Charge transfer at the Qo-site of the cytochrome bc1 complex leads to superoxide production

Adrian Bøgh Salo, Peter Husen, Ilia A. Solov'yov
Journal of Physical Chemistry B
121
1771-1782
2017
abstract
The cytochrome bc1 complex is the third protein complex in the electron transport chain of mitochondria orphotosynthetic bacteria, and it serves to create an electrochemical gradient across a cellular membrane, which is used to drive
ATP synthesis. The purpose of this study is to investigate interactions involving an occasionally trapped oxygen molecule (O2)
at the so-called Qo site of the bc1 complex, which is one of the central active sites of the protein complex, where redox reactions
are expected to occur. The investigation focuses on revealing the possibility of the oxygen molecule to influence the normal\øperation of the bc1 complex and acquire an extra electron, thus becoming superoxide, a biologically toxic free radical. The
process is modeled by applying quantum chemical calculations to previously performed classical molecular dynamics simulations.
Investigations reveal several spontaneous charge transfer modes from amino acid residues and cofactors at the Qo-site to the
trapped O2 molecule.
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