Amyloid-� (A�) is a self-associating protein of 39-43 amino acids that is linked to Alzheimer's disease (AD). Recently, it has been discovered that A� oligomers as small as dimers are closely correlated to the symptoms and progression of AD; however, little is known about their structures. We have used single-pair F�rster Resonance Energy Transfer (spFRET) to investigate structures and dynamics in surface-tethered dimers, determining FRET efficiencies (EFRET) between associated donor- and acceptor-labeled peptides. A histogram of characteristic dimer EFRET values reveals two peaks near 0.38 and 0.58, perhaps representing two preferred dimer structures. Single-dimer histograms reveal that approximately 70% of dimers exhibit one characteristic EFRET value; the other 30% show two or three characteristic EFRET values, likely indicative of structural dynamics. Collectively, these investigations provide some of the first experimental insights into structures of neurodegenerative A� dimers, and may lead to improved understanding and treatment of Alzheimer's disease.

Single-pair FRET analysis of structures and dynamics in amyloid-β dimers

244th National Meeting (2012)

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