Peptides that form β-sheets on hydrophobic surfaces accelerate surface-induced insulin amyloidal aggregation

•Insulin aggregation is accelerated by surface-adsorbed LVEALYL peptide at substoichiometric concentrations.•Peptides accelerating insulin aggregation adopt a beta-sheet conformation on hydrophobic surfaces.•The beta-sheet conformation of the peptide is essential for the effect on insulin aggregation.•The peptide (LKKLLKL)2, adopting an alpha-helix conformation on hydrophobic surfaces, strongly delays insulin aggregation.

Interactions between proteins and material or cellular surfaces are able to trigger protein aggregation in vitro and in vivo. The human insulin peptide segment LVEALYL is able to accelerate insulin aggregation in the presence of hydrophobic surfaces. We show that this peptide needs to be previously adsorbed on a hydrophobic surface to induce insulin aggregation. Moreover, the study of different mutant peptides proves that its sequence is less important than the secondary structure of the adsorbed peptide on the surface. Indeed, these pro-aggregative peptides act by providing stable β-sheets to incoming insulin molecules, thereby accelerating insulin adsorption locally and facilitating the conformational changes required for insulin aggregation. Conversely, a peptide known to form α-helices on hydrophobic surfaces delays insulin aggregation.

Structured summary of protein interactionsHI and HIbind by fluorescence technology (View interaction)