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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)

A morphological mutant (col-2) of Neurospora, which is partially deficient in glucose-6-phosphate dehydrogenase (G-6-PD) activity and has lower levels of reduced nicotinamide adenine dinucleotide phosphate (NADPH), accumulated three-fold more triglycerides during log-phase growth than the wild-type strain. Increased lipid deposition was not found in other strains that included slow-growing morphological mutants, NADPH-deficient strains, G-6-PD-deficient mutants, wild-type revertants from col-2, and a cel, col-2 double mutant. The cel, col-2 strain was supplemented with an exogenous source of fatty acids because it cannot synthesize these lipid moieties. The observed normal lipid content of this strain suggests that the lipid deposition in col-2 on glucose is due to an overstimulation of fatty acid synthesis and not a deficiency in fatty acid breakdown. The neutral lipid levels in both wild type and col-2 were decreased to identical levels when grown on glutamate as a carbon source. This effect was not due to changes in glutamic dehydrogenase levels. The omission of citrate from the glutamate medium reduced wild-type neutral lipid levels even further, but had no effect on col-2. The variations with time in the neutral lipid levels of col-2 upon changes in these carbon sources are presented, as well as a discussion of the possible types of regulatory effects unique to the col-2 mutation which might affect fatty acid synthesis.
J Bacteriol 1971 Dec
PMID:Effects of mutations and growth conditions on lipid synthesis in Neurospora crassa. 440 Mar 92

1. Pyruvate strongly inhibited aspartate production by mitochondria isolated from Ehrlich ascites-tumour cells, and rat kidney and liver respiring in the presence of glutamine or glutamate; the production of (14)CO(2) from l-[U-(14)C]glutamine was not inhibited though that from l-[U-(14)C]glutamate was inhibited by more than 50%. 2. Inhibition of aspartate production during glutamine oxidation by intact Ehrlich ascites-tumour cells in the presence of glucose was not accompanied by inhibition of CO(2) production. 3. The addition of amino-oxyacetate, which almost completely suppressed aspartate production, did not inhibit the respiration of the mitochondria in the presence of glutamine, though the respiration in the presence of glutamate was inhibited. 4. Glutamate stimulated the respiration of kidney mitochondria in the presence of glutamine, but the production of aspartate was the same as that in the presence of glutamate alone. 5. The results suggest that the oxidation of glutamate produced by the activity of mitochondrial glutaminase can proceed almost completely through the glutamate dehydrogenase pathway if the transamination pathway is inhibited. This indicates that the oxidation of glutamate is not limited by a high [NADPH]/[NADP(+)] ratio. 6. It is suggested that under physiological conditions the transamination pathway is a less favourable route for the oxidation of glutamate (produced by hydrolysis of glutamine) in Ehrlich ascites-tumour cells, and perhaps also kidney, than the glutamate dehydrogenase pathway, as the production of acetyl-CoA strongly inhibits the first mechanism. The predominance of the transamination pathway in the oxidation of glutamate by isolated mitochondria can be explained by a restricted permeability of the inner mitochondrial membrane to glutamate and by a more favourable location of glutamate-oxaloacetate transaminase compared with that of glutamate dehydrogenase.
Biochem J 1971 Dec
PMID:The pathway of glutamine and glutamate oxidation in isolated mitochondria from mammalian cells. 440 9

The isocitrate lyase from a thermophilic Bacillus is activated about threefold by a variety of salts. Such strong stimulation of activity is not seen with isocitrate lyase from the mesophiles, Bacillus licheniformis, Bacillus megaterium, Escherichia coli, and Aspergillus nidulans. The salt activation is markedly pH-dependent. At pH values above 8.6, salt (KCl) indeed inhibits the enzyme activity. Potassium chloride also causes a significant shift of the pH optimum of the enzyme towards the acid side. As the temperature of the enzyme reaction is raised, activation becomes progressively weaker. Potassium chloride also affords considerable protection against enzyme denaturation at 55 C. The activation and the stabilization, however, appear to be independent effects. Of six other enzymes in the thermophile that were examined, isocitrate dehydrogenase was equally strongly activated by KCl and malate synthase was less strongly, but significantly, activated; citrate synthase, malate dehydrogenase, glutamate dehydrogenase, and lactate dehydrogenase were unaffected or slightly inhibited by KCl. The property of being strongly activated by salt appears to be a peculiar characteristic of the thermophile isocitrate lyase and possibly evolved concomitantly with its thermostability.
J Bacteriol 1973 Dec
PMID:Isocitrate lyase from a thermophilic Bacillus: effect of salts on enzyme activity. 458

During growth of Aspergillus nidulans in medium containing ammonium the specific activities of most enzymes involved in catabolism of nitrogen sources are low (ammonium repression). The gdhA10 lesion, which results in loss of nicotinamide adenine dinucleotide phosphate-linked glutamate dehydrogenase activity, has been shown to lead to partial relief of ammonium repression of three amidase enzymes as well as histidase. The areA102 lesion led to altered levels of these enzymes but did not greatly affect ammonium repression. The double mutant areA102,gdhA10 was almost completely insensitive to ammonium repression of two of the amidase enzymes and histidase. This suggests that an interaction between the areA and gdhA genes in determining responses to ammonium occurs. Growth of mycelium in medium containing l-glutamate has been found to result in lowered levels of all four enzymes, and this occurs in strains insensitive to ammonium repression. Very strong repression in all strains occurred during growth in medium containing l-glutamine. Relief of these repressive effects of glutamate and glutamine was blocked by cycloheximide. Glutamate and glutamine had similar effects on the production of extracellular protease activity, and growth on glutamine led to low levels of urate oxidase. In contrast to the above enzymes, nitrate reductase was insensitive to the effects of glutamine and glutamate, even though this enzyme is very sensitive to ammonium repression. Although other possibilities exist, it is suggested that there may be mechanisms of general control of nitrogen-catabolic enzymes other than ammonium repression.
J Bacteriol 1974 Dec
PMID:Effects of ammonium, L-glutamate, and L-glutamine on nitrogen catabolism in Aspergillus nidulans. 461 4

