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)

Glutamate-auxotrophic mutants lacking phosphoenolpyruvate carboxylase(PC), citrate synthase (CS) or glutamate dehydrogenase (GD), an aspartate auxotroph lacking aspartate aminotransferase (TA), and a glutamate-aspartate double auxotroph lacking both aconitase (AH) and TA were obtained from Brevibacterium flavum No. 2247, a glutamate-producing bacterium. Prototrophic revertants further derived from the CS- and GD-lacking auxotrophs concomitantly recovered the enzyme activities that their parents had lost. These results indicate involvement of the tricarboxylic acid (TCA) cycle and GD in glutamate biosynthesis, that of PC in the biosynthesis of the TCA cycle intermediates and that of TA in aspartate biosynthesis. The CS-deficient mutants accumulated large amounts of acetate and small amounts of pyruvate, aspartate and alanine, while the GD-deficient strains accumulated large amounts of 2-oxo-glutarate and small amounts of citrate. Synthesis of PC was repressed by either glutamate or aspartate and those of CS and GD were repressed by glutamate, whereas those of pyruvate dehydrogenase (PD), AH, and isocitrate dehydrogenase were not affected significantly by glutamate; that of TA was also not affected by aspartate or by glutamate. The specific activities of PD and AH gave peaks during the cellular cultivation, related to the temporary accumulation of their substrates, pyruvate and citrate, respectively. These and previous results on the regulation of the enzymatic activities provide a definite regulatory mechanism for glutamate and aspartate syntheses.
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PMID:Enzymes of the glutamate and aspartate synthetic pathways in a glutamate-producing bacterium, Brevibacterium flavum. 72 99

The initial rate of incorporation of [15N]alanine into the 6-amino group of the adenine nucleotides in rat hepatocytes was about one-eighteenth of the rate of incorporation into urea. Thus the purine nucleotide cycle cannot provide most of the ammonia needed in urea synthesis for the carbamoyl phosphate synthase reaction (EC 2.7.2.5). On the other hand, contrary to the view expressed by McGivan & Chappell [(1975) FEBS Lett. 52, 1--7], the experiments support the view that hepatic glutamate dehydrogenase can supply the required ammonia.
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PMID:Sources of ammonia for mammalian urea synthesis. 74 49

With either alanine or a mixture of 15 different amino acids as nitrogen source, the addition of L-leucine inhibited the synthesis of urea by isolated rat liver cells. With alanine present leucine promoted the production of glutamate and glutamine. Comparison of effects of leucine on soluble glutamate dehydrogenase, mitochondria and isolated cells supports the postulate that leucine exerts its effect through activation of glutamate dehydrogenase. It is suggested that this latter enzyme may not be as important for the production of NH3 for carbamoyl phosphate synthesis as has been considered hitherto.
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PMID:The effects L-leucine on the synthesis of urea, glutamate and glutamine by isolated rat liver cells. 80 18

Mutants, designated tamAr, have been isolated on the basis of simultaneous resistance to toxic analogues thiourea, aspartate hydroxamate and chlorate with L-alanine as the sole nitrogen source. tamAr mutants are also resistant to methylammonium. This resistance of tamAr mutants is correlated with partially repressed activity of a number of enzyme and transport systems regulated by ammonium. Furthermore, tam-Ar mutants have low NADP-glutamate dehydrogenase (NADP-GDH) activity and also efflux ammonium under certain growth conditions. Mutants at the areA locus (areAr) have also been isolated on the basis of resistance to these analogues, with nitrate or L-aspartate as the nitrogen source. These, similar to tamAr lesions, result in resistance to methylammonium and are partially repressed for ammonium repressible system, but in contrast to tamAr, areAr alleles have wild-type NADP-GDH activity and normal ammonium efflux. tamAr and areAr mutants grow as wild type on all nitrogen or carbon sources tested, are recessive, and appear to be epistatic to all other mutations (gdhA1, meaA8 and meaB6) which result in derepressed levels of ammonium regulated system. Whereas tamAr and areAr phenotypes are additive, tamAr is epistatic to areAd phenotype.
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PMID:Studies of partially repressed mutants at the tamA and areA loci in Aspergillus nidulans. 110 54

