Expanding the Types of Lipids Amenable to Native Mass Spectrometry of Lipoprotein Complexes

Native mass spectrometry (MS) has become an important tool for the analysis of membrane proteins. Although detergent micelles are the most commonly used method for solubilizing membrane proteins for native MS, nanoscale lipoprotein complexes such as nanodiscs are emerging as a promising complementary approach because they solubilize membrane proteins in a lipid bilayer environment. However, prior native MS studies of intact nanodiscs have employed only a limited set of phospholipids that are similar in mass. Here, we extend the range of lipids that are amenable to native MS of nanodiscs by combining lipids with masses that are simple integer multiples of each other. Although these lipid combinations create complex distributions, overlap between resonant peak series allows interpretation of nanodisc spectra containing glycolipids, sterols, and cardiolipin. We also investigate the gas-phase stability of nanodiscs with these new lipids towards collisional activation. We observe that negative ionization mode or charge reduction stabilizes nanodiscs and is essential to preserving labile lipids such as sterols. These new approaches to native MS of nanodiscs will enable future studies of membrane proteins embedded in model membranes that more accurately mimic natural bilayers.Science Foundation Arizona; American Society for Mass Spectrometry Research Award; National Institute of General Medical Sciences; National Institutes of Health [R35 GM128624]12 month embargo; published online: 9 April 2019This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at repository@u.library.arizona.edu