title: Ultrafast hydrogen-bonding dynamics in the electronic excited state of photoactive yellow protein revealed by femtosecond stimulated Raman spectroscopy.
abstract: 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, S(1), can be obtained by using a Raman pump pulse in resonance with the S(1)-S(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(-1), which includes both vinyl bond C═C 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.
authors.affiliation: Science and Technology Entrepreneurship Laboratory, Osaka University, Suita, Osaka, Japan. r.nakamura@uic.osaka-u.ac.jp
authors.forename: Ryosuke
authors.initials: R
authors.lastname: Nakamura
authors.forename: Norio
authors.initials: N
authors.lastname: Hamada
authors.forename: Kenta
authors.initials: K
authors.lastname: Abe
authors.forename: Masayuki
authors.initials: M
authors.lastname: Yoshizawa
mesh_terms: D019943:Amino Acid Substitution; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D020587:Ectothiorhodospira / Q000378:metabolism; D004583:Electrons; D006860:Hydrogen Bonding; D020283:Photoreceptors, Microbial / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D013059:Spectrum Analysis, Raman
chemical_list: D001426:Bacterial Proteins; D020283:Photoreceptors, Microbial; C050162:photoactive yellow protein, Bacteria