Chapter 2 Characterization of Protein Higher Order Structure and Dynamics with ESI MS

Abstract

Publisher Summary Electrospray ionization (ESI) mass spectrometry (MS) has become a potent experimental tool in biophysics, which in many cases provides valuable information on various aspects of protein behavior in solution. One unique feature of the ESI process over other types of ionization methods used in MS is its ability to produce ions of polar and thermally labile species with multiple charges and transfer them to the gas phase. The solvent-exposed surface area of a protein in solution is dictated by its higher order structure and, as a result, the extent of multiple charging observed in ESI MS of a protein reflects its conformation in solution. It is for this reason that the analysis of protein charge-state distributions in ESI MS provides a very effective means of evaluating the integrity of the higher order structure of proteins and their complexes, as well as assessing their conformational heterogeneity. In addition to being an efficient tool to probe conformational dynamics, the correlation between the extent of multiple charging of protein ions in ESI MS and the degree of protein compactness in solution can also be used to provide estimates of solvent-accessible surface area (SASA) of natively folded proteins and their complexes.