Glomeruli from adult normal male Wistar rats were obtained by teasing a cortex slice with stainless steel needles. The enzyme content and the morphologic aspect of these glomeruli were assessed as a preliminary step to further metabolic studies. Robinson's medium appeared to be the most suitable medium. There was no loss of glutamic dehydrogenase, glucose-6-phosphate dehydrogenase or acid phosphatase. Lactate dehydrogenase was lost to about 50%. Electron microscopy showed morphologic signs of damage in the podocytes. The glomerular oxygen uptake was measured with the help of the Cartesian diver technique, using approximately 20 glomeruli per assay. The endogenous respiratory rate was linear for at least three hours. The endogenous respiratory rate was linear for at least three hours. The mean dry wt of lyophilized glomeruli was determined for 13 rats for which the glomerular oxygen uptake had been measured, and these data showed a glomerular Q-02 of 4 mul/hr/mg of dry wt. The following substances were tested for their influence on the oxygen uptake: acetate, alpha-oxoglutarate, citrate, oxalacetate, glutamate, alanine, all 10 mM; succinate, 2.5, 5 and 10 mM; glucose, 5, 10 and 20 mM; fructose 10 and 20 mM; and palmitate. Citrate increases the O-2 uptake/hr/glomerulus by 30%; glucose, 20 mM, by 30%; and succinate, 2.5 mM by 50% and 10 mM by 190%. In a Robinson's medium containing 35 mg of albumin/ml, the endogenous respiration is not different from that obtained in the inorganic medium but the oxygen uptake is increased 26% by glucose, 10 mM. From these data, it can be concluded that the oxygen uptake of the glomerulus is small. This fact explains its resistance to anoxia. The systematic investigation of possible substrates indicate that glucose, citrate and succinate may play a role in supporting this small oxidative metabolism.
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PMID:Oxidative metabolism of the normal rat glomerulus. 111 53

The only exogenous substrates oxidized by mitochondria isolated from the flight muscle of the Japanese beetle (Popillia japonica) are proline, pyruvate and glycerol 3-phosphate. The highest rate of oxygen consumption is obtained with proline. The oxidation of proline leads to the production of more NH3 than alanine, indicating a functioning glutamate dehydrogenase (EC 1.4.1.2). Studies of mitochondrial extracts confirm the presence of a very active glutamate dehydrogenase, and this enzyme is found to be activated by ADP and inhibited by ATP. These extracts also show high alanine aminotransferase activity (EC 2.6.1.2) and a uniquely active "malic' enzyme (EC 1.1.1.39). The "malic' enzyme is activated by succinate and inhibited by ATP and by pyruvate. It is suggested that the input of tricarboxylate-cycle intermediate from proline oxidation is balanced by the formation of pyruvate from malate, and the complete oxidation of the majority of the pyruvate. Studies of the steady-state concentrations of mitochondrial CoASH and CoA thioesters during proline oxidation show a high succinyl (3-carboxypropionyl)-CoA content which falls on activating respiration with ADP. There is a concomitant rise in CoASH. However, the reverse transition, from state-3 to state-4 respiration, causes only very slight changes in acylation. The reasons for this are discussed. Studies of the mitochondrial content of glutamate, 2-oxoglutarate, malate, pyruvate, citrate and isocitrate during the same phases of proline oxidation give results consistent with control at the level of glutamate dehydrogenase and isocitrate dehydrogenase during proline oxidation, with the possibility of further control at "malic' enzyme. During the oxidation of pyruvate all of the tricarboxylate-cycle intermediates and NAD(P)H follow the pattern of changes described in the blowfly (Johnson & Hansford, 1975; Hansford, 1974) and isocitrate dehydrogenase is identified as the primary site of control.?2OAuthor
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PMID:The nature and control of the tricarboxylate cycle in beetle flight muscle. 120 Sep 85

