1
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Gozzo TA, Bush MF. Effects of charge on protein ion structure: Lessons from cation-to-anion, proton-transfer reactions. MASS SPECTROMETRY REVIEWS 2024; 43:500-525. [PMID: 37129026 DOI: 10.1002/mas.21847] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Revised: 04/10/2023] [Accepted: 04/11/2023] [Indexed: 05/03/2023]
Abstract
Collision cross-section values, which can be determined using ion mobility experiments, are sensitive to the structures of protein ions and useful for applications to structural biology and biophysics. Protein ions with different charge states can exhibit very different collision cross-section values, but a comprehensive understanding of this relationship remains elusive. Here, we review cation-to-anion, proton-transfer reactions (CAPTR), a method for generating a series of charge-reduced protein cations by reacting quadrupole-selected cations with even-electron monoanions. The resulting CAPTR products are analyzed using a combination of ion mobility, mass spectrometry, and collisional activation. We compare CAPTR to other charge-manipulation strategies and review the results of various CAPTR-based experiments, exploring their contribution to a deeper understanding of the relationship between protein ion structure and charge state.
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Affiliation(s)
- Theresa A Gozzo
- Department of Chemistry, University of Washington, Seattle, Washington, USA
| | - Matthew F Bush
- Department of Chemistry, University of Washington, Seattle, Washington, USA
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2
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Gozzo TA, Bush MF. Quantitatively Differentiating Antibodies Using Charge-State Manipulation, Collisional Activation, and Ion Mobility-Mass Spectrometry. Anal Chem 2024; 96:505-513. [PMID: 38146701 DOI: 10.1021/acs.analchem.3c04638] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2023]
Abstract
Antibody-based therapeutics continue to expand both in the number of products and in their use in patients. These heterogeneous proteins challenge traditional drug characterization strategies, but ion mobility (IM) and mass spectrometry (MS) approaches have eased the challenge of higher-order structural characterization. Energy-dependent IM-MS, e.g., collision-induced unfolding (CIU), has been demonstrated to be sensitive to subtle differences in structure. In this study, we combine a charge-reduction method, cation-to-anion proton-transfer reactions (CAPTR), with energy-dependent IM-MS and varied solution conditions to probe their combined effects on the gas-phase structures of IgG1κ and IgG4κ from human myeloma. CAPTR paired with MS-only analysis improves the confidence of charge-state assignments and the resolution of the interfering protein species. Collision cross-section distributions were determined for each of the charge-reduced products. Similarity scoring was used to quantitatively compare distributions determined from matched experiments analyzing samples of the two antibodies. Relative to workflows using energy-dependent IM-MS without charge-state manipulation, combining CAPTR and energy-dependent IM-MS enhanced the differentiation of these antibodies. Combined, these results indicate that CAPTR can benefit many aspects of antibody characterization and differentiation.
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Affiliation(s)
- Theresa A Gozzo
- Department of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195-1700, United States
| | - Matthew F Bush
- Department of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195-1700, United States
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3
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James VK, Sanders JD, Aizikov K, Fort KL, Grinfeld D, Makarov A, Brodbelt JS. Expanding Orbitrap Collision Cross-Section Measurements to Native Protein Applications Through Kinetic Energy and Signal Decay Analysis. Anal Chem 2023; 95:7656-7664. [PMID: 37133913 DOI: 10.1021/acs.analchem.3c00594] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
The measurement of collision cross sections (CCS, σ) offers supplemental information about sizes and conformations of ions beyond mass analysis alone. We have previously shown that CCSs can be determined directly from the time-domain transient decay of ions in an Orbitrap mass analyzer as ions oscillate around the central electrode and collide with neutral gas, thus removing them from the ion packet. Herein, we develop the modified hard collision model, thus deviating from the prior FT-MS hard sphere model, to determine CCSs as a function of center-of-mass collision energy in the Orbitrap analyzer. With this model, we aim to increase the upper mass limit of CCS measurement for native-like proteins, characterized by low charge states and presumed to be in more compact conformations. We also combine CCS measurements with collision induced unfolding and tandem mass spectrometry experiments to monitor protein unfolding and disassembly of protein complexes and measure CCSs of ejected monomers from protein complexes.
