Fig. 7.

The a48/65(N62K) blocked amyloid fibril formation of amyloidogenic APOA2A peptides by inhibition of seeding activities. Amyloid fibril formation by the APOA2A peptides (a6/16 + a48/65) mixed with a48/65(N62K) at various times (A), with or without preincubated seeds (B), and the remaining amounts of premade fibrils after treatments with C-terminal peptides (E). Each symbol and bar represents the mean ± SD (n = 3 in A and B, and 5 in E). a.u., arbitrary units. (A) ThT plots of APOA2A peptides mixed with a48/65(N62K) from the beginning of agitation [initial phase (I)], after 4.5 h [linear phase (L)] and 24 h [plateau phase (P)] of incubation. Each concentration of peptides in the mixture was 50 µM. (B) ThT plots of the APOA2A peptides in the presence of preincubated seeds. (C) TEM images of the mixtures with preincubated seeds after 48 h of incubation in B. (Scale bars: 100 nm.) (D) TEM images of the preincubated seeds with biotin-labeled a48/65(N62K) using immunoelectron microscopy. Colloidal gold with streptavidin was detected close to the head of fibrils (arrows). (Scale bars: 50 nm.) (E) Remaining amounts of premade fibrils after incubation with C-terminal peptides. ThT intensities are expressed as a percentage of the level observed at the beginning of agitation. There was no significant difference among the curves of ThT intensities (one-way ANOVA).