There were revealed changes in the content of free amino acids and in the activity of glutamic dehydrogenase, aspartic- and alanine-aminotransferases in the course of development of the placenta in guinea pigs. The greatest values by the indices under study were reached by the 25th--30th days of pregnancy, i.e. by the period of final formation of the placenta. By the 40th day of pregnancy the activity of the enzymes and the content of free amino acids fell, and from the 45th day persisted at a certain stable level up to the occurrence of labour.
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PMID:[Free amino acids and some enzymes of placental amino acid metabolism at different stages of its development]. 122 23

Response characteristics are presented for a dual-enzyme fiber-optic biosensor for glutamate. An enzyme layer composed of glutamate dehydrogenase (GDH) and glutamate-pyruvate transaminase (GPT) is used to produce reduced nicotinamide adenine dinucleotide (NADH) at the tip of a fiber-optic probe. NADH luminescence is monitored through this probe and the measured fluorescence intensity is related to the concentration of glutamate. GDH catalyzes the formation of NADH, and GPT drives the GDH reaction by removing a reaction product and regenerating glutamate. Optimal response is obtained in a pH 7.4 Tris-HCl buffer maintained at 25 degrees C in the presence of 4 mM NAD+ and 10 mM L-alanine. The temperature profile reveals a strong negative temperature effect which is attributed to the temperature dependency of NADH luminescence. Under optimal conditions, the sensor sensitivity is 0.127 nA/microM over the 1-10 microM concentration range, the detection limit is 0.13 microM, and response times range from 4 to 8 min. The sensor response is stable for 12 days when stored at 4 degrees C. Selectivity for glutamate is excellent over most of the common amino acids as well as ascorbic acid, uric acid, taurine, and GABA. Only slight responses were observed for glutamine and lysine. The effect of ammonia on the glutamate response was found to be minimal at total ammonia nitrogen concentrations as high as 200 microM.
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PMID:Dual-enzyme fiber-optic biosensor for glutamate based on reduced nicotinamide adenine dinucleotide luminescence. 135 Apr 33

Characteristics of the three major ammonia assimilatory enzymes, glutamate dehydrogenase (GDH), glutamine synthetase (GS) and glutamate synthase (GO-GAT) in Corynebacterium callunae (NCIB 10338) were examined. The GDH of C. callunae specifically required NADPH and NADP+ as coenzymes in the amination and deamination reactions, respectively. This enzyme showed a marked specificity for alpha-ketoglutarate and glutamate as substrates. The optimum pH was 7.2 for NADPH-GDH activity (amination) and 9.0 for NADP(+)-GDH activity (deamination). The results showed that NADPH-GDH and NADP(+)-GDH activities were controlled primarily by product inhibition and that the feedback effectors alanine and valine played a minor role in the control of NADPH-GDH activity. The transferase activity of GS was dependent on Mn+2 while the biosynthetic activity of the enzyme was dependent on Mg2+ as essential activators. The pH optima for transferase and biosynthetic activities were 8.0 and 7.0, respectively. In the transfer reaction, the Km values were 15.2 mM for glutamine, 1.46 mM for hydroxylamine, 3.5 x 10(-3) mM for ADP and 1.03 mM for arsenate. Feedback inhibition by alanine, glycine and serine was also found to play an important role in controlling GS activity. In addition, the enzyme activity was sensitive to ATP. The transferase activity of the enzyme was responsive to ionic strength as well as the specific monovalent cation present. GOGAT of C. callunae utilized either NADPH or NADH as coenzymes, although the latter was less effective. The enzyme specifically required alpha-ketoglutarate and glutamine as substrates.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Some properties of glutamate dehydrogenase, glutamine synthetase and glutamate synthase from Corynebacterium callunae. 135 47

Isozyme analysis of L-alanine:2-oxoglutarate aminotransferase (ALT) in maize indicates that there are three genes encoding this enzyme activity. Two of the gene products interact with each other to form heterodimers, while the third gene product does not interact with the other two. Another isozyme that appears after gel electrophoresis and ALT staining is shown to be glutamate dehydrogenase-1. Anaerobic treatment does not result in increased ALT levels, indicating that the previously reported increase in alanine levels caused by this treatment may be due to increases in the level of pyruvate, a substrate of ALT.
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PMID:Analysis of L-alanine:2-oxoglutarate aminotransferase isozymes in maize. 144 81


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