Beziehungen der Aufnahme von Nitrat, Nitrit und Phosphat zur photosynthetischen Reduktion von Nitrat und Nitrit und zum ATP-Spiegel beiAnkistrodesmus braunii
✍ Scribed by C. I. Ullrich-Eberius
- Publisher
- Springer-Verlag
- Year
- 1973
- Tongue
- English
- Weight
- 553 KB
- Volume
- 115
- Category
- Article
- ISSN
- 0032-0935
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✦ Synopsis
The pH-dependence of NOs-and NO2-uptake is different from that of phosphate uptake, but similar to that of sulfate uptake, with optima between pH 7.4 and 8.2 and smaller peaks at higher H+-concentration.
Since the ATP-level is not affected by addition of ions and since phosphate uptake is not depressed by NO3-, the inhibition of phosphate uptake by K + reported in former papers cannot be explained by competition for the available energy(ATP) at the site of uptake.
NOs-uptake is strongly dependent on the activity of the NO3-reducing system, as can be seen from the inhibition of NOs-uptake in light by N2 compared with that in air. Furthermore, the pit-dependences of NO3-and NO2-uptake correspond to the pH-optima known for the reductases.
Phosphate uptake is enhanced by NOs-and NOs-in N2. Since the enhancement of phosphate uptake is sensitive to DCMU and since this DCMU-sensitive phosphate uptake is accompanied by 02-evolution, it is probably due to an NO3--stimulated noncyclic photophosphorylation which enhances the ATP-turnover and hence the incorporation of phosphate into organic compounds.
Einleitung
Die energieabh/tngige Phosphataufnahme ist bei Ankistrodesmus im neutralen und alkalischen pH-Bereich sehr niedrig, kann aber durch Na + im Gegensatz zu K + betr/~chtlich gef6rdert werden (Ullrich-Eberius und Simonis, 1970b). Um zu priifen, ob negative Festladungen im alkalischen pII-Bereich die Phosphataufnahme und allgemein die