Biological Advantage of the Arrangements of C-Phycocyanin Chromophores in Phycobilisome from the Electronic Energy Transfer Viewpoint

In the present study, we report the electronic energy transfer (EET) rate and the EET dynamics in the hexamer of C-phycocyanin (C-PC). The EET rate for the Forster theory was calculated by a quantum chemical method and a master equa-tion was used to describe the dynamics. Our calculation results suggest that the natural arrangements of phycocyanobilin (PCB) chromophores a84, ll84, and ll155 in C-PC are coopera-tively well-adjusted to achieve the shortest EET time -length. It is the appropriate regular periodicity of the intermolecular distances and intermolecular angles of the ground and the first excited transition dipole moments of PCBs a84, ll84, and ll155, i.e., the three -fold symmetry and stacking order of their layers found in terrestrial plants and algae, that are some of the most important requisites in achieving such a highly efficient EET in PBS.