title: Peptide-surfactant interactions: consequences for the amyloid-beta structure.
abstract: The conformation of amyloid-beta peptide (Aβ) determines if toxic aggregates are formed. The peptide structure by its turn depends on the environment and molecule-molecule interactions. We characterized the secondary structure of Aβ-(1-40) in surfactant solutions and interacting with monolayers. The peptide adopts β-sheet structure in solutions of ionic surfactants at sub-micelle concentrations and α-helix in the presence of ionic micelles. Uncharged micelles induce β-sheets. Aβ-(1-40) alters the critical micelle concentration value of the non-ionic surfactant, underlining hydrophobic interactions. At ionic monolayers the peptide forms β-sheets when its concentration at the surface is high enough. These results suggest that only electrostatic interactions of charged micelles that surround completely the peptide are able to induce non-aggregated α-helix structure.
authors.affiliation: LEPAE, Department of Chemical Engineering, Faculty of Engineering, University of Porto, Rua Roberto Frias, Porto, Portugal. sandra.rocha@fe.up.pt
authors.forename: Sandra
authors.initials: S
authors.lastname: Rocha
authors.forename: Joana A
authors.initials: JA
authors.lastname: Loureiro
authors.forename: Gerald
authors.initials: G
authors.lastname: Brezesinski
authors.forename: Maria do Carmo
authors.initials: Mdo C
authors.lastname: Pereira
mesh_terms: D000595:Amino Acid Sequence; D016229:Amyloid beta-Peptides / Q000737:chemistry*; D002942:Circular Dichroism; D006801:Humans; D008823:Micelles; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry*; D017433:Protein Structure, Secondary; D013501:Surface-Active Agents / Q000737:chemistry*
chemical_list: D016229:Amyloid beta-Peptides; D008823:Micelles; D010446:Peptide Fragments; D013501:Surface-Active Agents; C078592:amyloid beta-protein (1-40)