Possible β-sheet structures in the Aβ(1–42) 150kDa oligomers. A) The top and side views of the all-atom structural model of Model ±3 of N-strands. The color code for residues are: Grey K16, Red L17, Blue F19, Yellow F20. B) The top and side view of one structural model of a mixed β-sheet formed by both N-strands and C-strands. The N-strands are colored in cyan and the C-strands are in ochre. The color code for residues are: Grey K16, Red L17, Blue F19, Yellow F20, Green I31, Purple V36.