A new approach to the systematics on the energy transfer mechanism of energy transfer in photosynthesis based on the intermediary interaction

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Energy transfer processes and mechanism in the photo synthetic antenna systems were investigated based on the intermediary interaction between pigments, even though a very weak interaction has been assumed so far. We have analyzed antenna system from photosynthetic bacteria to higher plants, and obtained following results.(1) The normal mode analysis was performed on phycocyanin, one of phycobiliproteins, to investigate the interaction between pigments and peptide moieties. We found a specific interaction between nitrogen atoms of chromophores and the aspartic acid residue of peptide that determined the electronic state of chromophores. Compared with this interaction, interaction energy between pigments was lower, thus an intermediary interaction was not the case.(2) A cyanobacterium Acaryochloris marina was investigated to know the molecular architecture of the antenna system of Chlorophyll (Chl) d-containing algae. In photosystem II of this alga, an up-hill energy transfer is requisite for survival. This unique transfer system is sometime hindered by thermal energy in the case of a weak interaction, and is modified when in an intermediary interaction.(3) A typical example of the strong interaction is a pigment array in chlorosomes of a green photosynthetic bacterium Chlorofexus aurantiacus. Almost all pigments are included in the major constituents with a strong interaction, however minor components necessary for the vectorial energy flow were not included in the above category.(4) The PI has written two chapters in the textbook on the energy transfer processes and mechanisms based not on the weak interaction but on the intermediary interaction between pigments.