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:4.1.1.32 (phosphoenolpyruvate carboxykinase)
4,204 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

I compared the C(4) grass flora and climatic records for 32 sites in the United States. Consistent with previous studies, I found that the proportion of the grass flora that uses the NADP malic enzyme (NADP-ME) variant of C(4) photosynthesis greatly increases with increasing annual precipitation, while the proportion using the NAD malic enzyme (NAD-ME) variant (and also the less common phosphoenolpyruvate carboxykinase [PCK] variant) decreases. However the association of grass subfamilies with annual precipitation was even stronger than for the C(4) decarboxylation variants. Analysis of the patterns of distribution by partial correlation analysis showed that the correlations between the frequency of various C(4) types and rainfall were solely due to the association of the C(4) types with particular grass subfamilies. In contrast, there was a strong correlation of the frequency of the different subfamilies with annual precipitation that was independent of the influence of the different C(4) variants. It therefore appears that other, as yet unidentified, characteristics that differ among grass subfamilies may be responsible for their differences in distribution across natural precipitation gradients.
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PMID:Climate and the U.S. distribution of C4 grass subfamilies and decarboxylation variants of C4 photosynthesis. 1094 7

We describe a method for the detection of isoforms of several glycolytic enzymes by activity staining after native PAGE. The staining is based on coupled enzyme assays carried out on the gel after electrophoresis and is linked to the disappearance of NADH, which is visualized by fluorescence. This method offers reliable and sensitive detection for phosphoenolpyruvate carboxylase, PPi-dependent phosphofructokinase, and pyruvate kinase from plant tissues. It can be applied to the detection of all enzymes which are normally detected spectrophotometrically using coupled enzyme assays consuming NAD(P)H.
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PMID:A method for activity staining after native polyacrylamide gel electrophoresis using a coupled enzyme assay and fluorescence detection: application to the analysis of several glycolytic enzymes. 1174 96

The Tn5-induced mutant VG12 of Ralstonia eutropha HF39, which was isolated in this study, revealed an interesting phenotype: it grew on fructose and pyruvate as well as autotrophically like the wild-type, whereas growth on tricarboxylic acid intermediates and glyoxylic acid was reduced, and no growth occurred if acetate, propionate or levulinate were provided as carbon source. Tn5 was mapped in a gene encoding an NAD(H)-dependent malate dehydrogenase (MDH), and MDH activity was strongly diminished in VG12. Furthermore, the mdh gene was cloned, sequenced and heterologously expressed in Escherichia coli, conferring significantly higher specific MDH activity to the recombinant strain. The phenotype of VG12 sheds light on the C(3)/C(4) metabolism of R. eutropha, which mediates between the Entner-Doudoroff pathway and the tricarboxylic acid cycle (TCC), demonstrating that enzymes catalyzing the conversion of C(3) and C(4) metabolites can circumvent the metabolic disruption of the TCC in VG12 and that the phosphoenolpyruvate carboxykinase serves a dual and important function.
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PMID:The malate dehydrogenase of Ralstonia eutropha and functionality of the C(3)/C(4) metabolism in a Tn5-induced mdh mutant. 1211 28

Strategy I plants respond to Fe deficiency by inducing morphological and biochemical modifications at the root level that are apt to make iron available for uptake. Cucumber (Cucumis sativus L.) grown in the absence of Fe has been shown to increase the capacity to acidify the rhizosphere and Fe3+ reduction activity. We have determined in these roots some metabolic activities that might be correlated with the increased proton extrusion. Proton efflux from roots may be followed by a mechanism regulating the cytosolic pH according to the pH-stat theory. Roots grown in the absence of Fe showed an increase in dark 14CO2 fixation and organic acid synthesis and a 6-fold increase in the extractable phosphoenolpyruvate carboxylase activity with respect to the control roots. Dehydrogenase activities producing cytosolic NAD(P)H were also increased under Fe deficiency. The presence of Fe2+, but not Fe3+, inhibited dark 14CO2 fixation in a range between 24 and 52% but did not show any effect on the in vitro phosphoenolpyruvate carboxylase activity.
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PMID:Metabolic Implications in the Biochemical Responses to Iron Deficiency in Cucumber (Cucumis sativus L.) Roots. 1222 26

