Multiple Lyotropic Polymorphism of a Poly(ethylene glycol)-Peptide Conjugate in Aqueous Solution

Abstract

The observation of nematic and columnar phases in a poly(ethylene glycol) (PEG) peptide conjugate in which the peptide is a modified fragment of the amyloid β (Aβ) peptide, specifically KLVFF extended by two phenylalanine residues at the N terminus to FFKLVFF, was reported. The PEGylated conjugate was synthesized by solid phase peptide synthesis using standard FastMoc chemistry. FFKLVFF-PEG was synthesized on a 0.25 mmol scale using a fully automated peptide synthesizer, which allowed for direct conductivity monitoring of Fmoc deprotection. A PEGylated TentaGel PAP resin was used, with 0.21 mmol substitution of PLG3000 to provide C-terminal PEGylation upon cleavage from the resin. The crude peptide was purified by reversephase HPLC. Small-angle X-ray scattering exhibited spontaneous alignment, because of shear experienced by the sample on loading.