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Title: Catalysis of Ground State cis → trans Isomerization of Bacteriorhodopsin’s Retinal Chromophore by a Hydrogen-Bond Network

For the photocycle of the membrane protein bacteriorhodopsin to proceed efficiently, the thermal 13-cis to all-trans back-isomerization of the retinal chromophore must return the protein to its resting state on a time-scale of milliseconds. Here, we report on quantum mechanical/molecular mechanical energy calculations examining the structural and energetic determinants of the retinal cis–trans isomerization in the protein environment. The results suggest that a hydrogen-bonded network consisting of the retinal Schiff base, active site amino acid residues, and water molecules can stabilize the twisted retinal, thus reducing the intrinsic energy cost of the cis–trans thermal isomerization barrier.
ORCiD logo [1] ;  [2] ;  [3] ;  [4] ;  [5]
  1. Freie Univ., Berlin (Germany). Dept. of Physical and Theoretical Chemistry, Theoretical Molecular Biophysics, Inst. for Chemistry und Biochemistry
  2. Technische Univ. Braunschweig (Germany). Inst. of Physical and Theoretical Chemistry; BASF SE, Ludwigshafen am Rhein (Germany)
  3. Freie Univ., Berlin (Germany). Dept. of Physics, Theoretical Molecular Biophysics
  4. Karlsruhe Inst. of Technology (KIT) (Germany). Inst. for Physical Chemistry, Dept. of Theoretical Chemical Biology
  5. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Molecular Biophysics; Univ. of Tennessee, Knoxville, TN (United States). Dept. of Biochemistry and Molecular and Cellular Biology
Publication Date:
Grant/Contract Number:
AC05-00OR22725; EL 206/8-1
Accepted Manuscript
Journal Name:
Journal of Membrane Biology
Additional Journal Information:
Journal Volume: 251; Journal Issue: 3; Journal ID: ISSN 0022-2631
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
Country of Publication:
United States
59 BASIC BIOLOGICAL SCIENCES; Bacteriorhodopsin; Retinal; Isomerization; QM/MM; Energy; Calculations
OSTI Identifier: