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:1.1.1.37 (malate dehydrogenase)
4,591 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

The proteins of soybean roots undergoing anaerobiosis can be grouped into three classes. Class 1 proteins are induced severalfold and at least 28 of these were identified by in vivo labeling. These proteins include the enzymes alcohol dehydrogenase (ADH), fructose aldolase, pyruvate decarboxylase, phosphoglucomutase, and lactate dehydrogenase. Class 2 proteins include such enzymes as glucose phosphate isomerase, sucrase, and malate dehydrogenase; their specific activity remains constant in aerobiosis or anaerobiosis. The third class of proteins includes those enzymes such as peroxidase whose activity decreases more than 90% after just 1 day in anaerobiosis. Immunoblotting coupled with two-dimensional chromatography of in vitro translated plant extracts demonstrated that ADH level during anaerobiosis is controlled by its mRNA concentration. Little or no mRNA for ADH was detected in aerobically grown roots. This suggests that the increased level of ADH activity is due to de novo synthesis of the mRNA rather than activation of a sequestered mRNA or superactivation of the protein.
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PMID:Gene regulation during anaerobiosis in soya roots. 262 97

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

An electrophoretic method has been devised to investigate the changes in the enzymes and isoenzymes of carbohydrate metabolism, upon adding glucose to derepressed yeast cells. (i) Of the glycolytic enzymes tested, enolase II, pyruvate kinase and pyruvate decarboxylase were markedly increased. This increase was accompanied by an overall increase in glycolytic activity and was prevented by cycloheximide, an inhibitor of protein synthesis. (ii) In contrast, respiratory activity decreased after adding glucose. This decrease was clearly shown to be the result of repression of respiratory enzymes. A rapid decrease within a few minutes of adding glucose, by analogy with the so-called ' Crabtree effect', was not observed in yeast. (iii) The gluconeogenic enzymes, fructose-1,6-bisphosphatase and malate dehydrogenase, which are inactivated after adding glucose, showed no significant changes in electrophoretic mobilities. Hence, there was no evidence of enzyme modifications, which were postulated as initiating degradation. However, it was possible to investigate cytoplasmic and mitochondrial malate dehydrogenase isoenzymes separately. Synthesis of the mitochondrial isoenzyme was repressed, whereas only cytoplasmic malate dehydrogenase was subject to glucose inactivation.
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PMID:Regulation of enzymes and isoenzymes of carbohydrate metabolism in the yeast Saccharomyces cerevisiae. 632 15

1. The main pathway of the anaerobic metabolism of L-malate in Saccharomyces bailii is catalyzed by a L-malic enzyme. 2. The enzyme was purified more than 300-fold. During the purification procedure fumarase and pyruvate decarboxylase were removed completely, and malate dehydrogenase and oxalacetate decarboxylase were removed to a very large extent. 3. Manganese ions are not required for the reaction of malic enzyme of Saccharomyces bailii, but the activity of the enzyme is increased by manganese. 4. The reaction of L-malic enzyme proceeds with the coenzymes NAD and (to a lesser extent) NADP. 5. The Km-values of the malic enzyme of Saccharomyces bailii were 10 mM for L-malate and 0.1 mM for NAD. 6. A model based on the activity and substrate affinity of malic enzyme, the intracellular concentration of malate and phosphate, and its action on fumarase, is proposed to explain the complete anaerobic degradation of malate in Saccharomyces bailii as compared with the partial decomposition of malate in Saccharomyces cerevisiae.
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PMID:The anaerobic metabolism of malate of Saccharomyces bailii and the partial purification and characterization of malic enzyme. 704 7

