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] [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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Lin CW, Canonica F, Wüthrich S, Fettelschoss-Gabriel A, Schlapbach R, Nanni P. m-nitrobenzyl alcohol supercharging reagent enhances the chromatographic separation and the charging of disulfide bond linked and His-tag peptides. J Chromatogr A 2024; 1722:464828. [PMID: 38581973 DOI: 10.1016/j.chroma.2024.464828] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2023] [Revised: 02/27/2024] [Accepted: 03/20/2024] [Indexed: 04/08/2024]
Abstract
The linkages of disulfide bond (DSB) play important roles in protein stability and activity. Mass spectrometry-based (MS-based) techniques become accepted tools for DSB analysis in the recent decade. In the bottom-up approach, after enzyme digestion, the neighbouring amino acids of cysteines have great impacts on the physicochemical properties of resulting disulfide bond peptides, determining their retention behaviour on liquid chromatography (LC) and their MS ionization efficiency. In this study, the addition of supercharging reagent in LC mobile phase was used to examine the impact of supercharging reagent on the charge states of disulfide-bond peptides. The results showed that 0.1 % m-nitrobenzyl alcohol (m-NBA) in LC mobile phase increased the sensitivity and charge states of DSB peptides from our model protein, equine Interleukin-5 (eIL5), as well as the resolution of reversed-phase chromatography. Notably, also the sensitivity of C-terminal peptide with His-tag significantly improved. Our findings highlight the effectiveness of employing m-NBA as a supercharging reagent when investigating disulfide-linked peptides and the C-terminal peptide with a His-tag through nano-liquid chromatography mass spectrometry.
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Affiliation(s)
- Chia-Wei Lin
- Functional Genomics Center Zürich, University of Zürich/ETH Zürich, 8057 Zürich, Switzerland.
| | - Fabia Canonica
- Department of Dermatology, University of Zürich, 8952 Schlieren, Switzerland
| | - Simone Wüthrich
- Functional Genomics Center Zürich, University of Zürich/ETH Zürich, 8057 Zürich, Switzerland
| | | | - Ralph Schlapbach
- Functional Genomics Center Zürich, University of Zürich/ETH Zürich, 8057 Zürich, Switzerland
| | - Paolo Nanni
- Functional Genomics Center Zürich, University of Zürich/ETH Zürich, 8057 Zürich, Switzerland
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3
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Shaw J, Harvey S, Du C, Xu Z, Olmedillas E, Saphire EO, Wysocki VH. Protein complex heterogeneity and topology revealed by electron capture charge reduction and surface induced dissociation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.07.583498. [PMID: 38496594 PMCID: PMC10942452 DOI: 10.1101/2024.03.07.583498] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/19/2024]
Abstract
Herein, we focus on native mass spectrometry (nMS) combined with a fast, tunable gas-phase charge reduction, electron capture charge reduction (ECCR), and illustrate its utility in the characterization of protein complex topology and glycoprotein heterogeneity. ECCR is illustrated to effectively spread the charge states of tetradecameric GroEL, illustrating Orbitrap m/z measurement out to greater than 100,000 m/z. For both the pentameric C-reactive protein and tetradecameric GroEL, our novel device combining ECCR with surface induced dissociation (SID) lowers the charge states and produces more topologically informative fragmentation. While more native-like fragmentation has previously been illustrated for complexes charge reduced by proton abstraction in solution, this is the first illustration that ECCR can lead to more native-like SID fragmentation of protein complexes. Application to protein glycosylation, one of the most common and diverse protein posttranslational modifications, is also illustrated because glycosylation is important for structural and functional properties and plays essential roles in many key biological processes. The immense heterogeneity resulting from variability in glycosylation sites and glycan composition and structure poses significant analytical challenges that hinder a mechanistic understanding of the biological role of glycosylation. Data for stabilized heavily glycosylated SARS-CoV-2 spike protein trimer and thyroglobulin dimer illustrate that ECCR enables significantly improved resolution of glycan heterogeneity. Without ECCR, the charge states of a glycoprotein complex are not resolved and average mass determination is available only through the use of charge detection mass spectrometry or mass photometry. With ECCR after narrow m/z selection, multiple glycoform m/z values are apparent, providing quick global, glycoform profiling and providing a future path for glycan localization on individual intact glycoforms (e.g., though top-down dissociation).
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Affiliation(s)
- Jared Shaw
- Department of Chemistry, University of Nebraska, Lincoln, NE 68588
| | - Sophie Harvey
- Native Mass Spectrometry Guided Structural Biology Center, Ohio State University, Columbus, OH 43210
| | - Chen Du
- Department of Chemistry and Biochemistry, Ohio State University, Columbus, OH 43210
- Native Mass Spectrometry Guided Structural Biology Center, Ohio State University, Columbus, OH 43210
| | - Zhixin Xu
- Department of Chemistry and Biochemistry, Ohio State University, Columbus, OH 43210
- Native Mass Spectrometry Guided Structural Biology Center, Ohio State University, Columbus, OH 43210
| | - Eduardo Olmedillas
- Center for Vaccine Innovation, La Jolla Institute for Immunology, La Jolla, CA 92037
| | - Erica Ollmann Saphire
- Center for Vaccine Innovation, La Jolla Institute for Immunology, La Jolla, CA 92037
- Department of Medicine, University of California San Diego, La Jolla, CA 92037
| | - Vicki H Wysocki
- Department of Chemistry and Biochemistry, Ohio State University, Columbus, OH 43210
- Native Mass Spectrometry Guided Structural Biology Center, Ohio State University, Columbus, OH 43210
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4
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Kaltashov IA, Ivanov DG, Yang Y. Mass spectrometry-based methods to characterize highly heterogeneous biopharmaceuticals, vaccines, and nonbiological complex drugs at the intact-mass level. MASS SPECTROMETRY REVIEWS 2024; 43:139-165. [PMID: 36582075 PMCID: PMC10307928 DOI: 10.1002/mas.21829] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 11/21/2022] [Accepted: 11/22/2022] [Indexed: 06/17/2023]
Abstract
The intact-mass MS measurements are becoming increasingly popular in characterization of a range of biopolymers, especially those of interest to biopharmaceutical industry. However, as the complexity of protein therapeutics and other macromolecular medicines increases, the new challenges arise, one of which is the high levels of structural heterogeneity that are frequently exhibited by such products. The very notion of the molecular mass measurement loses its clear and intuitive meaning when applied to an extremely heterogenous system that cannot be characterized by a unique mass, but instead requires that a mass distribution be considered. Furthermore, convoluted mass distributions frequently give rise to unresolved ionic signal in mass spectra, from which little-to-none meaningful information can be extracted using standard approaches that work well for homogeneous systems. However, a range of technological advances made in the last decade, such as the hyphenation of intact-mass MS measurements with front-end separations, better integration of ion mobility in MS workflows, development of an impressive arsenal of gas-phase ion chemistry tools to supplement MS methods, as well as the revival of the charge detection MS and its triumphant entry into the field of bioanalysis already made impressive contributions towards addressing the structural heterogeneity challenge. An overview of these techniques is accompanied by critical analysis of the strengths and weaknesses of different approaches, and a brief overview of their applications to specific classes of biopharmaceutical products, vaccines, and nonbiological complex drugs.
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Affiliation(s)
- Igor A. Kaltashov
- Department of Chemistry, University of Massachusetts-Amherst, Amherst MA 01003
| | - Daniil G. Ivanov
- Department of Chemistry, University of Massachusetts-Amherst, Amherst MA 01003
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5
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Brandner S, Habeck T, Lermyte F. New Insights into the Intrinsic Electron-Based Dissociation Behavior of Cytochrome c Oligomers. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2023; 34:1908-1916. [PMID: 37227392 DOI: 10.1021/jasms.3c00106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Between 2003 and 2017, four reports were published that demonstrated the intrinsic ability of the native iron-containing proteins cytochrome c and ferritin to undergo radical-based backbone fragmentation in the gas phase without the introduction of exogenous electrons. For cytochrome c in particular, this effect has so far only been reported to occur in the ion source, preventing the in-depth study of reactions occurring after gas-phase isolation of specific precursors. Here, we report the first observation of this intrinsic native electron capture dissociation behavior after quadrupole isolation of specific charge states of the cytochrome c dimer and trimer, providing direct experimental support for key aspects of the mechanism proposed 20 years ago. Furthermore, we provide evidence that, in contrast to some earlier proposals, these oligomeric states are formed in bulk solution rather than during the electrospray ionization process and that the observed fragmentation site preferences can be rationalized through the structure and interactions within these native oligomers rather than the monomer. We also show that the observed fragmentation pattern─and indeed, whether or not fragmentation occurs─is highly sensitive to the provenance and history of the protein samples, to the extent that samples can show distinct fragmentation behavior despite behaving identically in ion mobility experiments. This rather underexplored method therefore represents an exquisitely sensitive conformational probe and will hopefully receive more attention from the biomolecular mass spectrometry community in the future.
