ISBN: 978-83-60043-10-3 - eurobic9

Eurobic9, 2-6 September, 2008, Wrocław, Poland
P102. Electron Transfer Dynamics of Cytochrome C at Interfaces
A. Kranich a , K. H. Ly a , P. Hildebrandt a , D. H. Murgida. b
a Institut für Chemie, TU Berlin, Str. des 17. Juni 135, 10623, Berlin, Germany
e-mail: anja.kranich@tu-berlin.de
b INQUIMAE, Universidad de Buenos Aires, , C1428EH, Buenos Aires, Argentina
Elucidating the mechanism and dynamics of electron transfer processes between redox proteins is one of the
fundamental challenges in molecular biophysics. Upon coating Ag electrodes with self-assembled monolayers
of amphiphiles, it is possible to mimic biological interfaces where most of the electron transfer processes of
redox proteins take place. This approach has the specific advantage of facilitating the determination of ET rate
constants as a function of distance by simply varying the chain length of the thiols. In most of the studies
reported so far, “unusual” distance-dependences of the non-adiabatic electron transfer rate constants have been
found. The origin for this behavior has been elusive and discussed controversially. Using a two-colour timeresolved
surface enhanced resonance Raman spectroelectrochemical approach we have been able to monitor
simultaneously and in real time the structure, electron transfer kinetics and configurational fluctuations of
cytochrome c electrostatically adsorbed to SAM-coated electrodes. It is shown that the overall electron transfer
kinetics is determined by protein dynamics rather than by tunnelling probabilities and, in turn, is controlled by
the interfacial electric field. Implications for inter-protein electron transfer at biological membranes are
discussed.
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