Figure 1. Structural models of double-layer Aβ segmental polymorphism proposed by Eisenberg group.
(A) Schematic representation of the U turn structure of Aβ single layer based on ss-NMR. The first beta sheet (green) and the second beta sheet (yellow) are represented by a thick line. The thin (black) line represents the loop region that connects the two sheets. The crystal structure of Aβ16−21 form II (blue) serves as an interface for model 16–21P (Figure B) and model 16–21AP (Figure C) of Aβ16−21. The model 16–21AP displays antiparallel β sheet. In the model 27–32 (Figure D) interactions between double-layer Aβ is through the crystal structure of Aβ27−32. The model 35–42 in Figure 1 E is based on the crystal structures of Aβ35−42 form II as the interface between double-layer Aβ. The fifth model (Figure 1F) is based on the long steric zipper interfaces consisting of Aβ30−35 and Aβ35−42 microcrystal structure. The blue color is used here to indicate the interfacial hydrophobic interactions based on the microcrystal structures.