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)

From the cell-free extract of fodder yeast Candida tropicalis NADP-specific glutamate dehydrogenase was isolated and partially purified (75-fold) by means of fractional precipitation by ammonium sulphate and ion-exchange chromatography on DEAE-cellulose. The preparation was investigated with the aid of polyacrylamide gel electrophoresis. Kinetic characteristics of the enzyme in the cell-free extract and partially purified preparation were derived.
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PMID:[Purification and properties of the NADP-specific glutamate dehydrogenase of Candida tropicalis feed yeasts]. 2 41

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

1) A lysosomal protease, a new cathepsin that inactivates glucose-6-phosphate dehydrogenase [EC 1.1.1.49] and some other enzymes and differs from cathepsin B [EC 3.4.22.1] was purified about 2,200-fold from crude extracts of rat liver by cell-fractionation, freezing and thawing, acetone treatment, gel filtration, and DEAE Sephadex and CM-Sephadex column chromatographies. 2) The new cathepsin was markedly activated by the thiol-reagent, 2-mercaptoethanol and inhibited by monoiodoacetate. 3) The molecular weight of the new cathepsin was found by Sephadex G-75 column chromatography to be 22,000, which is smaller than that of cathepsin B. 4) The optimum pH of the enzyme for inactivation of glucose-6-phosphate dehydrogenase was pH 5.0--5.5. The enzyme was unstable in alkali and on heat treatment. 5) The rates of inactivation of glucose-6-phosphate dehydrogenase, apo-ornithine aminotransferase [EC 2.6.1.13], apo-tyrosine aminotransferase [EC 2.6.1.5], apo-cystathionase [EC 4.4.1.1], glucokinase [EC 2.7.1.2], glyceraldehyde-3-phosphate dehydrogenase [EC 1.2.1.12], and malate dehydrogenase [EC 1.1.1.37] by the new cathepsin were higher than those by cathepsin B. However aldolase [EC 4.1.2.13] was inactivated more rapidly by cathepsin B than by the new cathepsin. Lactate dehydrogenase [EC 1.1.1.27], glutamate dehydrogenase [EC 1.4.1.2] and alcohol dehydrogenase [EC 1.1.1.1] were not inactivated by either cathepsin. Unlike cathepsin B, the new cathepsin scarcely hydrolyzes N-substituted derivatives of arginine.
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PMID:Purification and properties of a new cathepsin from rat liver. 3 59

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

When Escherichia coli was grown in a minimum medium with glucose as sole carbon source and a proper level of ammonia, NADP+ specific glutamate dehydrogenase (L-glutamate: NADP+ oxidoreductase (deaminating), ED 1.4.1.4) was induced. The enzyme was solubilized by French press treatment and purified to homogeneity by (NH4)2SO4 fractionation, heat treatment followed by DEAE-cellulose, hydroxylapatite and Bio-Gel chromatography with an overall yield of 30%. The enzyme proved to be heat stable and relatively resistant to protein denaturants. The optimum of enzymic activity for the reductive amination is at pH 8 and at pH 9 for the oxidative deamination. The activity is affected by adenine nucleotides. The molecular weight (about 250 000 for the native form and 46 000 for the inactive subunit) and amino acid composition, suggest strict similarities with the NADP+ enzyme from fungal origin.
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PMID:Glutamate dehydrogenase from Escherichia coli: induction, purification and properties of the enzyme. 23 98

Ammonium sulfate fractionation of proteins from extremely halophilic bacteria on Sepharose 4B, carboxymethylcellulose, diethylaminoethylcellulose, and hexamethylenediamine-Agarose is described. Halophilic proteins are absorbed on these gels at 2.5 M ammonium sulfate and eluted by decreasing concentration gradients of this salt. The method has enabled the separation of malate dehydrogenase from glutamate dehydrogenase and aspartate aminotransferase on Sepharose 4B and the additional 15-fold purification of glutamate dehydrogenase on DEAE-cellulose. The technique is simple and convenient, operates at low cost, and possesses great power of resolution. The mechanism of adsorption is discussed and compared to previous instances of "hydrophobic chromatography". It is concluded that the retention of halophilic proteins on the polysaccharide gels at 2.5 M ammonium sulfate is due to hydrophobic interactions.
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PMID:Hydrophobic chromatography and fractionation of enzymes from extremely halophilic bacteria using decreasing concentration gradients of ammonium sulfate. 127 45

The ppd1 mutant of yeast, Saccharomyces cerevisiae, was isolated as a suppressor of the cyr2 mutation which caused alteration of the catalytic subunit of cAMP-dependent protein kinase. Three peaks of phosphoprotein phosphatase activity (peak I, II and III) were identified by DEAE-Sephacel chromatography of crude extracts of the wild-type strain. The ppd1 mutant was deficient in peak III phosphoprotein phosphatase activity. The peak III enzyme efficiently utilized the phosphorylated forms of NAD-dependent glutamate dehydrogenase and trehalase as substrate. The ppd1 mutation did not suppress the cyr1, CYR3 or ras1 ras2 mutations. The ppd1 locus was located on chromosome II and had identical characteristics with glc1. The ppd1 mutation suppressed the G1 arrest caused by nutritional limitation, but maintained sensitivity to mating pheromone. In diploids homozygous for the ppd1 mutation, no premeiotic DNA replication and commitment to intragenic recombination occurred and no spores were formed, suggesting that the accumulation of phosphorylated proteins in the absence of one of the phosphoprotein phosphatases is required for mitosis but not for the initiation of meiosis.
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PMID:Isolation and characterization of a phosphoprotein phosphatase-deficient mutant in yeast. 285 99

