Electrospray ionization (ESI) with mass spectrometry (MS) is widely used for protein structural characterization and identification.  Native MS, where ions are formed from buffered aqueous solutions in which proteins have native structures and reactivities, enables large protein and other macromolecular complexes to transferred intact from solution into the gas phase.  Information about stoichiometries and structure can be obtained from such measurements.  A key question remains about what elements of solution-phase structure are retained in the gas phase.  Here, methods to manipulate protein structure in the electrospray droplet before ion formation will be discussed.  Supercharging methods, which can significantly increase the extent of ion charging in native mass spectrometry will be presented, and the origin of the supercharging effects will be discussed.  A novel method to perform rapid mixing immediately prior to ESI droplet formation using theta glass capillaries will be presented.  With this method, proteins can be induced to either unfold or to fold in the ESI droplets, and the reaction time can be readily varied by changing tip diameters.  This method can be used to investigate protein folding that occurs as fast as 1 μs, which is nearly an order of magnitude faster than is possible with conventional mixing experiments and uses ~10,000 times less material.<br/>

Evolution of protein structure in electrospray ionization: From solution into the gas phase

251st National Meeting (2016)

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