title: Molecular-level evidence of the surface-induced transformation of peptide structures revealed by scanning tunneling microscopy.
abstract: Molecular structures of polypeptide molecules (DELERRIRELEARIK) adsorbed at liquid-solid interfaces of graphite have been studied using scanning tunneling microscopy (STM). The polypeptide is originally stable with an alpha-helical conformation in solution and in its crystal states. STM observations reveal that the adsorbed polypeptides form homogeneous beta-sheet-like assemblies on the graphite surface. The separation (4.7+/-0.1 A) between two neighboring polypeptides and the full lengths of the polypeptides determined from STM images suggest distinctively different molecular conformations from the alpha-helical structure. The N 1s peak in the X-ray photoelectron spectroscopy (XPS) spectrum confirmed the presence of polypeptides on the graphite surface. In addition, the circular dichroism (CD) results provide supporting evidence that the polypeptides would undergo a structural transformation to beta-sheet secondary structure upon the addition of graphite particles to the peptide solution. Such conformational rearrangements upon adsorption on a hydrophobic surface could benefit the studies on protein-surface interactions.
authors.affiliation: National Center for Nanoscience and Technology, Beijing 100190, China.
authors.forename: Xiaobo
authors.initials: X
authors.lastname: Mao
authors.forename: Yibing
authors.initials: Y
authors.lastname: Wang
authors.forename: Lei
authors.initials: L
authors.lastname: Liu
authors.forename: Lin
authors.initials: L
authors.lastname: Niu
authors.forename: Yanlian
authors.initials: Y
authors.lastname: Yang
authors.forename: Chen
authors.initials: C
authors.lastname: Wang
mesh_terms: D000595:Amino Acid Sequence; D002942:Circular Dichroism; D016252:Microscopy, Scanning Tunneling; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D010455:Peptides