Electron transfer in pheophytin a‐modified reaction centers from Rhodobacter sphaeroides (R‐26)

FEBS Letters

Shkuropatov, A.Ya.¹  Shuvalov, V.A.¹ 

[1]Institute of Soil Sciences and Photosynthesis, Russian Academy of Sciences, Pushchino, Moscow region 142292, Russian Federation

关键词: Reaction center;    Primary electron donor and acceptor;    Electron transfer;    Bacteriopheophytin;    Pheophytin;    Rhodobacter sphaeroides;    BChl;    BPhe;    Chl and Phe;    bacteriochlorophyll a;    bacteriopheophytin a;    chlorophyll a and pheophytin a;    respectively;    BL and BM;    bacteriochlorophyll monomers located in L and M protein subunits;    respectively;    HL and HM;    bacteriopheophytins in L and M subunits;    respectively;    P;    primary electron donor;    bacteriochlorophyll dimer;    Qa and Qb;    primary and secondary quinons;    respectively;    Qy and Qx;    first and second electronic transitions in Chl-like molecules;    respectively;    RCs;    reaction centers;   

DOI  :  10.1016/0014-5793(93)81561-D

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The major part (> 90%) of bacteriopheophytin a in reaction centers (RCs) of Rhodobacter sphaeroides was substituted by plant pheophytin a. In modified RCs the photochemical formation of P⁺Q_a ⁻ occurs with with a quantum efficiency of 79%. The intermediary state P⁺I⁻ displayed a recombination time constant of 1.5 ns, and the electron transfer from I⁻ to Q_a was characterized by a time constant of 540 ps. On the basis of spectral properties of P⁺I⁻ for native and modified RCs, it was suggested that bacteriopheophytin, as well as bacteriochlorophyll monomers located in L protein branch, have a transition at 545 nm with approx. equal extinction coefficients. Accordingly, the state P⁺I⁻ in modified RCs is proposed to consist of a thermodynamic mixture of P⁺BL⁻ (∼ 80%) and P⁺Phe⁻ (∼ 20%).

【 授权许可】

Unknown