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Affiliation(s)
- Sarah Brandner
- Department of Chemistry, Clemens-Schöpf Institute of Organic Chemistry and Biochemistry, Technical University of Darmstadt, Peter-Grünberg-Strasse 4, 64287 Darmstadt, Germany
| | - Tanja Habeck
- Department of Chemistry, Clemens-Schöpf Institute of Organic Chemistry and Biochemistry, Technical University of Darmstadt, Peter-Grünberg-Strasse 4, 64287 Darmstadt, Germany
| | - Frederik Lermyte
- Department of Chemistry, Clemens-Schöpf Institute of Organic Chemistry and Biochemistry, Technical University of Darmstadt, Peter-Grünberg-Strasse 4, 64287 Darmstadt, Germany
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6
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Peris-Díaz MD, Wu S, Mosna K, Liggett E, Barkhanskiy A, Orzeł A, Barran P, Krężel A. Structural Characterization of Cu(I)/Zn(II)-metallothionein-3 by Ion Mobility Mass Spectrometry and Top-Down Mass Spectrometry. Anal Chem 2023; 95:10966-10974. [PMID: 37440218 PMCID: PMC10372872 DOI: 10.1021/acs.analchem.3c00989] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Accepted: 06/29/2023] [Indexed: 07/14/2023]
Abstract
Mammalian zinc metallothionein-3 (Zn7MT3) plays an important role in protecting against copper toxicity by scavenging free Cu(II) ions or removing Cu(II) bound to β-amyloid and α-synuclein. While previous studies reported that Zn7MT3 reacts with Cu(II) ions to form Cu(I)4Zn(II)4MT3ox containing two disulfides (ox), the precise localization of the metal ions and disulfides remained unclear. Here, we undertook comprehensive structural characterization of the metal-protein complexes formed by the reaction between Zn7MT3 and Cu(II) ions using native ion mobility mass spectrometry (IM-MS). The complex formation mechanism was found to involve the disassembly of Zn3S9 and Zn4S11 clusters from Zn7MT3 and reassembly into Cu(I)xZn(II)yMT3ox complexes rather than simply Zn(II)-to-Cu(I) exchange. At neutral pH, the β-domain was shown to be capable of binding up to six Cu(I) ions to form Cu(I)6Zn(II)4MT3ox, although the most predominant species was the Cu(I)4Zn(II)4MT3ox complex. Under acidic conditions, four Zn(II) ions dissociate, but the Cu(I)4-thiolate cluster remains stable, highlighting the MT3 role as a Cu(II) scavenger even at lower than the cytosolic pH. IM-derived collision cross sections (CCS) reveal that Cu(I)-to-Zn(II) swap in Zn7MT3 with concomitant disulfide formation induces structural compaction and a decrease in conformational heterogeneity. Collision-induced unfolding (CIU) experiments estimated that the native-like folded Cu(I)4Zn(II)4MT3ox conformation is more stable than Zn7MT3. Native top-down MS demonstrated that the Cu(I) ions are exclusively bound to the β-domain in the Cu(I)4Zn(II)4MT3ox complex as well as the two disulfides, serving as a steric constraint for the Cu(I)4-thiolate cluster. In conclusion, this study enhances our comprehension of the structure, stability, and dynamics of Cu(I)xZn(II)yMT3ox complexes.
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Affiliation(s)
- Manuel David Peris-Díaz
- Department
of Chemical Biology, Faculty of Biotechnology, University of Wrocław, F. Joliot-Curie 14a, 50-383 Wrocław, Poland
- Michael
Barber Centre for Collaborative Mass Spectrometry, Manchester Institute of Biotechnology, 131 Princess Street, Manchester M1 7DN, United
Kingdom
| | - Sylwia Wu
- Department
of Chemical Biology, Faculty of Biotechnology, University of Wrocław, F. Joliot-Curie 14a, 50-383 Wrocław, Poland
| | - Karolina Mosna
- Department
of Chemical Biology, Faculty of Biotechnology, University of Wrocław, F. Joliot-Curie 14a, 50-383 Wrocław, Poland
| | - Ellen Liggett
- Michael
Barber Centre for Collaborative Mass Spectrometry, Manchester Institute of Biotechnology, 131 Princess Street, Manchester M1 7DN, United
Kingdom
| | - Alexey Barkhanskiy
- Michael
Barber Centre for Collaborative Mass Spectrometry, Manchester Institute of Biotechnology, 131 Princess Street, Manchester M1 7DN, United
Kingdom
| | - Alicja Orzeł
- Department
of Chemical Biology, Faculty of Biotechnology, University of Wrocław, F. Joliot-Curie 14a, 50-383 Wrocław, Poland
| | - Perdita Barran
- Michael
Barber Centre for Collaborative Mass Spectrometry, Manchester Institute of Biotechnology, 131 Princess Street, Manchester M1 7DN, United
Kingdom
| | - Artur Krężel
- Department
of Chemical Biology, Faculty of Biotechnology, University of Wrocław, F. Joliot-Curie 14a, 50-383 Wrocław, Poland
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7
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Christofi E, Barran P. Ion Mobility Mass Spectrometry (IM-MS) for Structural Biology: Insights Gained by Measuring Mass, Charge, and Collision Cross Section. Chem Rev 2023; 123:2902-2949. [PMID: 36827511 PMCID: PMC10037255 DOI: 10.1021/acs.chemrev.2c00600] [Citation(s) in RCA: 30] [Impact Index Per Article: 30.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/26/2023]
Abstract
The investigation of macromolecular biomolecules with ion mobility mass spectrometry (IM-MS) techniques has provided substantial insights into the field of structural biology over the past two decades. An IM-MS workflow applied to a given target analyte provides mass, charge, and conformation, and all three of these can be used to discern structural information. While mass and charge are determined in mass spectrometry (MS), it is the addition of ion mobility that enables the separation of isomeric and isobaric ions and the direct elucidation of conformation, which has reaped huge benefits for structural biology. In this review, where we focus on the analysis of proteins and their complexes, we outline the typical features of an IM-MS experiment from the preparation of samples, the creation of ions, and their separation in different mobility and mass spectrometers. We describe the interpretation of ion mobility data in terms of protein conformation and how the data can be compared with data from other sources with the use of computational tools. The benefit of coupling mobility analysis to activation via collisions with gas or surfaces or photons photoactivation is detailed with reference to recent examples. And finally, we focus on insights afforded by IM-MS experiments when applied to the study of conformationally dynamic and intrinsically disordered proteins.
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Affiliation(s)
- Emilia Christofi
- Michael Barber Centre for Collaborative Mass Spectrometry, Manchester Institute of Biotechnology, University of Manchester, Princess Street, Manchester M1 7DN, United Kingdom
| | - Perdita Barran
- Michael Barber Centre for Collaborative Mass Spectrometry, Manchester Institute of Biotechnology, University of Manchester, Princess Street, Manchester M1 7DN, United Kingdom
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8
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Chen Q, Dai R, Yao X, Chaihu L, Tong W, Huang Y, Wang G. Improving Accuracy in Mass Spectrometry-Based Mass Determination of Intact Heterogeneous Protein Utilizing the Universal Benefits of Charge Reduction and Alternative Gas-Phase Reactions. Anal Chem 2022; 94:13869-13878. [PMID: 36170625 DOI: 10.1021/acs.analchem.2c02586] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In mass analysis of proteins, mass spectrometry directly measures the mass to charge ratios of ionized proteins and promises higher accuracy than that of indirect approaches measuring other physicochemical properties, provided that the charge states of detected ions are determined. Accurate mass determination of heterogeneously glycosylated proteins is often hindered by unreliable charge determination due to the insufficient resolution of signals from different charge states and inconsistency among mass profiles of ions in individual charge states. Limited charge reduction of a subpopulation of proteoforms using electron transfer/capture reactions (ETnoD/ETnoD) solves this problem by narrowing the mass distribution of examined proteoforms and preserving the mass profile of the precursor charge state in the reduced charge states. However, the limited availability of ETnoD/ETnoD function in commercial instruments limits the application of this approach. Here, utilizing a range of charge-dependent and accuracy-affecting spectral features revealed by a systematic evaluation at levels of both the ensemble and subpopulation of proteoforms based on theoretical models and experiments, we developed a limited charge reduction workflow that enables using collision-induced dissociation and higher energy collisional dissociation, two widely available reactions, as alternatives to ETnoD/ETnoD while providing adequate accuracy. Alternatively, substituting proton transfer charge reduction for ETnoD/ETnoD provides higher accuracy of mass determination. Performing mass selection in a window-sliding manner improves the accuracy and allows profiling of the whole proteoform distribution. The proposed workflow may facilitate the development of universal characterization strategies for more complex and heterogeneous protein systems.
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Affiliation(s)
- Qingrong Chen
- School of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210023, China.,Institute for Cell Analysis, Shenzhen Bay Laboratory, Shenzhen 518132, China
| | - Rongrong Dai
- School of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210023, China.,Institute for Cell Analysis, Shenzhen Bay Laboratory, Shenzhen 518132, China
| | - Xiaopeng Yao
- School of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210023, China.,Institute for Cell Analysis, Shenzhen Bay Laboratory, Shenzhen 518132, China
| | - Lingxiao Chaihu
- School of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210023, China.,Institute for Cell Analysis, Shenzhen Bay Laboratory, Shenzhen 518132, China
| | - Wenjun Tong
- School of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210023, China
| | - Yanyi Huang
- Institute for Cell Analysis, Shenzhen Bay Laboratory, Shenzhen 518132, China.,Biomedical Pioneering Innovation Centre, Peking University, Beijing 100871, China
| | - Guanbo Wang
- Institute for Cell Analysis, Shenzhen Bay Laboratory, Shenzhen 518132, China.,Biomedical Pioneering Innovation Centre, Peking University, Beijing 100871, China
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9
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Abstract
Native mass spectrometry (nMS) has emerged as an important tool in studying the structure and function of macromolecules and their complexes in the gas phase. In this review, we cover recent advances in nMS and related techniques including sample preparation, instrumentation, activation methods, and data analysis software. These advances have enabled nMS-based techniques to address a variety of challenging questions in structural biology. The second half of this review highlights recent applications of these technologies and surveys the classes of complexes that can be studied with nMS. Complementarity of nMS to existing structural biology techniques and current challenges in nMS are also addressed.
