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 reaction of glutamate dehydrogenase and glutamate (gl) with NAD+ and NADP+ has been studied with stopped-flow techniques. The enzyme was in all experiments present in excess of the coenzyme. The results indicate that the ternary complex (E-NAD(P)H-kg) is present as an intermediate in the formation of the stable complex (E-NAD(P)H-gl). The identification of the complexes is based on their absorption spectra. The binding of the coenzyme to (E-gl) is the rate-limiting step in the formation of (E-NAD(P)H-kg) while the dissociation of alpha-ketoglutarate (kg) from this complex is the rate-limiting step in the formation of (E-NAD(P)H-gl). The Km for glutamate was 20-25 mM in the first reaction and 3 mM in the formation of the stable complex. The Km values were independent of the coenzyme. The reaction rates with NAD+ were approximately 50% greater than those with NADP+. Furthermore, high glutamate concentration inhibited the formation of (E-NADH-kg) while no substrate inhibition was found with NADP+ as coenzyme. ADP enhanced while GTP reduced the rate of (E-NAD(P)H-gl) formation. The rate of formation of (E-NAD(P)H-kg) was inhibited by ADP, while it increased at high glutamate concentration when small amounts of GTP were added. The results show that the higher activity found with NAD+ compared to NADP+ under steady-state assay conditions do not necessarily involve binding of NAD+ to the ADP activating site of the enzyme. Moreover, the substrate inhibition found at high glutamate concentration under steady-state assay condition is not due to the formation of (E-NAD(P)H-gl) as this complex is formed with Km of 3 mM glutamate, and the substrate inhibition is only significant at 20-30 times this concentration.
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PMID:Formation of transient complexes in the glutamate dehydrogenase catalyzed reaction. 0 39

1. The activities of citrate synthase and NAD+-linked and NADP+-linked isocitrate dehydrogenases were measured in nervous tissue from different animals in an attempt to provide more information about the citric acid cycle in this tissue. In higher animals the activities of citrate synthase are greater than the sum of activities of the isocitrate dehydrogenases, whereas they are similar in nervous tissues from the lower animals. This suggests that in higher animals the isocitrate dehydrogenase reaction is far-removed from equilibrium. If it is assumed that isocitrate dehydrogenase activities provide an indication of the maximum flux through the citric acid cycle, the maximum glycolytic capacity in nervous tissue is considerably greater than that of the cycle. This suggest that glycolysis can provide energy in excess of the aerobic capacity of the tissue. 2. The activities of glutamate dehydrogenase are high in most nervous tissues and the activities of aspartate aminotransferase are high in all nervous tissue investigated. However, the activities of alanine aminotransferase are low in all tissues except the ganglia of the waterbug and cockroach. In these insect tissues, anaerobic glycolysis may result in the formation of alanine rather than lactate.
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PMID:Activities of citrate synthase, NAD+-linked and NADP+-linked isocitrate dehydrogenases, glutamate dehydrogenase, aspartate aminotransferase and alanine aminotransferase in nervous tissues from vertebrates and invertebrates. 0 Oct 3

The kinetic properties of the constitutive double specific glutamate dehydrogenase (NAD(P)--GDH) and the inducible NADP-specific glutamate dehydrogenase (NADP--GDH) of Chlorella pyrenoidosa Pringsheim 82T (thermophilic strain) in a deaminating reaction have been studied. NAD(P)-GDH behaves in a deamination as a Michaelis-Menten enzyme. NADP-GDH displays some lag-period before a steady-state phase. The duration of this lag depends on a substrate concentration. Besides that, an effect of all the substrates on a heat inactivation of both GDH and a product inhibition have been studied. All the substrates except the reduced co-factors protect effectively GDH from the heat inactivation, especially the thermolabille NADP-GDH. On the contrary, NAD(P)-H promote the heat inactivation of both GDH. The product inhibition analysis shows that the inducible NADP-GDH acts in vivo as a synthetic enzyme. In the previous paper (V. R. Shatilov et all., 1974, Dokl. Acad. Nauk USSR, 216,223) it was shown for the constitutive GDH that p-CMB strongly inhibited a desamination and slightly (if any) affect an amination. It this paper it is shown that action of p-CMB on the amination depends on the presence of NAD+ (not NADP+ or L-glutamate). p-CMB and NAD+ affect tha amination in a strongly sunergetic manner. Some suggestions about the intracellular localization of chlorella GDH are made.
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PMID:[Comparative study of glutamate dehydrogenases of Chlorella]. 0 35

