Computer simulation on kinetics of primary process in photosynthesis of algae (V)―Excitation energy transfer in phycoerythrocyanins

摘要

Excitation energy transfer in phycoerythrocyanins (PEC) was studied by use of computer simulation. The results observed from the simulation are as follows: (ⅰ) The α_(84) is a more efficient sensitizing chromophore than β_(155) and donates the excitation energy into β_(84) and β_(155) while it scarcely emits fluorescence itself, (ⅱ) Only the 1α_(84)→ 2β_(84) is the sub-picosecond process in a PEC trimer, therefore it is readily to obtain the time constant from fs-level time-resolved spectral measurement, (ⅲ) The β_(84) and β_(155) chromophores in PEC behave quite differently from those in C-PC because of the changes in α_(84). It is observed that 1β_(155)→6β_(155) is the dominant pathway linking two trimers and both of the chromophores possess much higher fluorescence fractions, and about 80% of the total fluorescence is emitted from the β_(84) chromophore. (ⅳ) A far less mean number of transfer times is observed through the fast-transfer pairs in PEC compared with that in C-PC because of slow transfer rate for the path from 2 β_(84) → 1α_(84). (ⅴ) Relatively, PEC could absorb and transfer excitation energy more efficiently than C-PC.