Interaction between soluble Aβ-(1-40) monomer and Aβ-(1-42) fibrils probed by paramagnetic relaxation enhancement

The most common isoforms of amyloid-beta (A beta) proteins are composed of 40 or 42 amino acid residues. While A beta-(1-40) is the predominant species, A beta-(1-42) is more fibrillogenic and neurotoxic, suggesting that A beta-(1-42) plays a critical role in the initiation of amyloid fibril formation. We investigated the mechanisms by which soluble A beta-(1-40) associates with preformed A beta-(1-42) seeds. A paramagnetic relaxation enhancement analysis showed that the A beta-(1-40) monomer and A beta(1-42) seed interact via their C-terminal region in a parallel fashion, and the N-terminal part does not to contribute to the interaction. Structured summary of protein interactions: A beta-(1-40) and A beta-(1-42) bind by fluorescence technology (View interaction) A beta-(1-42) and A beta-(1-40) bind by nuclear magnetic resonance (View interaction) (C) 2013 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.