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Affiliation(s)
- Kelly R Karch
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio, USA;
- Resource for Native Mass Spectrometry Guided Structural Biology, The Ohio State University, Columbus, Ohio, USA
| | - Dalton T Snyder
- Resource for Native Mass Spectrometry Guided Structural Biology, The Ohio State University, Columbus, Ohio, USA
| | - Sophie R Harvey
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio, USA;
- Resource for Native Mass Spectrometry Guided Structural Biology, The Ohio State University, Columbus, Ohio, USA
| | - Vicki H Wysocki
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio, USA;
- Resource for Native Mass Spectrometry Guided Structural Biology, The Ohio State University, Columbus, Ohio, USA
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10
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Bailey AO, Huguet R, Mullen C, Syka JEP, Russell WK. Ion-Ion Charge Reduction Addresses Multiple Challenges Common to Denaturing Intact Mass Analysis. Anal Chem 2022; 94:3930-3938. [PMID: 35189062 DOI: 10.1021/acs.analchem.1c04973] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Complete LC-MS-based protein primary sequence characterization requires measurement of intact protein profiles under denaturing and/or reducing conditions. To address issues of protein overcharging of unstructured proteins under acidic, denaturing conditions and sample heterogeneity (macro- and micro-scales) which often confound denaturing intact mass analysis of a wide variety of protein samples, we propose the use of broadband isolation of entire charge state distributions of intact proteins followed by ion-ion proton transfer charge reduction, which we have termed "full scan PTCR" (fsPTCR). Using rapid denaturing size exclusion chromatography coupled to fsPTCR-Orbitrap MS and time-resolved deconvolution data analysis, we demonstrate a strategy for method optimization, leading to significant analytical advantages over conventional MS1. Denaturing analysis of the flexible bacterial translation initiation factor 2 (91 kDa) using fsPTCR reduced overcharging and showed an 11-fold gain in S/N compared to conventional MS1. Analysis by fsPTCR-MS of the microheterogeneous glycoprotein fetuin revealed twice as many proteoforms as MS1 (112 vs 56). In a macroheterogeneous mixture of proteins ranging from 14 to 148 kDa, fsPTCR provided more than 10-fold increased sensitivity and quantitative accuracy for diluted bovine serum albumin (66 kDa). Finally, our analysis shows that collisional gas pressure is a key parameter which can be utilized during fsPTCR to retain or remove larger proteins from acquired spectra.
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Affiliation(s)
- Aaron O Bailey
- University of Texas Medical Branch, 301 University Drive, Galveston, Texas 77551, United States
| | - Romain Huguet
- Thermo Fisher Scientific, 355 River Oaks Pkwy, San Jose, California 95134, United States
| | - Christopher Mullen
- Thermo Fisher Scientific, 355 River Oaks Pkwy, San Jose, California 95134, United States
| | - John E P Syka
- Thermo Fisher Scientific, 355 River Oaks Pkwy, San Jose, California 95134, United States
| | - William K Russell
- University of Texas Medical Branch, 301 University Drive, Galveston, Texas 77551, United States
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11
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Wouters B, Currivan S, Abdulhussain N, Hankemeier T, Schoenmakers P. Immobilized-enzyme reactors integrated into analytical platforms: Recent advances and challenges. Trends Analyt Chem 2021. [DOI: 10.1016/j.trac.2021.116419] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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12
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Abstract
Native mass spectrometry (MS) is aimed at preserving and determining the native structure, composition, and stoichiometry of biomolecules and their complexes from solution after they are transferred into the gas phase. Major improvements in native MS instrumentation and experimental methods over the past few decades have led to a concomitant increase in the complexity and heterogeneity of samples that can be analyzed, including protein-ligand complexes, protein complexes with multiple coexisting stoichiometries, and membrane protein-lipid assemblies. Heterogeneous features of these biomolecular samples can be important for understanding structure and function. However, sample heterogeneity can make assignment of ion mass, charge, composition, and structure very challenging due to the overlap of tens or even hundreds of peaks in the mass spectrum. In this review, we cover data analysis, experimental, and instrumental advances and strategies aimed at solving this problem, with an in-depth discussion of theoretical and practical aspects of the use of available deconvolution algorithms and tools. We also reflect upon current challenges and provide a view of the future of this exciting field.
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Affiliation(s)
- Amber D Rolland
- Department of Chemistry and Biochemistry, University of Oregon, Eugene, Oregon 97403-1253, United States
| | - James S Prell
- Department of Chemistry and Biochemistry, University of Oregon, Eugene, Oregon 97403-1253, United States.,Materials Science Institute, University of Oregon, Eugene, Oregon 97403-1252, United States
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13
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Snyder DT, Lin YF, Somogyi A, Wysocki V. Tandem surface-induced dissociation of protein complexes on an ultrahigh resolution platform. INTERNATIONAL JOURNAL OF MASS SPECTROMETRY 2021; 461:116503. [PMID: 33889055 PMCID: PMC8057730 DOI: 10.1016/j.ijms.2020.116503] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
We describe instrumentation for conducting tandem surface-induced dissociation (tSID) of native protein complexes on an ultrahigh resolution Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer. The two stages of SID are accomplished with split lenses replacing the entrance lenses of the quadrupole mass filter (stage 1, referred to herein as SID-Q) and the collision cell (stage 2, Q-SID). After SID-Q, the scattered projectile ions and subcomplexes formed in transit traverse the 20 mm pre-filter prior to the mass-selecting quadrupole, providing preliminary insights into the SID fragmentation kinetics of noncovalent protein complexes. The isolated SID fragments (subcomplexes) are then fragmented by SID in the collision cell entrance lens (Q-SID), generating subcomplexes of subcomplexes. We show that the ultrahigh resolution of the FT-ICR can be used for deconvolving species overlapping in m/z, which are particularly prominent in tandem SID spectra due to the combination of symmetric charge partitioning and narrow product ion charge state distributions. Various protein complex topologies are explored, including homotetramers, homopentamers, a homohexamer, and a heterohexamer.
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Affiliation(s)
- Dalton T. Snyder
- Resource for Native MS Guided Structural Biology, The Ohio State University, Columbus OH, USA 43210
| | - Yu-Fu Lin
- Resource for Native MS Guided Structural Biology, The Ohio State University, Columbus OH, USA 43210
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus OH, USA 43210
| | - Arpad Somogyi
- Resource for Native MS Guided Structural Biology, The Ohio State University, Columbus OH, USA 43210
| | - Vicki Wysocki
- Resource for Native MS Guided Structural Biology, The Ohio State University, Columbus OH, USA 43210
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus OH, USA 43210
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14
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Snyder DT, Panczyk EM, Somogyi A, Kaplan DA, Wysocki V. Simple and Minimally Invasive SID Devices for Native Mass Spectrometry. Anal Chem 2020; 92:11195-11203. [PMID: 32700898 DOI: 10.1021/acs.analchem.0c01657] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
We describe a set of simple devices for surface-induced dissociation of proteins and protein complexes on three instrument platforms. All of the devices use a novel yet simple split lens geometry that is minimally invasive (requiring a few millimeters along the ion path axis) and is easier to operate than prior generations of devices. The split lens is designed to be small enough to replace the entrance lens of a Bruker FT-ICR collision cell, the dynamic range enhancement (DRE) lens of a Waters Q-IM-TOF, or the exit lens of a transfer multipole of a Thermo Scientific Extended Mass Range (EMR) Orbitrap. Despite the decrease in size and reduction in number of electrodes to 3 (from 10 to 12 in Gen 1 and ∼6 in Gen 2), we show sensitivity improvement in a variety of cases across all platforms while also maintaining SID capabilities across a wide mass and energy range. The coupling of SID, high resolution, and ion mobility is demonstrated for a variety of protein complexes of varying topologies.
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15
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Petroff JT, Tong A, Chen LJ, Dekoster GT, Khan F, Abramson J, Frieden C, Cheng WWL. Charge Reduction of Membrane Proteins in Native Mass Spectrometry Using Alkali Metal Acetate Salts. Anal Chem 2020; 92:6622-6630. [PMID: 32250604 DOI: 10.1021/acs.analchem.0c00454] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Native mass spectrometry (MS) provides the capacity to monitor membrane protein complexes and noncovalent binding of ligands and lipids to membrane proteins. The charge states produced by native MS of membrane proteins often result in gas-phase protein unfolding or loss of noncovalent interactions. In an effort to reduce the charge of membrane proteins, we examined the utility of alkali metal salts as a charge-reducing agent. Low concentrations of alkali metal salts caused marked charge reduction in the membrane protein, Erwinia ligand-gated ion channel (ELIC). The charge-reducing effect only occurred for membrane proteins and was detergent-dependent, being most pronounced in long polyethylene glycol (PEG)-based detergents such as C10E5 and C12E8. On the basis of these results, we propose a mechanism for alkali metal charge reduction of membrane proteins. Addition of low concentrations of alkali metals may provide an advantageous approach for charge reduction of detergent-solubilized membrane proteins by native MS.
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Affiliation(s)
| | | | | | | | - Farha Khan
- Department of Physiology, David Geffen School of Medicine at UCLA, 310833 Le Conte Avenue, Los Angeles, California 90095, United States
| | - Jeff Abramson
- Department of Physiology, David Geffen School of Medicine at UCLA, 310833 Le Conte Avenue, Los Angeles, California 90095, United States
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16
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Williams JP, Morrison LJ, Brown JM, Beckman JS, Voinov VG, Lermyte F. Top-Down Characterization of Denatured Proteins and Native Protein Complexes Using Electron Capture Dissociation Implemented within a Modified Ion Mobility-Mass Spectrometer. Anal Chem 2020; 92:3674-3681. [PMID: 31999103 DOI: 10.1021/acs.analchem.9b04763] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Electron-based fragmentation methods have revolutionized biomolecular mass spectrometry, in particular native and top-down protein analysis. Here, we report the use of a new electromagnetostatic cell to perform electron capture dissociation (ECD) within a quadrupole/ion mobility/time-of-flight mass spectrometer. This cell was installed between the ion mobility and time-of-flight regions of the instrument, and fragmentation was fast enough to be compatible with mobility separation. The instrument was already fitted with electron transfer dissociation (ETD) between the quadrupole and mobility regions prior to modification. We show excellent fragmentation efficiency for denatured peptides and proteins without the need to trap ions in the gas phase. Additionally, we demonstrate native top-down backbone fragmentation of noncovalent protein complexes, leading to comparable sequence coverage to what was achieved using the instrument's existing ETD capabilities. Limited collisional ion activation of the hemoglobin tetramer before ECD was reflected in the observed fragmentation pattern, and complementary ion mobility measurements prior to ECD provided orthogonal evidence of monomer unfolding within this complex. The approach demonstrated here provides a powerful platform for both top-down proteomics and mass spectrometry-based structural biology studies.
