Mass spectrometry and ion mobility with electrospray ionization (ESI) have capabilities for measuring large proteins and noncovalent complexes.  ESI-IMS (ion mobility mass spectrometry) have measured complexes to 4 MDa, and using an ion mobility method of gas-phase electrophoretic mobility molecular analysis (GEMMA), protein complexes, including viruses, representing a range of sizes to 13 MDa can be separated by their electrophoretic mobility in air.  Evidence suggests that the conformation of lower charged gas phase proteins and protein complexes are closer to their solution native structure than their higher charged counterparts.  Data also supports the advantages for studying more highly charged proteins.  Gas phase protein charge can be reduced by gas-phase proton transfer reactions and increased by addition of supercharging reagents to the analyte solution.  We compare ESI-ion mobility and ESI-IMS as a function of protein charge state and discuss the role of charge on the observed conformations of proteins.

Role of charge state on protein conformation and protein complexes probed by ion mobility and mass spectrometry

240th National Meeting (2010)

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