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)

The ATP-binding component (Component II, hereafter referred to as ClpA) of a two-component, ATP-dependent protease from Escherichia coli has been purified to homogeneity. ClpA is a protein with subunit Mr 81,000. It has an intrinsic ATPase activity and activates degradation of protein substrates only in the presence of a second component (Component I, hereafter referred to as ClpP), Mg2+, and ATP. The amount of ClpA varies by less than a factor of 2 in cells grown in different media and at temperatures from 30 to 42 degrees C. ClpA does not appear to be a heat-shock protein since its synthesis is not dependent on htpR. Antibodies against purified ClpA were used to identify lambda transducing phage bearing the clpA gene. The cloned gene contains a DNA sequence expected to code for the first 28 amino acids of ClpA, which were determined by protein sequencing of purified ClpA. The clpA gene in the phage was mutated by insertion of delta kan defective transposons and the mutations were transferred to E. coli by homologous recombination. The clpA gene was mapped to 19 min on the E. coli chromosome. Mutant cells with insertions early in the gene produce no ClpA protein detectable in Western blots, and extracts of such mutant cells have no detectable ClpA activity. clpA- mutants grow well under all conditions tested and are not defective in turnover of proteins during nitrogen starvation nor in the turnover of such highly unstable proteins as the lambda proteins O, N, and cII, or the E. coli proteins SulA, RcsA, and glutamate dehydrogenase. The degradation of abnormal canavanine-containing proteins is defective in clpA mutants especially in cells that also have a lon- mutation. Extracts of clpA- lon- cells have ATP-dependent casein degrading activity.
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PMID:The two-component, ATP-dependent Clp protease of Escherichia coli. Purification, cloning, and mutational analysis of the ATP-binding component. 304 6

The effect of hypoxia and post-hypoxic recovery were studied in gastrocnemius muscle of young-adult and mature beagle dogs. Furthermore, the possible interference of pharmacological treatment with nicergoline was evaluated in these conditions. Muscular glycolytic fuels, intermediates and end-products (glycogen, glucose, glucose 6-phosphate, pyruvate, lactate), Kreb's cycle intermediates (citrate, alpha-ketoglutarate, succinate, malate) and related free amino acids (glutamate, alanine), ammonium ion, energy store and mediators (ATP, ADP, AMP and creatine phosphate), and the energy charge potential were evaluated. Furthermore, in the crude extract and/or mitochondrial fraction of another portion of the same gastrocnemius muscle the maximum rate (Vmax) of some muscular enzymes related to the anaerobic glycolytic pathway (hexokinase, lactate dehydrogenase), the Kreb's cycle (citrate synthase, malate dehydrogenase), the aminoacid pool related to the Krebs' cycle (glutamate dehydrogenase and aspartate aminotransferase), the electron transfer chain (cytochrome oxidase) and NAD+/NADH exchanges (total NADH cytochrome c reductase) was evaluated. Some glycolytic metabolites and Krebs' cycle intermediates were modified by acute hypoxia, while free amino acids and energy mediators remained practically unchanged. The pharmacological treatment maintained the glucose and succinate muscular concentrations within the normal range, during hypoxia. The behaviour of muscular metabolites during hypoxia and/or post-hypoxic recovery is an age-related event. In fact, only in young-adult animals did the altered values return to normal in post-hypoxic recovery. In the present experimental conditions, only minor changes were observed as far as muscular enzyme activities are concerned. In any case, some enzyme activities tested showed different Vmax in young-adult dogs in comparison with mature ones.
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PMID:Effect of hypoxia, aging and pharmacological treatment on muscular metabolites and enzyme activities. 322 9

