| Budget Amount *help |
¥4,940,000 (Direct Cost: ¥3,800,000、Indirect Cost: ¥1,140,000)
Fiscal Year 2019: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
Fiscal Year 2018: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000)
Fiscal Year 2017: ¥2,730,000 (Direct Cost: ¥2,100,000、Indirect Cost: ¥630,000)
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| Outline of Final Research Achievements |
Photosystem II (PSII) is a multi-subunit pigment-protein complex embedded in thylakoid membranes in plants, algae, and cyanobacteria. PSII serves as light-driven water-oxidation reactions. In this study, we examined mechanisms of the water-oxidation reactions, especially proton release and charge separation, by means of infrared spectroscopy using PSII isolated from site-directed mutants.
The mutations were introduced into D1 and D2 subunits in PSII, which have important amino acid residues for the water-oxidation reactions as suggested by the X-ray crystal structure of PSII. The Fourier transformed infrared and time-resolved infrared analyses clearly showed that at least five amino acid residues, D1-Val157, D1-Ser169, D1-Asp170, D1-Asn298, and D2-Val156, contribute to the reactions, that is, D1-Val157 and D2-Val156 are involved in charge-separation reaction, and the remaining D1-Ser169, D1-Asp170, and D1-Asn298 function in water-oxidation reaction.
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