The activities of 13 liver and 6 brain enzymes were studied in 7-12 week old CD2F1 male mice that had been fed ad libitum and standardized either to 12 hours of light (0600-1800) alternating with 12 hours of darkness (1800-0600) (LD12:12); or to a reversed light-dark cycle (darkness 0600-1800; light 1800-0600) (DL12:12). Three separate studies were performed on two different days; in each experiment, subgroups of 14 animals were sacrificed at 3-hour intervals. Livers were assayed for: isocitrate dehydrogenase, glutamate dehydrogenase, lactate dehydrogenase, alcohol dehydrogenase, glutathione reductase, glyoxylate reductase, L-alanine aminotransferase, glutamate oxalacetate transaminase, pyruvate decarboxylase, fructose-1-phosphate aldolase, fructose diphosphate aldolase, fructose 1,6-diphosphatase, and fatty acid synthetase. Brains were assayed for phosphoglucose isomerase, adenosine triphosphatase, creatine phosphokinase, pyruvate kinase, adenylate kinase, and malate dehydrogenase. All 19 enzymes demonstrated a prominent circadian rhythm in at least one experiment. Moreover, each rhythmic variable showed a statistically significant fit to a 24-hour cosine (sine) curve by the method of least squares. In general, peak activities of the liver enzymes analyzed were associated with the beginning of the dark cycle and initiation of the animal's activity, while the group of brain enzymes had peak activities which occurred at the beginning of the animals' rest span and were near the beginning of the light cycle. The phasing of each of the rhythms could be reversed within a two-week span after reversing the environmental light-dark cycle 180 degrees.
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PMID:Circadian organization of thirteen liver and six brain enzymes of the mouse. 731 49

The effects of iron deficiency and iron resupply on the metabolism of leaf organic acids have been investigated in hydroponically grown sugar beet. Organic acid concentrations and activities in leaf extracts of several enzymes related to organic acid metabolism were measured. Enzymes assayed included phosphoenol pyruvate carboxylase (PEPC; EC 4.1.1.31), different Krebs cycle enzymes: malate dehydrogenase (MDH; EC 1.1.1.37), aconitase (EC 4.2.1.3), fumarase (EC 4.2.1.2), citrate synthase (CS; EC 4.1.3.7) and isocitrate dehydrogenase (ICDH; EC 1.1.1.42), glucose-6-phosphate dehydrogenase (G6PDH; EC 1.1.1.49) and two enzymes related to anaerobic metabolism (lactate dehydrogenase [LDH]; EC 1.1.1.27, and pyruvate decarboxylase [PDC]; EC 4.1.1.1). Iron concentration in leaves was severely decreased by iron deficiency. Iron resupply caused an increase in iron concentrations, reaching levels similar to the controls in 96 h. Iron deficiency induced a 2.3-fold (from 16 to 37 mmol m-2) increase in leaf total organic acid concentration. Organic anion concentrations were still 4-fold higher than the controls 24 h after resupply and decreased to values similar to those found in the controls after 96 h. All measured enzymes had increased activities in extracts of iron-deficient leaves when compared to the controls and generally decreased to control values 24 h after iron addition. These data provide evidence that organic acid accumulation in iron-deficient leaves is likely not due to an enhancement in leaf carbon fixation. Instead, this accumulation could be associated with organic acid export from the roots to the leaves via xylem.
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PMID:Changes induced by Fe deficiency and Fe resupply in the organic acid metabolism of sugar beet (Beta vulgaris) leaves. 1131 12

The effect of oxygen limitation on xylose fermentation by Pichia stipitis (CBS 6054) was investigated in continuous culture. The maximum specific ethanol productivity (0.20 g of ethanol g dry weight h) and ethanol yield (0.48 g/g) was reached at an oxygen transfer rate below 1 mmol/liter per h. In the studied range of oxygenation, the xylose reductase (EC 1.1.1.21) and xylitol dehydrogenase (EC 1.1.1.9) activities were constant as well as the ratio between the NADPH and NADH activities of xylose reductase. No xylitol production was found. The pyruvate decarboxylase (EC 4.1.1.1) activity increased and the malate dehydrogenase (EC 1.1.1.37) activity decreased with decreasing oxygenation. With decreasing oxygenation, the intracellular intermediary metabolites sedoheptulose 7-phosphate, glucose 6-phosphate, fructose 1,6-diphosphate, and malate accumulated slightly while pyruvate decreased. The ratio of the xylose uptake rate under aerobic conditions, in contrast to that under anaerobic assay conditions, increased with increasing oxygenation in the culture. The results are discussed in relation to the energy level in the cell, the redox balance, and the mitochondrial function.
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PMID:Effect of Oxygenation on Xylose Fermentation by Pichia stipitis. 1634 43

