Role of the Region 23-28 in Aβ Fibril Formation: Insights from Simulations of the Monomers and Dimers of Alzheimer's Peptides Aβ40 and Aβ42

Self-assembly of the 40/42 amino acid Aβ peptide is a key player in Alzheimer's disease. Aβ40 is the most prevalent species, while Aβ42 is the most toxic. It has been suggested that the amino acids 21-30 could nucleate the folding of Aβ monomer and a bent in this region could be the rate-limiting step in Aβ fibril formation. In this study, we review our current understanding of the computer-predicted conformations of amino acids 23-28 in the monomer of Aβ(21-30) and the monomers Aβ40 and Aβ42. On the basis of new simulations on dimers of full-length Aβ, we propose that the ratelimiting step involves the formation of a multimeric β-sheet spanning the central hydrophobic core (residues 17-21).