1. Aspergillus nidulans, Neurospora crassa and Escherichia coli were grown on media containing a range of concentrations of nitrate, or ammonia, or urea, or l-glutamate, or l-glutamine as the sole source of nitrogen and the glutamate dehydrogenate and glutamine synthetase of the cells measured. 2. Aspergillus, Neurospora and Escherichia coli cells, grown on l-glutamate or on high concentrations of ammonia or on high concentrations of urea, possessed low glutamate dehydrogenase activity compared with cells grown on other nitrogen sources. 3. Aspergillus, Neurospora and Escherichia coli cells grown on l-glutamate possessed high glutamine synthetase activity compared with cells grown on other nitrogen sources. 4. The hypothesis is proposed that in Aspergillus, Neurospora and Escherichia colil-glutamate represses the synthesis of glutamate dehydrogenase and l-glutamine represses the synthesis of glutamine synthetase. 5. A comparison of the glutamine-synthesizing activity and the gamma-glutamyltransferase activity of glutamine synthetase in Aspergillus and Neurospora gave no indication that these fungi produce different forms of glutamine synthetase when grown on ammonia or l-glutamate as nitrogen sources.
Biochem J 1969 Dec
PMID:Regulation of synthesis of glutamate dehydrogenase and glutamine synthetase in micro-organisms. 490 26

The carnitine acetyltransferase and glutamate dehydrogenase activities of guinea-pig liver and other tissues were estimated. Both enzymes are wholly mitochondrial, and can only be fully observed after disruption of the mitochondrion. Triton X-100 (0.1%) or freeze-drying revealed more activity than other methods tried. In mitochondria prepared and suspended in 0.25m-sucrose and in cell cytoplasm only small fractions of the total enzymic activity could be observed in guinea-pig liver: on average 7.5% of carnitine acetyltransferase and 5.5% of glutamate dehydrogenase. It is concluded that, in liver or mammary gland of goat, guinea pig or rat, little or no carnitine acetyltransferase is available in vivo to acetyl-CoA outside the mitochondrion.
Biochem J 1968 Dec
PMID:The availability of carnitine acetyltransferase in mitochondria from guinea-pig liver and other tissues. 570 22

The activity of the nicotinamide adenine dinucleotide-dependent glutamate dehydrogenase in Bacillus subtilis was influenced by the carbon source, but not the nitrogen source, in the growth medium. The highest specific activity for this enzyme was found when B. subtilis was grown in a minimal or rich medium that contained glutamate as the carbon source. It is proposed that glutamate dehydrogenase serves a catabolic function in the metabolism of glutamate, is induced by glutamate, and is subject to catabolite repression.
J Bacteriol 1981 Dec
PMID:Regulation of glutamate dehydrogenase in Bacillus subtilis. 611 56

The transient and steady-state kinetics of the oxidative deamination of L-glutamate by glutamate dehydrogenase and NADP in both aqueous solution and 30% methanol are compared. Methanol causes an approximately 5-fold tightening of the enzyme--L-glutamate binary complex and an approximately 2-fold reduction of the interaction parameter for the ternary enzyme--NADP--L-glutamate complex. The most dramatic effect of methanol on the time course of the reaction is what appears to be a conversion of the enzyme at substoichiometric initial levels of reactant NADP to a form from which product alpha-ketoglutarate does not readily dissociate. This conversion appears only at NADP concentrations over one-third of the enzyme active site concentration.
Biochemistry 1982 Dec 21
PMID:Effect of cryosolvent on transient kinetics of the glutamate dehydrogenase reaction. 613 Jul 83

Acute renal failure induced by glycerol results in increased metabolism of glutamine by renal cortical slices of rats 16 and 36 hr after onset, and there is also increased glutamine uptake by the kidney in vivo. Metabolism of glutamine and glutamate to glucose is inhibited. At 8 days after onset of renal failure, metabolism of glutamine returns to normal. Initially, activities of phosphate-dependent glutaminase (PDG) and glutamate dehydrogenase are depressed. The activity of glutaminase returns to normal by 8 days, but glutamate dehydrogenase activity is still inhibited. Increased ammoniagenesis and glutamine uptake are mainly a result of increased entry into the cell since activity of glutaminase is inhibited.
Kidney Int 1982 Dec
PMID:Renal metabolism of glutamine in rats with acute renal failure. 613 Nov 57

The effects of transcription and translation inhibitors on NADP-glutamate dehydrogenase and glutamine synthetase synthesis in nitrogen-starving Ankistrodesmus braunii cells have been studied. Considering the results obtained one can suggest that both enzymes are coded in the chloroplast genome and that during nitrogen starvation specific mRNA's are partly transferred from the chloroplast into the cytoplasm and can be translated there on 80S ribosomes.
Mol Cell Biochem 1982 Dec 10
PMID:The role of chloroplast and cytoplasm in the NADP-glutamate dehydrogenase and glutamine synthetase synthesis in Ankistrodesmus cells. 613 76


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