Protein Vibration Effects on Primary Electron Transfer Dynamics in Rhodobacter sphaeroides Photosynthetic Reaction Center

Primary electron
transfer (ET) in the chromophore subsystem in
a bacterial reaction center (RC) is a unique process, and is coupled
with the protein motion, which, like the ET, is caused by photoexcitation
of these chromophores. ET is also coupled with dissipative processes,
which are caused by interaction between chromophores and vibrations
of its surrounding protein. We propose a new dynamics calculation
method that accounts for both these effects of protein vibrations.
Within this method, the photoinduced protein motion causes an addition
of coherent component to the ET rate. We performed dynamics calculation
using this method and parameters, which were determined from the ab
initio wave functions of the chromophore subsystem and protein normal
vibrational modes. We showed that it is this protein motion that causes
oscillations in the time-dependencies of stimulated emission intensities
and of absorption at 1020 nm. Moreover, the latter oscillations are
related to the coherent component of the ET rate.