Ultrafast carotenoid band shifts correlated with ChlZ excited states in the photosystem II reaction center: are the carotenoids involved in energy transfer?

We show a correlation between the electronic excitation of the peripheral chlorophylls (Chls(Z)) of the photosystem II reaction center and a shift of the S(2) absorption bands of β-carotene, and suggest that the carotenoids may enhance the excitation energy transfer rate from these chlorophylls to the central cofactors.