Embryo axes isolated from germinating lupine seeds were cultivated in vitro for 24-96 h over media containing either 60 mmol/L sucrose or no sucrose. Ultrastructural studies showed that large vacuoles were accumulating in a central region of primary parenchyma cells in sucrose starved lupine embryo axes, whereas cytoplasm along with organelles were forced to a periphery of the cells. We suggest that the autolysis of cytoplasmic proteins contributes to the accumulation of the vacuoles and this suggestion is consistent with the results of the characterisation of protein content. The level of cytosolic proteins was reduced by 50% and the activity of cytosolic marker enzyme, PEP carboxylase, was reduced by 46% in starved embryos as compared to control. The mitochondria from starved tissues were not degraded. The level of mitochondrial proteins was reduced by only 10% and the activity of mitochondrial NAD-isocitrate dehydrogenase decreased by 8% as a result of starvation. As demonstrated by the results of Percoll density gradient centrifugation, sucrose starvation caused an increase of 49% in many of the higher density mitochondria fractions, whereas many of the lower density mitochondria fractions were decreased by 33%. The samples of mitochondria from starved embryo axes were determined to have higher respiration activity in the presence of glutamate and malate as compared to control samples. EPR-based analyses of free radicals showed the presence of free radicals with a signal at g = 2.0060 in embryo axes. The level of the radical was two times higher in sucrose-starved embryo axes than in control (the level of this radical increased in senescing plant tissues as well). The results of EPR-based quantitation of Mn2+ ions revealed that the level was a few times higher in starved material than in control. Starved embryo axes, however, do possess a number of adaptive mechanisms protecting them from oxidative damage. Densitometric analyses of gels revealed an increase in the activity of SOD in sugar-starved embryos, whereas CAT and POX activities were lower in axes grown without sucrose as compared to control. Superoxide dismutase, catalase and peroxidase zymogram analyses showed that synthesis of new isoforms was not induced by sugar starvation. An accumulation of phytoferritin was found in plastids of sucrose starved embryos. These results are discussed in relation to the metabolic changes observed in senescing plant tissues.
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PMID:Metabolic and ultrastructural responses of lupine embryo axes to sugar starvation. 1274 88

A comprehensive network structure for the autotrophic growth of Arthrospira platensis is proposed. The metabolic network was built up with 121 reactions and 134 metabolites including biomass synthesis, production of a growth-associated exopolysaccharide, and energy aspects. The model supports the existence of a metabolic shunt of PEP to pyruvate through PEP carboxylase, NAD(+)-dependent malate dehydrogenase and malic enzyme to convert NADH,H(+) into NADPH,H(+). A limit in Arthrospira growth metabolism due to NADH,H(+) balancing is evidenced, explaining why the maximal light-dependent mass yield of the growth-associated exopolysaccharide was 0.51 kg EPS kg(-1) biomass, consistent with experimental results.
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PMID:Identification of a metabolic network structure representative of Arthrospira (spirulina) platensis metabolism. 1459 79

To express foreign proteins in Actinobacillus succinogenes, a shuttle vector was constructed based on the Actinobacillus pleuropneumoniae-Escherichia coli shuttle vector, pGZRS-19. We demonstrated that A. succinogenes is transformed by electroporation at reasonably high efficiency, that pGZRS-19 is stable in A. succinogenes, and that the ampicillin resistance gene carried by pGZRS-19 is expressed in A. succinogenes. Three steps were then required to develop our A. succinogenes-E. coli shuttle vector. (i) The constitutively expressed A. succinogenes phosphoenolpyruvate carboxykinase gene, pckA, was cloned and sequenced. (ii) Its promoter region and ribosome-binding site were subcloned into pGZRS-19. (iii) Finally, the ColE1 origin of replication was added to the vector to increase its stability in E. coli. High levels of A. succinogenes phosphoenolpyruvate carboxykinase, E. coli NADP-dependent malic enzyme, and Bacillus subtilis NAD-dependent malic enzyme activities detected in recombinant A. succinogenes strains confirmed that A. succinogenes and foreign proteins could be expressed in A. succinogenes under control of the A. succinogenes pckA promoter carried by pLGZ920. A. succinogenes is sensitive to chloramphenicol and tetracycline. Although not expressed from their own promoters, the Tn9 chloramphenicol and the Tn10 tetracycline resistance genes are expressed under control of the pckA promoter, and they can be used as additional selection markers in A. succinogenes.
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PMID:Construction of a shuttle vector for the overexpression of recombinant proteins in Actinobacillus succinogenes. 1500 7