The effect of ammonia on the alanine metabolism was investigated in perfused rat liver. Gluconeogenesis was found to be stimulated by physiological concentrations of ammonia, while being inhibited at higher concentrations (5-10 mM). The stimulating effect of 0.5 mM ammonia was studied in greater detail. In addition to glucose formation seen enhanced five times, increased rates were observed for ureogenesis as well as the formation of lactate and pyruvate, demonstrating also activation of the total alanine turnover. Furthermore, the mitochondrial and cytosolic NAD systems were increasingly oxidized as reflected by the beta-hydroxybutyrate/acetoacetate and lactate/pyruvate ratios. The shift of the beta-hydroxybutyrate/acetoacetate ratio was correlated to the ATP demand by gluconeogenesis and ureogenesis. The elevated concentration of pyruvate was found to have caused stimulation of gluconeogenesis since there existed a Michaelis-Menten type relation between pyruvate concentration and glucose formation irrespective of the presence or absence of ammonia. The flux through glutamate dehydrogenase was calculated from the total alanine turnover and urea formation, and noted to be diminished in the presence of ammonia despite the increased alanine turnover. It is concluded that glutamate dehydrogenase, at least in part, controls the total alanine turnover in the absence of ammonia.
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PMID:Stimulation of alanine metabolism in rat liver by ammonia. 325 56

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

D-Glucose increased the cytosolic NADH/NAD+ ratio (but not the cytosolic NADPH/NADP+ ratio), augmented O2 uptake, raised the ATP/ADP ratio, decreased 86Rb outflow, and stimulated insulin release in tumoral insulin-producing cells of the RINm5F line. L-Leucine and 4-methyl-2-oxopentanoate also stimulated insulin secretion. In the RINm5F cells, as in normal islet cells, the nonmetabolized analogue of L-leucine, 2-aminobicyclo[2,2,1]heptane-2-carboxylic acid (BCH), activated glutamate dehydrogenase, augmented L-[U-14C]glutamine oxidation, and induced a more reduced state of cytosolic redox couples. However, in sharp contrast to either its effect in normal islet cells or that of D-glucose in the tumoral cells, BCH severely decreased O2 uptake, lowered the ATP/ADP ratio, increased 86Rb outflow, and inhibited insulin release in the RINm5F cells. These findings are interpreted to support the concept that the rate of ATP generation represents an essential determinant of the secretory response of insulin-producing cells to nutrient secretagogues.
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PMID:Opposite effects of D-glucose and a nonmetabolized analogue of L-leucine on respiration and secretion in insulin-producing tumoral cells (RINm5F). 354 45

Exposure of L929 murine fibroblasts to ozone resulted in K+ leakage and inhibition of several enzymes. Most sensitive to ozone exposure were glyceraldehyde-3-phosphate dehydrogenase and pyruvate kinase. The activities of another cytosolic enzyme, lactate dehydrogenase, the mitochondrial enzymes glutamate dehydrogenase, succinate dehydrogenase, cytochrome c oxidase and the activity of the lysosomal enzymes acid phosphatase and beta-glucuronidase were, initially, not or only slightly affected. The localization of the lysosomal enzymes did not change during ozone exposure. After prolonged exposure complete deterioration of the cells was observed and all enzyme activities declined. The activity of the enzymes was also monitored during ozone exposure of a sonicated cell suspension and it was shown that all these enzymes are in fact susceptible to ozone. These observations clearly demonstrate that, besides the structure and amino acid composition of an enzyme, the localization in the cell plays an important role in its susceptibility to ozone. The intracellular levels of reduced and oxidized glutathione were affected as well. The ATP content, however, proved to be insensitive to ozone exposure.
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PMID:Toxic effects of ozone on murine L929 fibroblasts. Enzyme inactivation and glutathione depletion. 359 71

