histidine that may be considered as a manifestation on the drug hepatotoxicity. The activities of transaminases, glutamate dehydrogenase, pyruvate dehydrogenase remained unchanged. Cyanamide effects were considerably abolished by the supplementary ethanol administration (0.5 g/kg). Cyanamide failed to affect vitamin-dependent enzymes reflecting thiamine pyrophosphate, pyridoxal phosphate and flavine adenine dinucleotide status of the rat organism.
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PMID:[Free amino acids of the liver and the characteristics of the amino acid metabolism in the liver and brain after cyanamide administration to rats]. 222 67

1. Glutamine was found to be the main carbon and nitrogen product of the metabolism of aspartate in isolated guinea-pig kidney-cortex tubules. Glutamate, ammonia and alanine were only minor products. 2. Carbon-balance calculations and the release of 14CO2 from [U-14C]aspartate indicate that oxidation of the aspartate carbon skeleton occurred. 3. A pathway involving aspartate aminotransferase, glutamate dehydrogenase, glutamine synthetase, phosphoenolpyruvate carboxykinase, pyruvate kinase, pyruvate dehydrogenase and enzymes of the tricarboxylic acid cycle is proposed for the conversion of aspartate into glutamine. 4. Evidence for this pathway was obtained by: (i) inhibiting aspartate removal by amino-oxyacetate, an inhibitor of transaminases, (ii) the use of methionine sulphoximine, an inhibitor of glutamine synthetase, which induced a large increase in ammonia release from aspartate, (iii) the use of quinolinate, an inhibitor of phosphoenolpyruvate carboxykinase, which inhibited glutamine synthesis from aspartate, (iv) the use of alpha-cyano-4-hydroxycinnamate, an inhibitor of the mitochondrial transport of pyruvate, which caused an accumulation of pyruvate from aspartate, and (v) the use of fluoroacetate, an inhibitor of aconitase, which inhibited glutamine synthesis with concomitant accumulation of citrate from aspartate.
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PMID:Glutamine synthesis from aspartate in guinea-pig renal cortex. 236 82

The activity of 7 mitochondrial enzymes, fumarase, NAD-malate dehydrogenase (MDH), citrate synthase (CS), valine dehydrogenase (VDH), succinate dehydrogenase (SDH), glutamate dehydrogenase (GDH), pyruvate dehydrogenase complex (PDHC) has been measured in platelet preparations from patients affected by Friedreich's ataxia (FA), dominant and non-dominant olivopontocerebellar atrophy (DOPCA, NDOPCA) and normal individuals. Significant decreases of GDH (P less than 0.01), PDHC (P less than 0.01), VDH (P less than 0.05) and SDH (P less than 0.05) activities were observed in FA patients. Significant decreases of GDH (P less than 0.01), PDHC (P less than 0.01), VDH (P less than 0.05), SDH (P less than 0.05) and CS (P less than 0.05) activities were Observed in ND-OPCA patients, whereas in DOPCA patients only GDH activity was significantly (P less than 0.05) decreased. In 8 of 10 patients with FA and in all patients with NDOPCA the activity of one or more of 4 enzymes, i.e. GDH, VDH, SDH, PDHC, was lower than the lowest of control values. Four of 6 patients with DOPCA had GDH activity lower than the lowest of control values. These results indicate that abnormalities of mitochondrial metabolism is a constant element in hereditary ataxia and suggest that the alteration primary leading to the different types of ataxias should be related to mitochondrial oxidative metabolism, at least at a regulatory level.
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PMID:Abnormalities of mitochondrial enzymes in hereditary ataxias. 281 70

