Open AccessMagnetic Alignment of Polymer Nanodiscs Probed by Solid-State NMR Spectroscopy
Author(s) -
Thirupathi Ravula,
JaeWoong Kim,
DongKuk Lee,
Ayyalusamy Ramamoorthy
Publication year - 2020
Publication title -
langmuir
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.042
H-Index - 333
eISSN - 1520-5827
pISSN - 0743-7463
DOI - 10.1021/acs.langmuir.9b03538
Subject(s) - solid state nuclear magnetic resonance , nuclear magnetic resonance spectroscopy , polymer , materials science , chemistry , lipid bilayer , spectroscopy , bilayer , model lipid bilayer , magnetic field , nuclear magnetic resonance , chemical physics , crystallography , membrane , organic chemistry , lipid bilayer phase behavior , biochemistry , physics , quantum mechanics
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 31 P and 14 N 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.