Primary charge separation in Chloroflexus aurantiacus reaction centers at room temperature: ultrafast transient absorption measurements on Q A -depleted preparations with native and chemically modified bacteriopheophytin composition.

Autor: Zabelin AA; Institute of Basic Biological Problems of the Russian Academy of Sciences, Federal Research Center 'Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences', Pushchino, Moscow Region, 142290, Russian Federation., Kovalev VB; Institute of Basic Biological Problems of the Russian Academy of Sciences, Federal Research Center 'Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences', Pushchino, Moscow Region, 142290, Russian Federation., Khristin AM; Institute of Basic Biological Problems of the Russian Academy of Sciences, Federal Research Center 'Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences', Pushchino, Moscow Region, 142290, Russian Federation., Khatypov RA; Institute of Basic Biological Problems of the Russian Academy of Sciences, Federal Research Center 'Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences', Pushchino, Moscow Region, 142290, Russian Federation., Shkuropatov AY; Institute of Basic Biological Problems of the Russian Academy of Sciences, Federal Research Center 'Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences', Pushchino, Moscow Region, 142290, Russian Federation. ashkur@mail.ru.
Jazyk: angličtina
Zdroj: Photosynthesis research [Photosynth Res] 2025 Feb; Vol. 163 (1), pp. 1-15. Date of Electronic Publication: 2024 Dec 19.
DOI: 10.1007/s11120-024-01122-5
Abstrakt: The initial electron transfer (ET) processes in reaction centers (RCs) of Chloroflexus (Cfl.) aurantiacus were studied at 295 K using femtosecond transient absorption (TA) difference spectroscopy. Particular attention was paid to the decay kinetics of the primary electron donor excited state (P * ) and the formation/decay of the absorption band of the monomeric bacteriochlorophyll a anion (B A - ) at ~ 1035 nm, which reflects the dynamics of the charge-separated state P + B A - . It was found that in Q A -depleted RCs containing native bacteriopheophytin a (BPheo) molecules at the H A and H B binding sites, the decay of P * to form the P + H A - state contains a fast (4 ps; relative amplitude 70%) and a slow (13 ps; relative amplitude 30%) kinetic components. The B A - absorption band at ~ 1035 nm was detected only for the fast component. Based on global analysis of the TA data, the results are discussed in terms of the presence of two P * populations: in one, P * decays in 4 ps via a dominant two-step activationless P * → P + B A - → P + H A - ET with a contribution of 70% to the overall primary charge separation process, and in the other, P * decays in 13 ps via a one-step superexchange P * → P + H A - ET (contribution of 30%). Similar femtosecond TA measurements on Q A -depleted-Pheo A -modified RCs, in which the charge separation energetics was changed by replacing BPheo H A with plant pheophytin a, suggest the presence of a P * population where P + H A - formation can occur via a thermally activated two-step ET process.
Competing Interests: Declarations. Competing interests: The authors declare no competing interests.
(© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)
Databáze: MEDLINE
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