The immersion depths (r) of the main functional components of the reaction centres of the Photosystem 2 in the thylakoid membranes were determined by ESR at 77K. It was shown that P680(+), Pheo(-) (pheophytin), and Z(+) (secondary electron donor) the r value was 2-4, 4-7 and 14-20 A, respectively. On the basis of these and reference data a model of location of the Photosystem 2 reaction centre components in the photosynthetic membrane was suggested.
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