Modification of glutamate dehydrogenase with 3,4,5,6-tetrahydrophthalic anhydride at pH 8.0 results in the progressive loss of enzymatic activity and a concomitant increase in the negative charge of the protein. Although the rate of inactivation at room temperature is too rapid to allow accurate rate constant determination, modification at 4 degrees C shows that the pseudo-first-order rate constant for inactivation appears to show a saturation effect with increasing reagent concentration, with a maximum of approximately 1 min-1. Control experiments showed that tetrahydrophthalic anhydride was hydrolyzed at a much slower rate, with a pseudo-first-order rate constant of 0.041 min-1. Protection studies indicated that inactivation was decreased by the active site ligands, NADP and 2-oxoglutarate. The extents of inactivation, whether assayed with glutamate at pH 7.0 or norvaline at pH 8.0, were the same. Changes in mobility on native gels and isoelectric point were used to follow the incorporated negative charge resulting from modification. Enzyme modified in the presence of protecting ligands (where activity is maintained) showed mobility changes which suggested that a single site of modification was protected. Modified enzyme incorporated 0.78 mol pyridoxal 5-phosphate less than native enzyme, consistent with modification of lysine-126. Enzyme modified under limiting conditions was shown to have a quaternary structure similar to that of the native enzyme, as judged by crosslinking patterns obtained with dimethylpimelimidate. The modified protein is readily resolved from unmodified protein using an NaCl double gradient elution from DEAE-Sephacel. The modification is reversed with regain of activity by incubation of the modified enzyme at low pH. We have made use of the recently demonstrated ability of guanidine hydrochloride to dissociate the hexamer of glutamate dehydrogenase into trimers that can then be reassociated to construct heterohexamers of glutamate dehydrogenase, in which one trimer of the heterohexamer contains native subunits while the other has been inactivated by the 3,4,5,6-tetrahydrophthalic anhydride modification. The heterohexamer is separated from either native or fully modified hexamers by DEAE-Sephacel chromatography. Significantly, the heterohexamer has little detectable catalytic activity, although activity is regained by reversal of the modification of the one modified trimer in the hexamer. This demonstrates that catalytic site cooperation between trimers in the hexamer of glutamate dehydrogenase is an essential component of the enzymatic activity of this enzyme.
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PMID:3,4,5,6-Tetrahydrophthalic anhydride modification of glutamate dehydrogenase: the construction and activity of heterohexamers. 337 6

The dual pyridine nucleotide-specific glutamate dehydrogenase [EC 1.4.1.3] was purified 37-fold from Bacteroides fragilis by ammonium sulfate fractionation, DEAE-Sephadex A-25 chromatography twice, and gel filtration on Sephacryl S-300. The enzyme had a molecular weight of approximately 300,000, and polymeric forms (molecular weights of 590,000 and 920,000) were observed in small amounts on polyacrylamide gel disc electrophoresis. The molecular weight of the subunit was 48,000. The isoelectric point of the enzyme was pH 5.1. This glutamate dehydrogenase utilized NAD(P)H and NAD(P)+ as coenzymes and showed maximal activities at pH 8.0 and 7.4 for the amination with NADPH and with NADH, respectively, and at pH 9.5 and 9.0 for the deamination with NADP+ and NAD+, respectively. The amination activity with NADPH was about 5-fold higher than that with NADH. The Lineweaver-Burk plot for ammonia showed two straight lines in the NADPH-dependent reactions. The values of Km for substrates were: 1.7 and 5.1 mM for ammonium chloride, 0.14 mM for 2-oxoglutarate, 0.013 mM for NADPH, 2.4 mM for L-glutamate, and 0.019 mM for NADP+ in NADP-linked reactions, and 4.9 mM for ammonium chloride, 7.1 mM for 2-oxoglutarate, 0.2 mM for NADH, 7.3 mM for L-glutamate, and 3.0 mM for NAD+ in NAD-linked reactions. 2-Oxoglutarate and L-glutamate caused substrate inhibition in the NADPH- and NADP+-dependent reactions, respectively, to some extent. NAD+- and NADH-dependent activities were inhibited by 50% by 0.1 M NaCl. Adenine nucleotides and dicarboxylic acids did not show remarkable effects on the enzyme activities.
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PMID:Properties of glutamate dehydrogenase purified from Bacteroides fragilis. 366 55

The cyr2 mutant of yeast, Saccharomyces cerevisiae, required cAMP for growth at 35 degrees C. The cyr2 mutation was suppressed by the bcy1 mutation which resulted in deficiency of the regulatory subunit of cAMP-dependent protein kinase. The DEAE-Sephacel elution profile of cyr2 cAMP-dependent protein kinase was markedly different from that observed for the wild-type enzyme. With histone as substrate, the cAMP-dependent protein kinase activity of cyr2 cells showed 100-fold greater Ka value for activation by cAMP at 35 degrees C than that of the wild-type cells, while the Kd value for cAMP of the mutant enzyme was not altered. The electrophoretic character, molecular weight, and pI value of the regulatory subunit of the mutant enzyme were the same as those of the wild-type enzyme. When histone, trehalase, and glutamate dehydrogenase were used as substrate, the free catalytic subunit of the mutant enzyme showed a markedly decreased affinity for ATP and was more thermolabile compared to that of the wild-type enzyme. The results indicated that the cyr2 phenotype was produced by a structural mutation in the cyr2 gene coding for the catalytic subunit of cAMP-dependent protein kinase in yeast.
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PMID:Characterization of cyclic AMP-requiring yeast mutants altered in the catalytic subunit of protein kinase. 609 37


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