Femtosecond infrared spectroscopy of bacteriorhodopsin chromophore isomerization.
The vibrational dynamics of the retinal chromophore all-trans-to-13-cis photoisomerization in bacteriorhodopsin has been studied with mid-infrared absorption spectroscopy at high time resolution (about 200 femtoseconds). After photoexcitation of light-adapted bacteriorhodopsin, the transient infrared absorption was probed in a broad spectral region, including vibrations with dominant C-C, C=C, and C=NH stretching mode amplitude. All photoproduct modes, especially those around 1190 reciprocal-centimeters that are indicative for a 13-cis configuration of the chromophore, rise with a time constant of approximately 0.5 picosecond. The results presented give direct vibrational-spectroscopic evidence for the isomerization taking place within 0.5 picosecond, as has been suggested by previous optical femtosecond time-resolved experiments but questioned recently by picosecond time-resolved vibrational spectroscopy experiments.
Herbst
Johannes
J
Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany.
Heyne
Karsten
K
Diller
Rolf
R
D001436:Bacteriorhodopsins / Q000737:chemistry* / Q000378:metabolism*; D001665:Binding Sites; D007536:Isomerism; D007700:Kinetics; D008027:Light; D010777:Photochemistry; D012172:Retinaldehyde / Q000737:chemistry* / Q000378:metabolism*; D013055:Spectrophotometry, Infrared / Q000379:methods*; D017550:Spectroscopy, Fourier Transform Infrared; D013997:Time Factors; D014732:Vibration
D001436:Bacteriorhodopsins; D012172:Retinaldehyde