Optimization of the design and preparation of nanoscale phospholipid bilayers for its application to solution NMR

Despite arduous efforts and recent technological developments structural investigation of integral membrane proteins remains a challenge. The primary deterrents include difficulties with their expression, low inherent solubility, and problems associated with existing membrane mimicking systems. A relatively new class of membrane mimetics, nanodiscs, is emerging as a promising alternative. Although nanodiscs have been proven successful for several biophysical applications, they yet remain to become the system of preferred choice for structure determination. We have hereby made nanodiscs more suitable for solution NMR applications by reducing the diameter of the self-assembly complex to its potential limit. We achieved a noticeable improvement in the quality of NMR spectra obtained for the transmembrane and cytoplasmic domains of integrin IIb incorporated into these smaller discs rendering them susceptible for a thorough structural investigation. In addition, we also present an on-column method for a rapid, efficient, single-step preparation of protein incorporated nanodiscs at high concentrations. These discs have been fully characterized by transmission electron microscopy, dynamic light scattering, and differential scanning calorimetry. Proteins 2013; 81:1222-1231. (c) 2013 Wiley Periodicals, Inc.