Space and Time Evolution of the Electrostatic Potential During the Activation of a Visual Pigment.
Animal and microbial retinal proteins employ the Schiff base of retinal as their chromophore. Here, the possible consequences of the charge translocation associated with the light-induced dynamics of the chromophore of a visual opsin are investigated along a representative semiclassical trajectory. We show that the evolution of the electrostatic potential projected by the chromophore onto the surrounding protein displays intense but topographically localized sudden variations in proximity of the decay region. pKa calculations carried out on selected snapshots used as probes, indicate that the only residue which may be sensitive to the electrostatic potential shift is Glu181. Accordingly, our results suggest that the frail Tyr191/268-Glu181-Wat2-Ser186 hydrogen bond network may be perturbed by the transient variations of the electrostatic potential.
Department of Chemistry, Bowling Green State University , Bowling Green, Ohio 43403, United States .
Federico
F
Melaccio
ISIS, UMR 7006 CNRS, Université de Strasbourg , F-67083 Strasbourg Cedex, France.
Nicolas
N
Calimet
Fritz Haber Center for Molecular Dynamics, Institute of Chemistry, The Hebrew University of Jerusalem , Jerusalem 91904, Israel.
Igor
I
Schapiro
Department of Chemistry, Bowling Green State University , Bowling Green, Ohio 43403, United States .
Alessio
A
Valentini
ISIS, UMR 7006 CNRS, Université de Strasbourg , F-67083 Strasbourg Cedex, France.
Marco
M
Cecchini
Dipartimento di Biotecnologie, Chimica e Farmacia, Università di Siena , via A. Moro 2, I-53100 Siena, Italy.|Department of Chemistry, Bowling Green State University , Bowling Green, Ohio 43403, United States .|Institut de Physique et Chimie des Matériaux de Strasbourg, UMR 7504 Université de Strasbourg-CNRS , F-67034 Strasbourg, France.
Massimo
M
Olivucci