Oxygen evolving center from Photosystem

Antenna photosynthetic pigment complex that absorbs energy and transfers it to a reaction center Photosystem I reaction center from oxygen-evolving photosynthetic organisms that oxidizes plastocyanin and reduces NADP+... 

The core of Photosystem I consists of two large subunits, which each bind many chlorophyll and carotenoid molecules. It is thus impossible to prepare, by mild biochemical treatments alone, a PS I subparticle which only binds a small number of carotenoid and chlorophyll molecules. After pigment extraction with cold ether, it is however possible to obtain a PS I preparation that only retains 6 chlorophyll a and a reduced number of carotenoid molecules. Resonance Raman studies performed on such samples led to the conclusion that the carotenoid still bound to PS I were in an all-trans conformation (P. Moenne-Loccoz and B. Robert, unpubhshed data). It thus seems that /3-carotene is always all-trans in reaction centers from oxygen-evolving organisms. 

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