Ion mobility mass spectrometry of proteins and proteinassemblies

Abstract

Traditionally, mass spectrometry has been a powerful analytical method enabling the structural analysis of small molecules, and later on peptides and proteins. With the advent of native mass spectrometry, using a combination of electrospray ionisation and time of flight analysis, mass spectrometry could also be applied to the mass determination of large protein complexes such as ribosomes and whole viruses. More recently, ion mobility has been coupled to mass spectrometry providing a new dimension in the analysis of biomolecules, with ion mobility separating ions according to differences in size and shape. In the context of native mass spectrometry, ion mobility mass spectrometry opens up avenues for the detailed structural analysis of large and heterogeneous protein complexes, providing information on the stoichiometry, topology and cross section of these assemblies and their composite subunits. With these characteristics, ion mobility mass spectrometry offers a complementary tool in the context of structural biology. Here, we critically review the development, instrumentation, approaches and applications of ion mobility in combination with mass spectrometry, focusing on the analysis of larger proteins and protein assemblies (185 references).

The impact of mass spectrometry on the study of intact antibodies: from post-translational modifications to structural analysis

“…Combining ion mobility spectrometry with MS (IMMS) 93 yields not only mass-based identification but also gasphase collision cross-sections, which may provide insight into the gas-phase structure, albeit at low resolution. IMMS has recently been applied in the determination of the structural heterogeneity of both mAbs (IgG2) and antigen targets.…”

EM∩IM: software for relating ion mobility mass spectrometry and electron microscopy data

“…A number of different algorithms 9-14 , tailored to specific applications, have been written to calculate the CCS of a given threedimensional structure, allowing the relation of IM measurements to structures derived from X-ray crystallography, NMR spectroscopy, or atomic modelling [15][16][17] An electron density map is typically a three-dimensional grid, with each voxel having a certain density value. In general, such a map is displayed as a volume demarcated by an isodensity surface, which is generated by specifying a contour-level, the lower electron density threshold (!…”

“…While the MS experiment provides a mass measurement, the IM dimension reports on the ability of an ion to traverse a region of low pressure that, depending on the experimental implementation 7, 8 , may be quantified through an orientationally averaged collision cross-section (CCS). The CCS can subsequently be exploited to validate existing atomic coordinates, assess differing candidate structures, or to guide model building directly [1][2][3][4][5][6] .A number of different algorithms 9-14 , tailored to specific applications, have been written to calculate the CCS of a given threedimensional structure, allowing the relation of IM measurements to structures derived from X-ray crystallography, NMR spectroscopy, or atomic modelling [15][16][17] An electron density map is typically a three-dimensional grid, with each voxel having a certain density value. In general, such a map is displayed as a volume demarcated by an isodensity surface, which is generated by specifying a contour-level, the lower electron density threshold (!…”

“…A number of different algorithms [9][10][11][12][13][14] , tailored to specific applications, have been written to calculate the CCS of a given threedimensional structure, allowing the relation of IM measurements to structures derived from X-ray crystallography, NMR spectroscopy, or atomic modelling [15][16][17] . These algorithms are however limited to taking a coordinate file (e.g.…”

Stabilization of Compact Protein Structures by Macrocyclic Hosts Cucurbit[n]urils in the Gas Phase

“…The advancement of electrospray ionization (ESI) in combination with ion mobility mass spectrometry (IM-MS) enabled characterization of protein tertiary and quaternary structures using MS. 1,2 In addition to mass-tocharge ratio (m/z), IM-MS provides collision cross-section (Ω D ) of an ion, which is related to the size and shape of the ion. Recent studies utilizing ESI-IM-MS have provided important insights on the structural dynamics of proteins and protein complexes.…”