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Affiliation(s)
- Jonathan P Williams
- Waters Corporation, Stamford Avenue, Altrincham Road, Wilmslow SK9 4AX, United Kingdom
| | - Lindsay J Morrison
- Waters Corporation, Stamford Avenue, Altrincham Road, Wilmslow SK9 4AX, United Kingdom
| | - Jeffery M Brown
- Waters Corporation, Stamford Avenue, Altrincham Road, Wilmslow SK9 4AX, United Kingdom
| | - Joseph S Beckman
- e-MSion Inc., 2121 NE Jack London Drive, Corvallis, Oregon 97330, United States.,Linus Pauling Institute and the Department of Biochemistry and Biophysics, Oregon State University, Corvallis, Oregon 97331, United States
| | - Valery G Voinov
- e-MSion Inc., 2121 NE Jack London Drive, Corvallis, Oregon 97330, United States.,Linus Pauling Institute and the Department of Biochemistry and Biophysics, Oregon State University, Corvallis, Oregon 97331, United States
| | - Frederik Lermyte
- School of Engineering, University of Warwick, Coventry CV4 7AL, United Kingdom.,Department of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom
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17
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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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18
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Mehaffey MR, Schardon CL, Novelli ET, Cammarata MB, Webb LJ, Fast W, Brodbelt JS. Investigation of GTP-dependent dimerization of G12X K-Ras variants using ultraviolet photodissociation mass spectrometry. Chem Sci 2019; 10:8025-8034. [PMID: 31853358 PMCID: PMC6837035 DOI: 10.1039/c9sc01032g] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Accepted: 07/14/2019] [Indexed: 12/14/2022] Open
Abstract
Mutations in the GTPase enzyme K-Ras, specifically at codon G12, remain the most common genetic alterations in human cancers. The mechanisms governing activation of downstream signaling pathways and how they relate back to the identity of the mutation have yet to be completely defined. Here we use native mass spectrometry (MS) combined with ultraviolet photodissociation (UVPD) to investigate the impact of three G12X mutations (G12C, G12V, G12S) on the homodimerization of K-Ras as well as heterodimerization with a downstream effector protein, Raf. Electrospray ionization (ESI) was used to transfer complexes of WT or G12X K-Ras bound to guanosine 5'-diphosphate (GDP) or GppNHp (non-hydrolyzable analogue of GTP) into the gas phase. Relative abundances of homo- or hetero-dimer complexes were estimated from ESI-MS spectra. K-Ras + Raf heterocomplexes were activated with UVPD to probe structural changes responsible for observed differences in the amount of heterocomplex formed for each variant. Holo (ligand-bound) fragment ions resulting from photodissociation suggest the G12X mutants bind Raf along the expected effector binding region (β-interface) but may interact with Raf via an alternative α-interface as well. Variations in backbone cleavage efficiencies during UV photoactivation of each variant were used to relate mutation identity to structural changes that might impact downstream signaling. Specifically, oncogenic upregulation for hydrogen-bonding amino acid substitutions (G12C, G12S) is achieved by stabilizing β-interface interactions with Raf, while a bulkier, hydrophobic G12V substitution leads to destabilization of this interface and instead increases the proximity of residues along the α-helical bundles. This study deciphers new pieces of the complex puzzle of how different K-Ras mutations exert influence in downstream signaling.
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Affiliation(s)
- M Rachel Mehaffey
- Department of Chemistry , University of Texas at Austin , Austin , TX 78712-0165 , USA . ; Tel: +1-512-471-0028
| | - Christopher L Schardon
- Division of Chemical Biology and Medicinal Chemistry , College of Pharmacy , University of Texas at Austin , Austin , TX 78712 , USA
| | - Elisa T Novelli
- Department of Chemistry , University of Texas at Austin , Austin , TX 78712-0165 , USA . ; Tel: +1-512-471-0028
| | - Michael B Cammarata
- Department of Chemistry , University of Texas at Austin , Austin , TX 78712-0165 , USA . ; Tel: +1-512-471-0028
| | - Lauren J Webb
- Department of Chemistry , University of Texas at Austin , Austin , TX 78712-0165 , USA . ; Tel: +1-512-471-0028
| | - Walter Fast
- Division of Chemical Biology and Medicinal Chemistry , College of Pharmacy , University of Texas at Austin , Austin , TX 78712 , USA
| | - Jennifer S Brodbelt
- Department of Chemistry , University of Texas at Austin , Austin , TX 78712-0165 , USA . ; Tel: +1-512-471-0028
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19
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Lermyte F, Tsybin YO, O'Connor PB, Loo JA. Top or Middle? Up or Down? Toward a Standard Lexicon for Protein Top-Down and Allied Mass Spectrometry Approaches. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2019; 30:1149-1157. [PMID: 31073892 PMCID: PMC6591204 DOI: 10.1007/s13361-019-02201-x] [Citation(s) in RCA: 78] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Revised: 03/13/2019] [Accepted: 03/14/2019] [Indexed: 05/18/2023]
Abstract
In recent years, there has been increasing interest in top-down mass spectrometry (TDMS) approaches for protein analysis, driven both by technological advancements and efforts such as those by the multinational Consortium for Top-Down Proteomics (CTDP). Today, diverse sample preparation and ionization methods are employed to facilitate TDMS analysis of denatured and native proteins and their complexes. The goals of these studies vary, ranging from protein and proteoform identification, to determination of the binding site of a (non)covalently-bound ligand, and in some cases even with the aim to study the higher order structure of proteins and complexes. Currently, however, no widely accepted terminology exists to precisely and unambiguously distinguish between the different types of TDMS experiments that can be performed. Instead, ad hoc developed terminology is often used, which potentially complicates communication of top-down and allied methods and their results. In this communication, we consider the different types of top-down (or top-down-related) MS experiments that have been performed and reported, and define distinct categories based on the protocol used and type(s) of information that can be obtained. We also consider the different possible conventions for distinguishing between middle- and top-down MS, based on both sample preparation and precursor ion mass. We believe that the proposed framework presented here will prove helpful for researchers to communicate about TDMS and will be an important step toward harmonizing and standardizing this growing field. Graphical Abstract.
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Affiliation(s)
- Frederik Lermyte
- School of Engineering, University of Warwick, Coventry, CV4 7AL, UK.
- Department of Chemistry, University of Warwick, Coventry, CV4 7AL, UK.
| | - Yury O Tsybin
- Spectroswiss, EPFL Innovation Park, 1015, Lausanne, Switzerland
| | - Peter B O'Connor
- Department of Chemistry, University of Warwick, Coventry, CV4 7AL, UK
| | - Joseph A Loo
- Department of Chemistry and Biochemistry, Department of Biological Chemistry, David Geffen School of Medicine, and UCLA/DOE Institute of Genomics and Proteomics, University of California, Los Angeles, CA, USA
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20
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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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21
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Chouinard CD, Nagy G, Smith RD, Baker ES. Ion Mobility-Mass Spectrometry in Metabolomic, Lipidomic, and Proteomic Analyses. ADVANCES IN ION MOBILITY-MASS SPECTROMETRY: FUNDAMENTALS, INSTRUMENTATION AND APPLICATIONS 2019. [DOI: 10.1016/bs.coac.2018.11.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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22
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Lermyte F, Valkenborg D, Loo JA, Sobott F. Radical solutions: Principles and application of electron-based dissociation in mass spectrometry-based analysis of protein structure. MASS SPECTROMETRY REVIEWS 2018; 37:750-771. [PMID: 29425406 PMCID: PMC6131092 DOI: 10.1002/mas.21560] [Citation(s) in RCA: 61] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Revised: 01/19/2018] [Accepted: 01/19/2018] [Indexed: 05/11/2023]
Abstract
In recent years, electron capture (ECD) and electron transfer dissociation (ETD) have emerged as two of the most useful methods in mass spectrometry-based protein analysis, evidenced by a considerable and growing body of literature. In large part, the interest in these methods is due to their ability to induce backbone fragmentation with very little disruption of noncovalent interactions which allows inference of information regarding higher order structure from the observed fragmentation behavior. Here, we review the evolution of electron-based dissociation methods, and pay particular attention to their application in "native" mass spectrometry, their mechanism, determinants of fragmentation behavior, and recent developments in available instrumentation. Although we focus on the two most widely used methods-ECD and ETD-we also discuss the use of other ion/electron, ion/ion, and ion/neutral fragmentation methods, useful for interrogation of a range of classes of biomolecules in positive- and negative-ion mode, and speculate about how this exciting field might evolve in the coming years.
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Affiliation(s)
- Frederik Lermyte
- Biomolecular and Analytical Mass Spectrometry Group, Department of Chemistry, University of Antwerp, Antwerp, Belgium
- Centre for Proteomics, University of Antwerp, Antwerp, Belgium
- School of Engineering, University of Warwick, Coventry, United Kingdom
| | - Dirk Valkenborg
- Centre for Proteomics, University of Antwerp, Antwerp, Belgium
- Interuniversity Institute for Biostatistics and Statistical Bioinformatics, Hasselt University, Agoralaan, Diepenbeek, Belgium
- Applied Bio and Molecular Systems, Flemish Institute for Technological Research (VITO), Mol, Belgium
| | - Joseph A Loo
- Department of Biological Chemistry, David Geffen School of Medicine, University of California-Los Angeles, Los Angeles, California
- UCLA/DOE Institute for Genomics and Proteomics, University of California-Los Angeles, Los Angeles, California
- Department of Chemistry and Biochemistry, University of California-Los Angeles, Los Angeles, California
| | - Frank Sobott
- Biomolecular and Analytical Mass Spectrometry Group, Department of Chemistry, University of Antwerp, Antwerp, Belgium
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, United Kingdom
- School of Molecular and Cellular Biology, University of Leeds, Leeds, United Kingdom
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23
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Mehaffey MR, Sanders JD, Holden DD, Nilsson CL, Brodbelt JS. Multistage Ultraviolet Photodissociation Mass Spectrometry To Characterize Single Amino Acid Variants of Human Mitochondrial BCAT2. Anal Chem 2018; 90:9904-9911. [PMID: 30016590 PMCID: PMC6323636 DOI: 10.1021/acs.analchem.8b02099] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Unraveling disease mechanisms requires a comprehensive understanding of how the interplay between higher-order structure and protein-ligand interactions impacts the function of a given protein. Recent advances in native mass spectrometry (MS) involving multimodal or higher-energy activation methods have allowed direct interrogation of intact protein complexes in the gas phase, allowing analysis of both composition and subunit connectivity. We report a multistage approach combining collisional activation and 193 nm ultraviolet photodissociation (UVPD) to characterize single amino acid variants of the human mitochondrial enzyme branched-chain amino acid transferase 2 (BCAT2), a protein implicated in chemotherapeutic resistance in glioblastoma tumors. Native electrospray ionization confirms that both proteins exist as homodimers. Front-end collisional activation disassembles the dimers into monomeric subunits that are further interrogated using UVPD to yield high sequence coverage of the mutated region. Additionally, holo (ligand-bound) fragment ions resulting from photodissociation reveal that the mutation causes destabilization of the interactions with a bound cofactor. This study demonstrates the unique advantages of implementing UVPD in a multistage MS approach for analyzing intact protein assemblies.
