Quantum mechanics/molecular mechanics calculations based on ab initio multiconfigurational second order perturbation theory are employed to construct a computer model of Bacteriorhodopsin that reproduces the observed static and transient electronic spec-tra, the dipole moment changes, and the energy stored in the photocycle intermediate K. The computed reaction coordinate indicates that the isomerization of the retinal chromophore occurs via a complex motion accounting for three distinct regimes: (i) production of the excited state intermediate I, (ii) evolution of I toward a conical intersection between the excited state and the ground state, and (iii) formation of K. We show that, during stage ii, a space-saving mechanism dominated by an asynchronous double bicycle-pedal deformation of the C10 ═ C11 ─ C12 ═ C13 ─ C14 ═ N moiety of the chromophore dominates the isomerization. On this same stage a N ─ H∕water hydrogen bond is weakened and initiates a breaking process that is completed during stage iii.

Altoè, P., Cembran, A., Olivucci, M., & Garavelli, M. (2010). An aborted double bicycle-pedal isomerization with hydrogen bond-breaking is the primary event in the Bacteriorhodopsin proton-pumping. PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, 107(47), 20172-20177 [10.1073/pnas.1007000107].

An aborted double bicycle-pedal isomerization with hydrogen bond-breaking is the primary event in the Bacteriorhodopsin proton-pumping

OLIVUCCI, MASSIMO;
2010

Abstract

Quantum mechanics/molecular mechanics calculations based on ab initio multiconfigurational second order perturbation theory are employed to construct a computer model of Bacteriorhodopsin that reproduces the observed static and transient electronic spec-tra, the dipole moment changes, and the energy stored in the photocycle intermediate K. The computed reaction coordinate indicates that the isomerization of the retinal chromophore occurs via a complex motion accounting for three distinct regimes: (i) production of the excited state intermediate I, (ii) evolution of I toward a conical intersection between the excited state and the ground state, and (iii) formation of K. We show that, during stage ii, a space-saving mechanism dominated by an asynchronous double bicycle-pedal deformation of the C10 ═ C11 ─ C12 ═ C13 ─ C14 ═ N moiety of the chromophore dominates the isomerization. On this same stage a N ─ H∕water hydrogen bond is weakened and initiates a breaking process that is completed during stage iii.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11365/26296
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