Structure Comparison of Beta Amyloid Peptide Aβ 1-42 Isoforms. Molecular Dynamics Modeling

Area of Science:

• Biochemistry
• Computational Biology
• Neuroscience

Background:

• Beta-amyloid peptide Aβ42 (Aβ42) plays a dual role, essential physiologically but toxic in Alzheimer's disease (AD).
• Neurotoxic Aβ42 isoforms are linked to early-onset AD, yet Aβ42 lacks a defined structure under physiological conditions.
• Understanding Aβ42 structure is critical for elucidating AD mechanisms and developing therapeutic strategies.

Purpose of the Study:

• To establish a robust molecular dynamics (MD) methodology for modeling Aβ42 isoforms.
• To generate a uniform and representative set of structures for key Aβ42 and Aβ16 isoforms.
• To provide a reliable structural dataset for investigating the neurotoxic and amyloidogenic properties of Aβ42 variants.

Main Methods:

• Force field selection, verification, and convergence testing for MD simulations.
• Replica exchange MD and conventional MD modeling of multiple Aβ42 and Aβ16 isoforms.
• Calculation of standardized structural ensembles from MD trajectories, representing free energy minima.

Main Results:

• A validated MD methodology was established for modeling intrinsically disordered Aβ42 and Aβ16.
• A comprehensive dataset of representative structures for wild-type and mutant Aβ42/Aβ16 isoforms was generated.
• Differences among Aβ42 isoform structures were evaluated for potential functional relevance.

Conclusions:

• The developed MD approach provides a standardized structural ensemble for neurotoxic Aβ42 isoforms.
• This structural dataset enhances the reliability of computational studies, such as molecular docking, for AD research.
• The findings contribute to a deeper understanding of Aβ42's role in Alzheimer's disease pathogenesis.