Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
9575333 | Chemical Physics | 2005 | 12 Pages |
Abstract
A new model of the primary events of the bacteriorhodopsin (BR) photocycle is derived from the analysis of vibrational spectroscopic data obtained from native BR (BR-570) and three artificial BR pigments containing structurally modified retinals with carbon rings bridging specific C-C and CC bonds (BR6.11, BR6.9, and BR5.12). Vibrational spectra from the ground-states and from picosecond intermediates appearing in the respective photo-reactions are measured by coherent anti-Stokes Raman spectroscopy (CARS). Special attention is given to an analysis of the time-dependent bandwidth changes in vibrational bands assigned to the CC stretching and hydrogen-out-of-plane (HOOP) modes. The bandwidth analysis reveals an intramolecular, vibrational dephasing mechanism in the lowest-energy electronic excited state, involving a coupling between out-of-plane motion along the retinal backbone and CC stretching modes. The mode-selective coupling plays a significant role as a precursor to the all-trans â 13-cis isomerization in BR and accounts for primary events in the BR photocycle not previously demonstrated.
Related Topics
Physical Sciences and Engineering
Chemistry
Physical and Theoretical Chemistry
Authors
Andrew C. Terentis, Laszlo Ujj, Halina Abramczyk, George H. Atkinson,