Ellipsometry of cytochrome c on gold surfaces: effect of 4,4′-dipyridyl disulfide

A. Szucs, G. D. Hitchens, J. O.M. Bockris

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Ellipsometry has been used to study the mode of adsorption of horse heart cytochrome c on gold in the presence and absence of the promoter 4,4′-dipyridyl disulfide. In the absence of 4,4′-dipyridyl disulfide, cytochrome c unfolds on the surface and forms an irreversibly adsorbed layer that completely covers the electrode. Adsorbed cytochrome c can mediate the reduction of cytochrome c in solution via electron transfer through the unfolded protein layer; the oxidation of cytochrome c in solution was not observed. On gold modified with 4,4′-dipyridyl disulfide, cytochrome c adsorbs irreversibly but retains its native configuration. Ellipsometry and charge transfer measurements show that the layer of adsorbed cytochrome c completely covers the gold surface in the presence of the promoter. Both the reduction and oxidation of cytochrome c in solution occurs through the adsorbed protein layer on the modified surface. These results show that 4,4′-dipyridyl disulfide plays a key role in preventing the unfolding of adsorbed cytochrome c at the electrode solution interface.

Original languageEnglish
Pages (from-to)403-412
Number of pages10
JournalElectrochimica Acta
Issue number3
Publication statusPublished - Mar 1992



  • cytochrome c
  • ellipsometry
  • modified electrode surface.
  • promoters
  • redox proteins

ASJC Scopus subject areas

  • Chemical Engineering(all)
  • Electrochemistry

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