Biomolecule Analysis by Ion Mobility Spectrometry

Abstract

Although nonnative protein conformations, including intermediates along the folding pathway and kinetically trapped misfolded species that disfavor the native state, are rarely isolated in the solution phase, they are often stable in the gas phase, where macromolecular ions from electrospray ionization can exist in varying charge states. Differences in the structures of nonnative conformations in the gas phase are often large enough to allow different shapes and charge states to be separated because of differences in their mobilities through a gas. Moreover, gentle collisional activation can be used to induce structural transformations. These new structures often have different mobilities. Thus, there is the possibility of developing a multidimensional separation that takes advantage of structural differences of multiple stable states. This review discusses how nonnative states differ in the gas phase compared with solution and presents an overview of early attempts to utilize and manipulate structures in order to develop ion mobility spectrometry as a rapid and sensitive technique for separating complex mixtures of biomolecules prior to mass spectrometry.

Differential Mobility Spectrometry-Hydrogen Deuterium Exchange (DMS-HDX) as a Probe of Protein Conformation in Solution

“…I on mobility spectrometry (IMS) is increasingly used as an added dimension in mass spectrometry analyses, providing gas-phase separations of ionized analytes based upon their collision cross sections [1]. IMS is now commonly used in structural biology for low-resolution analysis of protein structure, conformational dynamics, and complex topology [2].…”

Evidence for the Preservation of Native Inter- and Intra-Molecular Hydrogen Bonds in the Desolvated FK-Binding Protein·FK506 Complex Produced by Electrospray Ionization

“…A major question concerning the application of MS in studying protein structure and interactions is to what extent the native, solution based, conformation(s) of a protein is preserved following ionization and desolvation by ESI. Significant effort has been directed towards this question [8]. Ion mobility spectrometry (IMS), a gas-phase electrophoretic technique, is now often used in conjunction with MS analyses and allows low resolution structural information of analytes to be directly accessed in the desolvated MS environment [8][9][10][11][12][13][14].…”

“…Significant effort has been directed towards this question [8]. Ion mobility spectrometry (IMS), a gas-phase electrophoretic technique, is now often used in conjunction with MS analyses and allows low resolution structural information of analytes to be directly accessed in the desolvated MS environment [8][9][10][11][12][13][14]. These studies have provided insights into gas-phase protein structure, and it is generally accepted that on the timescales of IMS-MS experiments, major structural perturbations can be avoided for low charge state ions [15,16].…”

Statistical Analysis of Ion Mobility Spectrometry. I. Unbiased and Guided Replica-Exchange Molecular Dynamics

“…The combination of ion mobility spectrometry (IMS) with MS gives a great insight into the three-dimensional conformation, the folding mechanisms, or the way such biomolecules assemble together in covalent or noncovalent complexes [1][2][3][4][5]. IMS measurements are usually analyzed by calculating cross-sections for unsolvated trial conformations obtained from computational chemical methods.…”