Femtochemistry of Rhodopsins

Abstract The review considers the spectral kinetic data obtained by us femtosecond absorption laser spectroscopy for photochromic reaction of retinal isomerization in animal rhodopsin (type II), namely, bovine visual and microbial rhodopsins I), such as Exiguobacterium sibiricum Halobacterium salinarum bacteriorhodopsin. It is shown that elementary act photoreaction type I II can be interpreted a transition through conical intersection with retention coherence vibrational wave packets generated during excitation. coherent nature most pronounced result barrier-free movement along excited surface potential energy, which also leads to an extremely high rate compared rhodopsins. Differences dynamics photochemical reactions related both differences initial isomeric forms their chromophores (all- trans 11- cis retinal, respectively), well effect protein environment on chromophore. Despite practically identical values quantum yields direct bacteriorhodopsin, reverse much less effective (? = 0.15) than case bacteriorhodopsin 0.81). assumed photobiological mechanism converting light into information process evolutionarily younger rhodopsins) should more reliable photoenergetic ancient rhodopsins). low value yield considered increase reliability forward reaction, triggers phototransduction.