This study was prompted by the paradox of strong presence of mitochondria in an anaerobic protozoan, recently reclassified from the yeasts. Stemming from publication in 1911 to 1912, Blastocystis hominis has been generally accepted as a harmless intestinal yeast of humans, with short standardized textbook (parasitology) descriptions, even to the present day. Reports since 1967 have changed the classification of B. hominis from yeast to protozoan (Sarcodina), and this has been followed by interest in B. hominis-caused disease, resulting in documentation of disease in humans and other primates. In this study of B. hominis, the basic ultrastructure of the mitochondria was shown by thin-section electron microscopy to be identical to that of an archetypical mitochondrion. There were hundreds of them in large B. hominis cells (100 to 200 microns in diameter). Mitochondria were confined to a peripheral ring of cytoplasm bounded by the outer cell membrane (there is no cell wall) and the membrane of the large, spherical, organelle-free central body that constitutes 75% of the cell's volume. Mitochondria tended to surround the cell's usual two to four nuclei. Rhodamine 123 stained the mitochondria selectively, visualized by fluorescence microscopy. The cell was devoid of cytochromes. Addition of 0.1% cytochrome c to the growth medium increased utilization of glucose by 34% and that of lactate by 17%. Furthermore, it markedly increased the number of mitochondrion-filled cells. At higher concentrations, cytochrome c inhibited the growth of the cells. Despite the presence of large numbers of mitochondria, activities of the mitochondrial enzymes pyruvate dehydrogenase complex, alpha-ketoglutarate dehydrogenase complex, isocitrate dehydrogenase, glutamate dehydrogenase, and cytochrome c oxidase were absent. Thus, the function of the mitochondria in B. hominis remains unknown. Considerable activities of aspartate aminotransferase and alanine aminotransferase were found. Aldolase activity was prominent. Pyruvate decarboxylase was present. Diaphorase and lactate dehydrogenase were detectable but in suspect quantities. Other missing enzymes were gamma glutamyl transpeptidase, alkaline phosphatase (a lysosomal marker), and creatine kinase isoenzymes.
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PMID:Biochemical and ultrastructural study of Blastocystis hominis. 283 9

Brain ammonia is generated from many enzymatic reactions, including glutaminase, glutamate dehydrogenase, and the purine nucleotide cycle. In contrast, the brain possesses only one major enzyme for the removal of exogenous ammonia, i.e., glutamine synthetase. Thus, following administration of [13N]ammonia to rats [via either the carotid artery or cerebrospinal fluid (csf)], most metabolized label was in glutamine (amide) and little was in glutamate (plus aspartate). Since blood-and csf-borne ammonia are converted to glutamine largely, if not entirely, in the astrocytes, it is not possible from these types of experiments to predict with certainty the metabolic fate of the bulk of endogenously produced ammonia. By comparing the specific activity of L-[13N]glutamate to that of L-[amine-13N]glutamine following intracarotid [13N]ammonia administration it was concluded that metabolic compartmentation is no longer intact in the brains of rats treated with the glutamine synthetase inhibitor L-methionine-SR-sulfoximine (MSO) and that blood and brain ammonia pools mix in such animals. In MSO-treated animals, recovery of label in brain was low (approximately 20% of controls), and of the label remaining, a prominent portion was in glutamine (amide) (despite an 87% decrease in brain glutamine synthetase activity). These data are consistent with the hypothesis that glutamine synthetase is the major enzyme for metabolism of endogenously--as well as exogenously--produced ammonia. The rate of turnover of blood-derived ammonia to glutamine in normal rat brain is extremely rapid (t1/2 less than or equal to 3 s), but is slowed in the brains of chronically (12-14-wk portacaval-shunted) or acutely (urease-treated) hyperammonemic rats (t1/2 less than or equal to 10 s). The slowed turnover rate may be caused by an increased astrocytic ammonia, decreased glutamine synthetase activity, or both. In the hyperammonemic rat brain, glutamine synthetase is still the only important enzyme for the removal of blood-borne ammonia. Hyperammonemia causes an increase in brain lactate/pyruvate ratios and decreases in brain glutamate and brainstem ATP, consistent with an interference with the malate-aspartate shuttle. In vitro, pathological levels of ammonia also inhibit brain alpha-ketoglutarate dehydrogenase complex and, less strongly, pyruvate dehydrogenase complex. The rat brain does not adapt to prolonged hyperammonemia by increasing its glutamine synthetase activity.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Cerebral ammonia metabolism in normal and hyperammonemic rats. 288 66

