High-resolution NMR characterization of low abundance oligomers of amyloid-β without purification

Samuel A. Kotler, Jeffrey R. Brender, Subramanian Vivekanandan, Yuta Suzuki, Kazutoshi Yamamoto, Martine Monette, Janarthanan Krishnamoorthy, Patrick Walsh, Meagan Cauble, Mark M. Banaszak Holl, E. Neil G. Marsh, Ayyalusamy Ramamoorthy

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Alzheimer's disease is characterized by the misfolding and self-assembly of the amyloidogenic protein amyloid-β (Aβ). The aggregation of Aβ leads to diverse oligomeric states, each of which may be potential targets for intervention. Obtaining insight into Aβ oligomers at the atomic level has been a major challenge to most techniques. Here, we use magic angle spinning recoupling 1H-1H NMR experiments to overcome many of these limitations. Using 1H-1H dipolar couplings as a NMR spectral filter to remove both high and low molecular weight species, we provide atomic-level characterization of a non-fibrillar aggregation product of the Aβ1-40 peptide using non-frozen samples without isotopic labeling. Importantly, this spectral filter allows the detection of the specific oligomer signal without a separate purification procedure. In comparison to other solid-state NMR techniques, the experiment is extraordinarily selective and sensitive. A resolved 2D spectra could be acquired of a small population of oligomers (6 micrograms, 7% of the total) amongst a much larger population of monomers and fibers (93% of the total). By coupling real-time 1H-1H NMR experiments with other biophysical measurements, we show that a stable, primarily disordered Aβ1-40 oligomer 5-15 nm in diameter can form and coexist in parallel with the well-known cross-β-sheet fibrils.

Original languageEnglish
Article number11811
Number of pages12
JournalScientific Reports
Publication statusPublished - 3 Jul 2015
Externally publishedYes

Cite this

Kotler, S. A., Brender, J. R., Vivekanandan, S., Suzuki, Y., Yamamoto, K., Monette, M., Krishnamoorthy, J., Walsh, P., Cauble, M., Holl, M. M. B., Marsh, E. N. G., & Ramamoorthy, A. (2015). High-resolution NMR characterization of low abundance oligomers of amyloid-β without purification. Scientific Reports, 5, [11811]. https://doi.org/10.1038/srep11811