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:1.4.3.11 (glutamate dehydrogenase)
4,437 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cell-free extracts of Rhizopus arrhizus contain exclusively cytosolic pyruvate carboxylase and NAD-glutamate dehydrogenase, a single mitochondrial isoenzyme of NADP-isocitrate dehydrogenase, and both mitochondrial and cytosolic isoenzymes of NADP-malate dehydrogenase (decarboxylating). Other enzymes examined have sub-cellular localisations similar to those characteristic of mammalian liver. Purified preparations of R. arrhizus pyruvate carboxylase are subject to partial regulatory inhibition by L-aspartate and 2-oxoadipate. L-Glutamate acts as a less effective analogue of L-aspartate while 2-oxoglutarate is ineffective. Competition studies indicate the presence of separate inhibitory sites for L-aspartate and 2-oxoadipate. Under routine assay conditions R. arrhizus pyruvate carboxylase shows significant activation by acyl derivatives of coenzyme A with long chain acyl CoA being more effective than acetyl-CoA. This activation is no longer observed in the presence of high concentrations of pyruvate, MgATP2- and HCO-3. The concentrations of L-aspartate and 2-oxoadipate required to give 50% inhibition ([I]0.5), and the maximal extents of inhibition, are increased by addition of acetyl-CoA. Acetyl-CoA increases the sigmoidal character of the relationship: initial rate/[L-aspartate], but decreases this parameter for the relationship: initial rate/[2-oxoadipate]. The studies indicate that R. arrhizus possesses an entirely cytosolic pathway for the conversion of glucose to fumaric acid and that both the organisation of pyruvate metabolism and the regulation of pyruvate carboxylase differ significantly in this organism as compared to that proposed previously for Aspergillus nidulans.
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PMID:The sub-cellular localisation and regulatory properties of pyruvate carboxylase from Rhizopus arrhizus. 397 71

Using affinity chromatography of F-actin-sepharose 4B, the ability of proteins from rat liver submitochondrial fractions to interact with rabbit skeletal muscle actin was studied. The bulk of the actin-bound components was detected in the soluble compartments of the mitochondria, i.e., mitochondrial matrix and intermembrane space. The interaction was predominantly weak, since the desorption of the proteins from the column occurred at increased ionic strength of the solution. In membrane fractions, four polypeptides with Mr 65 000, 62 000, 59 000 and 10 500 eluting from the column only under effects of denaturating agents were predominant, thus suggesting the specificity of their binding to the immobilized actin. In a model system involving mitochondrial enzyme preparations (cytochrome c, glutamate dehydrogenase, isocitrate dehydrogenase, catalase), the possibility of their adsorption of F-actin-sepharose was investigated. It was shown that the highest adsorption capacity was observed in the case of immobilized actin with respect to catalase, the lowest one-to glutamate dehydrogenase. The data obtained suggest that the interaction of the actin-like mitochondrial protein with the system of solubilized enzymes may serve as a basis for their normal functioning.
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PMID:[Study of the ability of mitochondrial proteins to interact with actin]. 400 24

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

Fat-cells were prepared from rat and guinea-pig epididymal adipose tissue and compared on the basis of the intracellular distributions and activities of enzymes and with respect to their utilization of various U-(14)C-labelled substrates for lipogenesis. 1. Compared with the rat, guinea-pig extramitochondrial enzyme activities differed in that aconitate hydratase, alanine aminotransferase, ATP-citrate lyase, lactate dehydrogenase, NAD-malate dehydrogenase, NADP-malate dehydrogenase and phosphoenolpyruvate carboxykinase activities were appreciably lower, whereas aspartate aminotransferase, glucose 6-phosphate dehydrogenase, NADP-isocitrate dehydrogenase and 6-phosphogluconate dehydrogenase activities were appreciably higher. Mitochondrial activities of citrate synthase, NADP-isocitrate dehydrogenase and pyruvate carboxylase were appreciably lower, whereas mitochondrial activities of aspartate aminotransferase, glutamate dehydrogenase, NAD-malate dehydrogenase and phosphoenolpyruvate carboxykinase were higher in the guinea pig compared with the rat. 2. In general guinea-pig fat-cells incorporated acetate and lactate into fatty acids more readily than rat fat-cells, whereas rat fat-cells incorporated glucose and pyruvate more readily than guinea-pig fat-cells. 3. Acetate stimulated the incorporation of glucose into fatty acids in rat fat-cells, but had no appreciable effect upon this process in guinea-pig fat-cells. Acetate greatly decreased the incorporation of lactate into fatty acids in cells from both species. 4. Lactate/pyruvate ratios produced by incubation of guinea-pig cells with glucose+insulin were very low compared with those found with rat cells under the same conditions. 5. With glucose (+insulin) or with glucose+acetate (+insulin) as substrates guinea-pig cells produced enough NADPH by the hexose monophosphate pathway to satisfy the NADPH requirements of lipogenesis. In rat fat-cells under the same conditions, hexose monophosphate-pathway NADPH provision was not sufficient to meet the requirements of lipogenesis. 6. These results are discussed, particularly in relationship to the disposition of cytosolic reducing equivalents in the cells.
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PMID:Lipogenesis in rat and guinea-pig isolated epididymal fat-cells. 415 67

