European Biophysics Journal

, Volume 36, Issue 8, pp 1039–1048

Kinetics of the electron transfer reaction of Cytochrome c552 adsorbed on biomimetic electrode studied by time-resolved surface-enhanced resonance Raman spectroscopy and electrochemistry

  • Sophie Bernad
  • Nadine Leygue
  • Hafsa Korri-Youssoufi
  • Sophie Lecomte
Original Paper

DOI: 10.1007/s00249-007-0173-z

Cite this article as:
Bernad, S., Leygue, N., Korri-Youssoufi, H. et al. Eur Biophys J (2007) 36: 1039. doi:10.1007/s00249-007-0173-z

Abstract

Cytochrome c552 (Cyt-c552) and its redox partner ba3-oxidase from Thermus thermophilus possess structural differences compared with Horse heart cytochrome c (cyt-c)/cytochrome c oxidase (CcO) system, where the recognition between partners and the electron transfer (ET) process is initiated via electrostatic interactions. We demonstrated in a previous study by surface-enhanced resonance Raman (SERR) spectroscopy that roughened silver electrodes coated with uncharged mixed self-assembled monolayers HS–(CH2)n–CH3/HS–(CH2)n + 1–OH 50/50, n = 5, 10 or 15, was a good model to mimic the Cyt-c552 redox partner. All the adsorbed molecules are well oriented on such biomimetic electrodes and transfer one electron during the redox process. The present work focuses on the kinetic part of the heterogeneous ET process of Cyt-c552 adsorbed onto electrodes coated with such mixed SAMs of different alkyl chain length. For that purpose, two complementary methods were combined. Firstly cyclic voltammetry shows that the ET between the adsorbed Cyt-c552 and the biomimetic electrode is direct and reversible. Furthermore, it allows the estimation of both the density surface coverage of adsorbed Cyt-c552 and the kinetic constants values. Secondly, time-resolved SERR (TR-SERR) spectroscopy showed that the ET process occurs without conformational change of the Cyt-c552 heme group and allows the determination of kinetic constants. Results show that the kinetic constant values obtained by TR-SERR spectroscopy could be compared to those obtained from cyclic voltammetry. They are estimated at 200, 150 and 40 s−1 for the ET of Cyt-c552 adsorbed onto electrodes coated with mixed SAMs HS–(CH2)n–CH3/HS–(CH2)n + 1–OH 50/50, n = 5, 10 or 15, respectively.

Keywords

Cytochrome c552Surface-enhanced resonance Raman spectroscopyTime-resolved SERSSelf-assembled monolayersCoated electrodes

Copyright information

© EBSA 2007

Authors and Affiliations

  • Sophie Bernad
    • 1
  • Nadine Leygue
    • 1
  • Hafsa Korri-Youssoufi
    • 2
  • Sophie Lecomte
    • 1
  1. 1.LADIR, CNRS/UPMC (UMR 7075)ThiaisFrance
  2. 2.Equipe de Chimie Bioorganique et Bioinorganique, Institut de Chimie Moléculaire et des Matériaux d’OrsayOrsayFrance