Bacillus subtilis PCI 219 has a single glutamate dehydrogenase (GDH) [EC 1.4.1.3] with dual coenzyme specificity [for NAD(H) and NADP(H)]. The enzyme was purified 800-fold from crude extracts of B. subtilis from the post-exponential phase of growth and showed one significant protein band on gel electrophoresis. This band was determined, by activity staining, to have all the GDH nucleotide specificities. Its molecular weight was estimated to be 250,000+/-20,000 by gel filtration, and 270,000+/-30,000 by zone centrifugation in a sucrose density gradient. Polyacrylamide gel electrophoresis in sodium dodecyl sulfate showed that GDH has a subunit size of about 57,000. The pI of GDH was found to bepH 3.7 by isoelectric focusing. GDH exhibited nonlinear kinetics in the reduction of NAD+, and in the reverse direction, the substrate, NH4+, was strongly inhibitory at high concentrations. Purine nucleotides did not affect the activity. The oxidative demination of glutamate was significantly inhibited by the metabolites oxaloacetate and citrate, which acted as allosteric effectors of this enzyme,inhibiting the reaction in one direction. The pH optimum of each of the activities of GDH and the stability of GDH are also reported.
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PMID:Glutamate dehydrogenase from Bacillus subtilis PCI 219. I. Purification and properties. 1 49

The ratio NAD+/NAD-H was detemined in mitochondria of the loach oocytes and eggs on the basis of concentrations of the glutamate dehydrogenase reaction intermediates. This ratio increases 6 times upon the oocyte maturation. The importance of this ratio in the metabolism of oocyte and embryo is discussed.
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PMID:[NAD+/NADH ratio in the mitochondria of the oocytes and ova of groundling, Misgurnus fossilis (L.)]. 1 88

1. The activity of glutamate dehydrogenase was measured in the tissues of the squid, Loligo pealeii. The enzyme occurs in high activity in digestive pouch, systemic heart, and all muscle tissues. 2. Glutamate dehydrogenase from mantle muscle is located intra-mitochondrially, has a molecular weight of 310,000, and is electrophoretically similar to the enzyme from all other squid tissues. 3. The enzyme from mantle muscle was purified 40-fold by elution from DEAE-cellulose and used for kinetic studies. The enzyme is NAD+-specific, activated by ADP, AMP, and leucine, and inhibited by GTP, GDP, ATP, and reaction products (in particular NADH). 4. Squid glutamate dehydrogenase shows an almost absolute dependence on ADP. The purified enzyme is activated over 100-fold by saturating concentrations of ADP (Ka = 0,75 7M); The pH optima are also altered significantly by ADP. 5. The enzyme appears to be kinetically adapted to favour glutamate oxidation in comparison to glutamate dehydrogenase from other resources. The evidence indicates that the primary role of glutamate dehydrogenase in squid mantle muscle is in regulating the catabolism of amino acids for energy production.
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PMID:Purification and properties of glutamate dehydrogenase from the mantle muscle of the squid, Loligo pealeii. Role of the enzyme in energy production from amino acids. 2 72

o-Aminobenzoic acid (OABA, anthranilic acid) and related compounds which are known to stimulate the biosynthesis of streptothricin-type antibiotic nourseothricin by Streptomyces noursei JA 3890b were found to increase strongly the NADH/NAD+ ratio in growing mycelium of this strain suggesting that these effectors are capable of interfering with the function of the respiratory chain. In parallel, a complex shift of metabolism was induced shown by simultaneous alteration of mycelial activities of alanine dehydrogenase, glutamine synthetase, and glutamate dehydrogenase. These changes may be responsible for the observed delay of amino acid catabolism and may improve the precursor supply of the secondary metabolism.
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PMID:Regulative influence of o-aminobenzoic acid on the biosynthesis of nourseothricin in cultures of Streptomyces noursei JA 3890b. III. Change of redox state of nicotinamide-adenine-dinucleotides in the presence of aminobenzoic acids. 3 66

