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)

Garlic has been proposed as a natural hypolipidemic substance. Most hypolipidemic compounds induce peroxisomal proliferation and increase enzyme activities associated with peroxisomal beta-oxidation in rat liver. Here we report that garlic methanol-extracts behave as hypolipidemic drugs, increasing the activity of peroxisomal fatty acyl-coenzyme A oxidase and of total carnitine acetyl-coenzyme A transferase in primary cultures of rat hepatocytes. Both enzymes are considered markers associated with increased peroxisomal beta-oxidation. As in the case of hypolipidemic peroxisome proliferators, garlic extracts partially prevented the decrease in fatty acyl-coenzyme A oxidase as the culture aged. No changes were observed in the activity of microsomal NADPH cytochrome c reductase or of mitochondrial glutamate dehydrogenase.
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PMID:Induction of peroxisomal fatty acyl-coenzyme A oxidase and total carnitine acetyl-coenzyme A transferase in primary cultures of rat hepatocytes by garlic extracts. 153 78

Three isozymes of glutamate dehydrogenase (GDH) of Chlamydomonas reinhardtii, induced under different trophic and stress conditions, have been purified about 800-1000-fold to electrophoretic homogeneity. They are hexamers of Mr 266,000-269,000 as deduced from gel filtration and sedimentation coefficient data. GDH1 consisted of six identical subunits of 44 kDa each, whereas both GDH2 and GDH3 consisted of six similar-sized monomers (4 of 44 kDa and 2 of 46 kDa). Optimum pH for the three activities with each pyridine nucleotide was identical (8.5 with NADH; 7.7 with NADPH; and 9.0 with NAD+). The isozymes exhibited similar high optimum temperature values (60-62 degrees C) and isoelectric points (7.9-8.1). Activity was enhanced in vitro by Ca2+ ions and strongly inhibited by pyridoxal 5'-phosphate, KCN, o-phenanthroline and EDTA, and to a lesser extent by pHMB and methylacetimidate. In the aminating reaction the three isozymes were inhibited in a concentration-dependent process by both NADH and NADPH, with apparent Km values for NH4+ ranging from 13-53 mM; 0.36-1.85 mM for 2-oxoglutarate and 0.07-0.78 mM for NADH and NADPH. In the deaminating reaction apparent Km values ranged from 0.64-3.52 mM for L-glutamate and 0.20-0.32 for NAD+. In addition, the three isozymes exhibited a non-hyperbolic kinetics for NAD+ with negative cooperativity (n = 0.8).
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PMID:Purification and properties of three NAD(P)+ isozymes of L-glutamate dehydrogenase of Chlamydomonas reinhardtii. 154 Jun 36

Giardia lamblia is believed to be the earliest branching derivative from the eucaryotic lineage. Genomic and cDNA clones encoding the giardia NADP-dependent glutamate dehydrogenase have been isolated and characterized. Southern hydridization using genomic DNA indicates that the gene encoding this activity is unique and single copy. Primer extension, S1 nuclease protection, and genomic and cDNA sequence analysis demonstrate that gene transcripts are initiated within a conserved AT-rich sequence element immediately preceding the ATG translation initiation codon and the short 5' untranslated region is not extended by transsplicing. The open reading frame is 1350 nucleotides in length and encodes a protein of 449 amino acids. The reading frame is not interrupted by introns and the primary transcript is probably not subjected to RNA editing. In the strictly anaerobic metabolism of giardia, NADP-dependent glutamate dehydrogenase activity participates along with alanine aminotransferase, in the cyclic dissipation of reducing equivalents (NADPH) through the conversion of pyruvate to alanine. The deduced amino acid sequence of the giardia protein exhibits substantial homology to numerous fungal and eubacterial NADP-dependent glutamate dehydrogenases. Comparisons of alignment gap positions and amino acid identities indicate that the giardia sequence is at least as similar or more similar to the eubacterial sequence than it is to the fungal sequence. This supports the hypothesis that giardia diverged very early from the eucaryotic lineage.
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PMID:Isolation and characterization of a NADP-dependent glutamate dehydrogenase gene from the primitive eucaryote Giardia lamblia. 155 91

Injection with pharmacological doses of dexamethasone (5 mg/kg) and/or bovine glucagon (1 mg/kg) exerts pronounced effects on toadfish liver compared with vehicle-treated control fish. Affected parameters include hepatic levels of glycogen and the activities of glutamate dehydrogenase, aspartate aminotransferase, malate dehydrogenase, and enzymes involved in NADPH generation as well as the kinetics of pyruvate kinase. Activities of tyrosine aminotransferase, however, a prime target for hormonal induction in mammals, remain unchanged in Opsanus. In subsequently isolated toadfish hepatocytes, metabolite concentrations and flux through gluconeogenesis are altered as are in vitro responses to epinephrine and catfish glucagon in previously injected fish. Contrary to existing mammalian models, short-term regulation of urea cycle activity can be ruled out for toadfish, since hormone treatments fail to influence the activity of two ornithine-urea cycle enzymes or the rate of hepatocyte-urea synthesis. Treatment-dependent increases in hepatic glutamine synthetase, the unique feeder enzyme for ammonia "nitrogen" in fish urea cycle, indicate a potentially pivotal role for this enzyme in longer-term regulation of ureogenesis.
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PMID:Metabolic actions of glucagon and dexamethasone in liver of the ureogenic teleost Opsanus beta. 160 Dec 63

