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 metabolic properties of mitochondria from rat cerebral cortex and olfactory bulb were investigated. The pyruvate-supported oxygen uptake rates by olfactory bulb mitochondria were significantly lower than those by cerebrocortical mitochondria. This is consistent with the differences in pyruvate dehydrogenase complex activities between these mitochondrial preparations. Pyruvate dehydrogenase kinase, NAD-linked isocitrate dehydrogenase, and hexokinase activities in olfactory bulb mitochondria were significantly lower than those in cerebrocortical mitochondria. However, NADP-linked isocitrate dehydrogenase, and NAD-linked and NADP-linked glutamate dehydrogenase activities in olfactory bulb mitochondria were significantly higher than those in cerebrocortical mitochondria. The differences between these two mitochondrial preparations in terms of the activities of these energy-metabolizing enzymes reflect the differences detected in the homogenates of these regions.
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PMID:Differences in some of the metabolic properties of mitochondria isolated from cerebral cortex and olfactory bulb of the rat. 404 57

1. In epididymal adipose tissue synthesizing fatty acids from fructose in vitro, addition of insulin led to a moderate increase in fructose uptake, to a considerable increase in the flow of fructose carbon atoms to fatty acid, to a decrease in the steady-state concentration of lactate and pyruvate in the medium, and to net uptake of lactate and pyruvate from the medium. It is concluded that insulin accelerates a step in the span pyruvate-->fatty acid. 2. Mitochondria prepared from fat-cells exposed to insulin put out more citrate than non-insulin-treated controls under conditions where the oxaloacetate moiety of citrate was formed from pyruvate by pyruvate carboxylase and under conditions where it was formed from malate. This suggested that insulin treatment of fat-cells led to persistent activation of pyruvate dehydrogenase. 3. Insulin treatment of epididymal fat-pads in vitro increased the activity of pyruvate dehydrogenase measured in extracts of the tissue even in the absence of added substrate; the activities of pyruvate carboxylase, citrate synthase, glutamate dehydrogenase, acetyl-CoA carboxylase, NADP-malate dehydrogenase and NAD-malate dehydrogenase were not changed by insulin. 4. The effect of insulin on pyruvate dehydrogenase activity was inhibited by adrenaline, adrenocorticotrophic hormone and dibutyryl cyclic AMP (6-N,2'-O-dibutyryladenosine 3':5'-cyclic monophosphate). The effect of insulin was not reproduced by prostaglandin E(1), which like insulin may lower the tissue concentration of cyclic AMP (adenosine 3':5'-cyclic monophosphate) and inhibit lipolysis. 5. Adipose tissue pyruvate dehydrogenase in extracts of mitochondria is almost totally inactivated by incubation with ATP and can then be reactivated by incubation with 10mm-Mg(2+). In this respect its properties are similar to that of pyruvate dehydrogenase from heart and kidney where evidence has been given that inactivation and activation are catalysed by an ATP-dependent kinase and a Mg(2+)-dependent phosphatase. Evidence is given that insulin may act by increasing the proportion of active (dephosphorylated) pyruvate dehydrogenase. 6. Cyclic AMP could not be shown to influence the activity of pyruvate dehydrogenase in mitochondria under various conditions of incubation. 7. These results are discussed in relation to the control of fatty acid synthesis in adipose tissue and the role of cyclic AMP in mediating the effects of insulin on pyruvate dehydrogenase.
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PMID:Regulation of adipose tissue pyruvate dehydrogenase by insulin and other hormones. 515 98

1. Aerobically grown yeast having a high activity of glyoxylate-cycle, citric acid-cycle and electron-transport enzymes was transferred to a medium containing 10% glucose. After a lag phase of 30min. the yeast grew exponentially with a mean generation time of 94min. 2. The enzymes malate dehydrogenase, isocitrate lyase, succinate-cytochrome c oxidoreductase and NADH-cytochrome c oxidoreductase lost 45%, 17%, 27% and 46% of their activity respectively during the lag phase. 3. When growth commenced pyruvate kinase, pyruvate decarboxylase, alcohol dehydrogenase, glutamate dehydrogenase (NADP(+)-linked) and NADPH-cytochrome c oxidoreductase increased in activity, whereas aconitase, isocitrate dehydrogenase (NAD(+)- and NADP(+)-linked), alpha-oxoglutarate dehydrogenase, fumarase, malate dehydrogenase, succinate-cytochrome c oxidoreductase, NADH-cytochrome c oxidoreductase, NADH oxidase, NADPH oxidase, cytochrome c oxidase, glutamate dehydrogenase (NAD(+)-linked), glutamate-oxaloacetate transaminase, isocitrate lyase and glucose 6-phosphate dehydrogenase decreased. 4. During the early stages of growth the loss of activity of aconitase, alpha-oxoglutarate dehydrogenase, fumarase and glucose 6-phosphate dehydrogenase could be accounted for by dilution by cell division. The lower rate of loss of activity of isocitrate dehydrogenase (NAD(+)- and NADP(+)-linked), glutamate dehydrogenase (NAD(+)-linked), glutamate-oxaloacetate transaminase, NADPH oxidase and cytochrome c oxidase implies their continued synthesis, whereas the higher rate of loss of activity of malate dehydrogenase, isocitrate lyase, succinate-cytochrome c oxidoreductase, NADH-cytochrome c oxidoreductase and NADH oxidase means that these enzymes were actively removed. 5. The mechanisms of selective removal of enzyme activity and the control of the residual metabolic pathways are discussed.
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PMID:The kinetics of enzyme changes in yeast under conditions that cause the loss of mitochondria. 566 Jun 27

