Understanding the energy transfer function of LHCII, the major light-harvesting complex of green plants

Since the crystal structure of the major light-harvesting complex IT (LHCII ) of green plants was obtained by Kuhlbrandt, Wang and Fujiyoshi (Nature 19 94, 367, 614-621), this chlorophyll-containing trimeric membrane protein ha s been the subject of intensive investigation. The complex contains between 36 and 42 chlorophyll molecules per trimer (Chl a and Chi b) and 10 to 12 xanthophyll molecules (lutein, neoxanthin and violaxanthin). The protein di splays a rich spectrum of interactions, both between pigments and between t he pigments and the protein, and these interactions have been studied with a multitude of different techniques. In this article we present an overview of the most important experimental results that have become available over the past decade and relate these to the structural knowledge. Emphasis wil l be put on the pigment identities, their spectroscopic features, and the i nteractions between the pigments, which determine both steady-state (polari zed) properties and singlet and triplet energy transfer dynamics. Remaining questions will be pinpointed and hopefully they can help direct research i n the near future.