Initial-rate studies were made of the oxidation of L-glutamate by NAD+ and NADP+ catalysed by highly purified preparations of dogfish liver glutamate dehydrogenase. With NAD+ as coenzyme the kinetics show the same features of coenzyme activation as seen with the bovine liver enzyme [Engel & Dalziel (1969) Biochem. J. 115, 621--631]. With NADP+ as coenzyme, initial rates are much slower than with NAD+, and Lineweaver--Burk plots are linear over extended ranges of substrate and coenzyme concentration. Stopped-flow studies with NADP+ as coenzyme give no evidence for the accumulation of significant concentrations of NADPH-containing complexes with the enzyme in the steady state. Protection studies against inactivation by pyridoxal 5'-phosphate indicate that NAD+ and NADP+ give the same degree of protection in the presence of sodium glutarate. The results are used to deduce information about the mechanism of glutamate oxidation by the enzyme. Initial-rate studies of the reductive amination of 2-oxoglutarate by NADH and NADPH catalysed by dogfish liver glutamate dehydrogenase showed that the kinetic features of the reaction are very similar with both coenzymes, but reactions with NADH are much faster. The data show that a number of possible mechanisms for the reaction may be discarded, including the compulsory mechanism (previously proposed for the enzyme) in which the sequence of binding is NAD(P)H, NH4+ and 2-oxoglutarate. The kinetic data suggest either a rapid-equilibrium random mechanism or the compulsory mechanism with the binding sequence NH4+, NAD(P)H, 2-oxoglutarate. However, binding studies and protection studies indicate that coenzyme and 2-oxoglutarate do bind to the free enzyme.
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PMID:Kinetic studies of dogfish liver glutamate dehydrogenase. 3 53

NAD-linked glutamate dehydrogeanse [EC 1.4.1.2] was detected together with NADP-linked glutamate dehydrogenase [EC 1.4.1.4] and aspartase [EC 4.3.1.1] in Pseudomonas fluorescens cells. The three enzymes were distinctly separated by DEAE-Sephadex column chromatography. The NAD-linked enzyme was extremely thermolabile and was rapidly inactivated even at temperatures as low as 35--40 degrees C. The combined addition of NAD+ and glutamate, however, effectively stabilized the enzyme. The glutamate saturation profile of the NAD-linked enzyme exhibited cooperativity with a Hill coefficient (n) of 1.4. ATP inhibited the enzyme in an allosteric manner, increasing the n value to 2.2. These results suggest a novel type of metabolic regulation shared by the three enzymes in the biosynthesis and catabolism of amino acids.
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PMID:Occurrence of thermolabile and regulatory NAD-linked glutamate dehydrogenase in Pseudomonas fluorescens. 3 48

Biotin deficiency in Aspergillus nidulans resulted in a 70% increase of the protein content and increased levels of free and bound aspartate, glutamate, serine, leucine and methionine. Likewise, the activities of NADP+ glutamate dehydrogenase, NAD+ gluatmate dehydrogenase, aspartate aminotransferase and alanine aminotransferase were significantly increased. The total RNA content increased while the DNA content was unaffected. The rRNA/tRNA ratio remained higher in biotin-deficient cells. Supplementation of glutamate, aspartate, serine, leucine and methionine to the culture medium raised the rRNA/tRNA ratio, and the difference observed in the qualitative and the quantitative patterns of protein and dry cell mass between normal and biotin-deficient cultures was abolished.
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PMID:Factors affecting protein synthesis during biotin deficiency in Aspergillus nidulans. 4 77


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