Malic acid is a potential biomass-derivable "building block" for chemical synthesis. Since wild-type Saccharomyces cerevisiae strains produce only low levels of malate, metabolic engineering is required to achieve efficient malate production with this yeast. A promising pathway for malate production from glucose proceeds via carboxylation of pyruvate, followed by reduction of oxaloacetate to malate. This redox- and ATP-neutral, CO(2)-fixing pathway has a theoretical maximum yield of 2 mol malate (mol glucose)(-1). A previously engineered glucose-tolerant, C(2)-independent pyruvate decarboxylase-negative S. cerevisiae strain was used as the platform to evaluate the impact of individual and combined introduction of three genetic modifications: (i) overexpression of the native pyruvate carboxylase encoded by PYC2, (ii) high-level expression of an allele of the MDH3 gene, of which the encoded malate dehydrogenase was retargeted to the cytosol by deletion of the C-terminal peroxisomal targeting sequence, and (iii) functional expression of the Schizosaccharomyces pombe malate transporter gene SpMAE1. While single or double modifications improved malate production, the highest malate yields and titers were obtained with the simultaneous introduction of all three modifications. In glucose-grown batch cultures, the resulting engineered strain produced malate at titers of up to 59 g liter(-1) at a malate yield of 0.42 mol (mol glucose)(-1). Metabolic flux analysis showed that metabolite labeling patterns observed upon nuclear magnetic resonance analyses of cultures grown on (13)C-labeled glucose were consistent with the envisaged nonoxidative, fermentative pathway for malate production. The engineered strains still produced substantial amounts of pyruvate, indicating that the pathway efficiency can be further improved.
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PMID:Malic acid production by Saccharomyces cerevisiae: engineering of pyruvate carboxylation, oxaloacetate reduction, and malate export. 1834 40

Concentrations of acetaldehyde, ethanol, ethyl acetate (EA), organic acids and activities and gene expression of alcohol dehydrogenase (ADH; EC 1.1.1.1), pyruvate decarboxylase (PDC; EC 4.1.1.1), alcohol acyltransferase (AAT; EC 1.4.1.14), malate dehydrogenase (MDH; EC 1.1.1.37), malic enzyme (ME; EC 1.1.1.40) and glutamate dehydrogenase (EC 1.4.1.14) were investigated in two strawberry (Fragaria x ananassa Duch) cultivars with different responses to CO(2) during storage. 'Jewel' fruit treated with CO(2) accumulated acetaldehyde and ethanol but little EA, while 'Cavendish' accumulated little acetaldehyde or ethanol but accumulated EA. In CO(2)-treated fruit, PDC activity was positively correlated with EA accumulation in 'Jewel' but not in 'Cavendish', while no differential effect of atmosphere was observed on its gene expression. ADH activity and gene expression show a correlation with ethanol accumulation in 'Cavendish'. In 'Jewel', there was a positive correlation between ADH gene expression and enzyme activity; however, this correlation does not explain ethanol accumulation in this cultivar. EA accumulation did not show any correlation with AAT activity and gene expression in any of the cultivars. Succinate concentrations were highest and those of malate lowest in CO(2)-treated fruit of both cultivars, but MDH and ME activities were not affected by CO(2). Gene expression of MDH and ME were not affected by atmosphere in 'Cavendish', although in 'Jewel' the MDH expression was slightly lower in CO(2)- than air-treated fruit. The results of this study show that differences in fermentation products and malate accumulation in CO(2)-treated strawberry fruit are not consistently correlated with enzyme activities and gene expression.
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PMID:Fermentation and malate metabolism in response to elevated CO2 concentrations in two strawberry cultivars. 1849 36


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