Table 1.
Characteristics of Aβ assemblies
| Sample | α-Helix* | β-Sheet* | SC* | Diameter† | Height‡ | EC50§ |
|---|---|---|---|---|---|---|
| Uncross-linked | 9.4 | 25.2 | 65.4 | 1.15 ± 0.17 (79) | 0.14 ± 0.01 (135) | 102.5 ± 5.6 |
| Cross-linked | 11.1 | 33.6 | 55.3 | 12.39 ± 2.13 (55) | 2.93 ± 0.40 (56) | 43.0 ± 2.7 |
| Pure monomer | 8.7 | 24.0 | 67.3 | 1.30 ± 0.13 (127) | 0.24 ± 0.01 (178) | 67.3 ± 8.7 |
| Pure dimer | 10.5 | 38.6 | 50.9 | 1.78 ± 0.23 (116) | 0.53 ± 0.03 (165) | 41.6 ± 3.9 |
| Pure trimer | 10.3 | 40.8 | 48.9 | 7.22 ± 1.12 (64) | 0.94 ± 0.13 (67) | 24.5 ± 1.9 |
| Pure tetramer | 12.7 | 44.9 | 42.4 | 11.00 ± 2.08 (39) | 1.51 ± 0.30 (38) | 20.5 ± 0.4 |
| Fibrils | ND | 57.0 | 43.0 | ND | ND | 57.6 ± 2.2 |
ND, not determined.
*CD data are expressed as percent of each secondary structure element.
†Mean diameter ± SE, in nm, is listed for (n) Aβ assemblies visualized by EM.
‡Mean height ± SE, in nm, is listed for (n) Aβ assemblies visualized by AFM.
§Effective concentration (EC50) is the concentration of a particular Aβ assembly that produced a level of toxicity in MTT assays that was half maximal. EC50 [mean concentration (μM) ± SE] values were calculated after sigmoidal curve fitting of the data shown in Fig. S5, using GraphPad Prism software (version 4.0a).