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Thermal Fluctuations Determine the Electron-Transfer Rates of Cytochrome c in Electrostatic and Covalent Complexes
Zitatschlüssel ISI:000277666900014
Autor Ly, Hoang Khoa and Marti, Marcelo A. and Martin, Diego F. and Alvarez-Paggi, Damian and Meister, Wiebke and Kranich, Anja and Weidinger, Inez M. and Hildebrandt, Peter and Murgida, Daniel H.
Seiten 1225-1235
Jahr 2010
ISSN 1439-4235
DOI 10.1002/cphc.200900966
Adresse PO BOX 10 11 61, D-69451 WEINHEIM, GERMANY
Journal Chem. Phys. Chem.
Jahrgang 11
Nummer 6
Monat APR 26
Zusammenfassung The heterogeneous electron transfer (ET) reaction of cytochrome c (Cyt-c) electrostatically or covalently immobilized on electrodes coated with self-assembled monolayers (SAMs) of cofunctionalized alkanethiols is analyzed by surface-enhanced resonance Raman (SERR) spectroscopy and molecular dynamics (MD) simulations. Electrostatically bound Cyt-c on pure carboxyl-terminated and mixed carboxyl/hydroxyl-terminated SAMs reveals the same distance dependence of the rate constants, that is, electron tunneling at long distances and a regime controlled by the protein orientational distribution and dynamics that leads to a nearly distance-independent rate constant at short distances. Qualitatively, the same behavior is found for covalently bound Cyt-c, although the apparent ET rates in the plateau region are lower since protein mobility is restricted due to formation of amide bonds between the protein and the SAM. The experimental findings are consistent with the results of MD simulations indicating that thermal fluctuations of the protein and interfacial solvent molecules can effectively modulate the electron tunneling probability.
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