title: Sheet-like assemblies of charged amphiphilic α/β-peptides at the air-water interface.
abstract: There is growing interest in the design of molecules that undergo predictable self-assembly. Bioinspired oligomers with well-defined conformational propensities are attractive from this perspective, since they can be constructed from diverse building blocks, and self-assembly can be directed by the identities and sequence of the subunits. Here we describe the structure of monolayers formed at the air-water interface by amphiphilic α/β-peptides with 1:1 alternation of α- and β-amino acid residues along the backbone. Two of the α/β-peptides, one a dianion and the other a dication, were used to determine differences between self-assemblies of the net negatively and positively charged oligomers. Two additional α/β-peptides, both zwitterionic, were designed to favor assembly in a 1:1 molar ratio mixture with parallel orientation of neighboring strands. Monolayers formed by these α/β-peptides at the air-water interface were characterized by surface pressure-area isotherms, grazing incidence X-ray diffraction (GIXD), atomic force microscopy and ATR-FTIR. GIXD data indicate that the α/β-peptide assemblies exhibited diffraction features similar to those of β-sheet-forming α-peptides. The diffraction data allowed the construction of a detailed model of an antiparallel α/β-peptide sheet with a unique pleated structure. One of the α/β-peptide assemblies displayed high stability, unparalleled among previously studied assemblies of α-peptides. ATR-FTIR data suggest that the 1:1 mixture of zwitterionic α/β-peptides assembled in a parallel arrangement resembling that of a typical parallel β-sheet secondary structure formed by α-peptides. This study establishes guidelines for design of amphiphilic α/β-peptides that assemble in a predictable manner at an air-water interface, with control of interstrand orientation through manipulation of Coulombic interactions along the backbone.
authors: Avram and Stella Goldstein-Goren Department of Biotechnology Engineering and The Ilze Katz Institute for Nanoscale Technology, Ben Gurion University of the Negev, P. O. Box 653, Beer-Sheva 84105, Israel.
authors: Shlomit
authors: S
authors: Segman-Magidovich
authors: Myung-ryul
authors: MR
authors: Lee
authors: Vladimir
authors: V
authors: Vaiser
authors: Bernd
authors: B
authors: Struth
authors: Samuel H
authors: SH
authors: Gellman
authors: Hanna
authors: H
authors: Rapaport
mesh_terms: D000388:Air; D000596:Amino Acids / Q000737:chemistry*; D018625:Microscopy, Atomic Force; D008968:Molecular Conformation; D010455:Peptides / Q000138:chemical synthesis* / Q000737:chemistry*; D057786:Peptidomimetics / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D013501:Surface-Active Agents / Q000737:chemistry*; D014867:Water; D014961:X-Ray Diffraction
chemical_list: D000596:Amino Acids; D010455:Peptides; D057786:Peptidomimetics; D013501:Surface-Active Agents; D014867:Water