Analysis of the factors that influence the C=N stretching frequency of polyene Schiff bases. Implications for bacteriorhodopsin and rhodopsin. |
| |
Authors: | H S Gilson B H Honig A Croteau G Zarrilli K Nakanishi |
| |
Affiliation: | Department of Biochemistry and Molecular Biophysics, Columbia University, New York, New York 10032. |
| |
Abstract: | In this study quantum mechanical calculations of force constants and normal mode analysis are used to elucidate the factors that influence the C=C and C=N stretching frequencies in polyenes and in protonated Schiff bases. The C=N stretching frequency is found to depend on both the C=N stretching force constant and the C=N-H bending force constant. Due to the contributions of these two modes, the C=N stretching frequency is particularly sensitive to the magnitude of the Schiff base counterion interactions and to the hydrogen bonding environment of the Schiff base nitrogen. Models for chromophore-protein interactions in the retinal binding site and for the photochemical transformations of bacteriorhodopsin and rhodopsin are evaluated in light of these results. |
| |
Keywords: | |
|
|