title: Electron transfer across α-helical peptide monolayers: importance of interchain coupling.
abstract: Four helical peptides with the general formula (Boc)-Cys-(S-Acm)-(Ala-Leu)(n)-NH-(CH(2))(2)-SH (n = 4-7) were synthesized and further used for the preparation of self-assembled monolayers (SAMs) on gold substrates. The electron-transfer behavior of these systems was probed using current-sensing atomic force microscopy (CS-AFM). It was found that the electron transmission through SAMs of helical peptides trapped between an AFM conductive tip and a gold substrate occurs very efficiently and that the distance dependence obeys the exponential trend with a decay constant of 4.6 nm(-1). This result indicates that the tunneling mechanism is operative in this case. Conductance measurements under mechanical stress show that peptide-mediated electron transmission occurs with the possible contribution of intermolecular electron tunneling between adjacent helices. It was also demonstrated that an external electric field applied between metallic contacts can affect the structure of the peptide SAM by changing its thickness. This explains the asymmetry of the current-voltage response of metal-monolayer-metal junction.
authors.affiliation: Department of Chemistry, University of Warsaw, Pasteura 1, 02-093 Warsaw, Poland.
authors.forename: Jan
authors.initials: J
authors.lastname: Pawlowski
authors.forename: Joanna
authors.initials: J
authors.lastname: Juhaniewicz
authors.forename: Dagmara
authors.initials: D
authors.lastname: Tymecka
authors.forename: Slawomir
authors.initials: S
authors.lastname: Sek
mesh_terms: D004579:Electron Transport; D006046:Gold / Q000737:chemistry*; D018625:Microscopy, Atomic Force; D010455:Peptides / Q000737:chemistry*; D017433:Protein Structure, Secondary; D013499:Surface Properties
chemical_list: D010455:Peptides; D006046:Gold