As a test of the hypothesis that mitochondrial abnormalities are common in patients with hereditary ataxias, the activities of two mitochondrial enzymes were studied in platelets from an unselected series of patients. For the group of ataxics, the activity of the pyruvate dehydrogenase complex (PDHC) was 68% of the control (P less than 0.01) and that of glutamate dehydrogenase (GDH) was 81% of the control (P less than 0.05). Of the ataxics studied, 30% had activities of either or both mitochondrial enzymes more than 2 SD below the control mean. Immunoblots of PDHC revealed antibody cross-reacting material in platelets and fibroblasts very similar to those in human brain and appeared normal in platelets from patients with ataxias. Immunoblots of GDH showed a single antibody cross-reacting material in brain but at least two species in normal fibroblasts and platelets. The pathophysiology of hereditary ataxias may often involve mitochondrial damage associated with secondary decreases in the activities of mitochondrial enzymes.
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PMID:Mitochondrial enzymes in hereditary ataxias. 318 26

Treatment of a yeast suspension with ozone inactivates a number of cytosolic enzymes. Among 15 studied, the most drastic inactivation was found for glyceraldehyde-3-phosphate dehydrogenase and to lesser extents: NAD-glutamate dehydrogenase, pyruvate decarboxylase, phosphofructokinase-1 and NAD-alcohol dehydrogenase. Ozone treatment also effects the quantity of ATP and of other nucleoside triphosphates, reducing to about 50% of the initial value. The ATP missing in the cells appears in the medium. NAD and protein also accumulate in the medium suggesting that the yeast cells have been permeabilized. Permeabilization of the yeast cells by treatment with ozone precedes the inactivation of glyceraldehyde-3-phosphate dehydrogenase and other cytosolic enzymes.
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PMID:Effect of ozone on ATP, cytosolic enzymes and permeability of Saccharomyces cerevisiae. 329 86

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

The activities of certain key enzymes have been measured in the ventral medial and ventral lateral areas of the hypothalamus, which are implicated in feeding behaviour, and compared with enzyme activities in the cortex and brainstem. The enzymes measured are concerned with glucose metabolism [hexokinase (EC 2.7.1.1) and glucose-6-phosphate dehydrogenase (EC 1.1.1.49)], ketone body metabolism [3-hydroxybutyrate dehydrogenase (EC 1.1.1.30)], fatty acid utilisation [carnitine palmitoyl transferase (EC 2.3.1.7)], citric acid cycle activity [pyruvate dehydrogenase (EC 1.2.4.2) and citrate synthase (EC 4.1.3.7)] and neurotransmitter synthesis [glutamate dehydrogenase (EC 1.4.1.3)].
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PMID:Enzyme activities in regions of the hypothalamus. 380 3

The activity of the pyruvate dehydrogenase complex (PDHC; EC 1.2.4.1, EC 2.3.1.12, and EC 1.6.4.3) was reduced to about 30% of control values in histologically unaffected occipital cortex of the brains of patients with Alzheimer's disease, as well as in histologically affected frontal cortex. In contrast, activity of another mitochondrial enzyme, glutamate dehydrogenase, was normal. Neither age nor time until postmortem study correlated significantly with PDHC activity in either Alzheimer or control samples, and PDHC was not inactivated significantly on incubation with homogenates of either Alzheimer or control brain. Antibodies against the highly purified bovine PDHC inhibited Alzheimer and control PDHC equally per unit of enzyme activity. Immunoblots also indicated that the PDHC antigens were not different in normal and Alzheimer brains. This antibody, however, inhibited Alzheimer PDHC more effectively than it did control PDHC, based on milligrams of protein, suggesting a reduced amount of normal PDHC protein. Other data suggest that the PDHC deficiency is related to mitochondrial damage and to impaired calcium homeostasis in Alzheimer nerve cells, which may then mediate a variety of other cellular impairments.
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PMID:An immunochemical study of the pyruvate dehydrogenase deficit in Alzheimer's disease brain. 400 69


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