Figure 1.

(a) Electrophoretic mobilities (μ_e) and (b) diffusivities in water (D_w) of the purified prion protein fibrils as a function of pH at ionic strengths of 5 and 50 mM. Despite the abundance of positively charged residues in PrP, the purified fibrils exhibit negative μ_e values at all tested pH values. As a point of reference, Figure S3 displays the μ_e data as apparent ζ-potentials estimated using a uniform cylinder assumption.⁷²