FIGURE 8.

Heparin-induced aggregation of WT peptide is pH-dependent. A and B, 100 μm WT peptide was allowed to aggregate at 25 °C for 18 h at pH 5.0 (black bars) or pH 7.5 (gray bars) in the absence or presence of heparin (10, 20, or 30 μm as mentioned), and the absorbance at 330 nm (A) or Th-T binding (B) was evaluated. C and D, TEM images of the fibrils grown in the presence of 30 μm heparin. Bars, 1 and 0.5 μm, as indicated. E, WT peptide aggregation kinetics at pH 5.0 and 25 °C induced by increasing heparin concentrations, as followed by absorbance at 330 nm (filled circles, 10 μm heparin; triangles, 20 μm heparin; squares, 30 μm heparin). Note that WT peptide does not aggregate in the absence of heparin (hollow squares). Error bars, S.E.