Aggregation of amyloidogenic peptides near hydrophobic and hydrophilic surfaces.

The general effect of surface hydrophobicity/hydrophilicity on the aggregation of peptides is studied by simulations of oversaturated aqueous solutions of hydrophobic and hydrophilic amyloidogenic peptides. Peptide aggregation was studied in bulk solution, in solutions confined between hydrophobic boundaries (smooth planar paraffin-like surfaces and liquid-vapor interfaces) and in solutions confined between hydrophilic surfaces (smooth planar silica-like surfaces). Aggregation of hydrophobic peptides strongly enhances due to the confinement between hydrophobic surfaces with all peptides adsorbed at the boundaries and aligned predominantly parallel to them. In the other three cases considered, the peptides are repelled from the walls and do not reveal orientational ordering with respect to the surface. The degree of peptide aggregation in these cases is only slightly affected by the confinement (it is enhanced for hydrophobic peptides and decreased for hydrophilic peptides). Our results show that even a single environmental factor such as water-mediated peptide-surface interaction has a drastic effect on the degree and character of peptide aggregation. A wide diversity of possible scenarios can be expected when specific peptide-surface interactions are additionally taken into account.