Electron acceptors of photosystem 2 in the cyanobacterium Phormidium laminosum

FEBS Letters

Evans, M.C.W.¹  Atkinson, Y.E.¹ 

[1] Department of Botany and Microbiology, University College London, Gower Street, London WC1E 6BT, England

关键词: Phormidium laminosum;    Photosystem 2;    Electron acceptor;    Iron—quinone;    Pheophytin;    Triplet;    PS2;    photosystem 2;    DCMU;    3-(3';    4'-dichlorophenyl)-1;    1-dimethylurea;    EPR;    electron paramagnetic resonance;    LDAO;    lauryldimethylamine oxide;    HEPES;    N-2-hydroxymethylpiperazine-N'-2-ethanesulphonic acid;   

DOI  :  10.1016/0014-5793(83)80433-5

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Photosystem 2 preparations with very high rates of oxygen evolution from the thermophilic cyanobacterium Phormidium laminosum have been studied by EPR spectrometry. In the presence of DCMU the g = 1.82 signal of the iron—quinone electron acceptor (Q) can be observed. It is proposed that DCMU is necessary to disrupt a magnetic interaction, between the semiquinone forms of Q and the secondary acceptor B, which otherwise prevents detection of the Q⁻Fe signal. A doublet EPR signal arising from magnetic interaction between Q⁻Fe and the reduced intermediary electron acceptor pheophytin (I⁻), and a spin-polarized triplet signal assumed to arise from the back reaction between I⁻ and P680⁺ can also be seen. Preliminary redox titrations of Q reduction have been carried out, indicating E _m ⋍ 0 mV.

【 授权许可】

Unknown