Energy transfer in photosystem II core complexes: comparison with bacterial systems

摘要

Spectrally-resolved pico- and nanosecond fluorescence kinetics of photosystem II reaction center (RC) preparations and RC together with CP47 proximal antenna have been studied at room temperature and at 77 K. The following conclusions have been made. (1) At room temperature the average trapping time proportional to the charge separation time and the number of cooperating pigments is observed. This time is equal to 13 $POM 3 ps in RCs and 25 $POM 10 ps in RC $PLU CP47 complexes. (2) All other decays at room temperature are of a recombination origin and reflect complex relaxation of the metastable radical pair state. (3) At low temperatures an energetically directed excitation transfer, qualitatively very similar to the one observed in the core antenna of some purple bacteria, is observed. This energy transfer is relatively slow with an apparent transfer time 10 - 20 ps at 77 K.