Comparison of calculated and experimentally resolved rate constants for excitation energy transfer in C-phycocyanin. 1. Monomers

Rate constants for excitation energy transfer in light-harvesting protein, C-phycocyanin (PC), in the monomeric aggregation state, isolated from the cyanobacterium cynechococcus sp. PCC 7002, are calculated, using Foerster theory and compared with the results of time-resolved fluorescence measurements. The assignments of the energy-transfer rate constants in PC monomers are confirmed here by time-resolved fluorescence anisotropy measurements of the PC monomers isolated from both the wild-type and a mutant strain (cpcB/C155S) whose PC is missing the β₁₅₅ chromophore. It is concluded that the Foerster mogel of resonant energy transfer in the weak coupling limit successfully describes the dominant energy-transfer processes in this protein in the monomeric state.