Purification, characterization, and cDNA sequence of glucose‐6‐phosphate dehydrogenase from potato (<i>Solatium tuberosum</i> L.)

Graeve, K. G. de; Schaewen, Antje von; Scheibe, Renate

doi:10.1111/j.1365-313x.1994.00353.x

Cited by 120 publications

(133 citation statements)

References 25 publications

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“…It was unequivocally shown that chloroplast/cytosol isoenzymes exist for G6PDH and 6PGDH both in green leaf cells (Schnarrenberger et al, 1973) and in nongreen tissues (Schnarrenberger et al, 1975;Simcox et al, 1977;Simcox and Dennis, 1978;Nishimura and Beevers, 1981). Cytosolic G6PDH has even been cloned from potato tuber (Graeve et al, 1994).…”

Section: Discussionmentioning

confidence: 99%

Enzymatic Evidence for a Complete Oxidative Pentose Phosphate Pathway in Chloroplasts and an Incomplete Pathway in the Cytosol of Spinach Leaves

1995

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l h e intracellular localization of transaldolase, transketolase, ribose-5-phosphate isomerase, and ribulose-5-phosphate epimerase was reexamined in spinach (Spinacia oleracea 1,) leaves. We found a highly predominant if not exclusive localization of these enzyme activities in chloroplasts isolated by isopyknic centrifugation in sucrose gradients. Clucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, glucose phosphate isomerase, and triose phosphate isomerase activity was present in the chloroplast fraction but showed additional activity in the cytosol (supernatant) fraction attributable to the cytosol-specific isoforms known to exist for these enzymes. Anion-exchange chromatography of proteins of crude extracts on diethylaminoethyl-Fractogel revealed only a single enzyme each for transaldolase, transketolase, ribose-5-phosphate isomerase, and ribulose-5-phosphate epimerase. The data indicate that chloroplasts of spinach leaf cells possess the complete complement of enzymes of the oxidative pentose phosphate pathway (OPPP), whereas the cytosol contains only the first two reactions, contrary to the widely held view that plants generally possess a cytosolic OPPP capable of cyclic function. l h e chloroplast enzymes transketolase, ribose-5-phosphate isomerase, and ribulose-5-phosphate epimerase appear to be amphibolic for the Calvin cycle and OPPP.

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Section: Discussionmentioning

confidence: 99%

Enzymatic Evidence for a Complete Oxidative Pentose Phosphate Pathway in Chloroplasts and an Incomplete Pathway in the Cytosol of Spinach Leaves

1995

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“…G6PDH activity was determined by using a spectrophotometric assay reported previously [21]. The assays were performed at room temperature with a 20 μg extract of cellular protein in a buffer consisting of 0.1 M Tris-HCl (pH 8.5), 0.2 mM NADP and 2 mM glucose-6-phosphate.…”

Section: G6pdh Activity Assaymentioning

confidence: 99%

“…G6PDH activity was measured by exposing identical amounts of cell protein extracts from the wild type and GK-overexpressing H4IIE cell lines, to G6P and NADPH under assay conditions described previously [21]. The NADPH produced per unit assay time is directly proportional to the G6PDH activity.…”

