TY - JOUR
T1 - Theory and Electrochemistry of Cytochrome c
AU - Seyedi, Salman S.
AU - Waskasi, Morteza M.
AU - Matyushov, Dmitry
N1 - Funding Information:
The authors acknowledge Hadi Dinpajooh and Daniel Martin for their help in setting up the simulations. David Waldeck provided us with experimental kinetic data. This research was supported by the National Science Foundation (CHE- 1464810). CPU time was provided by the National Science Foundation through XSEDE resources (TG-MCB080071).
Publisher Copyright:
© 2017 American Chemical Society.
PY - 2017/5/18
Y1 - 2017/5/18
N2 - Extensive simulations of cytochrome c in solution are performed to address the apparent contradiction between large reorganization energies of protein electron transfer typically reported by atomistic simulations and much smaller values produced by protein electrochemistry. The two sets of data are reconciled by deriving the activation barrier for electrochemical reaction in terms of an effective reorganization energy composed of half the Stokes shift (characterizing the medium polarization in response to electron transfer) and the variance reorganization energy (characterizing the breadth of electrostatic fluctuations). This effective reorganization energy is much smaller than each of the two components contributing to it and is fully consistent with electrochemical measurements. Calculations in the range of temperatures between 280 and 360 K combine long, classical molecular dynamics simulations with quantum calculations of the protein active site. The results agree with the Arrhenius plots for the reaction rates and with cyclic voltammetry of cytochrome c immobilized on self-assembled monolayers. Small effective reorganization energy, and the resulting small activation barrier, is a general phenomenology of protein electron transfer allowing fast electron transport within biological energy chains.
AB - Extensive simulations of cytochrome c in solution are performed to address the apparent contradiction between large reorganization energies of protein electron transfer typically reported by atomistic simulations and much smaller values produced by protein electrochemistry. The two sets of data are reconciled by deriving the activation barrier for electrochemical reaction in terms of an effective reorganization energy composed of half the Stokes shift (characterizing the medium polarization in response to electron transfer) and the variance reorganization energy (characterizing the breadth of electrostatic fluctuations). This effective reorganization energy is much smaller than each of the two components contributing to it and is fully consistent with electrochemical measurements. Calculations in the range of temperatures between 280 and 360 K combine long, classical molecular dynamics simulations with quantum calculations of the protein active site. The results agree with the Arrhenius plots for the reaction rates and with cyclic voltammetry of cytochrome c immobilized on self-assembled monolayers. Small effective reorganization energy, and the resulting small activation barrier, is a general phenomenology of protein electron transfer allowing fast electron transport within biological energy chains.
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U2 - 10.1021/acs.jpcb.7b00917
DO - 10.1021/acs.jpcb.7b00917
M3 - Article
C2 - 28443664
AN - SCOPUS:85020679284
SN - 1520-6106
VL - 121
SP - 4958
EP - 4967
JO - Journal of Physical Chemistry B
JF - Journal of Physical Chemistry B
IS - 19
ER -