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Impressum
(c) 2002 BMO

"First Steps of Retinal Photoisomerization in Proteorhodopsin"
Martin O. Lenz, Robert Huber, Bernhard Schmidt, Peter Gilch, Rolf Kalmbach, Martin Engelhard and Josef Wachtveitl
Biophys J. 91 (2006) 255


Abstract:
The early steps (<1 ns) in the photocycle of the detergent solubilized proton pump proteorhodopsin are analyzed by ultrafast spectroscopic techniques. A comparison to the first primary events in reconstituted proteorhodopsin as well as to the well known archaeal proton pump bacteriorhodopsin is given. A dynamic Stokes shift observed in fs-time-resolved fluorescence experiments allows a direct observation of early motions on the excited state potential energy surface. The initial dynamics is dominated by sequentially emerging stretching (<150 fs) and torsional (~300 fs) modes of the retinal. The different protonation states of the primary proton acceptor Asp-97 drastically affect the reaction rate and the overall quantum efficiencies of the isomerization reactions, mainly evidenced for time scales above 1 ps. However, no major influence on the fast time scales (~150 fs) could be seen, indicating that the movement out of the Franck-Condon region is fairly robust to electrostatic changes in the retinal binding pocket. Based on fs-time-resolved absorption and fluorescence spectra, ground and exited state contributions can be disentangled and allow to construct a reaction model that consistently explains pH-dependent effects in solubilized and reconstituted proteorhodopsin.

BMO authors (in alphabetic order):
Peter Gilch
Robert Huber
Bernhard Schmidt
Josef Wachtveitl

Assoziierte Projekte:
Spectroscopy of the functional dynamics of proteins


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Letzte Änderung: 2016-09-14 13:34