Saha, J.; Ravula, T.; Ramamoorthy, A.

Magic-angle spinning (MAS) solid-state NMR (SSNMR) has been widely used to determine amyloid fibril structures at atomic resolution. Such studies typically rely on homogeneous fibril preparations that produce narrow line widths and high spectral resolution, enabling reliable resonance assignment and structural analysis. However, many biologically relevant amyloid aggregates are structurally heterogeneous, resulting in spectral broadening and reduced sensitivity that hinder atomic-resolution characterization. Lipids are known to modulate amyloid aggregation pathways and promote the formation of toxic species that are often less homogeneous, further complicating NMR-based investigations. Here, we evaluate the feasibility of utilizing the benefits associated with ultrahigh field SSNMR for studying ganglioside GD3 catalyzed Ab42 aggregates. Uniformly 13C,15N labeled Ab42 was incubated with GD3 to generate lipid-associated aggregates and analyzed under MAS conditions. 13C cross-polarization magic-angle spinning spectra and 2D 13C-13C chemical shift correlation experiments using CORD mixing were acquired and compared with data collected at 600 MHz. Despite the heterogeneous nature of the GM1 associated assemblies, the 1.1 GHz spectra exhibit enhanced sensitivity and improved spectral resolution. Better resolved resonances corresponding to selectively structured regions of Ab42 are observed, indicating the presence of an ordered core within the lipid-associated aggregates. These results demonstrate that ultrahigh-field SSNMR significantly improves the characterization of heterogeneous amyloid assemblies and provides a promising approach for atomic-level investigation of biologically relevant, lipid-modulated Ab42-GD3 aggregates.