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Affiliation(s)
- M. Rachel Mehaffey
- Department of Chemistry, University of Texas at Austin, Austin, TX 78712
| | - James D. Sanders
- Department of Chemistry, University of Texas at Austin, Austin, TX 78712
| | - Dustin D. Holden
- Department of Chemistry, University of Texas at Austin, Austin, TX 78712
| | - Carol L. Nilsson
- Institute of Experimental Medical Sciences, Lund University, SE-221, Lund Sweden
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24
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Metwally H, Konermann L. Crown Ether Effects on the Location of Charge Carriers in Electrospray Droplets: Implications for the Mechanism of Protein Charging and Supercharging. Anal Chem 2018; 90:4126-4134. [DOI: 10.1021/acs.analchem.8b00099] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Haidy Metwally
- Department of Chemistry, The University of Western Ontario, London, Ontario N6A 5B7, Canada
| | - Lars Konermann
- Department of Chemistry, The University of Western Ontario, London, Ontario N6A 5B7, Canada
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25
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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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26
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Riley NM, Westphall MS, Coon JJ. Sequencing Larger Intact Proteins (30-70 kDa) with Activated Ion Electron Transfer Dissociation. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2018; 29:140-149. [PMID: 29027149 PMCID: PMC5786479 DOI: 10.1007/s13361-017-1808-7] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Revised: 08/31/2017] [Accepted: 09/02/2017] [Indexed: 05/12/2023]
Abstract
The analysis of intact proteins via mass spectrometry can offer several benefits to proteome characterization, although the majority of top-down experiments focus on proteoforms in a relatively low mass range (<30 kDa). Recent studies have focused on improving the analysis of larger intact proteins (up to ~75 kDa), but they have also highlighted several challenges to be addressed. One major hurdle is the efficient dissociation of larger protein ions, which often to do not yield extensive fragmentation via conventional tandem MS methods. Here we describe the first application of activated ion electron transfer dissociation (AI-ETD) to proteins in the 30-70 kDa range. AI-ETD leverages infrared photo-activation concurrent to ETD reactions to improve sequence-informative product ion generation. This method generates more product ions and greater sequence coverage than conventional ETD, higher-energy collisional dissociation (HCD), and ETD combined with supplemental HCD activation (EThcD). Importantly, AI-ETD provides the most thorough protein characterization for every precursor ion charge state investigated in this study, making it suitable as a universal fragmentation method in top-down experiments. Additionally, we highlight several acquisition strategies that can benefit characterization of larger proteins with AI-ETD, including combination of spectra from multiple ETD reaction times for a given precursor ion, multiple spectral acquisitions of the same precursor ion, and combination of spectra from two different dissociation methods (e.g., AI-ETD and HCD). In all, AI-ETD shows great promise as a method for dissociating larger intact protein ions as top-down proteomics continues to advance into larger mass ranges. Graphical Abstract ᅟ.
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Affiliation(s)
- Nicholas M Riley
- Genome Center of Wisconsin, Madison, WI, USA
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | | | - Joshua J Coon
- Genome Center of Wisconsin, Madison, WI, USA.
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, 53706, USA.
- Department of Biomolecular Chemistry, University of Wisconsin-Madison, Madison, WI, 53706, USA.
- Morgridge Institute for Research, Madison, WI, USA.
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27
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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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28
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Ciach MA, Łącki MK, Miasojedow B, Lermyte F, Valkenborg D, Sobott F, Gambin A. Estimation of Rates of Reactions Triggered by Electron Transfer in Top-Down Mass Spectrometry. J Comput Biol 2017; 25:282-301. [PMID: 28945460 DOI: 10.1089/cmb.2017.0156] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Electron transfer dissociation (ETD) is a versatile technique used in mass spectrometry for the high-throughput characterization of proteins. It consists of several concurrent reactions triggered by the transfer of an electron from its anion source to sample cations. Transferring an electron causes peptide backbone cleavage while leaving labile post-translational modifications intact. The obtained fragmentation spectra provide valuable information for sequence and structure analyses. In this study, we propose a formal mathematical model of the ETD fragmentation process in the form of a system of stochastic differential equations describing its joint dynamics. Parameters of the model correspond to the rates of occurring reactions. Their estimates for various experimental settings give insight into the dynamics of the ETD process. We estimate the model parameters from the relative quantities of fragmentation products in a given mass spectrum by solving a nonlinear optimization problem. The cost function penalizes for the differences between the analytically derived average number of reaction products and their experimental counterparts. The presented method proves highly robust to noise in silico. Moreover, the model can explain a considerable amount of experimental results for a wide range of instrumentation settings. The implementation of the presented workflow, code-named ETDetective, is freely available under the two-clause BSD license.
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Affiliation(s)
| | | | - Błażej Miasojedow
- 1 Faculty of Mathematics, Informatics, and Mechanics, University of Warsaw , Warsaw, Poland
| | - Frederik Lermyte
- 2 Biomolecular and Analytical Mass Spectrometry Group, Department of Chemistry, University of Antwerp , Antwerp, Belgium .,3 Centre for Proteomics, University of Antwerp , Antwerp, Belgium
| | - Dirk Valkenborg
- 3 Centre for Proteomics, University of Antwerp , Antwerp, Belgium .,4 Interuniversity Institute for Biostatistics and Statistical Bioinformatics, Hasselt University , Hasselt, Belgium
| | - Frank Sobott
- 2 Biomolecular and Analytical Mass Spectrometry Group, Department of Chemistry, University of Antwerp , Antwerp, Belgium
| | - Anna Gambin
- 1 Faculty of Mathematics, Informatics, and Mechanics, University of Warsaw , Warsaw, Poland
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29
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R Julian R. The Mechanism Behind Top-Down UVPD Experiments: Making Sense of Apparent Contradictions. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2017; 28:1823-1826. [PMID: 28702929 PMCID: PMC5711567 DOI: 10.1007/s13361-017-1721-0] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Revised: 05/15/2017] [Accepted: 05/22/2017] [Indexed: 05/21/2023]
Abstract
Top-down ultraviolet photodissociation (UVPD) allows greater sequence coverage than any other currently available method, often fracturing the vast majority of peptide bonds in whole proteins. At the same time, UVPD can be used to dissociate noncovalent complexes assembled from multiple proteins without breaking any covalent bonds. Although the utility of these experiments is unquestioned, the mechanism underlying these seemingly contradictory results has been the subject of many discussions. Herein, some fundamental considerations of photochemistry are briefly summarized within the context of a proposed mechanism that rationalizes the experimental results obtained by UVPD. Considerations for future instrument design, in terms of wavelength choice and power, are briefly discussed. Graphical Abstract ᅟ.
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Affiliation(s)
- Ryan R Julian
- Department of Chemistry, University of California, Riverside, 501 Big Springs Road, Riverside, CA, 92521, USA.
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30
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Laszlo KJ, Bush MF. Interpreting the Collision Cross Sections of Native-like Protein Ions: Insights from Cation-to-Anion Proton-Transfer Reactions. Anal Chem 2017. [PMID: 28636334 DOI: 10.1021/acs.analchem.7b01474] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The effects of charge state on structures of native-like cations of serum albumin, streptavidin, avidin, and alcohol dehydrogenase were probed using cation-to-anion proton-transfer reactions (CAPTR), ion mobility, mass spectrometry, and complementary energy-dependent experiments. The CAPTR products all have collision cross-section (Ω) values that are within 5.5% of the original precursor cations. The first CAPTR event for each precursor yields products that have smaller Ω values and frequently exhibit the greatest magnitude of change in Ω resulting from a single CAPTR event. To investigate how the structures of the precursors affect the structures of the products, ions were activated as a function of energy prior to CAPTR. In each case, the Ω values of the activated precursors increase with increasing energy, but the Ω values of the CAPTR products are smaller than the activated precursors. To investigate the stabilities of the CAPTR products, the products were activated immediately prior to ion mobility. These results show that additional structures with smaller or larger Ω values can be populated and that the structures and stabilities of these ions depend most strongly on the identity of the protein and the charge state of the product, rather than the charge state of the precursor or the number of CAPTR events. Together, these results indicate that the excess charges initially present on native-like ions have a modest, but sometimes statistically significant, effect on their Ω values. Therefore, potential contributions from charge state should be considered when using experimental Ω values to elucidate structures in solution.