NADP-dependent glutamate dehydrogenase from Dictyostelium discoideum was purified 9300 fold with a yield of 4.6%. The enzyme is a hexamer of apparent molecular weight 294 kDa on Sephacryl S400 and a subunit molecular weight of 52 kDa as determined by SDS gel electrophoresis. The apparent Kms for alpha-ketoglutarate, NADPH and NH4+ are 1.2 mM, 9.7 microM and 2.2 mM respectively, and the purified enzyme has a broad pH optimum with a peak at pH 7.75. GTP has a slight stimulatory effect (22% at 83 microM) as does ADP (11% at 1 mM), and AMP is slightly inhibitory (9% at 1 mM) whereas adenosine, ATP and cAMP have little or no effect. Neither the Zn2+ chelating compound 1,10-phenanthroline nor EDTA have any effect on the enzyme while p-hydroxymercuribenzoic acid inhibits enzyme activity (50% at 80 microM) yet N-ethylmaleimide does not. In addition, the NADP-GDH activity varies little during the various stages of morphogenesis.
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PMID:Purification and properties of the NADP-dependent glutamate dehydrogenase from Dictyostelium discoideum. 165 3

NADP(+)-specific glutamate dehydrogenase of Salmonella typhimurium was previously shown to react irreversibly at the coenzyme site with the nucleotide analogue 2-((4-bromo-2,3-dioxobutyl)thio)-1,N6-ethenoadenosine 2',5'-bisphosphate (2-BDB-T epsilon A 2',5'-DP) yielding a partially active enzyme, and inactivation was attributed to modification of the peptide Leu282-Cys-Glu-Ile-Lys286 (Bansal, A., Dayton, M.A., Zalkin, H., and Colman, R.F. (1989) J. Biol. Chem. 264, 9827-9835). Three mutant enzymes have now been engineered, expressed in Escherichia coli, and purified: the single mutants C283I and E284Q and the double mutant C283I:E284Q. The wild-type and mutant enzymes have similar specific activities and Km values for alpha-ketoglutarate, ammonium ion, and NADPH, indicating that neither cysteine 283 nor glutamic acid 284 is essential for activity. The mutant enzyme E284Q, like wild-type glutamate dehydrogenase, is substantially inactivated by 2-BDB-T epsilon A 2',5'-DP. In contrast, the two cysteine mutant enzymes, C283I and C283I:E284Q, are not inactivated by 2-BDB-T epsilon A 2',5'-DP. Modified tryptic peptides with the sequence Leu-X-Glu(Gln)-Ile-Lys were isolated from wild-type or E284Q enzymes inactivated by 2-BDB-T epsilon A 2',5'-DP. This peptide was absent from digests of active wild-type enzyme modified in the presence of the protectant NADPH and from digests of active C283I enzyme after incubation with 2-BDB-T epsilon A 2',5'-DP. Although it is not required for catalytic activity, cysteine 283 is implicated by the results of the affinity labeling experiments as the reaction target of the nucleotide analogue and is located in the region of the coenzyme binding site.
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PMID:Evaluation of cysteine 283 and glutamic acid 284 in the coenzyme binding site of Salmonella typhimurium glutamate dehydrogenase by site-directed mutagenesis and reaction with the nucleotide analogue 2-[4-bromo-2,3-dioxobutyl)thio)-1,N6-ethenoadenosine 2',5'-bisphosphate. 167 12

The reaction mechanism of Azospirillum brasilense glutamate synthase has been investigated by several approaches. 15N nuclear magnetic resonance studies demonstrate that the amide nitrogen of glutamine is reductively transferred to 2-oxoglutarate in an irreversible manner with no release of the transferred ammonia group into the medium. Identical results were obtained using thio-NADPH and acetylpyridine-NADPH, which are shown to be less efficient substrates of the enzyme than NADPH. Similarly, no exchange of the ammonia group being transferred with exogenous ammonium ion was observed during catalysis. The glutamate formed as the product of the iminoglutarate reduction was determined to be in the L configuration. The enzyme was also found to catalyze, under anaerobic conditions, the exchange of the 4proS H of NADPH with solvent both in the absence and in the presence of 2-oxoglutarate and glutamine. The reductive half-reaction is therefore a reversible segment of the overall irreversible amidotransferase reaction. 15N NMR studies also showed that the enzyme does not catalyze glutamate dehydrogenase/oxidase reactions or any observable glutaminase activity under neutral (pH 7.5) conditions. Glutaminase activity was also not observable with the reduced enzyme alone or in the presence of D-glutamate (a competitive inhibitor of glutamate synthase with respect to 2-oxoglutarate, with a Ki of about 11 microM) or with the oxidized enzyme in the presence of 2-oxoglutarate, D-glutamate, or NADP+. These data confirm species-dependent differences of A. brasilense glutamate synthase with respect to the enzyme from other sources.
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PMID:Mechanistic studies on Azospirillum brasilense glutamate synthase. 168 91

