Figure 3.

Schematic representation (left) of one Aβ40 molecule from the 2LMO model showing the two β-sheets spanning residues 11–24 and 30–40 (angular black backbone segments) and two structurally uncharacterized segments [residues 1–8 at the N-terminus and residues 25–29 comprising a loop connecting the two sheets (smooth gray backbone segments)]. Residues for which protection factors were determined are color-coded according to the legend. Note that all residues with protection factors of <20 are on the outer surface of this model. Cross section (right) of the 2LMO model with van der Waals spheres for non-hydrogen atoms, illustrating a proposed quaternary relationship between two filaments. The eight N-terminal residues and residues 25–29 have been omitted from this model. The N-termini are marked G9, and the C-termini are marked V40. Note that two residues with low protection factors (I31, marked with number signs, and M35, marked with asterisks) are buried in this model, while residues with high protection factors (V39 and V40) are exposed.