Ferredoxin:NADP+ Oxidoreductase Associated with Cytochrome b6f Complex is Highly Active in Plastoquinone Reduction
Three methods, differing in the preservation of the cytochrome b6f-associated ferredoxin:NADP+ oxidoreductase (FNR), have been applied for the isolation of the cytochrome b6f complex from spinach. The complexes isolated by all three methods showed presence of FNR peptide(s), as revealed immunoblot analysis. However, when incorporated into liposome membranes, the NADPH-PQ (plastoquinone) oxidoreductase activity was not detected for the cytochrome b6f complex isolated with the classical method including NaBr wash. Partial activity was found for the complex isolated with the omission of the wash, but the highest activity was detected for the complex isolated with the use of digitonin. The reaction rate was not significantly influenced by the addition of free FNR or ferredoxin. The reaction was neither affected by triphenyltin nor isobutyl cyanide. On the other hand, the reaction was severely inhibited by NQNO, an competitive inhibitor of PQ at the Qi site. The obtained data indicate that FNR associated with the cytochrome b6f complex can participate in the cyclic electron transport or chlororepiration as PSI-PQ or NADPH-PQ oxidoreductase, respectively. Moreover, we have shown that PQ in liposomes can be non-enzymatically reduced by ascorbate and this reaction might contribute to dark-reduction pathways of PQ-pool in chloroplasts.
Ferredoxin:NADP+ reductase Cytochrome b6f, Plastoquinone Cyclic electron transport Chlororespiration
Renata Szyma(n)ska Jolanta Pier(s)ci(n)ska Ireneusz (S)lesak Jerzy Kruk
Department of Plant Physiology and Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnolo Institute of Plant Physiology, Polish Academy of Sciences, ul. Niezapominajek 21, 30-239 Krak6w, Pol
国际会议
15th International Conference on Photosynthesis(第15届国际光合作用大会)
北京
英文
169-173
2010-08-22（万方平台首次上网日期，不代表论文的发表时间）