Synergistic Approach Maps Peptide Nanodisc Architecture and Motion

Peptide nanodiscs are innovative self-assembling nanoscale lipid bilayer systems, often stabilized by amphipathic peptides, designed to mimic cellular membranes. These systems are invaluable tools for studying integral membrane proteins—like G-protein coupled receptors (GPCRs) and ion channels—in a native-like lipid environment, which is crucial for understanding their function and for drug discovery. Understanding their precise structure, stability, and dynamics at an atomic level is paramount for optimizing their design and expanding their applications. However, the detailed atomic-level architecture and dynamic behavior of these peptide-stabilized systems have remained challenging to fully characterize with a single technique.

The combined data from NMR, SAS, and MD simulations provided an unprecedented, high-resolution view of the NDP-1 peptide nanodiscs. The nanodiscs consistently exhibited a highly stable and monodisperse population, with SAS measurements confirming an average diameter of ~10.5 nm and a thickness of ~5.2 nm, with <5% aggregation observed across all tested lipid concentrations. NMR spectroscopy revealed that the NDP-1 peptide adopted a stable alpha-helical conformation within the lipid bilayer, maintaining >92% helicity as determined by circular dichroism and NMR chemical shifts. MD simulations further elucidated the dynamic interactions, showing that the peptide's hydrophobic face interacts strongly with the lipid acyl chains, while its hydrophilic face stabilizes the disc's edge. The study precisely mapped the peptide's orientation and mobility, demonstrating a 28% reduction in lipid acyl chain dynamics near the peptide belt compared to the center of the nanodisc, indicating strong stabilizing interactions and reduced lipid fluidity at the periphery. This detailed characterization provides critical insights into how the peptide stabilizes the lipid bilayer without forming vesicles.