Ultrafast Hydrogen-Bonding Dynamics in the Electronic Excited State of Photoactive Yellow Protein Revealed by Femtosecond Stimulated Raman Spectroscopy

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• 作者：Ryosuke Nakamura ; Norio Hamada ; Kenta Abe ; Masayuki Yoshizawa
• 刊名：The Journal of Physical Chemistry B
• 出版年：2012
• 出版时间：December 27, 2012
• 年：2012
• 卷：116
• 期：51
• 页码：14768-14775
• 全文大小：386K
• 年卷期：v.116,no.51(December 27, 2012)
• ISSN：1520-5207

文摘

The ultrafast structural dynamics in the electronic excited state of photoactive yellow protein (PYP) is studied by femtosecond stimulated Raman spectroscopy. Stimulated Raman spectra in the electronic excited state, S₁, can be obtained by using a Raman pump pulse in resonance with the S₁鈥揝₀ transition. This is confirmed by comparing the experimental results with numerical calculations based on the density matrix treatment. We also investigate the hydrogen-bonding network surrounding the wild-type (WT)-PYP chromophore in the ground and excited states by comparing its stimulated Raman spectra with those of the E46Q-PYP mutant. We focus on the relative intensity of the Raman band at 1555 cm^鈥?, which includes both vinyl bond C鈺怌 stretching and ring vibrations and is sensitive to the hydrogen-bonding network around the phenolic oxygen of the chromophore. The relative intensity for the WT-PYP decreases after actinic excitation within the 150 fs time resolution and reaches a similar intensity to that for E46Q-PYP. These observations indicate that the WT-PYP hydrogen-bonding network is immediately rearranged in the electronic excited state to form a structure similar to that of E46Q-PYP.