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 Neurospora crassa super-suppressor mutation, ssu-1, suppresses the auxotrophic phenotype of the mutant am(17) by inserting tyrosine at residue 313 of NADP-specific glutamate dehydrogenase, a position occupied in the wild type by glutamate. Two classes of am(17) revertants due to further mutation within the am gene have, respectively, tyrosine and leucine at residue 313. These replacements are consistent with a chain-terminating codon in am(17) of either the amber (UAG) or the ochre type (UAA), but are inconsistent with UGA. The Leu313 and Tyr313 variants of the enzyme have effective activity but are grossly different from the wild type in Michaelis constants (especially for ammonium) and heat stabilities at two different pH values. They show smaller but significant differences in these respects from each other.
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PMID:Amino acid replacements resulting from suppression and missense reversion of a chain-terminator mutation in Neurospora. 1 80

A sequence is presented for the COOH-terminal 669 residues of the NAD-specific glutamate dehydrogenase of Neurospora crassa. Comparison of this sequence with those of the vertebrate glutamate dehydrogenases of chicken and bovine liver and with the NADP-specific enzyme of Neurospora shows some similarities in sequences around residues previously identified as important for the function of these enzymes. These are: (a) the reactive lysine residue of low pK in the NADP and the vertebrate enzymes; (b) the tyrosine residue of the NADP enzyme that is readily nitrated by tetranitromethane with inactivation, a residue protected by NADP or by NMN; and (c) the arginine residue of the NADP-enzyme that is reactive with 1,2-cyclohexanedione with inactivation. Despite these similarities, comparison of the sequence of the NAD-enzyme with those of the other glutamate dehydrogenases of known sequences revealed relatively little overall homology as determined by computer analysis.
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PMID:Nicotinamide adenine dinucleotide-specific glutamate dehydrogenase of Neurospora. IV. The COOH-terminal 669 residues of the peptide chain; comparison with other glutamate dehydrogenases. 2 Nov 91

Chronic ammonia toxicity in experimental mice was induced by exposing them for 2 and 5 days to 5 % (v/v) ammonia solution. The enzymes concerned with glutamate metabolism (aspartate-, alanine- and tyrosine aminotransferases, glutamate dehydrogenase and glutamine synthetase) and (Na+ + K+)-ATPase were estimated in the three regions of brain (cerebellum, cerebral cortex and brain stem) and in liver. Glutamate, aspartate, alanine, glutamine and GABA, RNA and protein were also estimated in the three regions of brain and liver. A significant rise in the activity of (Na+ + K+)-ATPase in all the three regions of brain along with a fall in the activity of alanine aminotransferase was noticed. Changes in the activities of other enzymes were also observed. A significant increase in alanine and a decrease in glutamic acid was observed while no change was observed in the content of other amino acids belonging to the glutamate family. As a result of this, changes in the ratios of glutamate/glutamine and glutamate + aspartate/GABA was observed. The results indicated that the brain was in a state of more depression and less of excitation. Under these conditions the liver tissue was showing a profound rise in the activity of the enzymes of glutamate metabolism. The results are further discussed.
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PMID:Chronic metabolic effects of ammonia in mouse brain. 9 19

Neurospora glutamate dehydrogenase (NADP-specific) is rapidly inactivated upon reaction with tetranitromethane. This inactivation is completely prevented by the presence of coenzyme (NADP) or nicotinamide mononucleotide (NMN) but not by substrate. NADH, or 2'-monophosphoadenosine-5'-diphosphoribose. Amino acid analysis indicates that the primary effect of modification is nitration of a single residue of tyrosine per polypeptide chain. We have identified the reactive tyrosine by isolation of a single, uniquely labeled peptide after hydrolysis with trypsin followed by cleavage with cyanogen bromide. The modified residue proved to be tyrosine-168 in the linear sequence. This residue is not present in the part of the sequence that had been previously implicated as involved in the binding of the adenylate portion of the coenzyme. Both NMN and 2-monophosphoadenosine-5'-diphosphoribose act as competitive inhibitors of NADP in the oxidation of glutamate with Ki values of 4.65 x 10(-4) M and 4.30 x 10(-4) M, respectively. Thus, the specific protection afforded by NADP and NMN, but not by 2'-monophosphoadenosine-5'-diphosphoribose, indicates that tyrosine-168 is involved in binding the nicotinamide portion of the coenzyme.
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PMID:Nicotinamide adenine dinucleotide phosphate-specific glutamate dehydrogenase of Neurospora. III. Inactivation by nitration of a tyrosine residue involved in coenzyme binding. 23 46

