Nanosecond electron transfer kinetics in photosystem I as obtained from transient EPR at room temperature

FEBS Letters

van der Est, Arthur J.²  Bock, Christian H.²  Brettel, Klaus¹  Stehlik, Dietmar² 

[1] Max-Volmer-Institut für Biophysikalische und Physikalische Chemie, Technische Universität Berlin, Straße des 17. Juni 135, D-1000 Berlin 12, Germany;Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, D-1000 Berlin 33, Germany

关键词: Photosystem I;    Electron spin polarization;    P700;    (Synechococcus);    A;    absorption;    Chl;    chlorophyll;    CIDEP;    chemically induced dynamic electron polarization;    CIDNP;    chemically induced dynamic nuclear polarization;    E;    emission;    ESP;    electron spin polarization;    FeS;    iron-sulfur center;    MV;    methylviologen;    PMS;    phenazine methosulfate;    PS I;    photosystem I;    T 1;    longitudinal spin relaxation time;    T 2;    transverse spin relaxation time;   

DOI  :  10.1016/0014-5793(89)81247-5

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Transient EPR spectra of photosystem I (PS I) in spinach chloroplasts and PS I particles prepared from Synechococcus are presented. Two consecutive spectra are observed after the laser pulse. The decay time of the first spectrum is equal to the rise time of the second spectrum. The two spectra represent sequential charge-separated states in the electron transfer chain and the time constant of the electron transfer step between them is found to be t _1/e = 260 ± 20 ns for the Synechococcus PS I particles as well as for the spinach chloroplasts. The first spectrum is assigned to the P⁺ ₇₀₀ A⁻ ₁ pair, where A⁻ ₁ is the second electron acceptor, probably a quinone-like molecule. The second spectrum covers the region of the P⁺ ₇₀₀ signal and may be part of the spectrum due to the coupled radical pair P⁺ ₇₀₀ (FeS), where (FeS)⁻ is the first iron-sulfur center along the electron transfer chain.

【 授权许可】

Unknown