Developmental dynamics was investigated in the activity of glutamate dehydrogenase (GDH, E.C. 1.4.1.2.-4) and glutamine synthetase (GS, E.C. 6.3.1.2) in different parts of the digestive tract of lambs, in dependence on the age from 10 to 90 days; the goal of these investigations was to elucidate in greater detail the role of the above enzymes in nitrogen metabolism. The activity of GDH, and of the coenzymes NADH and NADPH, was followed in the digesta because simple organisms (bacteria, fungi, plants) have two glutamate dehydrogenases: they differ from each other by coenzyme specificity, unlike GDH from animal sources which can utilize both NADH coenzyme and NADPH coenzyme (Fahien et al., 1965; Frieden, 1964). The following activities of GDH and GS were found out in trials with lambs at the age of 10, 20, 30, 40 and 90 days, as to the different parts of digestive tract: in the tissues of rumen, omasum, reticulum, spleen, duodenum, jejunum, ileum, int. caecum and colon the activity of GDH (NADH) varied from 0.031 to 0.305 nkat/mg dry matter, in the digesta from 0 to 2.92 nkat/mg dry matter. An investigation of GDH (NADH, NADPH) dynamics in the digesta of lambs showed the relatively high activity of GDH (NADH) in the digesta of colon at the age of 10 days and that of GDH (NADPH) in the digesta of int. caecum. The activity of GDH (NADH) was also found to be high in the digesta of int. caecum at the age of 20 days. In that period the activity of GDH (NADH, NADPH) in the digesta of rumen, omasum and reticulum was zero.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Glutamate dehydrogenase and glutamine synthetase activity in the digestive tract in lambs in relation to age]. 168 31

Two pathways serve for assimilation of ammonia in Paracoccus denitrificans. Glutamate dehydrogenase (NADP+) catalyzes the assimilation at a high NH4+ concentration. If nitrate serves as the nitrogen source, glutamate is synthesized by glutamate-ammonia ligase and glutamate synthase (NADPH). At a very low NH4+ concentration, all three enzymes are synthesized simultaneously. No direct relationship exists between glutamate dehydrogenase (NADP+) and glutamate-ammonia ligase in P. denitrificans, while the glutamate synthase (NADPH) activity changes in parallel with that of the latter enzyme. Ammonia does not influence the induction or repression of glutamate dehydrogenase (NADP+). The inner concentration of metabolites indicates a possible repression of glutamate dehydrogenase (NADP+) by the high concentration of glutamine or its metabolic products as in the case when NH4+ is formed by assimilative nitrate reduction. No direct effect of the intermediates of nitrate assimilation on the synthesis of glutamate dehydrogenase (NADP+) was observed.
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PMID:Assimilation of ammonia in Paracoccus denitrificans. 168 63

We established a simple and rapid enzymatic method for measuring potassium ion in serum by using tryptophanase (EC 4.1.99.1) purified from Escherichia coli K12 strain (E. coli K12 IFO 3301). The presence of pyridoxal 5-phosphate promotes this enzymatic reaction, and potassium and (or) ammonium ions further accelerate it, with ammonium and potassium ions providing equivalent acceleration. We eliminated endogenous ammonium ion by using glutamate dehydrogenase (GLDH; EC 1.4.1.4), then produced ammonium ion in the presence of tryptophanase, tryptophan, and pyridoxal 5-phosphate. The concentration of formed ammonium ion, which was proportional to that of potassium ion in sample, was determined by adding GLDH to produce NADP+ in the presence of 2-oxoglutarate and NADPH; we then read the change of absorbance at 340 nm. The standard curve was linear for potassium ion concentrations up to 7.00 mmol/L. The within-assay variation (CV) was 0.89% at 5.51 mmol/L and 1.32% at 3.37 mmol/L. The day-to-day CVs were 0.99% at 6.85 mmol/L and 1.71% at 3.52 mmol/L. Analytical recoveries ranged from 98.7% to 108.9%. The correlation coefficient between values obtained with this enzymatic assay (y) and by flame photometry (x) was 0.995: y = 0.984x + 0.091 mmol/L (Sy.x = 0.105, n = 100). The presence of hemoglobin, bilirubin, or other cations little affects this system.
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PMID:New enzymatic method with tryptophanase for determining potassium in serum. 173 5


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