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Dynamics of the excited state of the primary electron donor in reaction centers of Rhodopseudomonas viridis as revealed by hole burning at 1.7K
Author(s) -
Shkuropatov A.Ya.,
Ganago A.O.,
Shuvalov V.A.
Publication year - 1991
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(91)80035-2
Subject(s) - excited state , photosynthetic reaction centre , chemistry , phonon , relaxation (psychology) , absorbance , spectral line , electron transfer , molecular physics , atomic physics , crystallography , analytical chemistry (journal) , physics , photochemistry , condensed matter physics , psychology , social psychology , chromatography , astronomy
The spectra of absorbance changes (Δ A ) due to the formation of P + Q − (P, primary electron donor. Q, primary quinone acceptor) at 1.7K in Rhodopseudomonas viridis reaction centers (RCs) excited at 1014nm has been shown to include, besides a progression of broad (170 190 cm −1 ) Gaussian vibronic bands separated by 150 cm −1 , a ‘narrow’ structure near 1014 nm which can be simulated by a Lorentian zero‐phonon hole (ZPH) and Lorentian one‐mode (26.8 cm −1 ) phonon wings. The widths of ZPH of ≈ 17 cm −1 for Δ A reflecting the formation of P + Q − decaying in the ms time domain and of 6.8 ± 0.4 cm −1 for P + Q − decaying in the min time domain at 1.7K, seems to correspond to different conformations of RCs with a relaxation time of P ∗ of ≈0.6 ps (in agreement with measurements in this time domain) and 1.6 ± 0.1 ps. respectively. The comparison of the spectra of Δ A in the region of the B 1 , band for slow (min) and fast (ms) decaying components suggests a different mutual arrangement of P and B L for different conformations of RCs. It is assumed that the broad and narrow structures of the P band reflect the transitions to two configurations with different P‐protein interactions. ‘Narrow’ structure of Δ A spectrum with essentially the same phonon wings and ZPH (width of 3.8 ± 0.4 cm −1 ) was observed within the P band when H I was photoreduced at 1.7K.