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Current state of the primary charge separation mechanism in photosystem I of cyanobacteriaстатья
- Авторы: Cherepanov Dmitry A., Semenov Alexey Yu, Mamedov Mahir D., Aybush Arseniy V., Gostev Fedor E., Shelaev Ivan V., Shuvalov Vladimir A., Nadtochenko Victor A.
- Журнал: Biophysical Reviews
- Том: 14
- Год издания: 2022
- Издательство: Springer Verlag
- Местоположение издательства: Germany
- Первая страница: 805
- Последняя страница: 820
- DOI: 10.1007/s12551-022-00983-1
- Аннотация: This review analyzes new data on the mechanism of ultrafast reactions of primary charge separation in photosystem I (PS I) of cyanobacteria obtained in the last decade by methods of femtosecond absorption spectroscopy. Cyanobacterial PS I from many species harbours 96 chlorophyll a (Chl a) molecules, including six specialized Chls denoted Chl1A/Chl1B (dimer P700, or PAPB), Chl2A/Chl2B, and Chl3A/Chl3B arranged in two branches, which participate in electron transfer reactions. The current data indicate that the primary charge separation occurs in a symmetric exciplex, where the special pair P700 is electronically coupled to the symmetrically located monomers Chl2A and Chl2B, which can be considered together as a symmetric exciplex Chl2APAPBChl2B with the mixed excited (Chl2APAPBChl2B)* and two charge-transfer states P700+Chl2A− and P700+Chl2B−. The redistribution of electrons between the branches in favor of the A-branch occurs after reduction of the Chl2A and Chl2B monomers. The formation of charge-transfer states and the symmetry breaking mechanisms were clarified by measuring the electrochromic Stark shift of β-carotene and the absorption dynamics of PS I complexes with the genetically altered Chl2B or Chl2A monomers. The review gives a brief description of the main methods for analyzing data obtained using femtosecond absorption spectroscopy. The energy levels of excited and charge-transfer intermediates arising in the cyanobacterial PS I are critically analyzed.
- Добавил в систему: Семенов Алексей Юрьевич