Interaction of Amyloid-β-(1-42) Peptide and Its Aggregates with Lipid/Water Interfaces Probed by Vibrational Sum-Frequency Generation Spectroscopy

S. Strazdaite*, S. J. Roeters*, A. Sakalauskas, T. Sneideris, J. Kirschner, K. B. Pedersen, B. Schiøtt, F. Jensen, T. Weidner, V. Smirnovas, G. Niaura

*Corresponding author for this work

Research output: Contribution to journal/Conference contribution in journal/Contribution to newspaperJournal articleResearchpeer-review

Abstract

In this study, we use surface-sensitive vibrational sum-frequency generation (VSFG) spectroscopy to investigate the interaction between model lipid monolayers and Aβ(1-42) in its monomeric and aggregated states. Combining VSFG with atomic force microscopy (AFM) and thioflavin T (ThT) fluorescence measurements, we found that only small aggregates with probably a β-hairpin-like structure adsorbed to the zwitterionic lipid monolayer (DOPC). In contrast, larger aggregates with an extended β-sheet structure adsorbed to a negatively charged lipid monolayer (DOPG). The adsorption of small, initially formed aggregates strongly destabilized both monolayers, but only the DOPC monolayer was completely disrupted. We showed that the intensity of the amide-II′ band in achiral (SSP) and chiral (SPP) polarization combinations increased in time when Aβ(1-42) aggregates accumulated at the DOPG monolayer. Nevertheless, almost no adsorption of preformed mature fibrils to DOPG monolayers was detected. By performing spectral VSFG calculations, we revealed a clear correlation between the amide-II′ signal and the degree of amyloid aggregates (e.g., oligomers or (proto)fibrils) of various Aβ(1-42) structures. The calculations showed that only structures with a significant amyloid β-sheet content have a strong amide-II′ intensity, in line with previous Raman studies. The combination of the presented results substantiates the amide-II(′) band as a legitimate amyloid marker.

Original languageEnglish
JournalJournal of Physical Chemistry B
Volume125
Issue40
Pages (from-to)11208-11218
Number of pages11
ISSN1520-6106
DOIs
Publication statusPublished - Oct 2021

Keywords

  • ALZHEIMERS-DISEASE
  • ATOMIC-RESOLUTION STRUCTURE
  • BETA-PEPTIDE
  • CONFORMATION
  • DYNAMICS
  • FIBRILS
  • ISLET AMYLOID POLYPEPTIDE
  • MECHANISM
  • MEMBRANE
  • PROTEIN AGGREGATION

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