Energy Transfer in the Accessory Pigments R‐phycoerythrin and C‐phycocyanin

The photosynthetic accessory pigments R‐phycoerythrin and C‐phycocyanin were extracted from a red sea‐weed and a filamentous blue‐green alga. Investigation of quenching of phycoerythrin fluorescence by phycocyanin at room and liquid nitrogen temperatures yielded rates for the SternVolmer quenching constants ( K q From these values, rate constants k (D–A) were calculated for the transfer of energy from phycoerythrin to phycocyanin. The transfer rate constants obtained were such that a collisional transfer mechanism was ruled out, and were of similar order of magnitude as the rate constants for transfer of electronic energy in mixed organic crystals.