Higher Magnetic Field NMR Renders Resolution Enhancement on Ganglioside GD3 Catalyzed Aβ₄₂ Aggregates.

Area of Science:

• Biophysics
• Structural Biology
• Neuroscience

Background:

• Magic-angle spinning (MAS) solid-state NMR (SSNMR) is crucial for atomic-resolution amyloid fibril structure determination.
• Homogeneous samples yield narrow linewidths and high spectral resolution, essential for analysis.
• Structurally heterogeneous amyloid aggregates, often influenced by lipids, present challenges due to spectral broadening and reduced sensitivity.

Purpose of the Study:

• To evaluate the utility of high-field (1.1 GHz) SSNMR for characterizing ganglioside GD3-catalyzed Aβ42 aggregates.
• To assess if ultrahigh-field SSNMR can overcome limitations in studying heterogeneous, lipid-associated amyloid assemblies.

Main Methods:

• Preparation of uniformly 13C, 15N-labeled Aβ42 incubated with ganglioside GD3 to form lipid-associated aggregates.
• Acquisition of 13C cross-polarization magic-angle spinning (CPMAS) spectra and 2D 13C-13C chemical shift correlation experiments using CORD mixing at 1.1 GHz.
• Comparison of 1.1 GHz data with spectra obtained at 600 MHz.

Main Results:

• The 1.1 GHz SSNMR spectra demonstrated significantly enhanced sensitivity and improved spectral resolution compared to 600 MHz data.
• Despite the heterogeneous nature of the GD3-associated Aβ42 assemblies, better-resolved resonances were observed.
• These resolved resonances indicate the presence of an ordered core within the lipid-associated aggregates.

Conclusions:

• Ultrahigh-field SSNMR substantially improves the characterization of heterogeneous amyloid assemblies.
• This technique offers a promising avenue for atomic-level investigation of biologically relevant, lipid-modulated Aβ aggregates.
• High-field SSNMR facilitates structural insights into complex amyloid structures that are otherwise difficult to resolve.