Quenched hydrogen/deuterium exchange NMR characterization of amyloid-β peptide aggregates formed in the presence of Cu2+ or Zn2+

• Alzheimer's disease, a neurodegenerative disorder causing synaptic impairment and neuronal cell death, is strongly correlated with aggregation of the amyloid-β peptide (Aβ). Divalent metal ions such as Cu2+ and Zn2+ are known to significantly affect the rate of aggregation and morphology of Aβ assemblies in vitro and are also found at elevated levels within cerebral plaques in vivo. The present investigation characterized the architecture of the aggregated forms of Aβ(1–40) and Aβ(1–42) in the presence or absence of either Cu2+ or Zn2+ using quenched hydrogen/deuterium exchange combined with solution NMR spectroscopy. The NMR analyses provide a quantitative and residue-specific structural characterization of metal-induced Aβ aggregates, showing that both the peptide sequence and the type of metal ion exert an impact on the final architecture. Common features among the metal-complexed peptide aggregates are two solvent-protected regions with an intervening minimum centered at Asn27, and a solvent-accessible N-terminal region, Asp1–Lys16. Our results suggest that Aβ in complex with either Cu2+ or Zn2+ can attain an aggregation-prone β-strand–turn–β-strand motif, similar to the motif found in fibrils, but where the metal binding to the N-terminal region guides the peptide into an assembly distinctly different from the fibril form.

Keyword

Alzheimer's disease

amyloid-β peptide

Cu2

H/D exchange NMR

Zn2

Publication and Content Type

ref (subject category)

art (subject category)