Angela M. Barragan, Klaus Schulten, and Ilia A. Solov'yov.
Mechanism of the primary charge transfer reaction in the cytochrome
bc1 complex.
Journal of Physical Chemistry B, 120:11369-11380, 2016.
BARR2016
The bc1 complex 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 bc1 complex upon quinol binding. In particular, the electron and
proton transfer reactions that trigger the Q-cycle in the bc1 complex 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 bc1 complex 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.
Download Full Text
The manuscripts available on our site are provided for your personal
use only and may not be retransmitted or redistributed without written
permissions from the paper's publisher and author. You may not upload any
of this site's material to any public server, on-line service, network, or
bulletin board without prior written permission from the publisher and
author. You may not make copies for any commercial purpose. Reproduction
or storage of materials retrieved from this web site is subject to the
U.S. Copyright Act of 1976, Title 17 U.S.C.
