Personne
Selma Schenkl
Publications associées (9)
On the excitation wavelength dependence of the fluorescence of bacteriorhodopsin
Majed Chergui, Erwin Portuondo Campa, Goran Zgrablic, Stefan Haacke, Selma Schenkl
We present a systematic study of the time-integrated fluorescence of native bacteriorhodopsin, as a function of excitation wavelength across the visible absorption band. While the fluorescence max. is unaffected, the spectrum broadens on the high-energy si ...
2007Absorption spectroscopy of three-dimensional bacteriorhodopsin crystals at cryogenic temperatures: effects of altered hydration
Majed Chergui, Erwin Portuondo Campa, Selma Schenkl
A comparative study of absorption spectroscopy at 100 K has been performed on three-dimensional crystals of bacteriorhodopsin extd. from a lipidic cubic phase and on native purple membrane. A modified microspectrophotometer has been designed which yields a ...
2006Insights into excited-state and isomerization dynamics of bacteriorhodopsin from ultrafast transient UV absorption
Majed Chergui, Frank van Mourik, Selma Schenkl
A visible-pump/UV-probe transient absorption is used to characterize the ultrafast dynamics of bacteriorhodopsin with 80-fs time resoln. We identify three spectral components in the 265- to 310-nm region, related to the all-trans retinal, tryptophan (Trp)- ...
2006Probing the ultrafast charge translocation of photoexcited retinal in bacteriorhodopsin
Majed Chergui, Frank van Mourik, Selma Schenkl
The ultrafast evolution of the electric field within bacteriorhodopsin was measured by monitoring the absorption changes of a tryptophan residue after excitation of retinal. The Trp absorption decreases within the first 200 femtoseconds and then recovers o ...
2005Influence of the protein environment on spectroscopy and ultrafast dynamics of retinal in bacteriorhodopsin
The environment is important for the exact course of a chemical reaction. As an example of the strong influence of the environment on the reaction, this work studies the isomerization reaction of the chromophore retinal in the binding pocket of the protein ...
EPFL2004Compositional Heterogeneity Reflects Partial Dehydration in Three-dimensional Crystals of Bacteriorhodopsin
Majed Chergui, Erwin Portuondo Campa, Goran Zgrablic, Stefan Haacke, Selma Schenkl
Absorption, fluorescence and excitation spectra of three-dimensional bacteriorhodopsin crystals harvested from a lipidic cubic phase are presented. The combination of the spectroscopic expts. performed at room temp., controlled pH and full external hydrati ...
2003Femtosecond and picosecond fluorescence of native bacteriorhodopsin and a nonisomerizing analog
The spectrally and temporally resolved fluorescence properties of native bacteriorhodopsin (bR) and bR reconstituted with a nonisomerizing analog of the retinal Schiff base (bR5.12) are examd. The first attempt to exptl. monitor the excited state relaxatio ...
2002Ultrafast energy relaxation in bacteriorhodopsin studied by time-integrated fluorescence
Majed Chergui, Erwin Portuondo Campa, Goran Zgrablic, Selma Schenkl
Time-integrated fluorescence expts. on native bacteriorhodopsin and on its non-isomerizing form bR5.12 are reported. The exptl. set-up was designed such as to observe emission exclusively from the excited state intermediate I-460. We obtain the first syste ...
2002Spectral and kinetic fluorescence properties of native and nonisomerizing retinal in bacteriorhodopsin
Majed Chergui, Stefan Haacke, Selma Schenkl
Steady-state and picosecond (ps) fluorescence studies of wild-type bacteriorhodopsin (wt-bR) and of a nonisomerizing analog locked in the all-trans configuration have been performed. Extending earlier work done by femtosecond absorption spectroscopy, we ob ...
2001