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Joseph Loo, University of California Los Angeles

Native mass spectrometry (MS) of proteins and protein assemblies reveals size and binding stoichiometry. Native MS and native top-down (TD) MS, i.e., fragmentation of the gas-phase protein, can be effective for deriving structural information for soluble and membrane protein complexes, and much of this information can be correlated to the solution-phase structure. TD-MS and middle down-MS (MD-MS) are emerging techniques that minimize sample preparation and preserve endogenous modifications. MD-MS can offer advantages for forced-degraded studies on mAbs and ADCs. Membrane proteins are essential for cellular functions and represent half of drug targets, but they pose a challenge for conventional structure biology methods. Sequence, higher-order structure, and lipid binding for membrane proteins can be characterized by native MS and native TD-MS. Moreover, atomic-level structural analyses of large macromolecules and protein-ligand complexes have been enhanced by tools such as X-ray crystallography and (cryo)electron microscopy. However, flexible regions, heterogeneous modifications, and bound ligands may not be readily apparent in electron density maps, for example. In such instances, native MS can offer crucial complementary information to aid the determination of the high-resolution structure. Examples of the integration of MS and crystallography/electron microscopy will be shown for nucleic acids and small protein-ligand complexes.

Joseph Loo

Appearances