Treatment of the inner membrane matrix fraction of rat liver mitochondria with the nonionic detergent Lubrol WX solubilized about 70% of the total protein and 90% or more of the following matrix activities: malate dehydrogenase, glutamate dehydrogenase, and isocitrate dehydrogenase (NADP). The Lubrol-insoluble fraction was enriched in cytochromes, phospholipids, and a Mg(++)-stimulated ATPase activity. Less than 2% of the total mitochondrial activity of monoamine oxidase, an outer membrane marker, or adenylate kinase, an intracristal space marker could be detected in this inner membrane fraction. Electron micrographs of negatively stained preparations showed vesicles (</=0.4 micro diameter) literally saturated on the periphery with the 90 A ATPase particles. These inner membrane vesicles, which appeared for the most part to be inverted with respect to the normal inner membrane configuration in intact mitochondria, retained the succinicoxidase portion of the electron-transport chain, an intact phosphorylation site II with a high affinity for ADP, and the capacity to accumulate Ca(++). A number of biochemical properties characteristic of intact mitochondria and the inner membrane matrix fraction, however, were either absent or markedly deficient in the inner membrane vesicles. These included stimulation of respiration by either ADP or 2,4-dinitrophenol, oligomycin-sensitive ADP-ATP exchange activity, atractyloside sensitivity of adenine nucleotide requiring reactions, and a stimulation of the Mg(++)-ATPase by 2,4-dinitrophenol.
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PMID:Biochemical and ultrastructural properties of a mitochondrial inner membrane fraction deficient in outer membrane and matrix activities. 425 78

Octanoic acid inhibits, in vitro, the bacterial enzymes glucose-6-phosphate dehydrogenase, phosphofructokinase, pyruvate kinase, fumarase, lactate dehydrogenase, and the malic enzyme of Arthrobacter crystallopoietes. The free fatty acid appears to act as an inhibitor of lipogenesis, although it does not affect the rate of gluconeogenesis. To demonstrate that this inhibition may be of physiological significance in vivo, those enzymes not involved in lipogenesis, such as fructose-1, 6-diphosphatase, phosphoglucomutase, phosphohexoisomerase, aconitase, nicotinamide adenine dinucleotide phosphate (NADP) isocitrate dehydrogenase, NADP glutamate dehydrogenase, malate dehydrogenase, and isocitrate lyase, were assayed and found not to be inhibited by the free fatty acid.
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PMID:Selective inhibition of bacterial enzymes by free fatty acids. 430 71

Enzyme-reduced coenzyme binary complexes produce previously unreported shifts in the spectrum of the free coenzyme. These shifts give rise to difference spectra which resemble a general environmental change for reduced diphosphopyridine nucleotide (DPNH) in the glutamic dehydrogenase-DPNH complex, and indicate a more specific enzyme-coenzyme interaction for yeast alcohol dehydrogenase-DPNH, isocitrate dehydrogenase-TPNH, and lactic dehydrogenase-DPNH complexes.
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PMID:Enzyme-coenzyme complexes of pyridine nucleotide-linked dehydrogenases. 438 Jan 8

1. A method is described for extracting separately mitochondrial and extramitochondrial enzymes from fat-cells prepared by collagenase digestion from rat epididymal fat-pads. The following distribution of enzymes has been observed (with the total activities of the enzymes as units/mg of fat-cell DNA at 25 degrees C given in parenthesis). Exclusively mitochondrial enzymes: glutamate dehydrogenase (1.8), NAD-isocitrate dehydrogenase (0.5), citrate synthase (5.2), pyruvate carboxylase (3.0); exclusively extramitochondrial enzymes: glucose 6-phosphate dehydrogenase (5.8), 6-phosphogluconate dehydrogenase (5.2), NADP-malate dehydrogenase (11.0), ATP-citrate lyase (5.1); enzymes present in both mitochondrial and extramitochondrial compartments: NADP-isocitrate dehydrogenase (3.7), NAD-malate dehydrogenase (330), aconitate hydratase (1.1), carnitine acetyltransferase (0.4), acetyl-CoA synthetase (1.0), aspartate aminotransferase (1.7), alanine aminotransferase (6.1). The mean DNA content of eight preparations of fat-cells was 109mug/g dry weight of cells. 2. Mitochondria showing respiratory control ratios of 3-6 with pyruvate, about 3 with succinate and P/O ratios of approaching 3 and 2 respectively have been isolated from fat-cells. From studies of rates of oxygen uptake and of swelling in iso-osmotic solutions of ammonium salts, it is concluded that fat-cell mitochondria are permeable to the monocarboxylic acids, pyruvate and acetate; that in the presence of phosphate they are permeable to malate and succinate and to a lesser extent oxaloacetate but not fumarate; and that in the presence of both malate and phosphate they are permeable to citrate, isocitrate and 2-oxoglutarate. In addition, isolated fat-cell mitochondria have been found to oxidize acetyl l-carnitine and, slowly, l-glycerol 3-phosphate. 3. It is concluded that the major means of transport of acetyl units into the cytoplasm for fatty acid synthesis is as citrate. Extensive transport as glutamate, 2-oxoglutarate and isocitrate, as acetate and as acetyl l-carnitine appears to be ruled out by the low activities of mitochondrial aconitate hydratase, mitochondrial acetyl-CoA hydrolyase and carnitine acetyltransferase respectively. Pathways whereby oxaloacetate generated in the cytoplasm during fatty acid synthesis by ATP-citrate lyase may be returned to mitochondria for further citrate synthesis are discussed. 4. It is also concluded that fat-cells contain pathways that will allow the excess of reducing power formed in the cytoplasm when adipose tissue is incubated in glucose and insulin to be transferred to mitochondria as l-glycerol 3-phosphate or malate. When adipose tissue is incubated in pyruvate alone, reducing power for fatty acid, l-glycerol 3-phosphate and lactate formation may be transferred to the cytoplasm as citrate and malate.
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PMID:The intracellular localization of enzymes in white-adipose-tissue fat-cells and permeability properties of fat-cell mitochondria. Transfer of acetyl units and reducing power between mitochondria and cytoplasm. 439 82

