The amyloidogenic peptide amyloid beta(16-22) displays facet dependent conformation on metal surfaces

Currently, it is not understood how metal nanoparticles influence the formation of protein fibrils, although recent literature highlights that the shape and chemical composition of such nanoparticles can strongly influence the process. Understanding this process at a fundamental level can potentially unlock routes to the development of new therapeutics, as well as novel materials for other applications. This requires a microscopic picture of the behaviour of amyloidogenic proteins on metal surfaces. Using replica exchange molecular dynamics simulations we investigate the adsorption of the model amyloidogenic peptide, A𝛽(16-22), on different gold and silver surfaces. While the peptide adsorbs onto these different surfaces, the adsorption can be considered to be enthalphically driven for the gold surfaces and entropically driven for silver. The conformation of the peptide on gold surfaces also shows a strong facet dependence for gold, with fibril-like conformations being promoted in the 100 surface and inhibited on the 111 surface. A smaller degree of facet dependence is seen for silver with the peptide behaving similar on both of these. The difference in the facet dependence can be related to the difference between direct adsorption onto the gold 111 surface, with a preference towards indirect (water mediated) adsorption onto the other surfaces. This new information on the behaviour of an amyloidogenic peptide on metal surfaces can give insight into the size-dependent effect of nanoparticles on fibril formation and the use of surfaces to control fibrillation.