Detergent-Free Formation and Physicochemical Characterization of Nanosized Lipid-Polymer Complexes: Lipodisq

摘要

A major challenge for biophysical studies of membrane proteins is obtaining stable, homogenous samples. Traditional detergent solubilization and liposome-based methods of reconstitution may lead to protein inactivation, heterogeneous and polydisperse sized particles, and sample aggregation. While membrane scaffold protein (MSP) stabilized nanodiscs have facilitated the formation of monodisperse protein samples, a drawback is the detergent-based preparation method. Here we present a physicochemical characterization of polymer-stabilized lipid particles termed Lipodisq, a novel nanosized lipid-based platform capable of incorporating membrane proteins. The polymers used in the Lipodisq technology can solubilize commonly used lipids such as dimyristoylphosphatidylcholine (DMPC) without the use of detergents. The small size of Lipodisq (diameter of around 9-10 nm at pH 7.4) renders them potentially suitable for many biophysical methodologies, including electron paramagnetic resonance (EPR) and nuclear magnetic resonance (NMR) spectroscopies, electron microscopy (EM), and circular dichroism (CD) spectroscopy.