The metabolism of pyruvate and lactate by rat adipose tissue was studied. Pyruvate and lactate conversion to fatty acids is strongly concentration-dependent. Lactate can be used to an appreciable extent only by adipose tissue from fasted-refed rats. A number of compounds, including glucose, pyruvate, aspartate, propionate, and butyrate, stimulated lactate conversion to fatty acids. Based on studies of incorporation of lactate-2-(3)H and lactate-2-(14)C into fatty acids it was suggested that the transhydrogenation sequence of the "citrate-malate cycle"(1) was not providing all of the NADPH required for fatty acid synthesis from lactate. An alternative pathway for NADPH formation involving the conversion of isocitrate to alpha-ketoglutarate via cytosolic isocitrate dehydrogenase was proposed. Indirect support for this proposal was provided by the rapid labeling of glutamate from lactate-2-(14)C by adipose tissue incubated in vitro, as well as the demonstration that glutamate can be readily metabolized by adipose tissue via reactions localized largely in the cytosol. Furthermore, isolated adipose tissue mitochondria convert alpha-ketoglutarate to malate, or in the presence of added pyruvate, to citrate. Glutamate itself can not be metabolized by these mitochondria, a finding in keeping with the demonstration of negligible levels of NAD-glutamate dehydrogenase activity in adipose tissue mitochondria. Pyruvate stimulated alpha-ketoglutarate and malate conversion to citrate and reduced their oxidation to CO(2). It is proposed that under conditions of excess generation of NADH malate may act as a shuttle carrying reducing equivalents across the mitochondrial membrane. Malate at low concentrations increased pyruvate conversion $$Word$$ citrate and markedly decreased the formation of CO(2) by isolated adipose tissue mitochondria. Malate also stimulated citrate and isocitrate metabolism by these mitochondria, an effect that could be blocked by 2-n-butylmalonate. This potentially important role of malate in the regulation of carbon flow during lipogenesis is underlined by the observation that 2-n-butylmalonate inhibited fatty acid synthesis from pyruvate, but not from glucose and acetate, and decreased the stimulatory effect of pyruvate on acetate conversion to fatty acids.
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PMID:Pathway of carbon flow during fatty acid synthesis from lactate and pyruvate in rat adipose tissue. 439 62

1. The activity of several tricarboxylic acid-cycle-associated dehydrogenases, adenine-metabolizing enzymes and glutathione reductase and the content of myoglobin were measured in rat diaphragm muscle after unilateral nerve section. 2. Consistent with morphological disintegration of the mitochondria there was a rapid diminution in activity of NAD- and NADP-linked isocitrate dehydrogenase, malate dehydrogenase and glutamate dehydrogenase. 3. Creatine phosphokinase and adenylate kinase, by contrast, showed little change in activity; adenylate deaminase and glutathione reductase activities increased during the hypertrophic phase. The concentration of myoglobin at first declined, then increased again. 4. The distribution of enzymes between the left and right hemidiaphragms was found not to be uniform. 5. Activities of adenine-metabolizing enzymes in the diaphragm were as great as in white muscle. It is suggested that their reputedly lower activities in red muscle properly refer to muscle containing a high proportion of intermediate fibres, which is not the case with diaphragm. 6. The possible causes of the transient hypertrophy after nerve section are discussed.
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PMID:Effects of denervation on the activities of some tricarboxylic acid-cycle-associated dehydrogenases and adenine-metabolizing enzymes in rat diaphragm muscle. 440 65


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