Nature 260, 679 - 683 (22 April 1976); doi:10.1038/260679a0

Bicycle-pedal model for the first step in the vision process

Arieh Warshel^*

Department of Chemical Physics, Weizmann Institute of Science, Rehovot, Israel, and MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 2QH, UK
^*Present address: Department of Chemistry, University of Southern California, Los Angeles, California 90007

Computer simulation of the molecular dynamics of retinal during its photoisomerisation inside a restrictive active site gives a detailed model for the sequence of events in the first step of the vision process. It is proposed that the prelumirhodopsin intermediate contains a strained all-trans retinal molecule produced directly and rapidly from the 11-cis, 12-s-trans conformation in rhodopsin by a bicycle-pedal isomerisation. The model reproduces the main experimental observations and explains how the protein makes the photoisomerisation path unique.

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