| Project/Area Number |
16K05670
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Research Field |
Physical chemistry
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| Research Institution | Hokuriku University |
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Principal Investigator |
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| Project Period (FY) |
2016-04-01 – 2019-03-31
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| Project Status |
Completed (Fiscal Year 2018)
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| Budget Amount *help |
¥5,070,000 (Direct Cost: ¥3,900,000、Indirect Cost: ¥1,170,000)
Fiscal Year 2018: ¥650,000 (Direct Cost: ¥500,000、Indirect Cost: ¥150,000)
Fiscal Year 2017: ¥2,210,000 (Direct Cost: ¥1,700,000、Indirect Cost: ¥510,000)
Fiscal Year 2016: ¥2,210,000 (Direct Cost: ¥1,700,000、Indirect Cost: ¥510,000)
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| Keywords | 励起状態 / 物理化学 / 生物物理 / 量子化学 |
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| Outline of Final Research Achievements |
A vibronic exciton model combined with a transition-density-fragment interaction (TDFI) method is developed, and it is applied to the calculations of absorption and circular dichroism (CD) spectra of xanthorhodopsin. The TDFI calculation clearly shows that Coulomb interaction predominantly contributes to the electronic coupling energy between carotenoid and retinal, whereas exchange interaction results in a negligible contribution. Thus, the antenna function of carotenoid is found to result from the Forster type of excitation-energy transfer, not from the Dexter one. The absorption and CD calculations successfully reproduce the main features of the experimental spectra. Based on these results, we investigate the mechanism of biphasic CD spectrum observed in xanthorhodopsin. The results indicate that vibronic coupling between carotenoid and retinal plays a significant role in the shape of the CD spectrum.
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| Academic Significance and Societal Importance of the Research Achievements |
これまで励起エネルギー移動（EET）に関する多くの研究が行われてきたが、それらの大多数は双極子・双極子近似が適用可能な系のみを扱ったものである。これに対し、私はこれまでにTDFI法という電子カップリング計算法を考案し、EETの研究対象を広げることに成功してきた。
本研究ではEETの研究対象を更に広げられるよう、TDFI法に振電相互作用を取り込むことを試みた。これにより、これまであまり研究されてこなかった振電カップリングの計算を可能にした。また本手法を生体分子のザントロドプシンに適用することで、EETの分子機構を解明することにも成功した。
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