Does amino acid sequence determine the properties of Aβ dimer?

Area of Science:

• Biophysics
• Computational Biology
• Polymer Physics

Background:

• Amyloid-beta (Aβ) peptides are implicated in neurodegenerative diseases.
• Understanding Aβ peptide aggregation into dimers is crucial for disease mechanism studies.
• The role of amino acid sequence in Aβ dimer properties remains an area of investigation.

Purpose of the Study:

• To investigate the impact of amino acid sequence randomization on Aβ peptide dimer properties.
• To determine if Aβ dimer thermodynamics and structure are sequence-dependent.
• To explore the underlying physical principles governing Aβ dimer formation.

Main Methods:

• Replica exchange molecular dynamics simulations.
• United atom implicit solvent model.
• Analysis of thermodynamic properties, structural states, and non-local interactions.

Main Results:

• Thermodynamics of dimer assembly and globule-like states are unaffected by sequence permutation.
• Amino acid distributions and non-local interactions within dimers remain largely unchanged after reshuffling.
• Gaussian statistics accurately describe peptide end-to-end distances, indicating effective screening of interactions.

Conclusions:

• Aβ dimer properties, such as large-scale structure and thermodynamics, are universal and sequence-independent.
• Peptides within dimers behave like ideal polymer chains, losing sequence memory.
• These findings have implications for understanding Aβ aggregation and designing therapeutic strategies.