Vibrational Motions Associated with Primary Processes in Bacteriorhodopsin Studied by Coherent Infrared Emission Spectroscopy - École polytechnique Accéder directement au contenu
Article Dans Une Revue Biophysical Journal Année : 2011

Vibrational Motions Associated with Primary Processes in Bacteriorhodopsin Studied by Coherent Infrared Emission Spectroscopy

Résumé

The primary energetic processes driving the functional proton pump of bacteriorhodopsin take place in the form of complex molecular dynamic events after excitation of the retinal chromophore into the Franck-Condon state. These early events include a strong electronic polarization, skeletal stretching, and all-trans-to-13-cis isomerization upon formation of the J intermediate. The effectiveness of the photoreaction is ensured by a conical intersection between the electronic excited and ground states, providing highly nonadiabatic coupling to nuclear motions. Here, we study real-time vibrational coherences associated with these motions by analyzing light-induced infrared emission from oriented purple membranes in the 750-1400 cm(-1) region. The experimental technique applied is based on second-order femtosecond difference frequency generation on macroscopically ordered samples that also yield information on phase and direction of the underlying motions. Concerted use of several analysis methods resulted in the isolation and characterization of seven different vibrational modes assigned as C-C stretches, out-of-plane methyl rocks, and hydrogen out-of-plane wags, whereas no in-plane H rock was found. Based on their lifetimes and several other criteria, we deduce that the majority of the observed modes take place on the potential energy surface of the excited electronic state. In particular, the direction sensitivity provides experimental evidence for large intermediate distortions of the retinal plane during the excited-state isomerization process.
Fichier principal
Vignette du fichier
VMAS0006349511001998.pdf (435.22 Ko) Télécharger le fichier
Origine : Fichiers éditeurs autorisés sur une archive ouverte
Loading...

Dates et versions

hal-00804602 , version 1 (17-04-2014)

Identifiants

Citer

Geza I. Groma, Anne Colonna, Jean-Louis Martin, Marten H. Vos. Vibrational Motions Associated with Primary Processes in Bacteriorhodopsin Studied by Coherent Infrared Emission Spectroscopy. Biophysical Journal, 2011, 100 (6), pp.1578. ⟨10.1016/j.bpj.2011.02.011⟩. ⟨hal-00804602⟩
201 Consultations
187 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More