Dresden 2011 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 34: New Technologies
BP 34.9: Vortrag
Freitag, 18. März 2011, 12:45–13:00, ZEU 260
Evolutionary algorithms used to study fluorescence decay curves of photosystem II core complexes from thermosynechococcus elongatus — •Joachim Börner1, Franz-Josef Schmitt1, Athina Zouni2, Hans Joachim Eichler1, and Gernot Renger2 — 1Institute of Optics and Atomic Physics, Berlin Institute of Technology — 2Max-Volmer-Laboratory of Biophysical Chemistry, Berlin Institute of Technology
The character of kinetic limitation of the exciton trapping in Photosystem II (PS II) is not yet clarified. It is a matter of discussion whether the excitation energy transfer (EET) from core antennas to the reaction center or the succeeding electron transfer (ET) is the rate limiting step of the overall process. In order to address this problem we investigated core complexes from Thermosynechococcus elongatus by using the technique of time correlated single photon counting with picosecond resolution. The obtained fluorescence decay curves were analyzed within the framework of a structure based model with a set of coupled differential equations. Self-designed evolutionary algorithms were used to achieve a satisfying fit of the experimental data by simulated decay curves. The algorithm allows the determination of transition rates of EET and ET processes in PS II and the stability and variance of these rates by random modifications of an initial set. Our results revealed that the EET from the core antennas to the reaction center is most likely limiting the overall exciton trapping with typical transfer time constants in the order of some tens of picoseconds whereas the charge separation (electron transfer) is accomplished within a few ps only.