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Zur photosynthetischen CO2-Fixierung von Synechococcus / Photosynthetic CO2 Fixation of Synechococcus

Döhler, Günter
Zeitschrift für Naturforschung 2014 v.35 no.11-12 pp. 978-981
3-phosphoglyceric acid, Calvin cycle, Synechococcus, aerobic conditions, aspartic acid, carbon, carbon dioxide, carbon dioxide fixation, carboxylation, glutamic acid, radionuclides, sugars, temperature, white light
The cyanobacterium Synechococcus (Anacystis nidulans strain L 1402-1) was grown at + 37 °C in 3.0 vol.% CO₂. The effect of preillumination with white light on the subsequent dark ¹⁴CO₂ fixation was studied under aerobic conditions at + 30 °C. The radioactive carbon first incoiporated into 3-phosphoglyceric acid was transferred during the later periods of dark ¹⁴CO₂ fixation to phosphoenolpyruvate and aspartate. No labelling or a very low label in sugar monophosphates could be observed. During the dark/light transients the initial fixation product was mainly aspartate. The pattern of ¹⁴C-incorporation into photosynthetic products under steady state conditions (10 min photosynthesis) varied with the temperature during the experiments. The radioactive carbon was firstly incorporated into 3-phosphoglyceric acid. During the later periods of photosynthetic ¹⁴CO₂ fixation an increased ¹⁴C-incorporation into aspartate and glutamate could be observed. Our findings were interpreted with operating of a phospho­enolpyruvate carboxylation besides the Calvin cycle.