Energy transfer in photosystem II is slow

Abstract

For a long time the charge separation in photosystem II (PSII) has been described with trap-limited models with varying levels of sophistication [1, 2] and excitation energy transfer rates are assumed to be much faster than the rate of charge separation. We recently obtained two independent lines of evidence that this assumption is not correct. Singlet-singlet annihilation studies on LHCII show that spatial equilibration in LHCII is relatively slow [3]. Moreover, modeling of the transfer events in LHCII, which was based on structural, spectroscopic and kinetic information that was obtained in the past, leads to the same conclusion. Consequences of the slow transfer will be discussed. [1] Schatz GH, Brock H and Holzwarth AR (1988) Biophysical J 66: 1597. [2] Barter LMC, Bianchetti M, Jeans C, Schilstra MJ, Hankamer B, Diner BA, Barber J, Durrant JR and Klug DR (2001) Biochemistry 40: 4026. [3] Barzda V, Gulbinas V, Kananavicius R, van Amerongen H, van Grondelle R, Valkunas L (2001) Biophys. J. 80, 2409. [4] van Amerongen H, van Grondelle R (2001) J. Phys. Chem. B 105: 604.