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THEORETICAL STUDY OF COLOR CONTROL MECHANISM IN RETINAL PROTEINS.: I. ROLE OF THE TRYPTOPHAN RESIDUE, TYROSINE RESIDUE AND WATER MOLECULE
Author(s) -
Beppu Yoshitaka,
Kakitani Toshiaki
Publication year - 1994
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1994.tb09673.x
Subject(s) - bathochromic shift , opsin , chromophore , chemistry , tryptophan , hypsochromic shift , rhodopsin , tyrosine , residue (chemistry) , retinal , molecule , stereochemistry , photochemistry , amino acid , biochemistry , fluorescence , organic chemistry , optics , physics
We calculated the opsin shift due to the electrostatic interaction between tryptophan or tyrosine residues and the chromophore by the perturbation method for various mutual configurations. The obtained opsin shift maps for these configurations demonstrated that when the above residues reside around the ionone ring side, the positive opsin shift (bathochromic shift) is obtained, and when they reside around the Schiff‐base side, the negative opsin shift (hypsochromic shift) is obtained. These properties hold true, irrespective of the orientation of those residues, indicating that higher order multipoles of the group play a central role. The maximum value of the opsin shift by these groups amounts to several hundred wavenumbers. These results indicate that the location of some of those amino acid residues at proper positions around the chromophore can cause a considerable opsin shift. We also calculated opsin shift maps for the various mutual configurations between a water molecule and the chromophore for comparison.