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Affiliation(s)
- Virginia K James
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States
| | - James D Sanders
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States
| | | | - Kyle L Fort
- Thermo Fisher Scientific, Bremen 28199, Germany
| | | | - Alexander Makarov
- Thermo Fisher Scientific, Bremen 28199, Germany
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, University of Utrecht, Utrecht 3584, The Netherlands
| | - Jennifer S Brodbelt
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States
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4
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Khajeh A, Rahman MH, Liu T, Panwar P, Menezes PL, Martini A. Thermal decomposition of phosphonium salicylate and phosphonium benzoate ionic liquids. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.118700] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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5
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Yin Z, Huang J, Miao H, Hu O, Li H. High-Pressure Electrospray Ionization Yields Supercharged Protein Complexes from Native Solutions While Preserving Noncovalent Interactions. Anal Chem 2020; 92:12312-12321. [DOI: 10.1021/acs.analchem.0c01965] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Zhibin Yin
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Jing Huang
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Hui Miao
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Ou Hu
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Huilin Li
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou 510006, China
- Guangdong Key Laboratory of Chiral Molecule and Drug Discovery, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou, Guangdong 510006, China
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6
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Panczyk EM, Gilbert JD, Jagdale GS, Stiving AQ, Baker LA, Wysocki VH. Ion Mobility and Surface Collisions: Submicrometer Capillaries Can Produce Native-like Protein Complexes. Anal Chem 2020; 92:2460-2467. [PMID: 31909984 DOI: 10.1021/acs.analchem.9b03666] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The use of submicrometer capillaries for nanoelectrospray ionization of native proteins and protein complexes effectively reduces the number of nonspecific salt adducts to biological molecules, therefore increasing the apparent resolution of a mass spectrometer without any further instrument modifications or increased ion activation. However, the increased interaction between proteins and the surface of the capillary has been shown to promote protein expansion and therefore loss of native structure. Here, we compare the effect of micrometer and submicrometer sized capillaries on the native structures of the protein complexes streptavidin, concanavalin A, and C-reactive protein under charge reducing conditions. We observe that the use of submicrometer capillaries did not result in a significantly higher charge state distribution, indicative of expansion, when compared to micrometer sized capillaries for complexes in 100 mM ammonium acetate and 100 mM triethylammonium acetate and for streptavidin in 200 mM ammonium acetate with no charge reduction. Additionally, no significant differences in collision cross sections were observed using ion mobility mass spectrometry. Finally, the dissociation behaviors of protein complexes ionized using micrometer and submicrometer capillaries were compared to determine if any structural perturbation occurred during ionization. Protein complexes from both capillary sizes displayed similar surface-induced dissociation patterns at similar activation energies. The results suggest that submicrometer capillaries do not result in significant changes to protein complex structure under charge reducing conditions and may be used for native mass spectrometry experiments. Submicrometer capillaries can be used to resolve small mass differences of biological systems on a QTOF platform; however, a laser tip puller is required for pulling reproducible submicrometer capillaries, and disruption in spray due to clogging was observed for larger protein complexes.
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Affiliation(s)
- Erin M Panczyk
- Department of Chemistry and Biochemistry , The Ohio State University , Columbus , Ohio 43210 , United States.,Resource for Native Mass Spectrometry Guided Structural Biology , The Ohio State University , Columbus , Ohio 43210 , United States
| | - Joshua D Gilbert
- Department of Chemistry and Biochemistry , The Ohio State University , Columbus , Ohio 43210 , United States
| | - Gargi S Jagdale
- Department of Chemistry , Indiana University , Bloomington , Indiana 47405 , United States
| | - Alyssa Q Stiving
- Department of Chemistry and Biochemistry , The Ohio State University , Columbus , Ohio 43210 , United States.,Resource for Native Mass Spectrometry Guided Structural Biology , The Ohio State University , Columbus , Ohio 43210 , United States
| | - Lane A Baker
- Department of Chemistry , Indiana University , Bloomington , Indiana 47405 , United States
| | - Vicki H Wysocki
- Department of Chemistry and Biochemistry , The Ohio State University , Columbus , Ohio 43210 , United States.,Resource for Native Mass Spectrometry Guided Structural Biology , The Ohio State University , Columbus , Ohio 43210 , United States
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7
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Foreman DJ, McLuckey SA. Recent Developments in Gas-Phase Ion/Ion Reactions for Analytical Mass Spectrometry. Anal Chem 2020; 92:252-266. [PMID: 31693342 PMCID: PMC6949396 DOI: 10.1021/acs.analchem.9b05014] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- David J Foreman
- Department of Chemistry , Purdue University , West Lafayette , Indiana 47907-2084 , United States
| | - Scott A McLuckey
- Department of Chemistry , Purdue University , West Lafayette , Indiana 47907-2084 , United States
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8
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Hong S, Bush MF. Collision-Induced Unfolding Is Sensitive to the Polarity of Proteins and Protein Complexes. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2019; 30:2430-2437. [PMID: 31502225 DOI: 10.1007/s13361-019-02326-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Revised: 08/11/2019] [Accepted: 08/16/2019] [Indexed: 06/10/2023]
Abstract
Collision-induced unfolding (CIU) uses ion mobility to probe the structures of ions of proteins and noncovalent complexes as a function of the extent of gas-phase activation prior to analysis. CIU can be sensitive to domain structures, isoform identities, and binding partners, which makes it appealing for many applications. Almost all previous applications of CIU have probed cations. Here, we evaluate the application of CIU to anions and compare the results for anions with those for cations. Towards that end, we developed a "similarity score" that we used to quantify the differences between the results of different CIU experiments and evaluate the significance of those differences relative to the variance of the underlying measurements. Many of the differences between anions and cations that were identified can be attributed to the lower absolute charge states of anions. For example, the extents of the increase in collision cross section over the full range of energies depended strongly on absolute charge state. However, over intermediate energies, there are significant difference between anions and cations with the same absolute charge state. Therefore, CIU is sensitive to the polarity of protein ions. Based on these results, we propose that the utility of CIU to differentiate similar proteins or noncovalent complexes may also depend on polarity. More generally, these results indicate that the relationship between the structures and dynamics of native-like cations and anions deserve further attention and that future studies may benefit from integrating results from ions of both polarities.
