Magnetic Alignment of Polymer Nanodiscs Probed by Solid-State NMR Spectroscopy

Langmuir. 2020 Feb 11;36(5):1258-1265. doi: 10.1021/acs.langmuir.9b03538. Epub 2020 Jan 30.

Abstract

The ability of amphipathic polymers to self-assemble with lipids and form nanodiscs has been a boon for the field of functional reconstitution of membrane proteins. In a field dominated by detergent micelles, a unique feature of polymer nanodiscs is their much-desired ability to align in the presence of an external magnetic field. Magnetic alignment facilitates the application of solid-state nuclear magnetic resonance (NMR) spectroscopy and aids in the measurement of residual dipolar couplings via well-established solution NMR spectroscopy. In this study, we comprehensively investigate the magnetic alignment properties of styrene maleimide quaternary ammonium (SMA-QA) polymer-based nanodiscs by using 31P and 14N solid-state NMR experiments under static conditions. The results reported herein demonstrate the spontaneous magnetic alignment of large-sized (≥20 nm diameter) SMA-QA nanodiscs (also called as macro-nanodiscs) with the lipid bilayer normal perpendicular to the magnetic field direction. Consequently, the orientation of macro-nanodiscs is further shown to flip the alignment axis parallel to the magnetic field direction upon the addition of a paramagnetic lanthanide salt. These results demonstrate the use of SMA-QA polymer nanodiscs for solid-state NMR applications including structural studies on membrane proteins.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Chlorides / chemistry
  • Dimyristoylphosphatidylcholine / chemistry
  • Lipid Bilayers / chemistry*
  • Magnetic Phenomena
  • Magnetic Resonance Spectroscopy / methods
  • Maleimides / chemistry*
  • Nanostructures / chemistry*
  • Nitrogen Isotopes / chemistry
  • Phosphorus / chemistry
  • Polystyrenes / chemistry*
  • Quaternary Ammonium Compounds / chemistry*
  • Ytterbium / chemistry

Substances

  • Chlorides
  • Lipid Bilayers
  • Maleimides
  • Nitrogen Isotopes
  • Polystyrenes
  • Quaternary Ammonium Compounds
  • Phosphorus
  • ytterbium trichloride
  • Ytterbium
  • Dimyristoylphosphatidylcholine