Cyclic electron transfer around Photosystem I mediated by 2,3-dichloro-1,4-naphtoquinone and ascorbate
Anastasia A Petrova1, Boris V Trubitsin2, Baina K Boskhomdzhieva1
1A.N. Belozersky Institute of Physical-Chemical Biology, M.V. Lomonosov Moscow State University, Russia.
Abstract:
In this work, we investigated electron transport around the photosynthetic pigment-protein complex of Photosystem I (PS I) mediated by external high-potential electron carrier 2,3-dichloro-1,4-naphtoquinone (Cl2 NQ) and ascorbate. It has been demonstrated that the oxidized species of Cl2 NQ and ascorbate serve as intermediates capable of accepting electrons from the iron-sulfur cluster FX of PS I. Reduced species of Cl2 NQ and ascorbate are oxidized by photooxidized PS I primary donor P700+ and/or by molecular oxygen. We have found the synergistic effect of Cl2 NQ and ascorbate on the rate of P700+ reduction. Accelerated electron flow to P700+, observed in the presence of both Cl2 NQ and ascorbate, is explained by an increase in the reduced species of Cl2 NQ due to electron transfer from ascorbate.
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