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 damaging effects of ADP/Fe/NADPH-induced lipid peroxidation were studied on the enzymes and membranes of rat liver mitochondria. Succinate, an inhibitor of mitochondrial lipid peroxidation, prevented or delayed most of the damage caused by the peroxidation on different mitochondrial structures and functions. There were marked abnormalities on the electrophoretic pattern of mitochondrial proteins during the course of lipid peroxidation. The disappearance of particular polypeptide bands and the accumulation of high-molecular-weight aggregates could be observed. Succinate was found to delay these effects. As a consequence of lipid peroxidation the succinate oxidase activity of mitochondria was decreased. The succinate dehydrogenase enzyme and the component(s) of the respiratory chain were inactivated. Succinate prevented the inactivation of succinate dehydrogenase but did not protect the other components of terminal oxidation chain. From the matrix enzymes the glutamate dehydrogenase retained its full activity but the NADP-linked isocitrate dehydrogenase was inactivated. The mitochondrial membranes became permeable to large protein molecules. Succinate prevented the inactivation of isocitrate dehydrogenase and delayed the release of protein molecules from mitochondria.
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PMID:Effect of succinate on mitochondrial lipid peroxidation. 2. The protective effect of succinate against functional and structural changes induced by lipid peroxidation. 303 29

The NAD-dependent glutamate dehydrogenase from Phycomyces spores was purified more than 300-fold. Estimation of Mr by gel filtration gave a value of 98,000 whereas after SDS-PAGE one major band of Mr 54,000 was found, suggesting that the enzyme is a dimer. The enzyme was virtually dependent on the presence of AMP for activity and showed half-maximal activation at 9.5 and 43 microM-AMP in the direction of animation and deamination respectively. ADP was nearly as effective at 20-fold higher concentrations. Other nucleotide monophosphates were ineffective and nucleoside triphosphates were slightly inhibitory. Hyperbolic kinetics were found for all substrates yielding Km values of about 10 mM for ammonium, 1 mM for 2-oxoglutarate and 0.1 mM for NADH in the direction of amination, and 10 mM for glutamate and 0.7 mM for NAD in the direction of deamination.
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PMID:Purification and properties of NAD-dependent glutamate dehydrogenase from Phycomyces spores. 322 Dec

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

Fluorescence stopped-flow techniques have been used to investigate the binding of the oxidised coenzyme eNAD to bovine liver glutamate dehydrogenase (L-glutamate:NAD(P)+ oxidoreductase (deaminating), EC 1.4.1.3) saturated with glutarate, a substrate analogue, by following the transient kinetics of fluorescence intensity changes associated with changes in the binding of 1,N6-etheno-NAD (eNAD) to the enzyme, using displacement by NAD, NADP, ADP or GTP. Computer simulations of the various kinetic models provide a detailed picture of the molecular interactions between the active site (site I) and regulatory sites (sites II and III), specific for adenine and guanine nucleotides, respectively. The observed enhancement of the eNAD dissociation rate constant from site I can satisfactorily be accounted for as being due to the effect of ADP or NAD (and to a lesser extent NADP) binding to site II. This provides a mechanism for the allosteric activation of this enzyme via a predominantly intrasubunit interaction. By contrast the isomerisation of the enzyme induced by ADP alone is markedly slowed down by the occupancy of site I by eNAD in the presence of glutarate. The inhibitory effect of the allosteric effector GTP correlates with a tightening of eNAD binding, causing a decrease of the coenzyme dissociation rate constant followed by a slow isomerisation of the enzyme complexed with eNAD and glutarate.
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PMID:Fluorescence stopped-flow studies on the binding of 1,N6-etheno-NAD to bovine liver glutamate dehydrogenase. 340 91

The time-correlated single photon counting (TCPC) fluorescence technique has been used as a novel approach to investigate ligand-protein interaction, for the case of the binding of the fluorescent coenzyme analogue 1,N6-ethenoNAD (epsilon NAD) to bovine liver glutamate dehydrogenase in the presence of glutarate, a substrate analogue which stabilizes the complex. System calibration was performed using solutions of epsilon ADP and carefully purified epsilon NAD mixed at variable molar ratios (pH 7.0, 0.05 M sodium phosphate buffer, 20 degrees C). The fluorescence lifetimes obtained after deconvolution were 2.4 ns (for epsilon NAD) and 23 ns (for epsilon ADP), in good agreement with literature values obtained under similar conditions. epsilon NAD binds to glutamate dehydrogenase in the presence of 50 mM glutarate, with a fluorescence quantum yield enhancement factor, Q, of about 17-fold, as previously reported (Favilla, R. and Mazzini, A. (1984) Biochim. Biophys. Acta 48-57). For this system, fluorescence lifetime values were obtained after deconvolution as 2.4 ns for free epsilon NAD and 21 ns for bound epsilon NAD. These values did not vary appreciably with enzyme concentration nor with degree of saturation, thus reflecting the existence of only one spectroscopically relevant type of complex. Addition of either GTP or ADP did not affect the lifetime of epsilon NAD bound to the enzyme, but only its affinity, thus allowing calculations of binding strengths. In the case of a simple binding (i.e., in the absence of GTP) the dissociation constant of the complex could be derived from a simple relationship, in which only the ratio between the pre-exponential factors and the parameter gamma, which represents the molar fraction of epsilon NAD molecules free in solution in the open conformation, are to be taken into account. The results are in good agreement with those reported by some of us (reference above) using a steady-state fluorescence technique, which by itself is, however, unable to resolve the number of relevant species present in the system.
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PMID:The binding of 1,N6-ethenoNAD to bovine liver glutamate dehydrogenase: studies using the time-correlated single photon counting fluorescence technique. 348 73