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Affiliation(s)
- Seoyeon Hong
- Department of Chemistry, University of Washington, Box 351700, Seattle, WA, 98195-1700, USA
| | - Matthew F Bush
- Department of Chemistry, University of Washington, Box 351700, Seattle, WA, 98195-1700, USA.
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9
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Khristenko N, Amato J, Livet S, Pagano B, Randazzo A, Gabelica V. Native Ion Mobility Mass Spectrometry: When Gas-Phase Ion Structures Depend on the Electrospray Charging Process. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2019; 30:1069-1081. [PMID: 30924079 DOI: 10.1007/s13361-019-02152-3] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Revised: 02/08/2019] [Accepted: 02/08/2019] [Indexed: 06/09/2023]
Abstract
Ion mobility spectrometry (IMS) has become popular to characterize biomolecule folding. Numerous studies have shown that proteins that are folded in solution remain folded in the gas phase, whereas proteins that are unfolded in solution adopt more extended conformations in the gas phase. Here, we discuss how general this tenet is. We studied single-stranded DNAs (human telomeric cytosine-rich sequences with CCCTAA repeats), which fold into an intercalated motif (i-motif) structure in a pH-dependent manner, thanks to the formation of C-H+-C base pairs. As i-motif formation is favored at low ionic strength, we could investigate the ESI-IMS-MS behavior of i-motif structures at pH ~ 5.5 over a wide range of ammonium acetate concentrations (15 to 100 mM). The control experiments consisted of either the same sequence at pH ~ 7.5, wherein the sequence is unfolded, or sequence variants that cannot form i-motifs (CTCTAA repeats). The surprising results came from the control experiments. We found that the ionic strength of the solution had a greater effect on the compactness of the gas-phase structures than the solution folding state. This means that electrosprayed ions keep a memory of the charging process, which is influenced by the electrolyte concentration. We discuss these results in light of the analyte partitioning between the droplet interior and the droplet surface, which in turn influences the probability of being ionized via a charged residue-type pathway or a chain extrusion-type pathway.
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Affiliation(s)
- Nina Khristenko
- Laboratoire Acides Nucléiques: Régulations Naturelle et Artificielle, Université de Bordeaux, Inserm & CNRS (ARNA, U1212, UMR5320), IECB, 2 rue Robert Escarpit, 33607, Pessac, France
| | - Jussara Amato
- Department of Pharmacy, University of Naples Federico II, via Domenico Montesano 49, 80131, Naples, Italy
| | - Sandrine Livet
- Laboratoire Acides Nucléiques: Régulations Naturelle et Artificielle, Université de Bordeaux, Inserm & CNRS (ARNA, U1212, UMR5320), IECB, 2 rue Robert Escarpit, 33607, Pessac, France
| | - Bruno Pagano
- Department of Pharmacy, University of Naples Federico II, via Domenico Montesano 49, 80131, Naples, Italy
| | - Antonio Randazzo
- Department of Pharmacy, University of Naples Federico II, via Domenico Montesano 49, 80131, Naples, Italy
| | - Valérie Gabelica
- Laboratoire Acides Nucléiques: Régulations Naturelle et Artificielle, Université de Bordeaux, Inserm & CNRS (ARNA, U1212, UMR5320), IECB, 2 rue Robert Escarpit, 33607, Pessac, France.
