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 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

Two membrane-bound glutamate dehydrogenases were found in adult Dirofilaria immitis, an NAD-linked enzyme (EC 1.4.1.2) in the cytosol (C-GDH) and an enzyme equally reactive with NAD or NADP (EC 1.4.1.3) in the mitochondria (M-GDH). The cytosolic enzyme had a pH optimum of 7.8-8.0 and exhibited 30% more activity at 25 C than at 37 C (pH 8.0). The mitochondrial enzyme had a pH optimum at 8.4 and exhibited 27% more activity at 37 C than at 25 C (pH 8.4); it was also more sensitive to heat denaturation. Gel filtration of worm subfractions separated four peaks of C-GDH activity with molecular weights of approximately 610, 285, 180, and less than 100 thousand, and a single major peak of M-GDH activity with a molecular weight of about 335,000. When assayed at pH 8, 37 C, and 200 microM NADH, the Km for the substrate, alpha-ketoglutarate, was equivalent for the two enzymes, but the Km for ADP (activator) was five times greater for M-GDH. When the two enzymes were assayed at pH 8.0, 37 C, and 100 microM NADH, 1 mM ADP approximately doubled and 1 mM ATP halved the velocity observed for each enzyme with no effector present. Under these assay conditions AMP, IDP, GDP, and GTP had opposite effects on the reaction velocities for the two enzymes. When the assay conditions were changed, the effects of added purine nucleotides varied, even directionally. Addition of up to 5 mM glutamate (product) had no significant effect on C-GDH kinetics, nor on the substrate Km of M-GDH.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Dirofilaria immitis: comparison of cytosolic and mitochondrial glutamate dehydrogenases. 395 79

Chemical crosslinking with dimethyl pimelimidate has been used to examine the quaternary structure and conformational mobility of bovine liver glutamate dehydrogenase. Crosslinking patterns are shown to be consistent with either a stacked or staggered dimer of trimers structure of the hexamer. Crosslinking in the absence of coligands results in a small loss of activity but an almost complete loss of GTP inhibitory effects. Protection experiments show that the active site can be protected by a variety of ligand combinations, and that the loss of GTP inhibition is protected by several complexes containing either NADH or NADPH, indicating that the second coenzyme site per subunit (which preferentially binds NADH) is not involved in the protection process. A significant loss of ADP activation occurs during crosslinking which is not protected against by any combination of protecting ligands tried, including those which involve second coenzyme site binding, showing that the ADP site is functionally distinct from the GTP site and from the second coenzyme binding site. Crosslinking in the presence of protecting ligands gives similar gel patterns to those obtained in the absence of protection. Affinity chromatography experiments show that the crosslinked enzyme still binds GTP despite the loss of GTP inhibition, and hysteresis experiments show that the second coenzyme site is left functional if protected with either coenzyme. A model is presented where crosslinking affects the conformational linkage between various ligand binding sites involved in GTP inhibition rather than the sites themselves.
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PMID:Investigation of the effects of crosslinking glutamate dehydrogenase with dimethyl pimelimidate. 400 63

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

Ox-liver glutamate dehydrogenase is known to utilise a wide range of amino acid substrates. Kinetic studies are presented here for L-threo-gamma-methylglutamate and L-alpha-amino-gamma-nitraminobutyrate in the presence of the allosteric effector ADP. The results presented are considered in the light of similar studies presented elsewhere in which the cofactor was systematically replaced by a variety of analogues. These amino acid analogues share the same pH optimum as glutamate, unlike the monocarboxylic amino acids including alanine and norvaline, and give linear double-reciprocal plots under the conditions used here. Studies with the alternative coenzymes have suggested an ordered addition of glutamate before coenzyme in the presence of ADP. The present results obtained under identical conditions support this conclusion.
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PMID:Kinetic studies of ox-liver glutamate dehydrogenase oxidative deamination of two glutamate analogues, L-threo-gamma-methylglutamate and L-alpha-amino-gamma-nitraminobutyrate, in the presence of the allosteric effector ADP. 405 26

Highly purified preparations of glutamate dehydrogenase were obtained from mitochondrial and cytoplasmic fractions of rabbit liver by affinity chromatography on CL-Sepharose 4B modified by adenosine diphosphate. Some physico-chemical properties of the purified enzymes (e. g., specific activity, molecular weight, quaternary structure, stability against denaturating effect of urea, pH optimum of catalyzed reactions, Km values for substrates and coenzymes) were found to be identical. The sole difference was detected in the ability of enzyme preparations to be activated by adenosine diphosphate. The activation of the cytoplasmic enzyme is 160%, that of mitochondrial glutamate dehydrogenase is 230-240% under the same conditions.
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PMID:[Purification of glutamate dehydrogenase from the rabbit liver and study of its major physico-chemical properties]. 407 89

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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