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Affiliation(s)
- Kenneth J Laszlo
- 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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31
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Laszlo KJ, Buckner JH, Munger EB, Bush MF. Native-Like and Denatured Cytochrome c Ions Yield Cation-to-Anion Proton Transfer Reaction Products with Similar Collision Cross-Sections. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2017; 28:1382-1391. [PMID: 28224394 PMCID: PMC5555649 DOI: 10.1007/s13361-017-1620-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Revised: 01/28/2017] [Accepted: 01/30/2017] [Indexed: 05/04/2023]
Abstract
The relationship between structures of protein ions, their charge states, and their original structures prior to ionization remains challenging to decouple. Here, we use cation-to-anion proton transfer reactions (CAPTR) to reduce the charge states of cytochrome c ions in the gas phase, and ion mobility to probe their structures. Ions were formed using a new temperature-controlled nanoelectrospray ionization source at 25 °C. Characterization of this source demonstrates that the temperature of the liquid sample is decoupled from that of the atmospheric pressure interface, which is heated during CAPTR experiments. Ionization from denaturing conditions yields 18+ to 8+ ions, which were each isolated and reacted with monoanions to generate all CAPTR products with charge states of at least 3+. The highest, intermediate, and lowest charge-state products exhibit collision cross-section distributions that are unimodal, multimodal, and unimodal, respectively. These distributions depend strongly on the charge state of the product, although those for the intermediate charge-state products also depend on that of the precursor. The distributions of the 3+ products are all similar, with averages that are less than half that of the 18+ precursor ions. Ionization of cytochrome c from native-like conditions yields 7+ and 6+ ions. The 3+ CAPTR products from these precursors have slightly more compact collision cross-section distributions that are indistinguishable from those for the 3+ CAPTR products from denaturing conditions. More broadly, these results indicate that the collision cross-sections of ions of this single domain protein depend strongly on charge state for charge states greater than ~4. Graphical Abstract ᅟ.
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Affiliation(s)
- Kenneth J Laszlo
- Department of Chemistry, University of Washington, Box 351700, Seattle, WA, 98195-1700, USA
| | - John H Buckner
- Department of Chemistry, University of Washington, Box 351700, Seattle, WA, 98195-1700, USA
- Department of Chemistry, Carleton College, One North College Street, Northfield, MN, 55057, USA
| | - Eleanor B Munger
- 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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32
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Riley NM, Hebert AS, Dürnberger G, Stanek F, Mechtler K, Westphall MS, Coon JJ. Phosphoproteomics with Activated Ion Electron Transfer Dissociation. Anal Chem 2017; 89:6367-6376. [PMID: 28383256 PMCID: PMC5555596 DOI: 10.1021/acs.analchem.7b00212] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The ability to localize phosphosites to specific amino acid residues is crucial to translating phosphoproteomic data into biological meaningful contexts. In a companion manuscript ( Anal. Chem. 2017 , DOI: 10.1021/acs.analchem.7b00213 ), we described a new implementation of activated ion electron transfer dissociation (AI-ETD) on a quadrupole-Orbitrap-linear ion trap hybrid MS system (Orbitrap Fusion Lumos), which greatly improved peptide fragmentation and identification over ETD and other supplemental activation methods. Here we present the performance of AI-ETD for identifying and localizing sites of phosphorylation in both phosphopeptides and intact phosphoproteins. Using 90 min analyses we show that AI-ETD can identify 24,503 localized phosphopeptide spectral matches enriched from mouse brain lysates, which more than triples identifications from standard ETD experiments and outperforms ETcaD and EThcD as well. AI-ETD achieves these gains through improved quality of fragmentation and MS/MS success rates for all precursor charge states, especially for doubly protonated species. We also evaluate the degree to which phosphate neutral loss occurs from phosphopeptide product ions due to the infrared photoactivation of AI-ETD and show that modifying phosphoRS (a phosphosite localization algorithm) to include phosphate neutral losses can significantly improve localization in AI-ETD spectra. Finally, we demonstrate the utility of AI-ETD in localizing phosphosites in α-casein, an ∼23.5 kDa phosphoprotein that showed eight of nine known phosphorylation sites occupied upon intact mass analysis. AI-ETD provided the greatest sequence coverage for all five charge states investigated and was the only fragmentation method to localize all eight phosphosites for each precursor. Overall, this work highlights the analytical value AI-ETD can bring to both bottom-up and top-down phosphoproteomics.
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Affiliation(s)
- Nicholas M. Riley
- Genome Center of Wisconsin, University of Wisconsin-Madison, Madison, WI, 53706, USA
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Alexander S. Hebert
- Genome Center of Wisconsin, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Gerhard Dürnberger
- Institute of Molecular Pathology (IMP), Campus-Vienna-Biocenter 1, A-1030 Vienna, Austria
- GMI, Gregor Mendel Institute of Molecular Plant Biology, Dr. Bohr Gasse 3, A-1030 Vienna, Austria
- IMBA, Institute of Molecular Biotechnology of the Austrian Academy of Sciences, Dr. Bohr Gasse 3, A-1030 Vienna, Austria
| | - Florian Stanek
- Institute of Molecular Pathology (IMP), Campus-Vienna-Biocenter 1, A-1030 Vienna, Austria
| | - Karl Mechtler
- Institute of Molecular Pathology (IMP), Campus-Vienna-Biocenter 1, A-1030 Vienna, Austria
- IMBA, Institute of Molecular Biotechnology of the Austrian Academy of Sciences, Dr. Bohr Gasse 3, A-1030 Vienna, Austria
| | - Michael S. Westphall
- Genome Center of Wisconsin, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Joshua J. Coon
- Genome Center of Wisconsin, University of Wisconsin-Madison, Madison, WI, 53706, USA
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, 53706, USA
- Department of Biomolecular Chemistry, University of Wisconsin-Madison, Madison, WI, 53706, USA
- Morgridge Institute for Research, Madison, Wisconsin, USA
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33
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Riley NM, Westphall MS, Coon JJ. Activated Ion-Electron Transfer Dissociation Enables Comprehensive Top-Down Protein Fragmentation. J Proteome Res 2017; 16:2653-2659. [PMID: 28608681 DOI: 10.1021/acs.jproteome.7b00249] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Here we report the first demonstration of near-complete sequence coverage of intact proteins using activated ion-electron transfer dissociation (AI-ETD), a method that leverages concurrent infrared photoactivation to enhance electron-driven dissociation. AI-ETD produces mainly c/z-type product ions and provides comprehensive (77-97%) protein sequence coverage, outperforming HCD, ETD, and EThcD for all proteins investigated. AI-ETD also maintains this performance across precursor ion charge states, mitigating charge-state dependence that limits traditional approaches.
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Affiliation(s)
| | | | - Joshua J Coon
- Morgridge Institute for Research , Madison, Wisconsin 53715, United States
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34
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Heirbaut M, Lermyte F, Martin EM, Beelen S, Sobott F, Strelkov SV, Weeks SD. Specific sequences in the N-terminal domain of human small heat-shock protein HSPB6 dictate preferential hetero-oligomerization with the orthologue HSPB1. J Biol Chem 2017; 292:9944-9957. [PMID: 28487364 DOI: 10.1074/jbc.m116.773515] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Revised: 04/20/2017] [Indexed: 12/17/2022] Open
Abstract
Small heat-shock proteins (sHSPs) are a conserved group of molecular chaperones with important roles in cellular proteostasis. Although sHSPs are characterized by their small monomeric weight, they typically assemble into large polydisperse oligomers that vary in both size and shape but are principally composed of dimeric building blocks. These assemblies can include different sHSP orthologues, creating additional complexity that may affect chaperone activity. However, the structural and functional properties of such hetero-oligomers are poorly understood. We became interested in hetero-oligomer formation between human heat-shock protein family B (small) member 1 (HSPB1) and HSPB6, which are both highly expressed in skeletal muscle. When mixed in vitro, these two sHSPs form a polydisperse oligomer array composed solely of heterodimers, suggesting preferential association that is determined at the monomer level. Previously, we have shown that the sHSP N-terminal domains (NTDs), which have a high degree of intrinsic disorder, are essential for the biased formation. Here we employed iterative deletion mapping to elucidate how the NTD of HSPB6 influences its preferential association with HSPB1 and show that this region has multiple roles in this process. First, the highly conserved motif RLFDQXFG is necessary for subunit exchange among oligomers. Second, a site ∼20 residues downstream of this motif determines the size of the resultant hetero-oligomers. Third, a region unique to HSPB6 dictates the preferential formation of heterodimers. In conclusion, the disordered NTD of HSPB6 helps regulate the size and stability of hetero-oligomeric complexes, indicating that terminal sHSP regions define the assembly properties of these proteins.
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Affiliation(s)
- Michelle Heirbaut
- From the Laboratory for Biocrystallography, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, 3000 Leuven, Belgium
| | - Frederik Lermyte
- the Biomolecular and Analytical Mass Spectrometry Group, Department of Chemistry, University of Antwerp, 2020 Antwerp, Belgium, and
| | - Esther M Martin
- the Biomolecular and Analytical Mass Spectrometry Group, Department of Chemistry, University of Antwerp, 2020 Antwerp, Belgium, and.,the Astbury Centre for Structural Molecular Biology and
| | - Steven Beelen
- From the Laboratory for Biocrystallography, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, 3000 Leuven, Belgium
| | - Frank Sobott
- the Biomolecular and Analytical Mass Spectrometry Group, Department of Chemistry, University of Antwerp, 2020 Antwerp, Belgium, and.,the Astbury Centre for Structural Molecular Biology and.,School of Molecular and Cellular Biology, University of Leeds, LS2 9JT, United Kingdom
| | - Sergei V Strelkov
- From the Laboratory for Biocrystallography, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, 3000 Leuven, Belgium,
| | - Stephen D Weeks
- From the Laboratory for Biocrystallography, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, 3000 Leuven, Belgium,
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35
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Riley NM, Westphall MS, Hebert AS, Coon JJ. Implementation of Activated Ion Electron Transfer Dissociation on a Quadrupole-Orbitrap-Linear Ion Trap Hybrid Mass Spectrometer. Anal Chem 2017; 89:6358-6366. [PMID: 28383247 DOI: 10.1021/acs.analchem.7b00213] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Using concurrent IR photoactivation during electron transfer dissociation (ETD) reactions, i.e., activated ion ETD (AI-ETD), significantly increases dissociation efficiency resulting in improved overall performance. Here we describe the first implementation of AI-ETD on a quadrupole-Orbitrap-quadrupole linear ion trap (QLT) hybrid MS system (Orbitrap Fusion Lumos) and demonstrate the substantial benefits it offers for peptide characterization. First, we show that AI-ETD can be implemented in a straightforward manner by fastening the laser and guiding optics to the instrument chassis itself, making alignment with the trapping volume of the QLT simple and robust. We then characterize the performance of AI-ETD using standard peptides in addition to a complex mixtures of tryptic peptides using LC-MS/MS, showing not only that AI-ETD can nearly double the identifications achieved with ETD alone but also that it outperforms the other available supplemental activation methods (ETcaD and EThcD). Finally, we introduce a new activation scheme called AI-ETD+ that combines AI-ETD in the high pressure cell of the QLT with a short infrared multiphoton dissociation (IRMPD) activation in the low-pressure cell. This reaction scheme introduces no addition time to the scan duty cycle but generates MS/MS spectra rich in b/y-type and c/z•-type product ions. The extensive generation of fragment ions in AI-ETD+ substantially increases peptide sequence coverage while also improving peptide identifications over all other ETD methods, making it a valuable new tool for hybrid fragmentation approaches.