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10
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Patrick JW, Laganowsky A. Generation of Charge-Reduced Ions of Membrane Protein Complexes for Native Ion Mobility Mass Spectrometry Studies. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2019; 30:886-892. [PMID: 30887461 PMCID: PMC6504596 DOI: 10.1007/s13361-019-02187-6] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Revised: 02/27/2019] [Accepted: 03/05/2019] [Indexed: 05/15/2023]
Abstract
Recent advances in native mass spectrometry (MS) have enabled the elucidation of how small molecule binding to membrane proteins modulates their structure and function. The protein-stabilizing osmolyte, trimethylamine oxide (TMAO), exhibits attractive properties for native MS studies. Here, we report significant charge reduction, nearly threefold, for three membrane protein complexes in the presence of this osmolyte without compromising mass spectral resolution. TMAO improves the ability to resolve individual lipid-binding events to the ammonia channel (AmtB) by over 200% compared to typical native conditions. The generation of ions with compact structure and access to a larger number of lipid-binding events through the incorporation of TMAO increases the utility of IM-MS for structural biology studies. Graphical Abstract.
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Affiliation(s)
- John W Patrick
- Department of Chemistry, Texas A&M University, College Station, TX, 77842, USA
- Janssen Research & Development, 1400 Mckean Road, Spring House, PA, 19477, USA
| | - Arthur Laganowsky
- Department of Chemistry, Texas A&M University, College Station, TX, 77842, USA.
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11
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Bashyal A, Sanders JD, Holden DD, Brodbelt JS. Top-Down Analysis of Proteins in Low Charge States. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2019; 30:704-717. [PMID: 30796622 PMCID: PMC6447437 DOI: 10.1007/s13361-019-02146-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2018] [Revised: 01/30/2019] [Accepted: 01/30/2019] [Indexed: 05/08/2023]
Abstract
The impact of charging methods on the dissociation behavior of intact proteins in low charge states is investigated using HCD and 193 nm UVPD. Low charge states are produced for seven different proteins using the following four different methods: (1) proton transfer reactions of ions in high charge states generated from conventional denaturing solutions; (2) ESI of proteins in solutions of high ionic strength to enhance retention of folded native-like conformations; (3) ESI of proteins in high pH solutions to limit protonation; and (4) ESI of carbamylated proteins. Comparison of sequence coverages, degree of preferential cleavages, and types and distribution of fragment ions reveals a number of differences in the fragmentation patterns depending on the method used to generate the ions. More notable differences in these metrics are observed upon HCD than upon UVPD. The fragmentation caused by HCD is influenced more significantly by the presence/absence of mobile protons, a factor that modulates the degree of preferential cleavages and net sequence coverages. Carbamylation of the lysines and the N-terminus of the proteins alters the proton mobility by reducing the number of proton-sequestering, highly basic sites as evidenced by decreased preferential fragmentation C-terminal to Asp or N-terminal to Pro upon HCD. UVPD is less dependent on the method used to generate the low charge states and favors non-specific fragmentation, an outcome which is important for obtaining high sequence coverage of intact proteins.
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Affiliation(s)
- Aarti Bashyal
- Department of Chemistry, The University of Texas at Austin, Austin, TX, 78712, USA
| | - James D Sanders
- Department of Chemistry, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Dustin D Holden
- Department of Chemistry, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Jennifer S Brodbelt
- Department of Chemistry, The University of Texas at Austin, Austin, TX, 78712, USA.
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12
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Gadzuk-Shea MM, Bush MF. Effects of Charge State on the Structures of Serum Albumin Ions in the Gas Phase: Insights from Cation-to-Anion Proton-Transfer Reactions, Ion Mobility, and Mass Spectrometry. J Phys Chem B 2018; 122:9947-9955. [DOI: 10.1021/acs.jpcb.8b08427] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Meagan M. Gadzuk-Shea
- Department of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195-1700, United States
| | - Matthew F. Bush
- Department of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195-1700, United States
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13
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Affiliation(s)
- Nicholas
M. Riley
- Department
of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
- Genome
Center of Wisconsin, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Joshua J. Coon
- Department
of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
- Genome
Center of Wisconsin, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
- Department
of Biomolecular Chemistry, University of
Wisconsin-Madison, Madison, Wisconsin 53706, United States
- Morgridge
Institute for Research, Madison, Wisconsin 53715, United States
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14
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Chandler SA, Benesch JL. Mass spectrometry beyond the native state. Curr Opin Chem Biol 2017; 42:130-137. [PMID: 29288996 DOI: 10.1016/j.cbpa.2017.11.019] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Revised: 11/27/2017] [Accepted: 11/30/2017] [Indexed: 12/31/2022]
Abstract
Native mass spectrometry allows the study of proteins by probing in vacuum the interactions they form in solution. It is a uniquely useful approach for structural biology and biophysics due to the high resolution of separation it affords, allowing the concomitant interrogation of multiple protein components with high mass accuracy. At its most basic, native mass spectrometry reports the mass of intact proteins and the assemblies they form in solution. However, the opportunities for more detailed characterisation are extensive, enabled by the exquisite control of ion motion that is possible in vacuum. Here we describe recent developments in mass spectrometry approaches to the structural interrogation of proteins both in, and beyond, their native state.
