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STRUCTURE OF HYPSORHODOPSIN: ANALYSIS BY FOURIER TRANSFORM INFRARED SPECTROSCOPY AT 10 K
Author(s) -
Sasaki Jun,
Maeda Akio,
Shichida Yoshinori,
Groesbeek Michel,
Lugtenburg Johan,
Yoshizawa Tôru
Publication year - 1992
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.1751-1097.1992.tb09730.x
Subject(s) - chromophore , rhodopsin , polyene , chemistry , infrared , photochemistry , protonation , spectroscopy , photoisomerization , infrared spectroscopy , crystallography , optics , isomerization , retinal , physics , organic chemistry , ion , biochemistry , quantum mechanics , catalysis
— Vibrational bands of hypsorhodopsin in the difference Fourier transform infrared spectra were identified as the bands which arose after formation of isorhodopsin by successive irradiations of bovine rhodopsin at 10 K with >500 nm light, and also as the bands disappeared upon conversion to bathorhodopsin by warming. The chromophore bands were assigned by the bands which shifted upon deuterium substitution of the polyene chain of the retinylidene chromophore. The presence of chromophore bands which shift by D 2 O exchange clearly shows that the Schiff base chromophore of hypsorhodopsin is protonated. The amide I bands and several other protein bands of hypsorhodopsin appeared at the same frequencies as those of bathorhodopsin, but they are different from those of rhodopsin and isorhodopsin. Furthermore, like bathorhodopsin, hypsorhodopsin displays the C l —H out‐of‐plane bending mode which is weakly coupled with C 12 ‐ ‐ –H out‐of‐plane mode. These facts show that hypsorhodopsin has a chromophore conformation and chromophore‐opsin interaction more similar to bathorhodopsin than to rhodopsin and isorhodopsin.