Rapid electron transfer reactions associated with oxygen evolution in photosystem II preparations from spinach and Phormidium laminosum

FEBS Letters

Evans, M.C.W.¹  Ford, R.C.¹  Schlodder, E.²  Brettel, K.²  Atkinson, Y.E.¹  Witt, H.T.² 

[1] Department of Botany and Microbiology, University College London, Gower Street, London WC1E6BT, England;Max-Volmer Institut fur Biophysikalische und Physikalische Chemie, Technische Universität Berlin, Strosse des 17 Juni 135, 1000 Berlin 12, FRG

关键词: Electron transfer;    Oxygen evolution;    Photosystem II;    Spinach;    Phormidium laminosum;    DCMU;    3-(3;    4-dichlorophenyl)-1;    1-dimethylurea;    DCIP;    2;    6-dichlorophenol indophenol;    DPC;    1;    5-diphenylcarbazide;    Mes;    2-(N-morpholino)-ethanesulfonic acid;    Tricine;    N-tris(hydroxymethyl)-methylglycine;   

DOI  :  10.1016/0014-5793(85)81119-4

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

We have measured the nanosecond kinetics of Chl-a⁺ _II reduction in oxygen-evolving detergent preparations of PS II from the cyanobacterium Phormidium laminosum and from higher plants (spinach) at 824 and 680 nm. Compared to earlier studies at 680 nm with higher plant material, we obtained an improved signal: noise ratio for measurements on a ns to ms time scale. The kinetics of Chl-a⁺ _II reduction in the ns range are consistent in the two preparations and are comparable to other studies of higher plant and cyanobacterial material. The ns kinetics are tightly connected to the ability for O₂ evolution. Analysis of the μs kinetics indicates three phases: (a) the slow phase (t _½ ~ 150 μs in spinach and ~ 500 μs in Phormidium) reflects the back reaction between Chl-a⁺ _II and Q⁻; (b) the phase with t _½ 5–10 μs is probably due to a donor which is not connected to an intact water oxidation system; (c) the intermediate μs component (t _½ 30–40 μs) may be related to water oxidation.

【 授权许可】

Unknown