Oxidation‐reduction potential dependence of reaction centre triplet formation in the isolated D1/D2/cytochrome b‐559 photosystem II complex

FEBS Letters

Evans, M.C.W.²  Barber, J.¹  Telfer, A.¹ 

[1] AFRC Photosynthesis Research Group, Department of Pure & Applied Biology, Imperial College, London SW7 2BB, England;Department of Biology, Darwin Building, University College, Gower Street, London WC1 E6BT, England

关键词: EPR;    Photosynthesis;    Primary charge separation;    Reaction center;    Triplet formation;    Photosystem II;    Electron transport;    (Pea);    Chl;    chlorophyll;    Cyt;    cytochrome;    D1;    psbA gene product;    D2;    psbD gene product;    P680;    primary electron donor of PS II;    Pheo;    pheophytin;    PS;    photosystem;    QA;    primary quinone acceptor of PS II;    QB;    secondary quinone acceptor of PS II;    Tricine;    N-[2-hydroxy-1;    1-bis(hydroxymethyl)-ethyl]glycine;   

DOI  :  10.1016/0014-5793(88)80418-6

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Formation of a spin-polarized triplet on illumination at low temperature is thought to be characteristic of charge separation in photosynthetic reaction centres. The formation of a spin-polarized triplet was confirmed in the D1/D2/cytochrome b-559 photosystem II reaction centre preparation. The oxidation-reduction potential range in which triplet formation occurs was determined. Triplet formation was observed at potentials between 400 and −530 mV. Loss of triplet formation, at more negative potentials, is suggested to reflect chemical reduction of the pheophytin acceptor. At potentials more oxidised than 400 mV, illumination results in formation of a radical at g = 2.0025 with a 0.75 mT linewidth. We propose that this is the result of oxidation of P680 coupled to reduction of an electron acceptor, possibly non-haem iron. The results confirm that none of the other electron acceptors normally found in photosystem II are functional in this preparation.

【 授权许可】

Unknown