Increase in the β-Sheet Character of an Amyloidogenic Peptide upon Adsorption onto Gold and Silver Surfaces.

Abstract

Fibrillation of amyloid beta (Aβ) peptide is the hallmark of Alzheimer's disease. Given that interactions at the bio-nano interface affect the fibrillation tendency of this peptide, an understanding of the interactions at Aβ peptide-inorganic surfaces on the microscopic level can help to determine the possible neurotoxicity of nanoparticles. Here, the interactions between a fibril-forming peptide, Aβ25-35 , and (111) and (100) facets of gold and silver surfaces have been studied by conducting atomistic molecular dynamics simulations. The obtained results indicate that the adsorption onto gold and silver surfaces force the peptide into the β-sheet-rich conformations, which is prone to aggregation, suggesting a new mechanism for the acceleration of fibril formation upon interaction with nanoparticles. To quantify the β-sheet content for a single peptide, a new metrics based on the Ramachandran probability distribution is introduced.