On the role of tryptophan as a superexchange mediator for quinone reduction in photosynthetic reaction centers

FEBS Letters

Plato, M.²  Michel-Beyerle, M.E.³  Jortner, J.¹  Bixon, M.¹ 

[1] School of Chemistry, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel-Aviv University, 69978 Tel-Aviv, Israel;Institut für Molekülphysik, Freie Universität Berlin, Arnimallee 14, D-1000 Berlin 33, Germany;Institut für Physikalische und Theoretische Chemie, Technische Universität München, Lichtenbergstr. 4, 8046 Garching, FRG

关键词: Reaction center;    Quinone reduction;    Electronic superexchange coupling;    Tryptophan;    RC;    reaction center;    P;    bacteriochlorophyll dimer;    QA;    quinone;    W;    tryptophan;   

DOI  :  10.1016/0014-5793(89)80018-3

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The role of tryptophan (W) in the quinone reduction in the reaction centers of R. viridis and Rb. sphaeroides is studied by a quantum chemical calculation of the electronic coupling matrix elements within the bacteriopheophytin-W-quinone subsystem, which is based on the X-ray structural data. The results favor the superexchange mechanism via W over the direct coupling. Uncertainties in the available X-ray coordinates and structural relaxation accompanying the formation of the P⁺H⁻ state result in large changes in the relative contributions of the electronic couplings due to electron and hole superexchange. Aromatic amino acid residues may serve as essential functional components in electron transfer.

【 授权许可】

Unknown