Research on Alzheimer’s disease (AD) needs rapid and reliable high-throughput characterization, so to address the structural diversity of Ab plaques and rationalize the role of peptide length, mutations, and post-translational modifications in their formation. These problems are beyond the capability of currently available techniques. Magic-angle spinning (MAS) NMR spectroscopy is an ideal technique for studying amyloids at atomic resolution but suffers from low sensitivity, requiring relatively large amounts of samples and extensive signal acquisition periods. Recent advances in 1H-detection at fast MAS and dynamic nuclear polarization (DNP) have ushered in a new era for NMR-based structural biology, but their potential has not yet been demonstrated for the structural investigation of complex amyloid assemblies. Here we show that resolved and sensitive 2D and 3D correlations are obtained on 13C,15N-enriched and fully-protonated samples of M0Ab1-42 fibrils by 1H detected NMR at ωr/2π =110 kHz and high field (23.4 T/ 1000 MHz for 1H) at room temperature and 13C detected DNP MAS NMR at ωr/2π=40 kHz and high field (18.8 T/ 800 MHz for 1H) at low temperature. These spectra enable nearly complete resonance assignment of the core of M0Ab1-42 (K16-A42) using sub-mg sample quantities, as well as the detection of numerous unambiguous inter-nuclear proximities defining both the structure of the core and the arrangement of the different monomers. Overall, this work demonstrates the possibility of expeditious structural analysis of amyloid fibrils without requiring preparation of large sample amounts, and illuminates the path to the study of unlabeled AD peptides derived from tissue samples available in limited quantities.

1H-detection and dynamic nuclear polarization-enhanced NMR of Ab1-42 fibrils

ACS Spring Meeting 2021

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