Cation recognition by self-assembled monolayers of oriented helical peptides having a crown ether unit.
Cation recognition of self-assembled monolayers (SAMs) of helical peptides having a crown ether unit was investigated by the impedance spectroscopy and cyclic voltammetry. Lipo-(Ala-Aib)8-Ala-Cr and Boc-Glu(Cr)-(Ala-Aib)8-Lipoa (Lipo, Lipoa, and Cr represent lipoic acid, lipoamide, and amidobenzo-18-crown-6, respectively) were synthesized and the helix SAMs were prepared. The peptides having a crown ether unit formed SAMs oriented nearly vertically to the substrate. The capacitance of the Lipo-(Ala-Aib)(8)-Ala-Cr SAM changed specifically with the addition of cations, and the binding constants of the SAM were larger than those of the crown ether in aqueous solution because of a large dipole moment of the helical peptide. In the case of the Boc-Glu(Cr)-(Ala-Aib)8-Lipoa SAM, the cation binding to the SAM showed a drastic decrease in the peak current of the cyclic voltammetry around 10(-5)M of K+ ion. In either capacitance measurement or cyclic voltammetry, the helical peptide SAM played an important role in the sensitive response to cations.
Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Yoshida Honmachi Sakyoku, Kyoto 606-8501, Japan.
Y
Y
Miura
S
S
Kimura
S
S
Kobayashi
Y
Y
Imanishi
J
J
Umemura
D002412:Cations / Q000378:metabolism*; D017097:Electric Impedance; D004563:Electrochemistry; D004988:Ethers, Cyclic / Q000737:chemistry* / Q000378:metabolism; D005782:Gels; D010455:Peptides / Q000737:chemistry* / Q000378:metabolism; D011188:Potassium / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D011485:Protein Binding; D017433:Protein Structure, Secondary; D017550:Spectroscopy, Fourier Transform Infrared; D013379:Substrate Specificity
D002412:Cations; D004988:Ethers, Cyclic; D005782:Gels; D010455:Peptides; D011188:Potassium