TY  - JOUR
AU  - Schenkl, S.
AU  - van Mourik, F.
AU  - Friedman, N.
AU  - Sheves, M.
AU  - Schlesinger, R.
AU  - Haacke, S.
AU  - Chergui, M.
TI  - Insights into excited-state and isomerization dynamics of bacteriorhodopsin from ultrafast transient UV absorption
JO  - Proceedings of the National Academy of Sciences of the United States of America
VL  - 103
SN  - 0027-8424
CY  - Washington, DC
PB  - Academy
M1  - PreJuSER-51340
SP  - 4101 - 4106
PY  - 2006
N1  - Record converted from VDB: 12.11.2012
AB  - A visible-pump/UV-probe transient absorption is used to characterize the ultrafast dynamics of bacteriorhodopsin with 80-fs time resolution. We identify three spectral components in the 265- to 310-nm region, related to the all-trans retinal, tryptophan (Trp)-86 and the isomerized photoproduct, allowing us to map the dynamics from reactants to products, along with the response of Trp amino acids. The signal of the photoproduct appears with a time delay of approximately 250 fs and is characterized by a steep rise ( approximately 150 fs), followed by additional rise and decay components, with time scales characteristic of the J intermediate. The delayed onset and the steep rise point to an impulsive formation of a transition state on the way to isomerization. We argue that this impulsive formation results from a splitting of a wave packet of torsional modes on the potential surface at the branching between the all-trans and the cis forms. Parallel to these dynamics, the signal caused by Trp response rises in approximately 200 fs, because of the translocation of charge along the conjugate chain, and possible mechanisms are presented, which trigger isomerization.
KW  - Bacteriorhodopsins: chemistry
KW  - Bacteriorhodopsins: genetics
KW  - Biophysical Phenomena
KW  - Biophysics
KW  - Halobacterium salinarum: chemistry
KW  - Halobacterium salinarum: genetics
KW  - Isomerism
KW  - Kinetics
KW  - Mutagenesis, Site-Directed
KW  - Spectrophotometry, Ultraviolet
KW  - Thermodynamics
KW  - Tryptophan: chemistry
KW  - Bacteriorhodopsins (NLM Chemicals)
KW  - Tryptophan (NLM Chemicals)
KW  - J (WoSType)
LB  - PUB:(DE-HGF)16
C6  - pmid:16537491
C2  - pmc:PMC1449653
UR  - <Go to ISI:>//WOS:000236429300032
DO  - DOI:10.1073/pnas.0506303103
UR  - https://juser.fz-juelich.de/record/51340
ER  -