(A) Thioflavin T and fluorescence were used to study the kinetics of polymerization of TasA. Purified TasA was treated with formic acid, dried under vacuum and mixed with physiological buffer (○) or DMSO (▲), plus 50 μM of AA-861 (●) or parthenolide (□). Transmission electron micrographs of samples taken after 24 hr of incubation of (B) TasA in buffer, (C) TasA treated with DMSO, (D) TasA treated with AA-861 and (E) TasA treated with parthenolide. Scale bars, 100 nm.