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 amino acid sequence of the NADP+-dependent enzyme ovine 6-phosphogluconate dehydrogenase has been determined by conventional direct protein sequence analysis of peptides resulting from digestion of the protein with trypsin and chemical cleavages with cyanogen bromide, hydroxylamine, and iodosobenzoic acid. The polypeptide contains 466 amino acids and its NH2 terminus is acetylated. The Candida utilis enzyme is inactivated by reaction of pyridoxal phosphate with two lysine residues (Minchiotti, L., Ronchi, S., and Rippa, M. (1981) Biochim. Biophys. Acta 657, 232-242). These residues are conserved in the ovine enzyme. In contrast to NAD+ dehydrogenases which have weakly related sequences and spatially related folds in their nucleotide-binding sites, no significant sequence homologies were detected between 6-phosphogluconate dehydrogenase and any of three other NADP+-requiring enzymes, glutamate dehydrogenase, p-hydroxybenzoate hydroxylase, and dihydrofolate reductase. This is in accord with structural data that show no spatial relationship between NADP+-binding sites in these enzymes.
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PMID:Amino acid sequence of ovine 6-phosphogluconate dehydrogenase. 668 25

1. The factors affecting the pathway of glutamate oxidation were studied in isolated rat-liver mitochondria in incubations of 2-3 min. 2. It was found that bicarbonate at a physiological concentration has a profound effect on the pathway of glutamate oxidation. Ammonia formation via glutamate dehydrogenase is stimulated by bicarbonate [from 5.48 +/- 0.29 (n = 10) to 9.57 +/- 0.73 (n = 8) nmol X min-1 X mg protein-1], whereas aspartate formation via the transamination pathway is inhibited [from 38.41 +/- 2.24 (n = 9) to 24.56 +/- 3.28 (n = 6) nmol X min-1 X mg protein-1]. 3. Bicarbonate has no effect on the rate of transport of glutamate via the glutamate-hydroxyl translocator. 4. The interaction of bicarbonate with the pathway of glutamate oxidation occurs primarily at the level of succinate dehydrogenase, due to competitive inhibition of the enzyme by bicarbonate. 5. Inhibition by bicarbonate of the transamination pathway leads to a decrease in intramitochondrial 2-oxoglutarate, so that the deamination pathway is stimulated. 6. Using an equation which describes flux through glutamate dehydrogenase kinetically, it could be shown that the bicarbonate-induced decrease in intramitochondrial 2-oxoglutarate quantitatively accounts for the enhanced rate of deamination. 7. It is concluded that in the intact liver flux through glutamate dehydrogenase is sufficient to account for the ammonia formation required for urea synthesis from substrates such as alanine.
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PMID:Bicarbonate and the pathway of glutamate oxidation in isolated rat-liver mitochondria. 685 31

The role of mitochondrial swelling in renal ammoniagenesis was studied by the administration of 10 mg.kg-1 2,4-dinitrophenol, in vivo, to normal and chronically acidotic rats. 2,4-Dinitrophenol increased ammonia excretion in in vivo and in vitro production from glutamine by renal cortical slices and isolated kidneys perfused with 1 mM L-glutamine. Ammonia production per glutamine molecule utilized rose towards 2, consistent with activation of the mitochondrial glutaminase-glutamate dehydrogenase pathway in 2,4-dinitrophenol-treated and acidotic rats. The rank order of 2,4-dinitrophenol stimulation of ammonia formation in vivo and in vitro was normal less than normal + 2,4-dinitrophenol less than acidotic less than acidotic + 2,4-dinitrophenol. 2,4-Dinitrophenol administration appears to enlarge the in situ proximal tubule mitochondrial population and to increase the number undergoing degradation, suggesting that mitochondrial alterations correlate with ammoniagenesis in vivo.
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PMID:2,4-dinitrophenol stimulation of renal ammoniagenesis. 707 39

The effect of chronic acid feeding and its subsequent withdrawal was determined on the amounts of the metabolic intermediates and enzymic activities of the purine nucleotide cycle. Sprague-Dawley rats were given 1.5% (w/v) NH4Cl in their drinking water for 5 days. The renal excretion of NH3 rose 70-fold and the rats developed acidosis. The amount of renal IMP rose from a control value of 4.5 +/- 2.2 to 20.4 +/- 3.7nmol/g of kidney after 48h of acid feeding (P less than 0.001) and fell to normal within 48h of the recovery. Adenylosuccinate concentrations fell from a control value of 4.5 +/- 0.9nmol/g of kidney to 1.2 +/- 0.3nmol/g (P less than 0.005) by day 5 of acidosis and continued to fall to undetectable values by 48h after recovery. The amount of AMP remained constant through the acid-feeding and the recovery periods. The activity of adenylosuccinate synthetase, the rate-limiting enzyme of the purine nucleotide cycle, paralleled the rise and fall in NH3 excretion. The activities of phosphate-dependent glutaminase and glutamate dehydrogenase were elevated during the acid-feeding and the recovery period. Thus changes in the purine nucleotide cycle correlate with changes in NH3 excretion to a more parallel degree than does the activity of glutaminase or glutamate dehydrogenase.
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PMID:The purine nucleotide cycle in the regulation of ammoniagenesis during induction and cessation of chronic acidosis in the rat kidney. 730 74

