Comparison of MAβ with Aβ. (A) SDS-PAGE using 16.5% Tris-Tricine gels at 21°C (lanes 1–4) or 4°C (lanes 5–8). Lanes 1 and 5: MAβ(1–40). 2 and 6: Aβ(1–40). 3 and 7: MAβ(1–42). 4 and 8: Aβ(1–42). Unlabeled lanes contain marker. Samples were incubated for 2 min at 95°C prior to loading. (B) Elution profiles of analytical SEC of MAβ(1–40) (red line), Aβ(1–40) (red circles), MAβ(1–42) (black line), Aβ(1–42) (black circles). (C) Far-UV CD spectra of MAβ(1–40) (red line), Aβ(1–40) (red circles), MAβ(1–42) (black line), Aβ(1–42) (black circles). (D) Kinetics of amyloid fibril formation of MAβ(1–42) (red) and Aβ(1–42) (black) monitored by thioflavin T fluorescence. The average of 3 time traces is shown with error bars representing the maximal and minimal values. The peptides were used at 25 μM in 20 mM sodium phosphate, 50 mM sodium chloride, 10 μM thioflavin T, pH 7.2. Temperature, 37°C. (E) and (F) Electron micrographs of amyloid fibrils formed by MAβ(1–42) (E) and Aβ(1–42) (F). Scale bar, 200 nm.