Light mediated regulation of nitrate assimilation in Synechococcus leopoliensis |
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Authors: | Rudolf Tischner Ahlert Schmidt |
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Institution: | (1) Pflanzenphysiologisches Institut, Universität Göttingen, Untere Karspüle 2, D-3400 Göttingen, Federal Republic of Germany;(2) Botanisches Institut, Universität München, Menzinger Str. 67, D-8000 München 19, Federal Republic of Germany |
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Abstract: | Synechococcus leopoliensis was cultivated in a light/dark regime of 12:12 h. After onset of the illumination (2 h), the specific activity of nitrite reductase, glutamine synthetase and isocitric dehydrogenase increased; that of glucose-6-phosphate dehydrogenase decreased and that of nitrate reductase and NAD- (NADP) glutamate dehydrogenase remained nearly unchanged.This stimulation of the enzymes in vivo was also observed in vitro. Also, when extracts from darkened cells were incubated with thioredoxin and dithioerythriol enzyme activities increased in the same amount as obtained in vivo. In addition, glucose-6-phosphate dehydrogenase and isocitric dehydrogenase were stimulated by Mn2+ and Mg2+ in the assay mixture. Glutamine synthetase activity was enhanced only by Mg2+ while Mn2+ was inhibitory.The results are discussed with respect to the regulation of nitrogen metabolism by light.Abbreviations GS
glutamine synthetase
- GOGAT
glutamate-oxoglutarate-aminotransferase
- TR
thioredoxin
- DTE
dithioerythritol
- LD
change from light to dark |
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Keywords: | Synechococcus leopoliensis Nitrogen metabolism Light mediated activation Thioredoxin |
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