Photochemical behavior of xanthophylls in the recombinant photosystem II antenna complex, CP26

The steady state absorption and fluorescence spectroscopic properties of th e xanthophylls, violaxanthin, zeaxanthin, and lutein, and the efficiencies of singlet energy transfer from the individual xanthophylls to chlorophyll have been investigated in recombinant CP26 protein overexpressed in Escheri chia coli and then refolded in vitro with purified pigments. Also, the effe ct of the different xanthophylls on the extents of static and dynamic quenc hing of chlorophyll fluorescence has been investigated. Absorption, fluores cence, and fluorescence excitation demonstrate that the efficiency of light harvesting from the xanthophylls to chlorophyll a is relatively high and i nsensitive to the particular xanthophyll that is present. A small effect of the different xanthophylls is observed on the extent of quenching of Chi f luorescence. The data provide the precise wavelengths of the absorption and fluorescence features of the bound pigments in the highly congested spectr al profiles from these light-harvesting complexes. This information is impo rtant in assessing the mechanisms by which higher plants dissipate excess e nergy in light-harvesting proteins.