Figure 4.

In situ tapping mode AFM images of aggregation of Aβ in contact with mica at high peptide concentration (500 μM). All images were digitally zoomed in from a 3- × 3-μm scan. (A–E) Time course of the process of assembly of globular aggregates into a linear protofibril located on the right side of an image. Notice that the branched protofibrillar assembly located on the left side remained mostly static over the same period. The time interval between the images was 256 s. (F) Three-dimensional rendering of the surface of mica covered with globular and protofibrillar aggregates of Aβ. (G) Schematic of the proposed mechanism of the early stages of formation of pseudomicellar aggregates of an amphipathic peptide on a hydrophilic substrate. (The hydrophilic and hydrophobic portions of peptide chains are colored, respectively, in purple and in yellow.)