Complete-active-space self-consistent-field/Amber parameterization of the Lys296-retinal-Glu113 rhodopsin chromophore-counterion system

Nicolas Ferré, Alessandro Cembran, Marco Garavelli, Massimo Olivucci

Research output: Contribution to journalArticlepeer-review

46 Scopus citations

Abstract

A special hybrid quantum mechanics/molecular mechanics forcefield is defined, parameterized and validated for studying the photoisomerization path of the retinal chromophore in the rhodopsin protein. It couples a multireference ab initio Hamiltonian (CASSCF and second-order multireference many-body perturbation theory using a CASSCF reference) to describe the chromophore while the rest of the protein is approximated with the Amber forcefield. The frontier has been carefully parameterized in order to reproduce full quantum mechanics torsional energy profiles, for both the ground state and the first excited state. It is also shown that replacing the chromophore counterion with point charges is a valid approximation. This result is interpreted in terms of a cancellation effect for which a possible explanation is given.

Original languageEnglish (US)
Pages (from-to)335-341
Number of pages7
JournalTheoretical Chemistry Accounts
Volume112
Issue number4
DOIs
StatePublished - Sep 1 2004

Keywords

  • Parameterization
  • Photoisomerization
  • Quantum mechanics/Molecular mechanics
  • Retinal
  • Rhodopsin

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