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Effect of dry trehalose glassy matrix on the forward electron transfer in Photosystem I from cyanobacteria Synechocystis sp. PCC 6803тезисы доклада Тезисы
- Авторы: Semenov A.Yu, Shelaev I., Gorka M., Savitsky A., Kurashov V., Gostev F., Nadtochenko V., Mobius K., Golbeck J.
- Сборник: Book of Abstracts of Modern Development of Magnetic Resonance, Kazan 2016
- Тезисы
- Год издания: 2016
- Первая страница: 42
- Последняя страница: 42
- Аннотация: The effect of dehydration on the kinetics of forward electron transfer has been studied in cyanobacterial Photosystem I (PS I) complexes in a trehalose glassy matrix by time-resolved optical and EPR spectroscopies. The kinetics of the flash-induced absorption changes in the subnanosecond time domain, which are due to primary and secondary charge separation steps, were monitored by pump-probe laser spectroscopy with 20-fs low-energy pump pulses. The backreaction kinetics of the PS I primary donor P700 were measured by high-field time-resolved EPR spectroscopy. The forward kinetics from the phylloquinone primary acceptor A1- to the iron-sulfur cluster FX were measured by time-resolved optical spectroscopy at 480 nm. The kinetics of the primary electron transfer reactions to form the primary P700+A0– and the secondary P700+A1– ion radical pairs were not affected by dehydration in the trehalose matrix, while the yield of the P700+A1– was decreased by ~20%. Forward electron transfer from the phylloquinone molecules in the A1A– and A1B– sites of the A and B branches of the cofactors to the iron-sulfur cluster FX slowed from ~200 ns and ~20 ns in solution to ~13 μs and ~80 ns, respectively. However, as shown by EPR spectroscopy, the ~14 μs kinetic phase also contains a small contribution from the recombination between A1B– and P700+. These data reveal that the initial electron transfer reactions from the excited P700* to A1 remain unaffected whereas electron transfer beyond A1A and A1B is slowed or prevented by constrained protein dynamics due to the dry trehalose glassy matrix. The kinetics of forward electron transfer between A1 and FX in dry trehalose glass generally mimicked the kinetics of PS I in water-glycerol at the temperature of the protein-glass transition (Agalarov and Brettel: BBA 1604, 7–12 (2003)).
- Добавил в систему: Семенов Алексей Юрьевич