A new guanosine nucleotide has been synthesized and characterized: guanosine 5'-O-[S-(3-bromo-2-oxopropyl)]thiophosphate (GMPSBOP), with a reactive functional group which can be placed at a position equivalent to the pyrophosphate region of GTP. This new analog is negatively charged at neutral pH and is similar in size to GTP. GMPSBOP has been shown to react with bovine liver glutamate dehydrogenase with an incorporation of 2 mol of reagent/mol of subunit. The modification reaction desensitizes the enzyme to inhibition by GTP, activation by ADP, and inhibition by high concentrations of NADH, but does not affect the catalytic activity of the enzyme. The rate constant for reaction of GMPSBOP with the enzyme exhibits a nonlinear dependence on reagent concentration with KD = 75 microM. The addition to the reaction mixture of alpha-ketoglutarate, GTP, ADP, or NADH alone results in little decrease in the rate constant, but the combined addition of 5 mM NADH with 0.4 mM GTP or with 10 mM alpha-ketoglutarate reduces the reaction rate approximately 6-fold. GMPSBOP modifies peptides containing Met-169 and Tyr-262, of which Tyr-262 is not critical for the decreased sensitivity of the enzyme toward allosteric ligands. The presence of 0.4 mM GTP plus 5 mM NADH protects the enzyme against reaction at both Met-169 and Tyr-262, but yields enzyme with 1 mol of reagent incorporated/mol of subunit which is modified at an alternate site, Met-469. In the presence of 0.2 mM GTP + 0.1 mM NADH, protection against modification of Tyr-262, but only partial protection against labeling of Met-169, is observed. In contrast, the presence of 10 mM alpha-ketoglutarate + 5 mM NADH protect only against reaction with Met-169. The results suggest that GMPSBOP reacts at the GTP-dependent NADH regulatory site [Lark, R. H., & Colman, R. F. (1986) J. Biol. Chem. 261, 10659-10666] of bovine liver glutamate dehydrogenase, which markedly affects the sensitivity of the enzyme to GTP inhibition. The reaction of GMPSBOP with Met-169 is primarily responsible for the altered allosteric properties of the enzyme.
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PMID:Guanosine 5'-O-[S-(3-bromo-2-oxopropyl)]thiophosphate: a new reactive purine nucleotide analog labeling Met-169 and Tyr-262 in bovine liver glutamate dehydrogenase. 132 52

The distribution of amino acids between plasma, liver and brain was studied in adult male rats, fed a diet containing 8.7, 17 (control animals), 32 and 51% of protein during 15 days. The caloric intake was nearly equal in all groups. The highest food intake was observed in the animals on the low protein diet. Changes in plasma amino acids were variable. In contrast to the behavior of most amino acids in plasma, the branched chain amino acids were highest in the animals fed the 51% protein diet. Despite the low protein intake in the animals fed a 8.7% protein diet, the concentration of serine, glutamic acid, glutamine, glycine, alanine, methionine, isoleucine, leucine, phenylalanine and ornithine were significantly higher compared to control animals, whereas in those receiving a high protein diet, valine, leucine, tyrosine, tryptophan and histidine increased in relation to the increased protein and amino acid intake. The plasma amino acid patterns are not greatly influenced by the amino acid distribution in the food and the amount ingested. Alanine aminotransferase, aspartate aminotransferase, glutamate dehydrogenase and cholinesterase showed a two- to fivefold increased activity in the liver of animals consuming a high protein diet. In the brain, the concentration of valine, leucine, isoleucine, phenylalanine and tyrosine in animals receiving the low protein diet was higher than in controls and increased further with increasing protein content of the diet. Glutamine was increased in all dietary groups. The predicted influx of amino acids showed increasing influx rates in dependence of the plasma amino acid concentration. The entry of tyrosine and tryptophan and their brain concentration was inversely proportional to the protein content of the diet. In the present study which considers long-term adaptation to an increasing protein and amino acid intake in comparison to a balanced control protein diet, the levels of the indispensable amino acids were maintained within narrow limits in the brain and liver. The results indicate that inspite of a variable protein intake, the body tends to keep organ amino acids in relatively narrow limits favoring in this way amino acid homeostasis.
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PMID:Effect of different protein diets on the distribution of amino acids in plasma, liver and brain in the rat. 159 Jun 69

Previously, the synthesis and validation of [32P]2N3NAD+ as an active site directed photoaffinity probe for glutamate dehydrogenase (GDH) was reported (8). This report shows that 2N3NAD+ is also an effective probe for the NAD+ binding site of lactate dehydrogenase (LDH). With the appropriate photolabeling procedures and immobilized boronate column chromatography the active site peptides of GDH and LDH involved in the adenine base binding domain have been isolated and sequenced. With both GDH and LDH a single photolabeled peptide, which contained the majority of the photoinserted radiolabel, was isolated. Additionally, these peptides had UV spectra that were markedly different from the nonphotolabeled peptides. The modified peptide from GDH corresponded to Cys270 through Lys289. Both sequencing and compositional analysis identified Glu275 as the site of photoinsertion. Sequencing of this peptide aborted at Glu275 after five rounds of analysis, indicating that insertion was blocking further progress. Compositional analysis showed that the entire sequence from residues 270 to 289 was present except that the single Glu residue was missing. This is interpreted as indicating that the photoinsertion is into the polypeptide backbone at the Glu site. The peptide isolated from LDH corresponded to Asp82 through Arg90. Sequencing of this peptide could be completed throughout with only the round at Tyr83 giving no identifiable residue. Compositional analysis of this peptide was in agreement with the peptide from Asp82 to Arg90 with the exception that the single Tyr residue was missing. This indicates that the photoinsertion is into the tyrosine side chain. This data was found to be in agreement with X-ray crystallographic results identifying the NAD(+)-binding domains.
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PMID:Identification of peptides in the adenine ring binding domain of glutamate and lactate dehydrogenase using 2-azido-NAD+. 168 10

