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- Title
Primary radical ion pairs in photosystem II core complexes.
- Authors
Nadtochenko, V.; Shelaev, I.; Mamedov, M.; Shkuropatov, A.; Semenov, A.; Shuvalov, V.
- Abstract
Ultrafast absorption spectroscopy with 20-fs resolution was applied to study primary charge separation in spinach photosystem II (PSII) reaction center (RC) and PSII core complex (RC complex with integral antenna) upon excitation at maximum wavelength 700-710 nm at 278 K. It was found that the initial charge separation between P680* and Chl (Chl-670) takes place with a time constant of ∼1 ps with the formation of the primary charge-separated state P680* with an admixture of: P680 (P680Chl), where δ ∼ 0.5. The subsequent electron transfer from P680Chl to pheophytin (Pheo) occurs within 13 ps and is accompanied by a relaxation of the absorption band at 670 nm (Chl) and bleaching of the Pheo bands at 420, 545, and 680 nm with development of the Pheoband at 460 nm. Further electron transfer to Q occurs within 250 ps in accordance with earlier data. The spectra of P680 and Pheo formation include a bleaching band at 670 nm; this indicates that Chl-670 is an intermediate between P680 and Pheo. Stimulated emission kinetics at 685 nm demonstrate the existence of two decaying components with time constants of ∼1 and ∼13 ps due to the formation of P680Chl and P680Pheo, respectively.
- Subjects
RADICAL ions; PHOTOSYSTEMS; ENERGY levels (Quantum mechanics); WAVELENGTHS; BLEACHING (Chemistry); STIMULATED emission; CHARGE exchange
- Publication
Biochemistry (00062979), 2014, Vol 79, Issue 3, p197
- ISSN
0006-2979
- Publication type
Article
- DOI
10.1134/S0006297914030043