Single-molecule imaging of gold-binding peptide adsorbed on Au(111).

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.