Synthesis and mass spectrometric characterization of a metal-affinity decapeptide: copper-induced conformational...

A decapeptide with high affinity toward heavy metal ions (RCHQYHHNRE) has been prepared by Fmoc strategy using TGR resin as solid support. The model peptide provides a simple system that can be used for a systematic study of the impact of different metal ions on peptide secondary structure on a molecular level; histidine residues were incorporated into the peptide in a sequence similar to beta-amyloid peptide (Abeta1-40) to generate possible complexation sites for Cu (2+) ions. The peptide secondary structure, as investigated by circular dichroism, and self-assembled nanostructures were observed to depend strongly on the presence of copper and sodium dodecyl sulfate (SDS). Atomic force microscopy (AFM) revealed also that copper and SDS affected slightly the Abeta1-40 nanostructures. An explanation for the effect of metal ions and SDS on the self-assembly of peptides was proposed. The extensive beta-sheet formation may further promote peptide self-assembly into longer fibers.