The freshwater murrel, Channa punctatus, was exposed to a sublethal concentration of mercuric chloride (3 micrograms/liter) for 120 days and the following effects were examined: changes in the levels of glucose and lactic acid in blood and of glycogen and lactic acid in liver and muscles; rate of absorption of glucose from the intestine; and changes in the activities of glucose-6-phosphatase (G-6-Pase), hexokinase, lactate dehydrogenase (LDH), pyruvate dehydrogenase (PDH), succinate dehydrogenase (SDH), malate dehydrogenase (MDH), glutamate dehydrogenase (GDH), L-amino acid oxidase (AO), and xanthine oxidase (XO) in brain, gills, intestine, kidney, liver, and muscles. Mercury-treated fish were hypoglycemic and hypolactemic. The glycogen content of liver and muscles remained unaltered but the muscle lactic acid level decreased significantly. The rate of intestinal absorption of glucose was reduced significantly by exposure to mercury. G-6-Pase activity was decreased in all the tissues. Hexokinase activity also decreased in mercury-exposed fish but it was significant only in intestine, kidney, and liver. The activities of LDH, PDH, SDH, and MDH also were decreased significantly except LDH in brain and MDH in kidney where an insignificant decrease and an insignificant increase, respectively, were recorded. GDH and AO activities were elevated in most of the tissues except GDH in gills, and AO in gills and muscles where a decrease was observed. XO activity in brain, gills, and kidneys was significantly elevated, but no marked alteration was noted in other tissues.
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PMID:Effect of mercuric chloride on some biochemical and physiological parameters of the freshwater murrel, Channa punctatus. 608 7

Addition of phenylephrine to isolated perfused rat liver is followed by an increased 14CO2 production from [1-14C]glutamate, [1-14C]glutamine, [U-14C]proline and [3-14C]pyruvate, but by a decreased 14CO2 production from [1-14C]pyruvate. Simultaneously, there is a considerable decrease in tissue content of 2-oxoglutarate, glutamate and citrate. Stimulation of 14CO2 production from [1-14C]glutamate is also observed in the presence of amino-oxyacetate, suggesting a stimulation of glutamate dehydrogenase and 2-oxoglutarate dehydrogenase fluxes by phenylephrine. Inhibition of pyruvate dehydrogenase flux by phenylephrine is due to an increased 2-oxoglutarate dehydroxygenase flux. Phenylephrine stimulates glutaminase flux and inhibits glutamine synthetase flux to a similar extent, resulting in an increased hepatic glutamine uptake. Whereas the effects of NH4+ ions and phenylephrine on glutaminase flux were additive, activation of glutaminase by glucagon was considerably diminished in the presence of phenylephrine. The reported effects are largely overcome by prazosin, indicating the involvement of alpha-adrenergic receptors in the action of phenylephrine. It is concluded that stimulation of gluconeogenesis from various amino acids by phenylephrine is due to an increased flux through glutamate dehydrogenase and the citric acid cycle.
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PMID:Effect of phenylephrine on glutamate and glutamine metabolism in isolated perfused rat liver. 614 74

To clarify the enzymatic mechanisms of brain damage in thiamin deficiency, glucose oxidation, acetylcholine synthesis, and the activities of the three major thiamin pyrophosphate (TPP) dependent brain enzymes were compared in untreated controls, in symptomatic pyrithiamin-induced thiamin-deficient rats, and in animals in which the symptoms had been reversed by treatment with thiamin. Although brain slices from symptomatic animals produced 14CO2 and 14C-acetylcholine from [U-14C]glucose at rates similar to controls under resting conditions, their K+-induced-increase declined by 50 and 75%, respectively. In brain homogenates from these same animals, the activities of two TPP-dependent enzymes transketolase (EC 2.2.1.1) and 2-oxoglutarate dehydrogenase complex (EC 1.2.4.2, EC 2.3.1.61, EC 1.6.4.3) decreased 60-65% and 36%, respectively. The activity of the third TPP-dependent enzyme, pyruvate dehydrogenase complex (EC 1.2.4.1, EC 2.3.1.12, EC 1.6.4.3) did not change nor did the activity of its activator pyruvate dehydrogenase phosphate phosphatase (EC 3.1.3.43). Although treatment with thiamin for seven days reversed the neurological symptoms and restored glucose oxidation, acetylcholine synthesis and 2-oxoglutarate dehydrogenase activity to normal, transketolase activity remained 30-32% lower than controls. The activities of other TPP-independent enzymes (hexokinase, phosphofructokinase, and glutamate dehydrogenase) were normal in both deficient and reversed animals.
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PMID:Correlation of enzymatic, metabolic, and behavioral deficits in thiamin deficiency and its reversal. 614 77