A single administration to rats of cyanamide (60 mg/kg, for 1 hour) was found to decrease the contents of cysteate, serine, glutamate, glycine, alanine, valine, methionine, isoleucine, tyrosine, ethanolamine, ornithine and histidine that may be considered as a manifestation on the drug hepatotoxicity. The activities of transaminases, glutamate dehydrogenase, pyruvate dehydrogenase remained unchanged. Cyanamide effects were considerably abolished by the supplementary ethanol administration (0.5 g/kg). Cyanamide failed to affect vitamin-dependent enzymes reflecting thiamine pyrophosphate, pyridoxal phosphate and flavine adenine dinucleotide status of the rat organism.
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PMID:[Free amino acids of the liver and the characteristics of the amino acid metabolism in the liver and brain after cyanamide administration to rats]. 222 67

Effects of stretching on muscle amino acids were tested in unloaded soleus by casting the foot in dorsiflexion on one limb of tail-casted, hindquarter-suspended rats. For comparison with unloading, amino acids also were measured in shortened extensor digitorum longus (EDL) in the same casted limb and in denervated leg muscles. Concentrations of tyrosine and glutamate were lower, while aspartate, ammonia, and the ratio of glutamine to glutamate were greater in the stretched than in the freely moving, unloaded soleus, but stretched did not differ from weight-bearing, control muscle. Therefore, stretching the soleus muscle prevented changes in certain amino acids due to unloading. Aspartate, ammonia, glutamine, and the ratio of glutamine to glutamate were lower in the shortened EDL than in the freely moving muscle of the contralateral limb, or in the control muscle. When denervated, these leg muscles also showed lower aspartate, ammonia, and ratio of glutamine to glutamate relative to innervated muscles. Since muscle shortening or denervation produced amino acid changes that mimicked the effects of unloading on the soleus, these responses must reflect the effect of muscle disuse. These data suggested that lower ammonia might cause the lower ratio of glutamine to glutamate with disuse. Because the fresh muscle energy charge, one factor which controls AMP deaminase, generally was not affected by disuse, altered deamination of glutamate via glutamate dehydrogenase may explain the variations in muscle ammonia.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effects of stretching and disuse on amino acids in muscles of rat hind limbs. 256 86

NADP+-specific glutamate dehydrogenase from Salmonella typhimurium, cloned and expressed in Escherichia coli, has been purified to homogeneity. The nucleotide sequence of S. typhimurium gdhA was determined and the amino acid sequence derived. The nucleotide analogue 2-[(4-bromo-2,3-dioxobutyl)thio]-1,N6-ethenoadenosine 2',5'-bisphosphate (2-BDB-T epsilon A-2',5'-DP) reacts irreversibly with the enzyme to yield a partially inactive enzyme. After about 60% loss of activity, no further inactivation is observed. The rate of inactivation exhibits a nonlinear dependence on 2-BDB-T epsilon A-2',5'-DP concentration with kmax = 0.160 min-1 and KI = 300 microM. Reaction of 200 microM 2-BDB-T epsilon A-2',5'-DP with glutamate dehydrogenase for 120 min results in the incorporation of 0.94 mol of reagent/mol of enzyme subunit. The coenzymes, NADPH and NADP+, completely protect the enzyme against inactivation by the reagent and decrease the reagent incorporation from 0.94 to 0.5 mol of reagent/mol enzyme subunit, while the substrate alpha-ketoglutarate offers only partial protection. These results indicate that 2-BDB-T epsilon A-2',5'-DP functions as an affinity label of the coenzyme binding site and that specific reaction occurs at only about 0.5 sites/enzyme subunit or 3 sites/hexamer. Glutamate dehydrogenase modified with 200 microM 2-BDB-T epsilon A-2',5'-DP in the absence and presence of coenzyme was reduced with NaB3H4, carboxymethylated, and digested with trypsin. Labeled peptides were purified by high performance liquid chromatography and characterized by gas phase sequencing. Two peptides modified by the reagent were isolated and identified as follows: Phe-Cys(CM)-Gln-Ala-Leu-Met-Thr-Glu-Leu-Tyr-Arg and Leu-Cys(CM)-Glu-Ile-Lys. These two peptides were located within the derived amino acid sequence as residues 146-156 and 282-286. In the presence of NADPH, which completely prevents inactivation, only peptide 146-156 was labeled. This result indicates that modification of the pentapeptide causes loss of activity. Glutamate 284 in this peptide is the probable reaction target and is located within the coenzyme binding site.
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PMID:Affinity labeling of a glutamyl peptide in the coenzyme binding site of NADP+-specific glutamate dehydrogenase of Salmonella typhimurium by 2-[(4-bromo-2,3-dioxobutyl)thio]-1,N6-ethenoadenosine 2',5'-bisphosphate. 265 14


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