Competition between electron acceptors in photosynthesis: Regulation of the malate valve during CO2fixation and nitrite reduction
✍ Scribed by Jan E. Backhausen; Camillo Kitzmann; Renate Scheibe
- Book ID
- 104615157
- Publisher
- Springer
- Year
- 1994
- Tongue
- English
- Weight
- 1001 KB
- Volume
- 42
- Category
- Article
- ISSN
- 0166-8595
No coin nor oath required. For personal study only.
✦ Synopsis
For maximal rates of C O 2 assimilation in isolated intact spinach chloroplasts the generation of the adequate NADPH/ATP ratio is achieved either by cyclic electron flow around photosystem I or by linear electron transport to oxaloacetate, nitrite or oxygen (Mehler-reaction). The interrelationships between these poising mechanisms turn out to be strictly hierarchical. In the presence of antimycin A, an inhibitor of ferredoxin-dependent cyclic electron transport, the reduction of both, oxaloacetate and nitrite, but not that of oxygen restores CO2 fixation. When oxaloacetate and nitrite are added at low concentrations simultaneously during steady-state CO2 fixation, the reduction of nitrite is clearly preferred over the reduction of oxaloacetate, but CO2 fixation is not influenced. Nitrite reduction is not decreased upon addition of oxaloacetate, but vice versa. This is due to the regulation of * Dedicated to Prof. Dr. Hans Walter Heldt on the occasion of his 60th birthday.