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Acidic pH Promotes Refolding and Macroscopic Assembly of Amyloid β (16-22) Peptides at the Air-Water Interface.

Hao LuLuca BellucciShumei SunDaizong QiMarta RosaRüdiger BergerStefano CorniMischa Bonn
Published in: The journal of physical chemistry letters (2022)
Assembly by amyloid-beta (Aβ) peptides is vital for various neurodegenerative diseases. The process can be accelerated by hydrophobic interfaces such as the cell membrane interface and the air-water interface. Elucidating the assembly mechanism for Aβ peptides at hydrophobic interface requires knowledge of the microscopic structure of interfacial peptides. Here we combine scanning force microscopy, sum-frequency generation spectroscopy, and metadynamics simulations to probe the structure of the central fragment of Aβ peptides at the air-water interface. We find that the structure of interfacial peptides depends on pH: at neutral pH, the peptides adopt a less folded, bending motif by forming intra-hydrogen bonds; at acidic pH, the peptides refold into extended β-strand fibril conformation, which further promotes their macroscopic assembly. The conformational transition of interfacial peptides is driven by the reduced hydrogen bonds, both with water and within peptides, resulting from the protonation of acidic glutamic acid side chains.
Keyphrases
  • ionic liquid
  • amino acid
  • molecular dynamics simulations
  • healthcare
  • high resolution
  • molecular dynamics
  • optical coherence tomography
  • electron transfer
  • living cells
  • fluorescent probe
  • transition metal
  • monte carlo