Gg. Kochendoerfer et Ra. Mathies, ULTRAFAST SPECTROSCOPY OF RHODOPSINS - PHOTOCHEMISTRY AT ITS BEST, Israel Journal of Chemistry, 35(3-4), 1995, pp. 211-226
Recent advances in laser technology now allow us to study the ultrafas
t primary photochemical events in rhodopsin, bacteriorhodopsin, and ha
lorhodopsin in real time. The results of various ultrafast studies of
rhodopsins are reviewed with an emphasis on (1) the relationship betwe
en the reaction rate and reaction efficiency and its implications for
the mechanism of isomerization, (2) the homogeneity of the reaction pa
thways, and (3) the role of the protein in the reaction dynamics. The
results mandate the introduction of a new paradigm to describe these u
ltrafast reactions that specifically considers the importance of the t
imescale of vibrational dephasing and relaxation relative to the react
ive motion and the contribution of vibrational coherence to the reacti
on mechanism.