1. The pathways and the fate of glutamate carbon and nitrogen were investigated in isolated guinea-pig kidney-cortex tubules. 2. At low glutamate concentration (1 mM), the glutamate carbon skeleton was either completely oxidized or converted into glutamine. At high glutamate concentration (5 mM), glucose, lactate and alanine were additional products of glutamate metabolism. 3. At neither concentration of glutamate was there accumulation of ammonia. 4. Nitrogen-balance calculations and the release of 14CO2 from L-[1-14C]glutamate (which gives an estimation of the flux of glutamate carbon skeleton through alpha-oxoglutarate dehydrogenase) clearly indicated that, despite the absence of ammonia accumulation, glutamate metabolism was initiated by the action of glutamate dehydrogenase and not by transamination reactions as suggested by Klahr, Schoolwerth & Bourgoignie [(1972) Am. J. Physiol. 222, 813-820] and Preuss [(1972) Am. J. Physiol. 222, 1395-1397]. Additional evidence for this was obtained by the use of (i) amino-oxyacetate, an inhibitor of transaminases, which did not decrease glutamate removal, or (ii) L-methionine DL-sulphoximine, an inhibitor of glutamine synthetase, which caused an accumulation of ammonia from glutamate. 5. Addition of NH4Cl plus glutamate caused an increase in both glutamate removal and glutamine synthesis, demonstrating that the supply of ammonia via glutamate dehydrogenase is the rate-limiting step in glutamine formation from glutamate. NH4Cl also inhibited the flux of glutamate through glutamate dehydrogenase and the formation of glucose, alanine and lactate. 6. The activities of enzymes possibly involved in the glutamate conversion into pyruvate were measured in guinea-pig renal cortex. 7. Renal arteriovenous-difference measurements revealed that in vivo the guinea-pig kidney adds glutamine and alanine to the circulating blood.
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PMID:Fate of glutamate carbon and nitrogen in isolated guinea-pig kidney-cortex tubules. Evidence for involvement of glutamate dehydrogenase in glutamine sythesis from glutamate. 747 41

The total protein increased in the gills and decreased in the muscle of the freshwater field crab Oziotelphusa senex senex at days 1 and 2 on exposure to lethal concentrations and at days 1 and 10 to sublethal concentrations of furadan, endosulfan, chlorpyrifos, and a mixture of these three in a 100:10:1 ratio. The increase in the gill protein was greater on exposure to the sublethal concentrations than to the lethal concentrations while the decrease in the muscle protein was greater on exposure to the lethal concentrations than to the sublethal concentrations. In the hepatopancreas, the protein content decreased on exposure to the lethal concentrations, but, in contrast, increased on exposure to the sublethal concentrations. These results clearly indicate that changes in the protein content are not only organ-dependent but also concentration-dependent, i.e., lethal versus sublethal. Irrespective of the changes in the total protein, the levels of free amino acids and the activities of protease, alanine and aspartate aminotransferases, and glutamate dehydrogenase increased in all the three organs of the crabs exposed to the lethal and sublethal concentrations, (more in lethal than in sublethal) and increased at a greater rate over time of exposure. Ammonia toxicity, measured by an increase in the hemolymph ammonia and a decrease in the urea, was also observed at the lethal concentrations of all the three pesticides. The ammonia and urea levels increased in the crabs exposed to the sublethal concentrations. Although the effect of each pesticide on the protein metabolism was similar, the degree of toxicity was the lowest on exposure to furadan, intermediate on exposure to endosulfan and chlorpyrifos, and cumulative on exposure to a mixture of the three pesticides.
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PMID:Pesticidal impact on the protein metabolism of freshwater field crab, Oziotelphusa senex senex (Fabricius). 754 42

A full-length cDNA clone, pMGDH1, encoding maize NADH-glutamate dehydrogenase (NADH-GDH) was isolated from a maize root cDNA library. The identity of the cDNA was established by the coincidence of the structure of the purified protein with that inferred from the nucleotide sequence of the cDNA. pMGDH1 had a cDNA insert of 1,638 bp and the open reading frame encoded 411 amino acid residues. The deduced amino acid sequence was similar to putative partial sequences of GDHs from higher plants and to the sequences of GDHs from organisms as diverse as mammals and bacteria. The NH2-terminal sequence deduced from the open reading frame had a typical structure that is associated with the import of proteins into the mitochondrial matrix. The cDNA hybridized to an RNA of about 1.6 kb. This transcript was more abundant in roots than in leaves and was localized in the bundle sheath cells in leaf tissues. Analysis of genomic DNA by Southern hybridization suggested the existence of gene(s) for another NADH-GDH subunit(s).
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PMID:Isolation and characterization of a cDNA that encodes maize glutamate dehydrogenase. 755 85

