Determination of the distance between Yox⋅ Z and Q−⋅ A in photosystem II by pulsed EPR spectroscopy on light‐induced radical pairs

FEBS Letters

Bittl, Robert¹  Lubitz, Wolfgang¹  Zech, Stephan G.¹  Renger, Gernot¹  Kurreck, Jens¹ 

[1] Max-Volmer-Institut für Biophysikalische Chemie und Biochemie, Technische Universität Berlin, Straße des 17. Juni 135, 10623 Berlin, Germany

关键词: Radical pair;    Cofactor distance;    Photosystem II;    Pulsed electron paramagnetic resonance;    bRC;    bacterial reaction center;    CAPS;    3-[cyclohexylamino]-1-propane-sulfonic acid;    EPR;    electron paramagnetic resonance;    ESEEM;    electron spin echo envelope modulation;    ET;    electron transfer;    Mw;    microwave;    P680;    primary donor of PS II;    QA;    primary quinone electron acceptor in PS II and bRCs;    A1;    primary quinone electron acceptor in PS I;    RP;    radical pair;    SFT;    sine Fourier transform;    YZ;    redox active tyrosine residue of polypeptide D1;   

DOI  :  10.1016/S0014-5793(98)01628-7

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Out-of-phase electron spin echo envelope modulation (ESEEM) spectroscopy was used to determine the distances within two consecutive radical pair states initiated by a laser flash in photosystem II membrane fragments at pH 11. The distance between the spin density centers of the primary electron donor cation radical, P^+⋅ ₆₈₀, and the reduced plastoquinone acceptor, Q^−⋅ _A, has been found to be 27.7±0.7 Å in agreement with previous results. Near room temperature and at high pH, P^+⋅ ₆₈₀ is reduced by Y_Z, a redox active tyrosine residue, on a sub-microsecond timescale. As a consequence, the subsequent radical pair state, Y^ox⋅ _ZQ^−⋅ _A, could be investigated after almost complete reduction of P^+⋅ ₆₈₀ by Y_Z. The determined dipolar electronic spin-spin coupling within the radical pair Y^ox⋅ _ZQ^−⋅ _A corresponds to a distance of 34±1 Å between the two molecules.

【 授权许可】

Unknown