Modeling the dimerization of amyloid-β(1-40) and amyloid-β(1-42).

Area of Science:

• Biophysics
• Computational Biology
• Neuroscience

Background:

• Amyloidogenic protein aggregation, particularly amyloid-beta (Aβ), is implicated in neurodegenerative diseases.
• Early-stage oligomeric aggregates are of significant pathogenic interest.
• Understanding the thermodynamics of Aβ dimerization is crucial for disease mechanism insights.

Purpose of the Study:

• To comparatively investigate the dimerization thermodynamics of Aβ(1-40) and Aβ(1-42).
• To elucidate the structural basis for differential aggregation rates between Aβ(1-40) and Aβ(1-42).

Main Methods:

• Utilized an intermediate-resolution protein model (PRIME20).
• Employed a flat-histogram Monte Carlo technique (stochastic approximation Monte Carlo).
• Analyzed secondary structure formation and intermolecular hydrogen bonding in Aβ dimers.

Main Results:

• Aggregation drives secondary structure (β-sheet) formation in both Aβ(1-40) and Aβ(1-42) dimers.
• Aβ(1-42) dimers show enhanced intermolecular hydrogen bonding and a more defined pattern compared to Aβ(1-40).
• Aβ(1-42) dimers exhibit less structural polymorphism than Aβ(1-40) dimers.

Conclusions:

• The findings provide a molecular explanation for the faster aggregation and fibril growth of Aβ(1-42) versus Aβ(1-40).
• Stronger, more defined intermolecular interactions in Aβ(1-42) dimers contribute to its accelerated aggregation.
• The study highlights the role of early dimerization thermodynamics in amyloid fibril formation.