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 levels of several enzymes have been studied during sporulation of Saccharomyces cerevisia. The specific activities of ribonuclease and aminopeptidase I raised several-fold after transfer of the cells to sporulation medium, whereas the specific activities of phosphofructokinase, glucose-6-phosphate dehydrogenase, tryptophan synthase and pyruvate decarboxylase were not significantly altered. The specific activities of NAD-dependent glutamate dehydrogenase, isocitrate lyase, malate dehydrogenase and fructose bisphosphatase all decreased from the onset of sporulation. The inactivation of these latter enzymes was inhibited by cycloheximide and by inhibitors of energy metabolism. Hexokinase, alcohol dehydrogenase and glutamate oxaloacetate transaminase were partially lost from the cells during the period of ascus maturation. None of the enzyme changes observed proved to be 'sporulation-specific' in that it occurred exclusively in sporulating diploid yeast cells. Therefore it is postulated that the meiotic events and the metabolic changes required for ascospore formation are under separate genetic control in this organism. During sporulation, the cellular content of cytochromes b, c, and aa3 was reduced to 20% or less of that present in vegetative derepressed cells. Since the relative percentage of total to cycloheximide-insensitive mitochondrial protein synthesis was not significantly altered throughout sporulation, and the pattern of mitochondrially synthesized polypeptides was rather similar both in vegetative and in sporulating cells, it appeared that not only degradation but also synthesis and therefore turnover of the mitochondrially coded polypeptides of cytochromes b and aa3 took place during sporulation. The activity ratio of cytochrome c oxidase to F1-ATPase in submitochondrial particles isolated from vegetative cells and from purified asci was almost identical. This indicates that the loss of membrane-bound mitochondrial cytochromes during sporulation is probably due to a nonselective degradation of inner mitochondrial membrane proteins.
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PMID:Protein degradation during yeast sporulation. Enzyme and cytochrome patterns. 18 44

Yeast mutant lacking proteinase B activity have been isolated [Wolf, D. H. and Ehmann, C. (1978) FEBS Lett. 92, 121--124]. One of these mutants (HP232) is characterized in detail. Absence of the vacuolar localized enzyme is confirmed by checking for proteinase B activity in isolated mutant vacuoles. Defective proteinase B activity segregates 2:2 in meiotic tetrads. The mutation is shown to be recessive. Mutant proteinase B activity is not only absent against the synthetic substrate. Azocoll, but also against the physiological substrate pre-chitin synthetase, cytoplasmic malate dehydrogenase and fructose-1,6-bisphosphatase. The mutant shows normal vegetative growth, a phenomenon not consistent with the idea that proteinase B might be the activating principle of chitin synthetase zymogen in vivo. Fluorescence microscopy shows normal chitin insertion. Enzymes underlying carbon-catabolite inactivation in wild-type cells (a mechanism proposed to be possibly triggered by proteinase B) such as cytoplasmic malate dehydrogenase, fructose-1,6-bisphosphatase, phosphoenolpyruvate carboxykinase and isocitrate lyase, are inactivated also in the mutant. NADP-dependent glutamate dehydrogenase, which is found to be inactivated in glucose-starved wild-type cells, proceeds normally in the mutant. Mutant cells show more than 40% reduced protein degradation under starvation conditions. Sporulating diploids, homozygous for proteinase B absence, also exhibit an approximately 40% reduced protein degradation as compared to homozygous wild-type diploids or diploids heterozygous for the mutant gene. The time of the appearance of the first ascospores of diploid cells, homozygous for proteinase B deficiency, is delayed about 50% and sporulation frequency is reduced to about the same extent as compared to homozygous wild-type diploids or diploids heterozygous for the mutant gene.
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PMID:Studies on a proteinase B mutant of yeast. 38 14

Heterologous hybridisation of the Aspergillus nidulans structural gene for isocitrate lyase (acuD) to a lambda genomic library of Neurospora crassa identified a recombinant phage containing the hybridising sequence on an internal 9 kb EcoRI fragment. A restriction fragment length polymorphism (RFLP) enabled the fragment to be assigned to linkage group V (LG V), the location of the acetate-inducible isocitrate lyase, acu-3 of Neurospora. Functional ectopic complementation by co-transformation of an am-, acu- double mutant using independent plasmid clones, carrying the entire 9 kb EcoRI fragment (pICLG1) and the selectable marker am+ (NADP-glutamate dehydrogenase), demonstrated that the clone contains the entire acetate-inducible transcription unit. However, Northern analysis revealed two species of mRNA, only one of which was inducible on acetate. Native polyacrylamide gel electrophoresis separated two iso-enzymic activities, again only one of which was acetate-inducible and deficient in acu-3- mutants. Further hybridisation of the acu-3 gene probe to an electrophoretic karyotype of Neurospora crassa identified sequences in an additional linkage group as well as in LG V, as anticipated. The isozymes are therefore sequence-related.
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PMID:Isolation and expression of the acetate-inducible isocitrate lyase gene (acu-3) from Neurospora crassa: evidence for a second constitutive isozyme. 168 13

