Interaction of Therapeutic D-Peptides with Aβ42 Monomers, Thermodynamics, and Binding Analysis

The aggregation of the amyloid-beta (A beta) peptide is a major hallmark of Alzheimer's disease. This peptide can aggregate into oligomers, proto-fibrils, and mature fibrils, which eventually assemble into amyloid plaques. The peptide monomers are the smallest assembly units and play an important role in most of the individual processes involved in amyloid fibril formation, such as primary and secondary nucleation and elongation. Several D-peptides have been confirmed as promising candidates to inhibit the aggregation of A beta into toxic oligomers and fibrils by specifically interacting with monomeric species. In this work, we elucidate the structural interaction and thermodynamics of binding between three D-peptides (D3, ANK6, and RD2) and A beta 42 monomers by means of enhanced molecular dynamics simulations. Our study derives thermodynamic energies in good agreement with experimental values and suggests that there is an enhanced binding for D3 and ANK6, which leads to more stable complexes than for RD2. The binding of D3 to A beta 42 is shown to be weakly exothermic and mainly entropically driven, whereas the complex formation between the ANK6 and RD2 with the A beta 42 free monomer is weakly endothermic. In addition, the changes in the solvent-accessible surface area and the radius of gyration support that the binding between A beta 42 and D-peptides is mainly driven by electrostatic and hydrophobic interactions and leads to more compact conformations.

Automated summary

The study elucidates the structural interaction and thermodynamics of binding between three D-peptides and A beta 42 monomers, revealing that the binding is mainly driven by electrostatic and hydrophobic interactions and leads to more compact conformations.