Self-assembly of a modified amyloid peptide fragment: pH-responsiveness and nematic phase formation

TY - JOUR

T1 - Self-assembly of a modified amyloid peptide fragment

T2 - pH-responsiveness and nematic phase formation

AU - Hamley, Ian W.

AU - Castelletto, Valeria

AU - Moulton, Claire

AU - Myatt, Daniel

AU - Siligardi, Giuliano

AU - Oliveira, Cristiano L.P.

AU - Pedersen, Jan Skov

AU - Abutbul, Inbal

AU - Danino, Dganit

PY - 2010/1/11

Y1 - 2010/1/11

N2 - The self-assembly of peptide YYKLVFFC based on a fragment of the amyloid beta (Aβ) peptide, Aβ16-20, KLVFF has been studied in aqueous solution. The peptide is designed with multiple functional residues to examine the interplay between aromatic interactions and charge on the self-assembly, as well as specific transformations such as the pH-induced phenol-phenolate transition of the tyrosine residue. Circular dichroism (CD) and Fourier-transform infrared (FTIR) spectroscopies are used to investigate the conditions for β-sheet self-assembly and the role of aromatic interactions in the CD spectrum as a function of pH and concentration. The formation of well-defined fibrils at pH 4.7 is confirmed by cryo-TEM (transmission electron microscope) and negative stain TEM. The morphology changes at higher pH, and aggregates of short twisted fibrils are observed at pH 11. Polarized optical microscopy shows birefringence at a low concentration (1 wt.-%) of YYKLVFFC in aqueous solution, and small-angle X-ray scattering was used to probe nematic phase formation in more detail. A pH-induced transition from nematic to isotropic phases is observed on increasing pH that appears to be correlated to a reduction in aggregate anisotropy upon increasing pH. (Figure Presented).

AB - The self-assembly of peptide YYKLVFFC based on a fragment of the amyloid beta (Aβ) peptide, Aβ16-20, KLVFF has been studied in aqueous solution. The peptide is designed with multiple functional residues to examine the interplay between aromatic interactions and charge on the self-assembly, as well as specific transformations such as the pH-induced phenol-phenolate transition of the tyrosine residue. Circular dichroism (CD) and Fourier-transform infrared (FTIR) spectroscopies are used to investigate the conditions for β-sheet self-assembly and the role of aromatic interactions in the CD spectrum as a function of pH and concentration. The formation of well-defined fibrils at pH 4.7 is confirmed by cryo-TEM (transmission electron microscope) and negative stain TEM. The morphology changes at higher pH, and aggregates of short twisted fibrils are observed at pH 11. Polarized optical microscopy shows birefringence at a low concentration (1 wt.-%) of YYKLVFFC in aqueous solution, and small-angle X-ray scattering was used to probe nematic phase formation in more detail. A pH-induced transition from nematic to isotropic phases is observed on increasing pH that appears to be correlated to a reduction in aggregate anisotropy upon increasing pH. (Figure Presented).

KW - Amyloid

KW - Gel

KW - Nematic

KW - Peptide

KW - Self-assembly

UR - http://www.scopus.com/inward/record.url?scp=75749129851&partnerID=8YFLogxK

U2 - 10.1002/mabi.200900217

DO - 10.1002/mabi.200900217

M3 - 文章

C2 - 19768777

AN - SCOPUS:75749129851

SN - 1616-5187

VL - 10

SP - 40

EP - 48

JO - Macromolecular Bioscience

JF - Macromolecular Bioscience

IS - 1

ER -