Electron transfer through a self-assembled monolayer of a double-helix peptide with linking the terminals by ferrocene.
A unique molecular structure, a double-helix peptide, was self-assembled on gold, and the electron transfer through the monolayer was studied. The double-helix peptide consists of two 9mer 3(10)-helical peptide chains having a disulfide group at each N terminal and being linked by a ferrocene dicarboxylic acid between the C terminals. Each helical peptide chain has three naphthyl groups in a linear arrangement along the helix. The monolayer properties and the electron transfer from the ferrocene unit to gold were studied with reference peptides with a similar double helix but without naphthyl groups, a single helix with a dicarboxylic ferrocene unit, and a single helix with a monocarboxylic ferrocene unit. It was demonstrated that the naphthyl groups on the side chains had no effect on electron transfer, and the electron-transfer rate in the double-helix monolayer was not promoted, despite the two electron pathways in the molecule. We propose that in the double-helix monolayer, molecular motions are suppressed, possibly by its rigid structure tethered by the two linkers on gold to cancel out acceleration effects of the 2-fold electron pathways and the ferrocene substitution number. The factors that affect the electron-transfer reaction across the helical peptide SAMs are discussed in depth.
Okamoto
Shinpei
S
Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Kyoto-Daigaku-Katsura, Nishikyo-ku, Kyoto 615-8510, Japan.
Morita
Tomoyuki
T
Kimura
Shunsaku
S
D002942:Circular Dichroism; D004220:Disulfides / Q000737:chemistry; D004563:Electrochemistry / Q000379:methods; D004583:Electrons; D005296:Ferrous Compounds / Q000737:chemistry*; D006046:Gold / Q000737:chemistry; D008567:Membranes, Artificial; D000075163:Metallocenes; D008956:Models, Chemical; D015394:Molecular Structure; D010455:Peptides / Q000737:chemistry*; D017434:Protein Structure, Tertiary; D012997:Solvents; D013050:Spectrometry, Fluorescence / Q000379:methods; D013499:Surface Properties
D004220:Disulfides; D005296:Ferrous Compounds; D008567:Membranes, Artificial; D000075163:Metallocenes; D010455:Peptides; D012997:Solvents; D006046:Gold; C004998:ferrocene