Study on energy transfer between carotenoid and chlorophyll a in cytochrome b 6 f complex from Bryopsis corticulans

The excitation energy transfer between carotenoid and chlorophyll (Chl) in the cytochrome b 6 f complex from Bryopsis corticulans ( B. corticulans ), in which the carotenoid is 9- cis- α-carotene, was investigated by means of fluorescence excitation and sub-microsecond time-resolved absorption spectroscopies. The presence of efficient singlet excitation transfer from α-carotene to Chl a was found with an overall efficiency as high as ∼ ∼24%, meanwhile the Chl a -to-α-carotene triplet excitation transfer was also evidenced. Circular dichroism spectroscopy showed that α-carotene molecule existed in an asymmetric environment and Chl a molecule had a certain orientation in this complex.