Title
Interaction of Amyloid Aβ(9–16) Peptide Fragment with Metal Ions: CD, FT-IR, and Fluorescence Spectroscopic Studies
Author
Manuela Murariu, Laura Habasescu, Catalina-Ionica Ciobanu, Robert Vasile Gradinaru. Aurel Pui, Gabi Drochioiu, Ionel Mangalagiu
Year
2018
Journal
International Journal of Peptide Research and Therapeutics
Abstract
Heavy metal ions and those of aluminum may interact with amyloid-β peptides (Αβ) associated with Alzheimer’s disease, contributing to Aβ aggregation and fibrillation that worsen this neuropathology. Nevertheless, the precise residues involved in metal ligation or interaction are yet to be established, although the N-terminal Aβ(1–16) peptide fragment is considered to be the metal-binding domain. However, because the results of the metal ion binding studies using Aβ(1–16) were not very conclusive, we have investigated shorter peptides. Here, we report the synthesis of truncated Aβ(9–16) peptide of the human Aβ(1–40) and Aβ(1–42) peptides, as well as its characterization by nuclear magnetic resonance and mass spectrometry. Furthermore, the Aβ(9–16) peptide interactions with various metal ions like Cu2+, Zn2+, Fe3+, Al3+, and Ni2+were studied by circular dichroism, Fourier transform-infrared, and fluorescence spectroscopy. Our results show that the newly synthesized peptide sequence, which contains just two histidine and one tyrosine residues, seems to be a key site for metal binding, which was not thoroughly investigated so far. Light scattering spectra of Aβ(9–16) and its complexes with metal ions were measured, whereas some fluorescence experiments were also performed. Our data suggest that Aβ(9–16) peptide fragment coordination by metal ions is dependent on the type of metal, and the amino acid residues involved in metal bonding.
Instrument
J-720
Keywords
Circular dichroism, Secondary structure, Ligand binding, Biochemistry