Binding of methylene blue to a surface cleft inhibits the oligomerization and fibrillization of prion protein

► MB is currently under study for neurodegenerative diseases. ► MB significantly affects the kinetics of PrP oligomerization. ► MB reduces the amount of PrP oligomer and completely suppresses fiber formation. ► NMR revealed that PrP hosts MB in a surface cleft. ► MB can be considered an anti-aggregation compound against proteinopathies.