Open AccessA multimer model for P680, the primary electron donor of photosystem II.
Author(s) -
James R. Durrant,
David R. Klug,
Stefan L.S. Kwa,
Rienk van Grondelle,
George Porter,
Jan Dekker
Publication year - 1995
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.92.11.4798
Subject(s) - p680 , photosynthetic reaction centre , pheophytin , photosystem ii , purple bacteria , photochemistry , chemistry , electron donor , electron acceptor , dimer , exciton , rhodobacter sphaeroides , photosystem i , electron transfer , photosynthesis , physics , catalysis , biochemistry , organic chemistry , quantum mechanics
We consider a model of the photosystem II (PS II) reaction center in which its spectral properties result from weak (approximately 100 cm-1) excitonic interactions between the majority of reaction center chlorins. Such a model is consistent with a structure similar to that of the reaction center of purple bacteria but with a reduced coupling of the chlorophyll special pair. We find that this model is consistent with many experimental studies of PS II. The similarity in magnitude of the exciton coupling and energetic disorder in PS II results in the exciton states being structurally highly heterogeneous. This model suggests that P680, the primary electron donor of PS II, should not be considered a dimer but a multimer of several weakly coupled pigments, including the pheophytin electron acceptor. We thus conclude that even if the reaction center of PS II is structurally similar to that of purple bacteria, its spectroscopy and primary photochemistry may be very different.