Analytical Sciences

Single-Molecule Imaging of Gold-Binding Peptide Adsorbed on Au(111)

Satoshi KANATA,* Tomoaki NISHINO,** Rie MAKIURA,** Sho SAIKI,*** and Nobuhiko HAYASHI**

*Department of Physics and Electronics, Graduate School of Engineering, Osaka Prefecture University, 1-1 Gakuencho, Naka, Sakai, Osaka 599-8531, Japan
**Nanoscience and Nanotechnology Research Center, Research Organization for the 21st Century, Osaka Prefecture University, 1-2 Gakuencho, Naka, Sakai, Osaka 599-8570, Japan
***Department of Physical Science, Graduate School of Science, Osaka Prefecture University, 1-1 Gakuencho, Naka, Sakai, Osaka 599-8531, Japan

Inorganic-binding peptides, which exhibit specific binding affinity to an inorganic material, are versatile building blocks in the construction of novel bio-conjugated materials. However, very little knowledge regarding their adsorbed structures on the target material is currently available. In this article, we report on the single-molecule analysis of such polypeptides by scanning tunneling microscopy (STM). The adsorbed structure of a gold-binding peptide (GBP) on Au(111) was observed at the single-molecule level. FTIR spectroscopy revealed the helical structure of the GBP, and ab initio calculations confirmed the correlation between the observed STM image and a sample helical structure. It has been demonstrated that the conformational structure of the polypeptide is highly pre-organized, allowing favorable binding onto the gold surface. Gaining such an insight into the relation between the structure and the binding function of the peptide leads to a fundamental understanding of inorganic-binding peptide, and, consequently, to a rational design of these peptides.

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