Mechanism of Photoisomerization of the Rhodopsin Chromophore

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N. S. Vassilieva-Vashakmadze^*, R. A. Gakhokidze, and A. R. Gakhokidze

Javakhishvili Tbilisi State University, pr. Chavchavadze 1, Tbilisi, Georgia; E-mail: nonavas@rambler.ru; tamazvashakmadze@yahoo.com; rgakhokidze@mail.ru

^* To whom correspondence should be addressed.

Received November 6, 2006; Revision received October 25, 2007

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This work is devoted to the problem connected with rhodopsin activation. Electrostatic forces involved in photoisomerization of retinal are considered. It is suggested that the repulsion force and rotating moment between electric dipole moments of methyl groups on the C₅ and C₁₃ atoms of retinal can promote isomerization upon light absorption because the pi-pi* transition is accompanied by a decrease in the potential barrier for torsional rotations around the C₁₁-C₁₂ bond.

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KEY WORDS: visual receptor, diamagnetism, dipole moment, rotating moment, isomerization

DOI: 10.1134/S0006297908060151

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