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Affiliation(s)
| | | | | | - Joshua J Coon
- Morgridge Institute for Research , Madison, Wisconsin 53715, United States
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36
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Lermyte F, Łącki MK, Valkenborg D, Gambin A, Sobott F. Conformational Space and Stability of ETD Charge Reduction Products of Ubiquitin. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2017; 28:69-76. [PMID: 27495285 DOI: 10.1007/s13361-016-1444-7] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Revised: 06/11/2016] [Accepted: 06/26/2016] [Indexed: 06/06/2023]
Abstract
Owing to its versatility, electron transfer dissociation (ETD) has become one of the most commonly utilized fragmentation techniques in both native and non-native top-down mass spectrometry. However, several competing reactions-primarily different forms of charge reduction-occur under ETD conditions, as evidenced by the distorted isotope patterns usually observed. In this work, we analyze these isotope patterns to compare the stability of nondissociative electron transfer (ETnoD) products, specifically noncovalent c/z fragment complexes, across a range of ubiquitin conformational states. Using ion mobility, we find that more extended states are more prone to fragment release. We obtain evidence that for a given charge state, populations of ubiquitin ions formed either directly by electrospray ionization or through collapse of more extended states upon charge reduction, span a similar range of collision cross-sections. Products of gas-phase collapse are, however, less stabilized towards unfolding than the native conformation, indicating that the ions retain a memory of previous conformational states. Furthermore, this collapse of charge-reduced ions is promoted if the ions are 'preheated' using collisional activation, with possible implications for the kinetics of gas-phase compaction. Graphical Abstract ᅟ.
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Affiliation(s)
- Frederik Lermyte
- Biomolecular and Analytical Mass Spectrometry Group, Department of Chemistry, University of Antwerp, Antwerpen, Belgium
- Center for Proteomics, University of Antwerp, Antwerpen, Belgium
| | | | - Dirk Valkenborg
- Center for Proteomics, University of Antwerp, Antwerpen, Belgium
- Interuniversity Institute for Biostatistics and Statistical Bioinformatics, Hasselt University, Hasselt, Belgium
- Applied Bio and Molecular Systems, Flemish Institute for Technological Research (VITO), Antwerp, Belgium
| | - Anna Gambin
- Institute of Informatics, University of Warsaw, Warsaw, Poland
| | - Frank Sobott
- Biomolecular and Analytical Mass Spectrometry Group, Department of Chemistry, University of Antwerp, Antwerpen, Belgium.
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, LS2 9JT, UK.
- School of Molecular and Cellular Biology, University of Leeds, Leeds, LS2 9JT, UK.
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37
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Tamara S, Dyachenko A, Fort KL, Makarov AA, Scheltema RA, Heck AJR. Symmetry of Charge Partitioning in Collisional and UV Photon-Induced Dissociation of Protein Assemblies. J Am Chem Soc 2016; 138:10860-8. [PMID: 27480281 PMCID: PMC6392339 DOI: 10.1021/jacs.6b05147] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Indexed: 01/08/2023]
Abstract
Tandem mass spectrometry can provide structural information on intact protein assemblies, generating mass fingerprints indicative of the stoichiometry and quaternary arrangement of the subunits. However, in such experiments, collision-induced dissociation yields restricted information due to simultaneous subunit unfolding, charge rearrangement, and subsequent ejection of a highly charged unfolded single subunit. Alternative fragmentation strategies can potentially overcome this and supply a deeper level of structural detail. Here, we implemented ultraviolet photodissociation (UVPD) on an Orbitrap mass spectrometer optimized for native MS and benchmark its performance to HCD fragmentation using various protein oligomers. We investigated dimeric β-lactoglobulin, dimeric superoxide dismutase, dimeric and tetrameric concanavalin A, and heptameric GroES and Gp31; ranging in molecular weight from 32 to 102 kDa. We find that, for the investigated systems, UVPD produces more symmetric charge partitioning than HCD. While HCD spectra show sporadic fragmentation over the full protein backbone sequence of the subunits with a bias toward fragmenting labile bonds, UVPD spectra provided higher sequence coverage. Taken together, we conclude that UVPD is a strong addition to the toolbox of fragmentation methods for top-down proteomics experiments, especially for native protein assemblies.
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Affiliation(s)
- Sem Tamara
- Biomolecular
Mass Spectrometry and Proteomics, Bijvoet Center for
Biomolecular Research and Utrecht Institute of Pharmaceutical Sciences, and Netherlands
Proteomics Center, Utrecht University, 3584 CH Utrecht, The Netherlands
| | - Andrey Dyachenko
- Biomolecular
Mass Spectrometry and Proteomics, Bijvoet Center for
Biomolecular Research and Utrecht Institute of Pharmaceutical Sciences, and Netherlands
Proteomics Center, Utrecht University, 3584 CH Utrecht, The Netherlands
| | - Kyle L. Fort
- Biomolecular
Mass Spectrometry and Proteomics, Bijvoet Center for
Biomolecular Research and Utrecht Institute of Pharmaceutical Sciences, and Netherlands
Proteomics Center, Utrecht University, 3584 CH Utrecht, The Netherlands
| | - Alexander A. Makarov
- Biomolecular
Mass Spectrometry and Proteomics, Bijvoet Center for
Biomolecular Research and Utrecht Institute of Pharmaceutical Sciences, and Netherlands
Proteomics Center, Utrecht University, 3584 CH Utrecht, The Netherlands
- Thermo
Fisher Scientific (Bremen), 28199 Bremen, Germany
| | - Richard A. Scheltema
- Biomolecular
Mass Spectrometry and Proteomics, Bijvoet Center for
Biomolecular Research and Utrecht Institute of Pharmaceutical Sciences, and Netherlands
Proteomics Center, Utrecht University, 3584 CH Utrecht, The Netherlands
| | - Albert J. R. Heck
- Biomolecular
Mass Spectrometry and Proteomics, Bijvoet Center for
Biomolecular Research and Utrecht Institute of Pharmaceutical Sciences, and Netherlands
Proteomics Center, Utrecht University, 3584 CH Utrecht, The Netherlands
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38
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Laszlo KJ, Munger EB, Bush MF. Folding of Protein Ions in the Gas Phase after Cation-to-Anion Proton-Transfer Reactions. J Am Chem Soc 2016; 138:9581-8. [PMID: 27399988 PMCID: PMC4999245 DOI: 10.1021/jacs.6b04282] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The structure and folding of a protein in solution depends on noncovalent interactions within the protein and those with surrounding ions and molecules. Decoupling these interactions in solution is challenging, which has hindered the development of accurate physics-based models for structure prediction. Investigations of proteins in the gas phase can be used to selectively decouple factors affecting the structures of proteins. Here, we use cation-to-anion proton-transfer reactions (CAPTR) to reduce the charge states of denatured ubiquitin ions in the gas phase, and ion mobility to probe their structures. In CAPTR, a precursor charge state is selected (P) and reacted with monoanions to generate charge-reduced product ions (C). Following each CAPTR event, denatured ubiquitin ions (13+ to 6+) yield products that rapidly isomerize to structures that have smaller collision cross sections (Ω). The Ω values of CAPTR product ions depend strongly on C and very weakly on P. Pre- and post-CAPTR activation was then used to probe the potential-energy surfaces of the precursor and product ions, respectively. Post-CAPTR activation showed that ions of different P fold differently and populate different regions of the potential-energy surface of that ion. Finally, pre-CAPTR activation showed that the structures of protein ions can be indirectly investigated using ion mobility of their CAPTR product ions, even for subtle structural differences that are not apparent from ion mobility characterization of the activated precursor ions. More generally, these results show that CAPTR strongly complements existing techniques for characterizing the structures and dynamics of biological molecules in the gas phase.
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Affiliation(s)
- Kenneth J. Laszlo
- University of Washington, Department of Chemistry, Box 351700 Seattle, WA 98195-1700
| | - Eleanor B. Munger
- University of Washington, Department of Chemistry, Box 351700 Seattle, WA 98195-1700
| | - Matthew F. Bush
- University of Washington, Department of Chemistry, Box 351700 Seattle, WA 98195-1700
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39
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Cleary SP, Thompson AM, Prell JS. Fourier Analysis Method for Analyzing Highly Congested Mass Spectra of Ion Populations with Repeated Subunits. Anal Chem 2016; 88:6205-13. [DOI: 10.1021/acs.analchem.6b01088] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Sean P. Cleary
- Department
of Chemistry and
Biochemistry, University of Oregon, Eugene, Oregon 97403-1253, United States
| | - Avery M. Thompson
- Department
of Chemistry and
Biochemistry, University of Oregon, Eugene, Oregon 97403-1253, United States
| | - James S. Prell
- Department
of Chemistry and
Biochemistry, University of Oregon, Eugene, Oregon 97403-1253, United States
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40
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Metwally H, McAllister RG, Popa V, Konermann L. Mechanism of Protein Supercharging by Sulfolane and m-Nitrobenzyl Alcohol: Molecular Dynamics Simulations of the Electrospray Process. Anal Chem 2016; 88:5345-54. [DOI: 10.1021/acs.analchem.6b00650] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Haidy Metwally
- Department
of Chemistry, The University of Western Ontario, London, Ontario N6A 5B7, Canada
| | - Robert G. McAllister
- Department
of Chemistry, The University of Western Ontario, London, Ontario N6A 5B7, Canada
| | - Vlad Popa
- Department
of Biochemistry, The University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Lars Konermann
- Department
of Chemistry, The University of Western Ontario, London, Ontario N6A 5B7, Canada
- Department
of Biochemistry, The University of Western Ontario, London, Ontario N6A 5C1, Canada
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41
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Göth M, Lermyte F, Schmitt XJ, Warnke S, von Helden G, Sobott F, Pagel K. Gas-phase microsolvation of ubiquitin: investigation of crown ether complexation sites using ion mobility-mass spectrometry. Analyst 2016; 141:5502-10. [DOI: 10.1039/c6an01377e] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The influence of side chain to backbone interactions on the gas-phase structure of ubiquitin and ubiquitin lysine-to-arginine mutants was analysed.