Octanoic acid inhibits, in vitro, the bacterial enzymes glucose-6-phosphate dehydrogenase, phosphofructokinase, pyruvate kinase, fumarase, lactate dehydrogenase, and the malic enzyme of Arthrobacter crystallopoietes. The free fatty acid appears to act as an inhibitor of lipogenesis, although it does not affect the rate of gluconeogenesis. To demonstrate that this inhibition may be of physiological significance in vivo, those enzymes not involved in lipogenesis, such as fructose-1, 6-diphosphatase, phosphoglucomutase, phosphohexoisomerase, aconitase, nicotinamide adenine dinucleotide phosphate (NADP) isocitrate dehydrogenase, NADP glutamate dehydrogenase, malate dehydrogenase, and isocitrate lyase, were assayed and found not to be inhibited by the free fatty acid.
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PMID:Selective inhibition of bacterial enzymes by free fatty acids. 430 71

The enzyme pattern of Saccharomyces cerevisiae was followed during batch growth and in continuous culture in a synthetic medium limited for glucose under aerobic conditions. Seven enzymes were measured: succinate-cytochrome c oxidoreductase, malate dehydrogenase, nicotinamide adenine dinucleotide-linked glutamate dehydrogenase, malate synthase, isocitrate lyase, aldolase, and nicotinamide adenine dinucleotide phosphate (NADP(+))-linked glutamate dehydrogenase. During fermentation of glucose and high growth rate (mu) during the first log phase in batch experiments, the first five enzymes (group I) were repressed, and aldolase and NADP(+)-linked glutamate dehydrogenase (group II) were derepressed. During growth on the accumulated ethyl alcohol and lower mu, the group I enzymes were preferentially formed and the other two were repressed. A sequence of derepression of the group I enzymes was found during the shift from glucose to ethyl alcohol metabolism, which can be correlated with a strong increase in the percentage of single (nonbudding) cells in the population. A correlation between the state of cells in the budding cycle and enzyme repression and derepression is suggested. In continuous culture, the enzyme pattern was shown to be related to the growth rate. The group I enzymes were repressed at high growth rates, while the group II enzymes were derepressed. Each enzyme exhibits a different dependence. The enzyme pattern is shown to depend on the rate of substrate consumption as well as on the type of metabolism and to be correlated with the budding cycle. The enzyme pattern is considered to be controlled by changes of intracellular catabolic or metabolic conditions inherent in the division cycle.
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PMID:Enzyme pattern and aerobic growth of Saccharomyces cerevisiae under various degrees of glucose limitation. 438 90

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.
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PMID:Isocitrate lyase from a thermophilic Bacillus: effect of salts on enzyme activity. 458

1. Aerobically grown yeast having a high activity of glyoxylate-cycle, citric acid-cycle and electron-transport enzymes was transferred to a medium containing 10% glucose. After a lag phase of 30min. the yeast grew exponentially with a mean generation time of 94min. 2. The enzymes malate dehydrogenase, isocitrate lyase, succinate-cytochrome c oxidoreductase and NADH-cytochrome c oxidoreductase lost 45%, 17%, 27% and 46% of their activity respectively during the lag phase. 3. When growth commenced pyruvate kinase, pyruvate decarboxylase, alcohol dehydrogenase, glutamate dehydrogenase (NADP(+)-linked) and NADPH-cytochrome c oxidoreductase increased in activity, whereas aconitase, isocitrate dehydrogenase (NAD(+)- and NADP(+)-linked), alpha-oxoglutarate dehydrogenase, fumarase, malate dehydrogenase, succinate-cytochrome c oxidoreductase, NADH-cytochrome c oxidoreductase, NADH oxidase, NADPH oxidase, cytochrome c oxidase, glutamate dehydrogenase (NAD(+)-linked), glutamate-oxaloacetate transaminase, isocitrate lyase and glucose 6-phosphate dehydrogenase decreased. 4. During the early stages of growth the loss of activity of aconitase, alpha-oxoglutarate dehydrogenase, fumarase and glucose 6-phosphate dehydrogenase could be accounted for by dilution by cell division. The lower rate of loss of activity of isocitrate dehydrogenase (NAD(+)- and NADP(+)-linked), glutamate dehydrogenase (NAD(+)-linked), glutamate-oxaloacetate transaminase, NADPH oxidase and cytochrome c oxidase implies their continued synthesis, whereas the higher rate of loss of activity of malate dehydrogenase, isocitrate lyase, succinate-cytochrome c oxidoreductase, NADH-cytochrome c oxidoreductase and NADH oxidase means that these enzymes were actively removed. 5. The mechanisms of selective removal of enzyme activity and the control of the residual metabolic pathways are discussed.
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PMID:The kinetics of enzyme changes in yeast under conditions that cause the loss of mitochondria. 566 Jun 27

