Professor Massimo Olivucci
Dipartimento di Chmica
Universit di Siena
Siena, Italy

Friday, August 31, 2001
11:00 am (CT)
3269 Beckman Institute

Abstract

The light-induced torsional deformation of the retinal chromophore provides the "molecular driving-force" underlying the biological activity of retinal proteins like vision (e.g. in humans), phototropism and proton-pumping (in bacteria). We present the results of a series of ab-initio CAS-SCF and multi- reference MP2 computation, that elucidate the photoisomerization mechanism of the realistic free and locked retinal chromophore models in isolated conditions. The analysis of the molecular and electronic structure changes along the isomerization paths provide the basis for the comprehension of conventional and time resolved spectra and, most importantly, of the dramatic catalytic effect of the protein environment on the photoisomerization rate and quantum yield.