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

The effect of long-chain acyl-CoA on glutamate dehydrogenase activity was studied in uncoupled rabbit kidney cortex mitochondria incubated with glutamate and palmitoylcarnitine in the presence of arsenite. The mitochondrial long-chain acyl-CoA (about 2 nmol/mg of protein) accumulated in the presence of arsenite resulted in an inhibition of ammonia production from 4.1 to 1.2 nmol/min per mg of protein. Leucine and ADP, activators of glutamate dehydrogenase, did not release the inhibitory effect of long-chain acyl-CoA on glutamate deamination. In view of the presented data it seems that inhibitory effect of long-chain acyl-CoA on glutamate dehydrogenase activity may have a physiological significance.
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PMID:The relationship between the rate of glutamate deamination and long-chain acyl-CoA accumulation in kidney cortex mitochondria of rabbit. 359 79

The protective effect of ADP on unspecific Ca2+ release and collapse of the transmembrane potential was analyzed in mitochondria from kidneys of rats. The presence of ADP in the incubation mixture prevents Ca2+ leakage and collapse of delta psi in sucrose-containing medium, but fails to do so in KCl medium. The effect of the adenine nucleotide in sucrose media correlates with an increase in the level of reduced pyridine nucleotides; the increase was due to a stimulatory effect on the activity of glutamic dehydrogenase. It also was observed that in KCl media, in the presence and in the absence of ADP the rate of NADH oxidation through the respiratory chain was higher than in sucrose; in this latter medium a high level of reduced pyridine nucleotides was found, in comparison to KCl media. It is proposed that the role of ADP is to increase glutamic dehydrogenase activity and in consequence to provoke a higher rate of formation of NADH which in turn controls Ca2+ release.
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PMID:Control of mitochondrial Ca2+ retention by ADP-stimulated glutamic dehydrogenase. 369 45

The 2',3'-dialdehyde derivative of NADPH (oNADPH) acts as a coenzyme for the reaction catalyzed by bovine liver glutamate dehydrogenase. Incubation of 250 microM oNADPH with enzyme for 300 min at 30 degrees C and pH 8.0 yields covalent incorporation of 1.0 mol of oNADPH/mol of enzyme subunit. The modified enzyme has a functional catalytic site and is activated by ADP, but is no longer inhibited by high NADH concentrations and exhibits decreased sensitivity to GTP inhibition. Using the change in inhibition by 600 microM NADH or 1 microM GTP to monitor the reaction leads to rate constants of 44.0 and 41.5 min-1 M-1, respectively, suggesting that loss of inhibition by the two regulatory compounds results from reaction by oNADPH at a single location. The oNADPH incorporation is proportional to the decreased inhibition by 600 microM NADH or 1 microM GTP, extrapolating to less than 1 mol of oNADPH/mol of subunit when the maximum change in NADH or GTP inhibition has occurred. Modified enzyme is still 93% inhibited at saturating levels of GTP, although its K1 is increased 20-fold to 4.6 microM. The kinetic effects caused by oNADPH are not prevented by alpha-ketoglutarate, ADP, 5 mM NADH, or 200 microM GTP alone, but are prevented by 5 mM NADH with 200 microM GTP. Incorporation of oNADPH into enzyme at 255 min is 0.94 mol/mol of peptide chain in the absence of ligands but only 0.53 mol/mol of peptide chain in the presence of the protectants 5 mM NADH plus 200 microM GTP. These results indicate that oNADPH modifies specifically about 0.4-0.5 sites/enzyme subunit or about 3 sites/enzyme hexamer and that reaction occurs at a GTP-dependent inhibitory NADH site of glutamate dehydrogenase.
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PMID:Reaction of the 2',3'-dialdehyde derivative of NADPH at a nucleotide site of bovine liver glutamate dehydrogenase. 373 24

Bovine liver glutamate dehydrogenase reacts covalently with the adenine nucleotide analogue 2-(4-bromo-2,3-dioxobutylthio)adenosine 5'-monophosphate (2-BDB-TAMP) with incorporation of about 1 mol of reagent/mol of enzyme subunit. The modified enzyme is not inactivated by this reaction as measured in the absence of allosteric effectors. Native glutamate dehydrogenase is activated by ADP and inhibited by high concentrations of NADH; both of these effects are irreversibly decreased upon reaction of the enzyme with 2-BDB-TAMP. The decrease in activation by ADP was used to determine the rate constant for reaction with 2-BDB-TAMP. The rate constant (kobs) for loss of ADP activation exhibits a nonlinear dependence on 2-BDB-TAMP concentration, suggesting a reversible binding of reagent (KR = 0.74 mM) prior to irreversible modification. At 1.2 mM 2-BDB-TAMP, kobs = 0.060 min-1 and is not affected by alpha-ketoglutarate or GTP, but is decreased to 0.020 min-1 by 5 mM NADH and to zero by 5 mM ADP. Incorporation after incubation with 1.2 mM 2-BDB-TAMP for 1 h at pH 7.1 is 1.02 mol/mol enzyme subunit in the absence but only 0.09 mol/subunit in the presence of ADP. The enzyme protected with 5 mM ADP behaves like native enzyme in its activation by ADP and in its inhibition by NADH. Native enzyme binds reversibly 2 mol of [14C]ADP/subunit, whereas modified enzyme binds only 1 mol of ADP/peptide chain. These results indicate that incorporation of 1 mol of 2-BDB-TAMP causes elimination of one of the ADP sites of the native enzyme. 2-BDB-TAMP acts as an affinity label of an ADP site of glutamate dehydrogenase and indirectly influences the NADH inhibitory site.
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PMID:Affinity labeling of an allosteric ADP site of glutamate dehydrogenase by 2-(4-bromo-2,3-dioxobutylthio)adenosine 5'-monophosphate. 378 79


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