The interactions between sulphur nutrition and Cd exposure were investigated in maize (Zea mays L.) plants. Plants were grown for 12 days in nutrient solution with or without sulphate. Half of the plants of each treatment were then supplied with 100 microM Cd. Leaves were collected 0, 1, 2, 3, 4 and 5 days from the beginning of Cd application and used for chemical analysis and enzyme assays. Cd exposure produced symptoms of toxicity (leaf chlorosis, growth reduction) and induced a noticeable accumulation of non-protein SH compounds. As phytochelatins are glutamate- and cysteine-rich peptides, the effect of cadmium on some enzyme activities involved in N and S metabolism of maize leaves was studied in relation to the plant sulphur supply. In vivo Cd application to S-sufficient plants resulted in a drop of all measured enzyme activities. On the other hand, S-deficient plants showed a decrease in nitrate reductase (NR; EC 1.6.6.1) and glutamine synthetase (GS; EC 6.3.1.2) activity, and an increase in NAD-dependent glutamate dehydrogenase (GDH; EC 1.4.1.2) and phosphoenolpyruvate carboxylase (PEPc; EC 4.1.1.31) activity as a result of the Cd treatment. Furthermore, in the same plants ATP sulphurylase (ATPs; EC 2.7.7.4) and O-acetylserine sulphydrylase (OASs; EC 4.2.99.8) showed a particular pattern as both enzymes exhibited a transient maximum value of activity after 4 days from the beginning of Cd exposure. Results provide evidence that the increase of ATPs, OASs, GDH and PEPc activities, observed exclusively in S-deficient Cd-treated plants, may be part of the defence mechanism based on the production of phytochelatins.
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PMID:Role of sulphur availability on cadmium-induced changes of nitrogen and sulphur metabolism in maize (Zea mays L.) leaves. 1531 68

An investigation was made of the respiratory properties and the role of the mitochondria isolated from one phosphoenolpyruvate carboxykinase (PCK)-CAM plant Ananas comosus (pineapple) in malate metabolism during CAM phase III. Pineapple mitochondria showed very high malate dehydrogenase (MDH), and low malic enzyme (ME) and glutamate-oxaloacetate transaminase (GOT) activities. The mitochondria readily oxidized succinate and NADH with high rates and coupling, while they only oxidized NADPH in the presence of Ca(2+). Pineapple mitochondria oxidized malate with low rates under most assay conditions, despite increasing malate concentrations, optimizing pH, providing cofactors such as coenzyme A, thiamine pyrophosphate, and NAD(+), and supplying individually external glutamate or GOT. However, providing glutamate and GOT simultaneously strongly increased the rates of malate oxidation. The OAA easily permeated the mitochondrial membranes to import into or export out of pineapple mitochondria during malate oxidation, but the mitochondria did not consume external Asp or alpha-KG. These results suggest that OAA played a significant role in the mitochondrial malate metabolism of pineapple, in which malate was mainly oxidized by active mMDH to produce OAA which could be exported outside the mitochondria via a malate-OAA shuttle. Cytosolic GOT then consumed OAA by transamination in the presence of glutamate, leading to a large increase in respiration rates. The malate-OAA shuttle might operate as a supporting system for decarboxylation in phase III of PCK-CAM pineapple. This shuttle system may be important in pineapple to provide a source of energy and substrate OAA for cytosolic PCK activity during the day when cytosolic OAA and ATP was limited for the overall decarboxylation process.
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PMID:Respiratory properties and malate metabolism in Percoll-purified mitochondria isolated from pineapple, Ananas comosus (L.) Merr. cv. smooth cayenne. 1536 38

Lactate and succinate were produced from glucose by Corynebacterium glutamicum under oxygen deprivation conditions without growth. Addition of bicarbonate to the reaction mixture led not only to a 3.6-fold increase in succinate production rate, but also to a 2.3- and 2.5-fold increase, respectively, of the rates of lactate production and glucose consumption, compared to the control. Furthermore, when small amounts of pyruvate were added to the reaction mixture, acid production rates and the glucose consumption rate were multiplied by a factor ranging from 2 to 3. These phenomena were paralleled by an increase in the NAD(+)/NADH ratio, thus corroborating the view that the efficient regeneration of NAD(+) could be triggered by the addition of either bicarbonate or pyruvate. To investigate the global metabolism of corynebacteria under oxygen deprivation conditions, we engineered several strains where the genes coding for key metabolic enzymes had been inactivated by gene disruption and replacement. A lactate dehydrogenase (LDH)-deficient mutant was not able to produce lactate, suggesting this enzyme has no other isozyme. Although a pyruvate carboxylase (pyc) mutant exhibited similar behavior to that of the wild type, phosphoenolpyruvate carboxylase (ppc) mutants were characterized by a dramatic decrease in succinate production, which was concomitant to decreased lactate production and glucose consumption rates. This set of observations corroborates the view that in coryneform bacteria under oxygen deprivation conditions the major anaplerotic reaction is driven by the ppc gene product rather than by the pyc gene product. Moreover, intracellular NADH concentrations in C. glutamicum were observed to correlate to oxygen-deprived metabolic flows.
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PMID:Metabolic analysis of Corynebacterium glutamicum during lactate and succinate productions under oxygen deprivation conditions. 1538 16


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