Dr. Shigehiko Hayashi
Beckman Institute
University of Illinois at Urbana-Champaign
Urbana, Illinois

Monday, September 30, 2002
3:00 pm (CT)
3269 Beckman Institute

Abstract

Retinal proteins are responsible for basic functions in living organisms, ranging from conversion of light to chemical energy in archaeal bacteria to color vision in human. Their response to different wavelengths of light is based on a fine tuned interaction with the chromophore, retinal. Photoactivation is triggered by isomerization of retinal, and results in thermally activated transitions between intermediate states. We have investigated the molecular mechanism of primary photoinduced events in retinal proteins by means of ab initio quantum mechanical (QM) calculations combined with molecular dynamics (MD) simulations. This lecture will discuss spectral tuning of retinal proteins, photoisomerization of the chromophore, and the subsequent structural changes that lead to protein activation. The description of photoisomerization involves all degrees of freedom of the chromophore and is based on force evaluation of the excited chromophore unveiling in complete molecular detail the anomalously fast event, including the molecular origin of dynamic spectral modulations observed in novel ultrafast spectroscopic experiments.

Tea and coffee will be served in R3151 Beckman Institute at 2:15pm.