Amyloid-β (Aβ) is a 39–42 residue protein produced by the cleavage of the amyloid
precursor protein (APP), which subsequently aggregates to form cross-β amyloid fibrils that
are a hallmark of Alzheimer's disease (AD). The most prominent forms of Aβ are Aβ1–40 and
Aβ1–42, which differ by two amino acids (I and A) at the C-terminus. However, Aβ42 is more
neurotoxic and essential to the etiology of AD. Here, we present an atomic resolution
structure of a monomorphic form of AβM01–42 amyloid fibrils derived from over 500 13C …