Dynamics of the excited state of the primary electron donor in reaction centers of Rhodopseudomonas viridis as revealed by hole burning at 1.7K

FEBS Letters

Shkuropatov, A.Ya.¹  Shuvalov, V.A.¹  Ganago, A.O.¹ 

[1] Institute of Soil Sciences and Photosynthesis, USSR Academy of Sciences, Pushchino, Moscow Region, 142 292, USSR

关键词: Reaction center;    Primary electron donor;    Hole burning;    ΔA;    light-minus-dark absorbancc changes;    bactcriochlorophyll located in L. protein subunit;    bactcriochlorophyll located in L. protein subunit;    HI and HM;    bacteriophenophylins located in L and M protein subunits;    respectively;    P;    primary electron donor;    bacteriochlorophyll dimer;    Q;    primary quinone acceptor QA;    S;    Pekar-Huang-Rhys factor equal to the ratio of integral intensity of 0–1 to that of 0–0 vibronic transition;    ZPH;    zero-phonon hole;   

DOI  :  10.1016/0014-5793(91)80035-2

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The spectra of absorbance changes (ΔA) 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 ΔA 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 ΔA in the region of the B₁, 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 ΔA 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.

【 授权许可】

Unknown