Low-frequency Raman spectra of amyloid fibrils.

Area of Science:

• Biophysics
• Spectroscopy
• Materials Science

Background:

• Amyloid fibrils are protein aggregates implicated in various diseases.
• Understanding their supramolecular structure is crucial for disease mechanism studies.
• Existing methods for structural investigation can be complex.

Purpose of the Study:

• To establish low-frequency Raman spectroscopy as a facile tool for amyloid fibril investigation.
• To correlate specific Raman spectral features with supramolecular structural parameters.
• To provide insights into the packing and ordering within amyloid fibril β-sheets.

Main Methods:

• Acquisition and analysis of low-frequency Raman spectra (<500 cm⁻¹).
• Preparation of six different amyloid fibrils from various peptides (amyloid-β1-40, amylin, etc.).
• Utilizing semi-empirical tight-binding calculations and literature data for band assignment.

Main Results:

• Demonstrated the utility of low-frequency Raman spectra (<500 cm⁻¹) for amyloid fibril analysis.
• Proposed band assignments for key vibrational modes.
• Showcased the ability of Raman modes to probe inter-strand and side-chain interactions.

Conclusions:

• Low-frequency Raman spectroscopy is an effective and accessible method for characterizing amyloid fibril supramolecular structures.
• The technique provides detailed information on the packing and ordering of β-sheets.
• This approach can advance the understanding of fibril formation and related pathologies.