The effects of either low (25 mumol/min) or high (235 mumol/min) infusion of NH4Cl into the mesenteric vein for 5 d were determined on O2 consumption plus urea and amino acid transfers across the portal-drained viscera (PDV) and liver of young sheep. Kinetic transfers were followed by use of 15NH4Cl for 10 h on the fifth day with simultaneous infusion of [1-13C]leucine to monitor amino acid oxidation. Neither PDV nor liver blood flow were affected by the additional NH3 loading, although at the higher rate there was a trend for increased liver O2 consumption. NH3-N extraction by the liver accounted for 64-70% of urea-N synthesis and at the lower infusion rate the additional N required could be more than accounted for by hepatic removal of free amino acids. At the higher rate of NH3 administration additional sources of N were apparently required to account fully for urea synthesis. Protein synthesis rates in the PDV and liver were unaffected by NH3 infusion but both whole-body (P < 0.05) and splanchnic tissue leucine oxidation were elevated at the higher rate of administration. Substantial synthesis of [15N]glutamine occurred across the liver, particularly with the greater NH3 supply, and enrichments exceeded considerably those of glutamate. The [15N]urea synthesized was predominantly as the single labelled, i.e. [14N15N], species. These various kinetic data are compatible with the action of ovine hepatic glutamate dehydrogenase (EC 1.4.1.2) in periportal hepatocytes in the direction favouring glutamate deamination. Glutamate synthesis and uptake is probably confined to the perivenous cells which do not synthesize urea.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Hepatic detoxification of ammonia in the ovine liver: possible consequences for amino acid catabolism. 762 87

Leucine dehydrogenase/L-amino acid oxidase was proposed as an enzymatic conversion system for ammonia and its application to amperometric assay of creatinine was investigated. Ammonia formed by creatinine deiminase catalyzed hydrolysis of creatinine was converted to L-leucine by leucine dehydrogenase, and the oxidation of L-leucine by L-amino acid oxidase was detected with an oxygen electrode. Two approaches were proposed to overcome the problem of endogenous ammonia and L-amino acids. The first was using glutamate dehydrogenase prereactor to remove endogenous ammonia; endogenous L-amino acids were corrected by a separate run. In the second approach, endogenous ammonia and L-amino acids were simultaneously compensated with a two-channel system. It resulted in double peak recording that the flow was split and rejoined between the two ends of creatinine deiminase reactor and a delay coil and a reference column were properly set at one of the two-channels. One gave the sum response of all responsible compounds, the other that of endogenous interferences except creatinine. Both approaches were applied to creatinine assay in urine and the results showed a good agreement with those obtained from the Jaffe method.
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PMID:Amperometric flow-injection analysis of creatinine based on immobilized creatinine deiminase, leucine dehydrogenase and L-amino acid oxidase. 791 82

Oxystarch was chosen as a model compound for studying biological ammonia-sequestering systems. Ammonia was determined by use of an ion-selective electrode, by L-glutamate dehydrogenase (L-GDH), and by two different Berthelot procedures, in the presence and absence of oxystarch. In the presence of total oxystarch the Berthelot method, particularly when low concentration reagents were used, detected significantly less (P < 0.10) free ammonia than either L-GDH or ion-selective electrode methods. A 0.5-kDa molecular weight cutoff sample ultrafiltration step was added prior to analysis by L-GDH and Berthelot procedures. To facilitate complete removal of oxystarch by the ultrafiltration step, oxystarch was dialyzed before use, yielding a high-molecular-weight fraction (> 1 kDa). Removal of high-molecular-weight oxystarch species and bound ammonia by ultrafiltration of samples prior to assay completely negated discrepancies between ammonia levels measured by L-GDH and both Berthelot methods. The correlation of the levels of measured ammonia, as determined by L-GDH and Berthelot methods, in mixtures with high-molecular-weight oxystarch was significantly improved by the addition of the sample ultrafiltration step. Improved correlation of results from such fundamentally different methods demonstrates the removal of interfering agents as well as the nonperturbatory nature of the improved procedure. The addition of such an ultrafiltration step may be applied to the determination of ammonia by the otherwise interference-prone Berthelot assay in mixtures with any interfering macromolecules, without the inconvenience or potential variabilities associated with distillation or diffusion procedures.
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PMID:An ultrafiltration method for the removal of interfering agents and its application to the determination of free ammonia in solutions of oxystarch by the Berthelot reaction method. 812 91


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