title: Tuning self-assembled morphology of the Aβ(16-22) peptide by substitution of phenylalanine residues.
abstract: The effects of the two phenylalanine (Phe) residues in the blocked Aβ(16-22) peptide on its self-assembly have been investigated by replacing both of them with two cyclohexylalanines (Chas) or two phenylglycines (Phgs). TEM and SANS studies revealed that the flat and wide nanoribbons of Aβ(16-22) were transformed into thin nanotubes when replaced with Chas, and thinner and twisted nanofibrils when replaced with Phgs. The red-shifting degree of characteristic CD peaks suggested an increased twisting in the self-assembly of the derivative peptides, especially in the case of Ac-KLV(Phg)(Phg)AE-NH2. Furthermore, molecular dynamics (MD) simulations also indicated the increasing trend in twisting when Chas or Phgs were substituted for Phes. These results demonstrated that the hydrophobic interactions and spatial conformation between Cha residues were sufficient to cause lateral association of β-sheets to twisted/helical nanoribbons, which finally developed into nanotubes, while for Phg residue, the loss of the rotational freedom of the aromatic ring induced much stronger steric hindrance for the lateral stacking of Ac-KLV(Phg)(Phg)AE-NH2 β-sheets, eventually leading to the nanofibril formation. This study thus demonstrates that both the aromatic structure and the steric conformation of Phe residues are crucial in Aβ(16-22) self-assembly, especially in the significant lateral association of β-sheets.
authors: Centre for Bioengineering and Biotechnology, China University of Petroleum (East China), Qingdao 266580, China. Electronic address: jqwang@upc.edu.cn.
authors: Jiqian
authors: J
authors: Wang
authors: Centre for Bioengineering and Biotechnology, China University of Petroleum (East China), Qingdao 266580, China.
authors: Kai
authors: K
authors: Tao
authors: Centre for Bioengineering and Biotechnology, China University of Petroleum (East China), Qingdao 266580, China.
authors: Peng
authors: P
authors: Zhou
authors: Biological Physics Group, School of Physics and Astronomy, University of Manchester, Schuster Building, Oxford Road, Manchester M13 9PL, United Kingdom.
authors: Elias
authors: E
authors: Pambou
authors: Biological Physics Group, School of Physics and Astronomy, University of Manchester, Schuster Building, Oxford Road, Manchester M13 9PL, United Kingdom.
authors: Zongyi
authors: Z
authors: Li
authors: Centre for Bioengineering and Biotechnology, China University of Petroleum (East China), Qingdao 266580, China. Electronic address: xuh@upc.edu.cn.
authors: Hai
authors: H
authors: Xu
authors: ISIS Pulsed Neutron Source, Rutherford Appleton Laboratory, Didcot, Oxon OX11 0QZ, United Kingdom.
authors: Sarah
authors: S
authors: Rogers
authors: ISIS Pulsed Neutron Source, Rutherford Appleton Laboratory, Didcot, Oxon OX11 0QZ, United Kingdom.
authors: Stephen
authors: S
authors: King
authors: Biological Physics Group, School of Physics and Astronomy, University of Manchester, Schuster Building, Oxford Road, Manchester M13 9PL, United Kingdom.
authors: Jian R
authors: JR
authors: Lu
mesh_terms: D016229:Amyloid beta-Peptides / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D006863:Hydrogen-Ion Concentration; D057927:Hydrophobic and Hydrophilic Interactions; D018625:Microscopy, Atomic Force; D046529:Microscopy, Electron, Transmission; D056004:Molecular Dynamics Simulation; D043942:Nanotubes / Q000737:chemistry*; D010649:Phenylalanine / Q000737:chemistry* / Q000378:metabolism; D053838:Scattering, Small Angle
chemical_list: D016229:Amyloid beta-Peptides; D010649:Phenylalanine
keywords: Amyloid peptides; Aromatic interaction; Morphology; Self-assembly; Steric hindrance