Electron donation by the high‐potential haems in Rhodopseudomonas viridis reaction centres at low temperatures

FEBS Letters

Hubbard, J.A.M.¹  Evans, M.C.W.¹ 

[1] Department of Biology, University College London, Gower St., London WC1E 6BT, England

关键词: Photosynthetic reaction center;    Cytochrome c;    Iron-quinone;    (Rhodopseudomonas viridis);    QA and QB;    primary and secondary quinone electron acceptors;    cyt;    cytochrome;    LDAO;    lauryldiethylamine N-oxide;    P;    reaction centre chlorophyll;   

DOI  :  10.1016/0014-5793(89)81165-2

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

EPR signals due to c-type cytochromes in Rhodopseudomonas viridis reaction centres are reported. Haems with E _m = 380 mV (1), 310 mV (1) and about 0 mV (2) were identified. At redox potentials where the low-potential cytochromes are oxidised, but the high-potential cytochromes are reduced, photooxidation of the high-potential cytochromes is observed as Q_A is photoreduced by low-temperature (15 K) illumination. Cyt c-556→cyt c-559→reaction centre→Q_A However, the signal attributed to Q_A is only 30–40% of the intensity and is narrower than that observed when Q_A photoreduced with all the haems reduced. It is suggested that reduction of the low-potential haems causes conformational changes in the reaction centre, altering the iron-quinone interaction and the electron-transfer process in the cytochrome chain.

【 授权许可】

Unknown