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Affiliation(s)
- Melanie Göth
- Department of Biology
- Chemistry
- Pharmacy
- Freie Universität Berlin
- 14195 Berlin
| | - Frederik Lermyte
- Biomolecular and Analytical Mass Spectrometry
- Chemistry Department
- University of Antwerp
- 2020 Antwerp
- Belgium
| | - Xiao Jakob Schmitt
- Department of Molecular Physics
- Fritz Haber Institute of the Max Planck Society
- 14195 Berlin
- Germany
| | - Stephan Warnke
- Department of Molecular Physics
- Fritz Haber Institute of the Max Planck Society
- 14195 Berlin
- Germany
| | - Gert von Helden
- Department of Molecular Physics
- Fritz Haber Institute of the Max Planck Society
- 14195 Berlin
- Germany
| | - Frank Sobott
- Biomolecular and Analytical Mass Spectrometry
- Chemistry Department
- University of Antwerp
- 2020 Antwerp
- Belgium
| | - Kevin Pagel
- Department of Biology
- Chemistry
- Pharmacy
- Freie Universität Berlin
- 14195 Berlin
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42
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Harvey SR, Yan J, Brown JM, Hoyes E, Wysocki VH. Extended Gas-Phase Trapping Followed by Surface-Induced Dissociation of Noncovalent Protein Complexes. Anal Chem 2015; 88:1218-21. [DOI: 10.1021/acs.analchem.5b03479] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- Sophie R. Harvey
- Department
of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States
- School
of Chemistry, Manchester Institute of Biotechnology, University of Manchester, Manchester, M1 7DN, United Kingdom
| | - Jing Yan
- Department
of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States
| | - Jeffery M. Brown
- Waters Corporation, Altrincham
Road, Wilmslow, SK9 4AX, United Kingdom
| | - Emmy Hoyes
- Waters Corporation, Altrincham
Road, Wilmslow, SK9 4AX, United Kingdom
| | - Vicki H. Wysocki
- Department
of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States
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43
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Laszlo KJ, Bush MF. Analysis of Native-Like Proteins and Protein Complexes Using Cation to Anion Proton Transfer Reactions (CAPTR). JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2015; 26:2152-61. [PMID: 26323617 PMCID: PMC4655144 DOI: 10.1007/s13361-015-1245-4] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Revised: 07/23/2015] [Accepted: 08/01/2015] [Indexed: 05/08/2023]
Abstract
Mass spectra of native-like protein complexes often exhibit narrow charge-state distributions, broad peaks, and contributions from multiple, coexisting species. These factors can make it challenging to interpret those spectra, particularly for mixtures with significant heterogeneity. Here we demonstrate the use of ion/ion proton transfer reactions to reduce the charge states of m/z-selected, native-like ions of proteins and protein complexes, a technique that we refer to as cation to anion proton transfer reactions (CAPTR). We then demonstrate that CAPTR can increase the accuracy of charge state assignments and the resolution of interfering species in native mass spectrometry. The CAPTR product ion spectra for pyruvate kinase exhibit ~30 peaks and enable unambiguous determination of the charge state of each peak, whereas the corresponding precursor spectra exhibit ~6 peaks and the assigned charge states have an uncertainty of ±3%. 15+ bovine serum albumin and 21+ yeast enolase dimer both appear near m/z 4450 and are completely unresolved in a mixture. After a single CAPTR event, the resulting product ions are baseline resolved. The separation of the product ions increases dramatically after each subsequent CAPTR event; 12 events resulted in a 3000-fold improvement in separation relative to the precursor ions. Finally, we introduce a framework for interpreting and predicting the figures of merit for CAPTR experiments. More generally, these results suggest that CAPTR strongly complements other mass spectrometry tools for analyzing proteins and protein complexes, particularly those in mixtures. Graphical Abstract ᅟ.
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Affiliation(s)
- Kenneth J Laszlo
- Department of Chemistry, University of Washington, Seattle, WA, 98195-1700, USA
| | - Matthew F Bush
- Department of Chemistry, University of Washington, Seattle, WA, 98195-1700, USA.
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44
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Sowole MA, Vuong S, Konermann L. Interactions of hemoglobin and myoglobin with their ligands CN(-), CO, and O2 monitored by electrospray ionization-mass spectrometry. Anal Chem 2015; 87:9538-45. [PMID: 26327529 DOI: 10.1021/acs.analchem.5b02506] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Electrospray ionization (ESI)-mass spectrometry (MS) can provide information on protein-ligand interactions via detection of the corresponding complexes as gaseous ions. Unfortunately, some systems are prone to dissociation upon transfer into the gas phase. The reversible oxygen binding to hemoglobin (Hb) has been extensively studied in solution using a wide range of biophysical techniques. In addition to O2, ferrous (Fe(II)) Hb can bind CO. High affinity interactions with CN(-) are limited to the ferric (Fe(III)) state. In analogous fashion, CN(-), CO, and O2 bind to myoglobin (Mb). It remains unclear whether any of these ligand-bound forms can be observed by ESI-MS. In this work we demonstrate the successful detection of MbCN, while MbCO and MbO2 do not survive under ESI-MS conditions. Control experiments suggest that an older report of "MbO2" detection by ESI-MS may involve the misassignment of oxidation artifacts formed under corona discharge conditions. The situation is more favorable for ESI-MS studies on Hb. The most intense signal in the HbCN mass distribution corresponds to the expected complex with four cyanide moieties bound. Ligand loss during ESI-MS is around 20%. HbCO is detectable as well, albeit with a more noticeable level of ligand dissociation (∼50%) which produces the 2CO-bound state as the highest intensity ion in the spectrum. In addition, our data suggest that low levels of HbO2 can survive the transition into the gas phase, evident from +64 Da and +128 Da signals that can be assigned to Hb carrying two and four oxygen molecules, respectively. The application of collisional activation induces neutral ligand loss for all three Hb derivatives. It appears that this is the first report on the detection of MbCN, HbCO, and HbO2 in the gas phase. We hope that this work will pave the way towards future spectroscopic investigations of desolvated Mb and Hb, complementing the extensive literature on CN(-), CO, and O2 bound globins in the condensed phase.
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Affiliation(s)
- Modupeola A Sowole
- Department of Chemistry, The University of Western Ontario , London, Ontario N6A 5B7, Canada
| | - Stephanie Vuong
- Department of Chemistry, The University of Western Ontario , London, Ontario N6A 5B7, Canada
| | - Lars Konermann
- Department of Chemistry, The University of Western Ontario , London, Ontario N6A 5B7, Canada
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Zhang J, Reza Malmirchegini G, Clubb RTCT, Loo JA. Native top-down mass spectrometry for the structural characterization of human hemoglobin. EUROPEAN JOURNAL OF MASS SPECTROMETRY (CHICHESTER, ENGLAND) 2015; 21:221-31. [PMID: 26307702 PMCID: PMC4731028 DOI: 10.1255/ejms.1340] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Native mass spectrometry (MS) has become an invaluable tool for the characterization of proteins and noncovalent protein complexes under near physiological solution conditions. Here we report the structural characterization of human hemoglobin (Hb), a 64 kDa oxygen-transporting protein complex, by high resolution native top-down MS using electrospray ionization and a 15-Tesla Fourier transform ion cyclotron resonance mass spectrometer. Native MS preserves the noncovalent interactions between the globin subunits, and electron capture dissociation (ECD) produces fragments directly from the intact Hb complex without dissociating the subunits. Using activated ion ECD, we observe the gradual unfolding process of the Hb complex in the gas phase. Without protein ion activation, the native Hb shows very limited ECD fragmentation from the N-termini, suggesting a tightly packed structure of the native complex and therefore a low fragmentation efficiency. Precursor ion activation allows a steady increase in N-terminal fragment ions, while the C-terminal fragments remain limited (38 c ions and four z ions on the α chain; 36 c ions and two z ions on the β chain). This ECD fragmentation pattern suggests that upon activation, the Hb complex starts to unfold from the N-termini of both subunits, whereas the C-terminal regions and therefore the potential regions involved in the subunit binding interactions remain intact. ECD-MS of the Hb dimer shows similar fragmentation patterns as the Hb tetramer, providing further evidence for the hypothesized unfolding process of the Hb complex in the gas phase. Native top-down ECD-MS allows efficient probing of the Hb complex structure and the subunit binding interactions in the gas phase. It may provide a fast and effective means to probe the structure of novel protein complexes that are intractable to traditional structural characterization tools.
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Affiliation(s)
| | | | - Robert T Clubb T Clubb
- Department of Chemistry and Biochemistry, UCLA/DOE Institute of Genomics and Proteomics, University of California, Los Angeles, California, 90095, United States.
| | - Joseph A Loo
- De partment of Chemistry and Biochemistry, Department of Biological Chemistry, David Geffen School of Medicine, UCLA/DOE Institute of Genomics and Proteomics, University of California, Los Angeles, California, 90095, United States.
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Maurer MM, Donohoe GC, Valentine SJ. Advances in ion mobility-mass spectrometry instrumentation and techniques for characterizing structural heterogeneity. Analyst 2015; 140:6782-98. [PMID: 26114255 DOI: 10.1039/c5an00922g] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Enabling IM-MS instrumentation and techniques for characterizing sample structural heterogeneity have developed rapidly over the last five years.
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Affiliation(s)
- Megan M. Maurer
- C. Eugene Bennett Department of Chemistry
- West Virginia University
- Morgantown
- USA
| | - Gregory C. Donohoe
- C. Eugene Bennett Department of Chemistry
- West Virginia University
- Morgantown
- USA
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