Section: G6pdh Activity Is Higher In the Gk-overexpressing Cell Linesmentioning

confidence: 99%

Global metabolic effects of glycerol kinase overexpression in rat hepatoma cells

Sriram

Rahib

et al. 2008

Molecular Genetics and Metabolism

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Glycerol kinase has several diverse activities in mammalian cells. Glycerol kinase deficiency is a complex, single-gene, inborn error of metabolism wherein no genotype-phenotype correlation has been established. Since glycerol kinase has been suggested to exhibit additional activities than glycerol phosphorylation, expression level perturbation in this enzyme may affect cellular physiology globally. To investigate this possibility, we conducted metabolic investigations of wild type and two glycerol kinase-overexpressing H4IIE rat hepatoma cell lines constructed in this study. The glycerol kinase-overexpressing cell lines exhibited a significantly higher consumption of carbon sources per cell, suggesting excess carbon expenditure. Furthermore, we quantified intracellular metabolic fluxes by employing stable isotope ( 13 C) labeling with a mathematically designed substrate mixture, gas chromatography-mass spectrometry, and comprehensive isotopomer balancing. This flux analysis revealed that the pentose phosphate pathway flux in the glycerol kinase-overexpressing cell lines was two-fold higher than that in the wild type, in addition to subtler flux changes in other pathways of carbohydrate metabolism. Furthermore, the activity and transcript level of the lipogenic enzyme glucose-6-phosphate dehydrogenase, the rate-limiting enzyme of the pentose phosphate pathway, were also about two-fold higher than that of the wild type; these data corroborate the flux analysis results. This study shows that glycerol kinase affects carbon metabolism globally, possibly through its additional functions, and highlights glycerol kinase's multifaceted role in cellular physiology.

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“…Chloroplastic G6PDH has high homology to the plant cytosolic, animal and yeast enzymes, but contains six specific cysteine residues which are not found in the cytosolic protein, all of them being located in the first third of the amino-acid sequence. These residues are also absent on the cyanobacterial enzyme which contains three cysteine residues located further downstream (Graeve, von Schaewen & Scheibe, 1994;von Schaewen et al, 1995). Nevertheless, the cyanobacterial enzyme appears to be also redox-controlled (Gleason, 1996).…”

Section: {D) Cf^-atpasementioning

confidence: 99%

Thioredoxins: structure and function in plant cells

1997

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SUMMARY Thioredoxins are ubiquitous small‐molecular‐weight proteins (typically 100–120 amino‐acid residues) containing an extremely reactive disulphide bridge with a highly conserved sequence ‐Cys‐Gly(Ala/Pro)‐Pro‐Cys‐. In bacteria and animal cells, thioredoxins participate in multiple reactions which require reduction of disulphide bonds on selected target proteins/ enzymes. There is now ample biochemical evidence that thioredoxins exert very specific functions in plants, the best documented being the redox regulation of chloroplast enzymes. Another area in which thioredoxins are believed to play a prominent role is in reserve protein mobilization during the process of germination. It has been discovered that thioredoxins constitute a large multigene family in plants with different‐subcellular localizations, a unique feature in living cells so far. Evolutionary studies based on these molecules will be discussed, as well as the available biochemical and genetic evidence related to their functions in plant cells. Eukaryotic photosynthetic plant cells are also unique in that they possess two different reducing systems, one extrachloroplastic dependent on NADPH as an electron donor, and the other one chloroplastic, dependent on photoreduced ferredoxin. This review will examine in detail the latest progresses in the area of thioredoxin structural biology in plants, this protein being an excellent model for this purpose. The structural features of the reducing enzymes ferredoxin thioredoxin reductase and NADPH thioredoxin reductase will also be described. The properties of the target enzymes known so far in plants will be detailed with special emphasis on the structural features which make them redox regulatory. Based on sequence analysis, evidence will be presented that redox regulation of enzymes of the biosynthetic pathways first appeared in cyanobacteria possibly as a way to cope with the oxidants produced by oxygenic photosynthesis. It became more elaborate in the chloroplasts of higher plants where a co‐ordinated functioning of the chloroplastic and extra chloroplastic metabolisms is required.

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Purification, characterization, and cDNA sequence of glucose‐6‐phosphate dehydrogenase from potato (Solatium tuberosum L.)

Cited by 120 publications

References 25 publications

Enzymatic Evidence for a Complete Oxidative Pentose Phosphate Pathway in Chloroplasts and an Incomplete Pathway in the Cytosol of Spinach Leaves

Enzymatic Evidence for a Complete Oxidative Pentose Phosphate Pathway in Chloroplasts and an Incomplete Pathway in the Cytosol of Spinach Leaves

Global metabolic effects of glycerol kinase overexpression in rat hepatoma cells

Thioredoxins: structure and function in plant cells

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