We analyzed aqueous extracts from multiple AD brains using an array of techniques.
Brains can contain at least four different Aβ assembly forms including: (i) monomers, (ii) a ∼7kDa Aβ species, and larger species (iii) from ∼30-150 kDa, and (iv) >160 kDa. High molecular weight species are by far the most prevalent and appear to be built from ∼7 kDa Aβ species. The ∼7 kDa Aβ species resist denaturation by chaotropic agents and have a higher Aβ42/Aβ40 ratio than monomers, and are unreactive with antibodies to Asp1 of Ab or APP residues N-terminal of Asp1.
Further analysis of brain-derived ∼7 kDa Aβ species, the mechanism by which they assemble and the structures they form should reveal therapeutic and diagnostic opportunities.