| Budget Amount *help |
¥3,900,000 (Direct Cost: ¥3,900,000)
Fiscal Year 2005: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 2004: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 2003: ¥2,300,000 (Direct Cost: ¥2,300,000)
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| Research Abstract |
1.Chlorophylls, such as Chl b, Chl a epimer and Phe a, all which do not act as intrinsic antenna in the PSI RC complex, were added with phosphatidylglycerol to the antenna-depleted PSI complex that had a Chl a/P700 ratio of 12. We found that the Chl a-binding site allows to receive Chl b with the same affinity as Chl a, but Chl a epimer with the affinity half of Chl a. The bound Chl b and Chl a epimer act as efficient antenna as Chl a. Phe a binds the antenna-depleted PSI complex, but without any efficient transfer of light energy to P700. We conclude that Chl a-binding site is tolerable to Chl with a side-chain different from Chl a, showing lower affinity with a large structural difference, and that Mg is essential to bind the site.
2.Chlorella, when grown in the dark with an extremely high concentration of Zn, formed Zn-Chl a in amount of about 30% of Chl a. We found that the Zn-Chl a binds to PSI and PSII RC complexes and acts as efficient antenna as Mg-Chl a.
3.PSI complex isolated from phylloquinone-depleted mutant of Arabidopsis, had no P700 but emitted the far red fluorescence at 77K which is characteristic to PSI antenna. We suggest that it had a PSI complex with antenna Chl a but without PSI electron carriers such as P700 and A_0.
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