title: Mechanism of the Primary Charge Transfer Reaction in the Cytochrome bc1Complex.
abstract: The bc1complex is a critical enzyme for the ATP production in photosynthesis and cellular respiration. Its biochemical function relies on the so-called Q-cycle, which is well established and operates via quinol substrates that bind inside the protein complex. Despite decades of research, the quinol-protein interaction, which initiates the Q-cycle, has not yet been completely described. Furthermore, the initial charge transfer reactions of the Q-cycle lack a physical description. The present investigation utilizes classical molecular dynamics simulations in tandem with quantum density functional theory calculations, to provide a complete and consistent quantitative description of the primary events that occur within the bc1complex upon quinol binding. In particular, the electron and proton transfer reactions that trigger the Q-cycle in the bc1complex from Rhodobacter capsulatus are studied. The coupled nature of these charge transfer reactions was revealed by obtaining the transition energy path connecting configurations of the Qo-site prior and after the transfers. The analysis of orbitals and partial charge distribution of the different states of the Qo-site has further supported the conclusion. Finally, key structural elements of the bc1complex that trigger the charge transfer reactions were established, manifesting the importance of the environment in the process, which is furthermore evidenced by free energy calculations.
authors.affiliation: Department of Physics, University of Illinois at Urbana-Champaign , 1110 West Green Street, Urbana, Illinois 61801, United States.|Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign , 405 North Mathews Avenue, Urbana, Illinois 61801, United States.
authors.forename: Angela M
authors.initials: AM
authors.lastname: Barragan
authors.affiliation: Department of Physics, University of Illinois at Urbana-Champaign , 1110 West Green Street, Urbana, Illinois 61801, United States.|Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign , 405 North Mathews Avenue, Urbana, Illinois 61801, United States.
authors.forename: Klaus
authors.initials: K
authors.lastname: Schulten
authors.affiliation: Department of Physics, Chemistry and Pharmacy, University of Southern Denmark , Campusvej 55, DK-5230 Odense M, Denmark.
authors.forename: Ilia A
authors.initials: IA
authors.lastname: Solov'yov
mesh_terms: D014450:Electron Transport Complex III / Q000737:chemistry / Q000378:metabolism*; D056004:Molecular Dynamics Simulation; D011789:Quantum Theory
chemical_list: D014450:Electron Transport Complex III