Design of Peptides for Inhibiting Amyloidogenesis by Blocking Hydrophobic Interactions

Abstract

Abstract Amyloid fibrils, formed by the mis-assembly of proteins with abnormal conformations, are responsible for several neurodegenerative disorders, including prion disease. To prevent amyloid formation, it is necessary to block aggregation of the stem-forming regions of these proteins. Here we have designed and tested peptides for blocking β-sheet aggregation based on two fundamental criteria of amyloid formation: first, the hydrophobic interactions between residues on neighboring antiparallel β-strands are formed along a fibril axis; and second, the interacting hydrophobic residues are located on only one face of the β-strands. Blocking peptides designed with hydrophilic substitutions in the stem-forming regions of barnase 1–24 (BM1-24) were prepared by solid-phase peptide synthesis using Fmoc chemistry. Their effect on amyloid formation by BM1-24 and peptides of other amyloid-forming proteins was assessed by Thioflavin T (ThT) fluorescence assay and circular dichroism (CD) spectroscopy in the far-UV region. BM1-24 showed considerable amyloid formation, as indicated by a change in ThT fluorescence intensity (ΔF > 3). The addition of blocking peptides resulted in much lower fluorescence intesity (ΔF < 0.5), showing that amyloid formation was inhibited. CD spectroscopy suggested that the blocking peptide stabilized the β-structure of BM1-24. Addition of the blocking peptide to amyloid-forming peptides of prion, Amyloid β, and Pmel 17 led to a similar decline in ΔF, suggesting that amyloid formation was also inhibited in these proteins. Our results indicate that blocking peptides, designed according to the essential linear arrangement of hydrophobic residues, is effective at inhibiting amyloidogenesis in various types of proteins.