Unveiling the effect of CaCl₂ on amyloid β aggregation via supercritical angle Raman and fluorescence spectroscopy...

Area of Science:

• Biochemistry
• Neuroscience
• Biophysics

Background:

• Amyloid-beta (Aβ) aggregation is a key hallmark of Alzheimer's disease (AD).
• Calcium homeostasis is intrinsically linked to Aβ aggregation dynamics.
• Directly studying Aβ-calcium ion interactions at membrane surfaces is crucial for understanding AD pathogenesis.

Purpose of the Study:

• To investigate the influence of calcium ions on amyloid-beta aggregation over time.
• To compare the effect of calcium ions on different amyloid-beta variants (Aβ42 vs. Aβ40).
• To elucidate the protective role of calcium ions on lipid membranes during protein aggregation.

Main Methods:

• Utilized supercritical angle Raman spectroscopy and fluorescence spectroscopy.
• Employed supercritical angle microscopy for surface-specific analysis.
• Investigated amyloid-beta aggregation kinetics and membrane interactions under varying calcium concentrations and time points.

Main Results:

• Calcium ions significantly influence amyloid-beta aggregation, with a more pronounced effect on amyloid-beta 1-42 compared to the 40 amino acid variant.
• A thin layer of calcium ions was observed to provide substantial protection to the lipid membrane.
• This protection was evident in the reduced protein insertion into the membrane.

Conclusions:

• Calcium ions play a critical role in modulating amyloid-beta aggregation at the membrane interface.
• Amyloid-beta 1-42 aggregation is more sensitive to calcium ion concentration than amyloid-beta 40.
• Calcium ions act as a protective agent for lipid membranes against amyloid-beta-induced damage, suggesting potential therapeutic implications for Alzheimer's disease.