The ribose-modified chromophoric and fluorescent analog of ATP, 2',3'-O-(2,4,6-trinitrocyclohexadienylidene)-ATP (TNP-ATP) (Hiratsuka, T., and Uchida, K. (1973) Biochim. Biophys. Acta 320, 635-647 and Hiratsuka, T. (1976) Biochim. Biophys. Acta 453, 293-297) has been widely used as an ATP analog for various ATPases. Although the corresponding analog of GTP,2',3'-O-(2,4,6-trinitrocyclohexadienylidene)-GTP (TNP-GTP) should be useful for the study of various GTP-requiring enzymes, it is difficult to prepare TNP-GTP by the conventional method. In the present study, we succeeded in the synthesis of TNP-GTP with the use of an alternative method. The analogs of GDP, GMP, and guanyl-5'-yl imidodiphosphate (Gpp(NH)p) were also synthesized. Visible absorption and fluorescent properties of TNP-GTP, TNP-GDP, TNP-GMP, and TNP-Gpp(NH)p were quite similar to those of TNP-ATP. TNP-GTP was found to be able to replace GTP as an inhibitor for bovine liver glutamate dehydrogenase. The enzyme was inhibited by TNP-GTP to a maximum extent of 54% at saturating concentrations of the analog with a KI of 2.7 microM. TNP-Gpp(NH)p and other ribose-modified fluorescent analogs of GTP,3'-O-anthraniloyl-GTP and 3'-O-(N-methylanthraniloyl)-GTP (Hiratsuka, T. (1983) Biochim. Biophys. Acta 742, 496-508), also inhibited the enzymatic activity. Binding of TNP-GTP to the enzyme was characterized by a 5.6-fold enhancement in analog fluorescence. In the presence of NADH, the limiting fluorescence enhancement of the bound analog decreased to 2.7-fold. As determined by fluorometric titration, the maximum number of TNP-GTP binding sites on the enzyme was 1.9 mol/mol of subunit with a KD of 0.66 microM in the absence of NADH and 2.2 mol/mol of subunit with two KD values of 0.11 and 0.71 microM in the presence of NADH. These observations suggest that NADH binding increases the affinity of only 1 mol of the 2 mol of TNP-GTP bound to the enzyme. These spectroscopic and biological properties of TNP-GTP should make this analog useful as a chromophoric and fluorescent probe for studies not only of glutamate dehydrogenase but also of various GTP-requiring enzymes, which have a high specificity for the base moiety of GTP.
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PMID:A chromophoric and fluorescent analog of GTP, 2',3'-O-(2,4,6-trinitrocyclohexadienylidene)-GTP, as a spectroscopic probe for the GTP inhibitory site of liver glutamate dehydrogenase. 398 36

Citrate, malate, and high levels of ATP dissociate the mitochondrial aspartate aminotransferase-glutamate dehydrogenase complex and have an inhibitory effect on the latter enzyme. These effects are opposed by Mg2+, leucine, Mg2+ plus ATP, and carbamyl phosphate synthase-I. In addition, Mg2+ directly facilitates formation of a complex between glutamate dehydrogenase and the aminotransferase and displaces the aminotransferase from the inner mitochondrial membrane which could enable it to interact with glutamate dehydrogenase in the matrix. Zn2+ also favors an aminotransferase-glutamate dehydrogenase complex. It, however, is a potent inhibitor of and has a high affinity for glutamate dehydrogenase. Leucine, however, enhances binding of Mg2+ and decreases binding of and the effect of Zn2+ on the enzyme. Thus, since both metal ions enhance enzyme-enzyme interaction and Zn2+ is a more potent inhibitor, the addition of leucine in the presence of both metal ions results in activation of glutamate dehydrogenase without disruption of the enzyme-enzyme complex. Furthermore, the combination of leucine plus Mg2+ produces slightly more activation than leucine alone. These results indicate that leucine, carbamyl phosphate synthase-I, and its substrate and cofactor, ATP and Mg2+, operate synergistically to facilitate glutamate dehydrogenase activity and interaction between this enzyme and the aminotransferase. Alternatively, Krebs cycle intermediates, such as citrate and malate, have opposing effects.
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PMID:Regulation of aminotransferase-glutamate dehydrogenase interactions by carbamyl phosphate synthase-I, Mg2+ plus leucine versus citrate and malate. 399 14

Kinetic constants were determined for commercially available samples of ox liver glutamate dehydrogenase, which had previously been shown to have suffered limited proteolysis during preparation, with a range of substrates and effectors. These were compared with the values obtained with enzyme preparations purified in such a way as to prevent this proteolysis from occurring [McCarthy, Walker & Tipton (1980) Biochem. J. 191, 605-611]. The Km values and maximum velocities determined with different substrates revealed little difference between the two preparations although the proteolysed enzyme had lower Km values for NH4+ and glutamate when the activities were determined with NADPH and NADP+ respectively. This preparation was more sensitive to inhibition by Cl- ions but less sensitive to inhibition by high concentrations of the substrate NADH. The two preparations also differed in their sensitivities to allosteric effectors, with the proteolysed enzyme being the less sensitive to inhibition by GTP. At high concentrations of NADH, this preparation was also more sensitive to activation by ADP and ATP.
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PMID:Ox glutamate dehydrogenase. Comparison of the kinetic properties of native and proteolysed preparations. 405 48

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


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