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PROTON TRANSFER IN THE PRIMARY PROCESS OF VISION
Author(s) -
Sarai Akinori,
Kakitani Toshiaki,
Kakitani Hiroko
Publication year - 1981
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.1751-1097.1981.tb05506.x
Subject(s) - proton , excited state , protonation , ground state , chemistry , schiff base , adiabatic process , photochemistry , base (topology) , atomic physics , physics , thermodynamics , crystallography , quantum mechanics , ion , mathematical analysis , mathematics , organic chemistry
— Proton transfer was theoretically examined as a possible primary process of vision. The motion of protons in the adiabatic potential of the Schiff base hydrogen bond was investigated in terms of quantum mechanics. The probability of proton transfer from the Schiff base nitrogen (i.e. the unprotonation of Schiff base) was found to increase as the retinal rotated around 11–12. double bond by 90°. The results also suggested that the proton transfer can take place before or during the transition from the excited to ground state (excited state proton transfer). We proposed that such excited state proton transfer is one of the elementary processes in primary visual photochemistry, and this process leads to the unprotonated visual pigment, hyposorhodopsin, which has been experimentally verified as one of the primary photoproducts of rhodopsin. The probability of this process could be comparable to the conventional process leading to the protonated intermediate, bathorhodopsin. The relation of these results with the recent experimental data is discussed.