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Affiliation(s)
- Shane A Chandler
- Department of Chemistry, Physical & Theoretical Chemistry Laboratory, University of Oxford, Oxford OX1 3QZ, UK
| | - Justin Lp Benesch
- Department of Chemistry, Physical & Theoretical Chemistry Laboratory, University of Oxford, Oxford OX1 3QZ, UK.
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15
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Majuta SN, Maleki H, Kiani Karanji A, Attanyake K, Loch E, Valentine SJ. Magnifying ion mobility spectrometry-mass spectrometry measurements for biomolecular structure studies. Curr Opin Chem Biol 2017; 42:101-110. [PMID: 29241076 DOI: 10.1016/j.cbpa.2017.11.013] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Revised: 11/20/2017] [Accepted: 11/21/2017] [Indexed: 12/31/2022]
Abstract
Ion mobility spectrometry-mass spectrometry (IMS-MS) provides information about the structures of gas-phase ions in the form of a collision cross section (CCS) with a neutral buffer gas. Indicating relative ion size, a CCS value alone is of limited utility. Although such information can be used to propose different conformer types, finer details of structure are not captured. The increased accessibility of IMS-MS measurements with commercial instrumentation in recent years has ballooned its usage in combination with separate measurements to provide enhanced data from which greater structural inferences can be drawn. This short review presents recent outstanding developments in scientific research that employs complementary measurements that when combined with IMS-MS data are used to characterize the structures of a wide range of compounds.
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Affiliation(s)
- Sandra N Majuta
- C. Eugene Bennett Department of Chemistry, West Virginia University, WV 26506, United States
| | - Hossein Maleki
- C. Eugene Bennett Department of Chemistry, West Virginia University, WV 26506, United States
| | - Ahmad Kiani Karanji
- C. Eugene Bennett Department of Chemistry, West Virginia University, WV 26506, United States
| | - Kushani Attanyake
- C. Eugene Bennett Department of Chemistry, West Virginia University, WV 26506, United States
| | - Elinore Loch
- C. Eugene Bennett Department of Chemistry, West Virginia University, WV 26506, United States
| | - Stephen J Valentine
- C. Eugene Bennett Department of Chemistry, West Virginia University, WV 26506, United States.
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16
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Laszlo KJ, Bush MF. Effects of Charge State, Charge Distribution, and Structure on the Ion Mobility of Protein Ions in Helium Gas: Results from Trajectory Method Calculations. J Phys Chem A 2017; 121:7768-7777. [PMID: 28910102 DOI: 10.1021/acs.jpca.7b08154] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Collision cross section (Ω) values of gas-phase ions of proteins and protein complexes are used to probe the structures of the corresponding species in solution. Ions of many proteins exhibit increasing Ω-values with increasing charge state but most Ω-values calculated for protein ions have used simple collision models that do not explicitly account for charge. Here we use a combination of ion mobility mass spectrometry experiments with helium gas and trajectory method calculations to characterize the extents to which increases in experimental Ω-values with increasing charge state may be attributed to increased momentum transfer concomitant with enhanced long-range interactions between the protein ion and helium atoms. Ubiquitin and C-to-N terminally linked diubiquitin ions generated from different solution conditions exhibit more than a 2-fold increase in Ω with increasing charge state. For native and energy-relaxed models of the proteins and most methods for distributing charge, Ω-values calculated using the trajectory method increase by less than 1% over the range of charge states observed from typical solution conditions used for native mass spectrometry. However, the calculated Ω-values increase by 10% to 15% over the full range of charge states observed from all solution conditions. Therefore, contributions from enhanced ion-induced dipole interactions with increasing charge state are significant but without additional structural changes can account for only a fraction of the increase in Ω observed experimentally. On the basis of these results, we suggest guidelines for calculating Ω-values in the context of applications in biophysics and structural biology.
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Affiliation(s)
- Kenneth J Laszlo
- University of Washington , Department of Chemistry, Box 351700, Seattle, Washington 98195-1700, United States
| | - Matthew F Bush
- University of Washington , Department of Chemistry, Box 351700, Seattle, Washington 98195-1700, United States
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