relationship between levels of cAMP and catabolite repression in yeasts has been investigated. Strains of Saccharomyces cerevisiae, Schizosaccharomyces pombe and Kluyveromyces fragilis were used. The yeasts were grown on different carbon sources to attain various degrees of repression. Galactose repressed as much as glucose, while maltose was less effective. Full derepression was achieved with ethanol. The enzymes tested were fructose-bisphosphatase, malate dehydrogenase, glutamate dehydrogenase (NAD dependent), cytochrome oxidase and isocitrate lyase (this last enzyme was found to be absent in Schizosaccharomyces). The levels of cAMP were 2-3 times higher in the repressed conditions than in the derepressed ones. It is therefore concluded that in yeasts catabolite repression is not mediated by a lowering of the intracellular concentration of cAMP.
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PMID:Catabolite repression in yeasts is not associated with low levels of cAMP. 632 8

The compartmentation of key processes in sugar, organic acid and amino acid metabolism was studied during the development of the flesh and seeds of grape (Vitis vinifera L.) berries. Antibodies specific for enzymes involved in sugar (cell wall and vacuolar invertases, pyrophosphate: fructose 6-phosphate phosphotransferase, aldolase, NADP-glyceraldehyde-P dehydrogenase, cytosolic fructose 1,6-bisphosphatase), photosynthesis (Rubisco, fructose 1,6-bisphosphatase, sedoheptulose 1,7-bisphosphatase), amino acid metabolism (cytosolic and mitochondrial aspartate aminotransferases, alanine aminotransferase, glutamate dehydrogenase, glutamine synthetase), organic acid metabolism (phosphoenolpyruvate carboxylase, NAD- and NADP-dependent malic enzyme, ascorbate peroxidase), and lipid metabolism (acetyl CoA carboxylase, isocitrate lyase) were used to determine how their abundance changed during development. There were marked changes in the abundance of many of these enzymes in both the flesh and seeds. The intercellular location of some enzymes was investigated using immunohistochemistry. Several enzymes (e.g. phosphoenolpyruvate carboxylase and those involved in amino acid metabolism) were associated with tissues likely to function in the transport of imported assimilates, such as the vasculature. Although other enzymes (e.g. NADP-malic enzyme and soluble acid invertase, involved in the metabolism of sugars and organic acids) were largely present in the parenchyma cells of the flesh, their distribution was extremely heterogeneous. This study shows that when considering the metabolism of complex structures such as fruit, it is essential to consider how metabolism is compartmentalized between and within different tissues, even when they are apparently structurally homogeneous.
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PMID:An immunohistochemical study of the compartmentation of metabolism during the development of grape (Vitis vinifera L.) berries. 1093 59

The activity level and some physico-chemical properties of enzymes of the tricarboxylic acid cycle (TCA cycle) and the associated enzymes isocitrate lyase and glutamate dehydrogenase of cyanobacterium Spirulina platensis grown under illumination of 5000 lk in batch conditions, have been studied. High activities of most of the studied enzymes except for alpha-ketoglutarate dehydrogenase (alpha-KGDH) and succinate dehydrogenase have been estimated. In some cases the activities were by an order higher than that of similar enzymes in other cyanobacteria. This reflects the microorganism ability to synthesize intensively organic substances and first of all protein. Absence of alpha-KGDH activity proves that TCA cycle of spirulina has a limited value for energy generation and mainly performs the biosynthetic function.
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PMID:[Activity of tricarboxylic acid cycle enzymes in cyanobacteria Spirulina platensis]. 1130 83


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