51424-44-3Relevant articles and documents
Spontaneous Emission Study of the Femtosecond Isomerization Dynamics of Rhodopsin
Kochendoerfer, Gerd G.,Mathies, Richard A.
, p. 14526 - 14532 (2007/10/03)
The spontaneous emission spectra and yields of the visual pigment rhodopsin and its 9-cis retinal analog isorhodopsin have been measured following excitation at 472.7, 514.5, and 568.2 nm.The fluorescence quantum yields are (0.9 +/- 0.3)E-5 for rhodopsin and (1.8 +/- 0.7)E-5 for isorhodopsin.By use of a Strickler-Berg analysis, these quantum yields correspond to excited electronic state lifetimes of 50 and 100 fs for rhodopsin and isorhodopsin, respectively.The fluorescence spectra also undergo a blue-shift of ca. 1800 cm-1 upon shifting the excitation wavelength from 568.2 to 472.7 nm.This is consistent with the idea that the emission arises from unrelaxed, nonstationary vibrational states.For rhodopsin, there is a correlation among these rapid initial nuclear dynamics out of the Franck-Condon region, the rapid photoisomerization rates, and the high isomerization quantum yields.These results support a new mechanism for the isomerization reaction dynamics in visual pigments where the reaction efficiency is mechanistically linked to the reaction rate through a dynamic Landau-Zener tunneling process.
High-Resolution Carbon-13 NMR of Retial Derivatives in the Solid State
Harbison, G. S.,Mulder, P. P. J.,Pardoen, H.,Lugtenburg, J.,Herzfeld, J.,Griffin, R. G.
, p. 4809 - 4816 (2007/10/02)
13C NMR spectra of a large number of crystalline retinal derivatives have been obtained by using cross-polarization and magic-angle sample spinning.Most derivatives yield spectra with narrow lines (width around 20 Hz) which can be assigned via their 13C-1H dipolar coupling, their chemical shift tensors, comparison with solution spectra, or specific labeling.Measurement of the rotational sideband intensities in the spectra permit calculation of the chemical shielding tensors, and these data have allowed us to analyze variations in isotropic shifts of these compounds in more detail.We show that the tensors exhibit an odd/even effect which results from the steric crowding on one side of the polyene chain, that ?-electron pertubations affect primarily the in-plane elements of the tensor, and, conversely, that strong steric interactions due to cis-trans isomerization affect the out-of-plane element.Finally, we observe a downfield shift at the C-5 position on isomerization about the 6-7 bond, and thus deduce from the observed shifts that retinal derivatives are 25-30percent 6-s-trans in solution.
