Figure 9. A Type 2A dodecamer model for α-Syn in the presence of Fe II and O2 and EM images of the assemblies. (a) Wedge representation of the model. (b) Flattened representations of two antiparallel subunits of the three concentric β-barrels. The inwardly oriented pleats of the middle and outer barrel are highlighted with black rectangles in the background. The Ct domains form two β-barrels, each with 6-fold radial symmetry, that stack end on with 2-fold perpendicular symmetry. (c) EM images [59] of antiparallel α-Syn oligomers. (Adapted with permission from Abeyawardhane DL, Fernandez RD, Murgas CJ, et al. Iron Redox Chemistry Promotes Antiparallel Oligomerization of alpha-Synuclein. J Am Chem Soc. 2018 Apr 18;140(15):5028-5032. Copyright 2018, American Chemical Society). The red circles superimposed on portions of the image have a diameter of ~ 9 nm as predicted by the dodecamer models that are enlarged ten-fold in the upper left and arranged in a hexagonal array.