Effects of model membranes on lysozyme amyloid aggregation

Area of Science:

• Biochemistry
• Biophysics
• Neuroscience

Background:

• Amyloidogenic peptides are implicated in neurodegenerative diseases.
• Understanding peptide-membrane interactions is key to elucidating cytotoxicity.
• Lysozyme aggregation serves as a model for amyloid formation.

Purpose of the Study:

• To investigate the effect of phospholipids (POPC and POPG) on lysozyme amyloid fibril formation.
• To explore how lipid presence influences the kinetics and structure of amyloid aggregation.
• To study these interactions both above and below the critical micellar concentration (CMC).

Main Methods:

• Dynamic Light Scattering (DLS) for aggregate size analysis.
• Atomic Force Microscopy (AFM) for structural visualization.
• UV-Vis Spectrophotometry to quantify secondary structure changes.
• Quartz Crystal Microbalance (QCM) for interaction monitoring.

Main Results:

• Phospholipids (POPC and POPG) were found to favor the formation of amyloid aggregates.
• Spectrophotometry and DLS data indicated an increase in beta-sheet structures in the presence of these lipids.
• The rate of amyloid nucleation increased significantly with POPG and POPC.
• The overall structure of the final amyloid fibrils remained unaltered.

Conclusions:

• Polar and zwitterionic phospholipids accelerate lysozyme amyloid nucleation and fibril formation.
• Lipid-membrane interactions play a significant role in modulating amyloid aggregation pathways.
• These findings contribute to understanding the role of cellular membranes in amyloid-related pathologies.