抄録
To understand the mechanism of photosynthetic oxygen evolution, it is indispensable to know the chemical natures of the interactions between the Mn cluster and substrate water molecules, and how respective interaction changes during the successive proceeding of the 4-step (S0-S1, S1-S2, S2-S3 and S3-S0 with O2 evolution) oxidation of water molecules to evolve oxygen. Low frequency (1000 - 350 cm-1) region vibrations can include the modes for direct interaction between metal and its ligands, and only available method to access this subject. Therefore, we applied this method to monitor the changes in interactions between the Mn cluster and its ligands including substrate water molecule during the S-state cycling. S-state dependent changes of low-frequency FTIR difference spectra, effects of universal 15N/13C labeling and 18O-water on the spectra will be presented. Furthermore, impact of modification of C-terminal Ala of the D1 protein on the spectra will be shown also.