In autopsied brain tissue from three cases with Leigh disease (subacute necrotizing encephalomyelitis, SNE) and controls, the activity of pyruvate dehydrogenase complex (PDHC) was determined under different conditions. It was found to be at the control level or increased, but not deficient. The activities of succinate dehydrogenase, fumarase, succinate cytochrome c reductase, cytochrome c oxidase, and glutamate dehydrogenase were measured as additional mitochondrial markers and showed no essential differences between SNE and control tissue. The metabolic defect in SNE remains unknown. According to the literature, the defect may be localized to the mitochondrial systems. However, the reported results indicate that it cannot be ascribed to PDHC function. Extensive biochemical studies are necessary for understanding of the pathogenesis in the fatal genetic metabolic disease.
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PMID:Pyruvate dehydrogenase activity is not deficient in the brain of three autopsied cases with Leigh disease (subacute necrotizing encephalomyelopathy, SNE). 643 63

NADH:ubiquinone reductase (complex I) of the mitochondrial inner membrane respiratory chain binds a number of mitochondrial matrix NAD-linked dehydrogenases. These include pyruvate dehydrogenase complex, alpha-ketoglutarate dehydrogenase complex, mitochondrial malate dehydrogenase, and beta-hydroxyacyl-CoA dehydrogenase. No binding was detected between complex I and cytosolic malate dehydrogenase, glutamate dehydrogenase, NAD-isocitrate dehydrogenase, lipoamide dehydrogenase, citrate synthase, or fumarase. The dehydrogenases that bound to complex I did not bind to a preparation of complex II and III, nor did they bind to liposomes. The binding of pyruvate dehydrogenase complex, alpha-ketoglutarate dehydrogenase complex, and mitochondrial malate dehydrogenase to complex I is a saturable process. Based upon the amount of binding observed in these in vitro studies, there is enough inner membrane present in the mitochondria to bind the dehydrogenases in the matrix space. The possible metabolic significance of these interactions is discussed.
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PMID:Complex I binds several mitochondrial NAD-coupled dehydrogenases. 643 16

The kinetic parameters of the individual reaction of pig heart alpha-ketoglutarate dehydrogenase complex, succinate thiokinase and the alpha-ketoglutarate dehydrogenase complex-succinate thiokinase coupled system were studied. The KCoAm of alpha-ketoglutarate dehydrogenase complex and the K-succinyl CoAm of succinate thiokinase decreased in the coupled system when compared to those of the individual enzyme reactions. This phenomenon can be explained by the interaction between the alpha-ketoglutarate dehydrogenase complex and succinate thiokinase. By means of poly(ethylene glycol) precipitation, ultracentrifugation and gel chromatography we were able to detect a physical interaction between the alpha-ketoglutarate dehydrogenase complex and succinate thiokinase. Of the seven investigated proteins only succinate thiokinase showed association with alpha-ketoglutarate dehydrogenase complex. On the other hand, succinate thiokinase did not associate with other high molecular weight mitochondrial enzymes such as pyruvate dehydrogenase complex and glutamate dehydrogenase. On this basis, the interaction between succinate thiokinase and alpha-ketoglutarate dehydrogenase complex was assumed to be specific. These in vitro data raise the possibility that a portion of the citric acid cycle enzymes exists as a large multienzyme complex in the mitochondrial matrix.
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PMID:Association between the alpha-ketoglutarate dehydrogenase complex and succinate thiokinase. 665 97

The activities of 13 liver and 6 brain enzymes were studied in 7-12 week old CD2F1 male mice that had been fed ad libitum and standardized either to 12 hours of light (0600-1800) alternating with 12 hours of darkness (1800-0600) (LD12:12); or to a reversed light-dark cycle (darkness 0600-1800; light 1800-0600) (DL12:12). Three separate studies were performed on two different days; in each experiment, subgroups of 14 animals were sacrificed at 3-hour intervals. Livers were assayed for: isocitrate dehydrogenase, glutamate dehydrogenase, lactate dehydrogenase, alcohol dehydrogenase, glutathione reductase, glyoxylate reductase, L-alanine aminotransferase, glutamate oxalacetate transaminase, pyruvate decarboxylase, fructose-1-phosphate aldolase, fructose diphosphate aldolase, fructose 1,6-diphosphatase, and fatty acid synthetase. Brains were assayed for phosphoglucose isomerase, adenosine triphosphatase, creatine phosphokinase, pyruvate kinase, adenylate kinase, and malate dehydrogenase. All 19 enzymes demonstrated a prominent circadian rhythm in at least one experiment. Moreover, each rhythmic variable showed a statistically significant fit to a 24-hour cosine (sine) curve by the method of least squares. In general, peak activities of the liver enzymes analyzed were associated with the beginning of the dark cycle and initiation of the animal's activity, while the group of brain enzymes had peak activities which occurred at the beginning of the animals' rest span and were near the beginning of the light cycle. The phasing of each of the rhythms could be reversed within a two-week span after reversing the environmental light-dark cycle 180 degrees.
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PMID:Circadian organization of thirteen liver and six brain enzymes of the mouse. 731 49


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