Structural Elucidation of Photosynthetic antenna and Its Application for Light Harvesting System.

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We have succeeded in preparing photosynthetic antennas from photosynthetic membranes of Chloroflexus aurantiacus and Chlorobium tepidum. The isolated antenna chlorosomes were studied by a solid state high resolution (cross polarization / magic angle spinning (CP/MAS)) ^<13>CNMR. We have clarified the cooridation states of the bacteriochlorophyll (BChl) c's, the interactions between BChl c's and the interactions of BChl c's with surrounding amino acid residues in native states and in situ. We have purified various BChl c and d derivatives by extraction with organic solvent and HPLC. The structures of the pigments were determined with one and two dimensional ^1H and ^<13>C NMR and FTIR. Excitation energy transfers in the antenna systems and also between the antennas and reaction centers were investigated with a pico-second time resolved fluorescence spectrometry. The results gave an evidence to elucidate the structures and mechanisms for the antenna systems to collect and utilize the light energy. The model antenna systems which resembled the native chlorosome antenna have been prepared for the first time from the purified BChl c and d derivatives with clarified structures. The organization of the synthesized model antenna were investigated with CP/MAS^<13>C NMR and FTIR. These investigations offered a guide line to construct a model antenna system and to utilize light energy efficiently.