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Dantus M. Tracking Molecular Fragmentation in Electron-Ionization Mass Spectrometry with Ultrafast Time Resolution. Acc Chem Res 2024; 57:845-854. [PMID: 38366970 PMCID: PMC10956387 DOI: 10.1021/acs.accounts.3c00713] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2023] [Revised: 01/24/2024] [Accepted: 01/26/2024] [Indexed: 02/19/2024]
Abstract
ConspectusMass spectrometry is a powerful analytical method capable of identifying compounds given a minute amount of material. The fragmentation pattern that results following molecular activation serves as a fingerprint that can be matched to a database compound for identification. Over the past half century, studies have addressed and, in many cases, named the chemical reactions that lead to some of the principal fragment ions. Theories have been developed to predict the observed fragmentation patterns, many of which assume that energy redistributes prior to dissociation. However, the existence of rearrangements and nonergodic processes complicates the prediction of fragmentation patterns and the identification of compounds that have yet to be entered into a curated database. To date, very few studies have addressed the time-dependent nature of the fragmentation of radical cations and, in particular, processes occurring with picosecond or shorter time scales where one expects to find nonergodic reactions.This Account focuses on a novel approach that enables tracking of molecular fragmentation in electron-ionization mass spectrometry with ultrafast time resolution. The two challenges that have prevented the time-resolved studies following electron ionization are the random impact parameter and moment of ionization of each molecule. In addition, medium-sized molecules can produce fragmentation patterns with tens if not hundreds of product ions. Spectroscopically interrogating all of these ions as a function of time is another major challenge. We describe strong field disruptive probing, a method that ionizes molecules on a femtosecond time scale and allows us to track in time the formation of all fragment ions simultaneously.Molecular fragmentation following ionization can occur on a very wide range of time scales. Metastable ions can survive from nanoseconds to microseconds; reactions that depend on vibrational energy redistribution can take picoseconds to nanoseconds; and direct dissociation processes and some rearrangements can take place in femtoseconds to picoseconds. All of these processes depend on the dynamics that occur during attoseconds and femtoseconds following the ionization process. Following a discussion of these time scales, we provide three examples of fragmentations that have been studied with femtosecond time resolution. Each of these examples include unforeseen reaction dynamics that involve a nonergodic process, highlighting the importance of time resolution in mass spectrometry. Finally, we explore future challenges and unresolved questions in mass spectrometry and, more broadly, in the domain of electron-initiated chemical reactions.
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Affiliation(s)
- Marcos Dantus
- Department
of Chemistry, Michigan State University, East Lansing, Michigan 48824, United States
- Department
of Physics and Astronomy, Michigan State
University, East Lansing, Michigan 48824, United States
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Stamm J, Kwon S, Sandhu S, Shaik M, Das R, Sandhu J, Curenton B, Wicka C, Levine BG, Sun L, Dantus M. The Surprising Dynamics of the McLafferty Rearrangement. J Phys Chem Lett 2023; 14:10088-10093. [PMID: 37917859 DOI: 10.1021/acs.jpclett.3c02102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2023]
Abstract
We report femtosecond time-resolved measurements of the McLafferty rearrangement following the strong-field tunnel ionization of 2-pentanone, 4-methyl-2-pentanone, and 4,4-dimethyl-2-pentanone. The pump-probe-dependent yields of the McLafferty product ion are fit to a biexponential function with fast (∼100 fs) and slow (∼10 ps) time constants, the latter of which is faster for the latter two compounds. Following nearly instantaneous ionization, the fast time scale is associated with rotation of the molecule to a six-membered cyclic intermediate that facilitates transfer of the γ-hydrogen, while the ∼50-100 times longer time scale is associated with a π-bond rearrangement and bond cleavage between the α- and β-carbons to produce the enol cation. These experimental measurements are supported by ab initio molecular dynamics trajectories, which further confirm the time scale of this important stepwise reaction in mass spectrometry.
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Affiliation(s)
- Jacob Stamm
- Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, United States
| | - Sung Kwon
- Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, United States
| | - Shawn Sandhu
- Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, United States
| | - Moaid Shaik
- Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, United States
| | - Rituparna Das
- Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, United States
| | - Jesse Sandhu
- Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, United States
| | - Bradley Curenton
- Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, United States
| | - Clayton Wicka
- Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, United States
| | - Benjamin G Levine
- Department of Chemistry and Institute of Advanced Computational Science, Stony Brook University, Stony Brook, New York 11794, United States
| | - Liangliang Sun
- Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, United States
| | - Marcos Dantus
- Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, United States
- Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, United States
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Li W, Kavatsyuk O, Douma W, Wang X, Hoekstra R, Mayer D, Robinson MS, Gühr M, Lalande M, Abdelmouleh M, Ryszka M, Poully JC, Schlathölter T. Multiple valence electron detachment following Auger decay of inner-shell vacancies in gas-phase DNA. Chem Sci 2021; 12:13177-13186. [PMID: 34745549 PMCID: PMC8513815 DOI: 10.1039/d1sc02885e] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Accepted: 09/10/2021] [Indexed: 01/05/2023] Open
Abstract
We have studied soft X-ray photoabsorption in the doubly deprotonated gas-phase oligonucleotide [dTGGGGT–2H]2−. The dominating decay mechanism of the X-ray induced inner shell vacancy was found to be Auger decay with detachment of at least three electrons, leading to charge reversal of the anionic precursor and the formation of positively charged photofragment ions. The same process is observed in heavy ion (12 MeV C4+) collisions with [dTGGGGT–2H]2− where inner shell vacancies are generated as well, but with smaller probability. Auger decay of a single K-vacancy in DNA, followed by detachment of three or more low energy electrons instead of a single high energy electron has profound implications for DNA damage and damage modelling. The production of three low kinetic energy electrons with short mean free path instead of one high kinetic energy electron with long mean free path implies that electron-induced DNA damage will be much more localized around the initial K-shell vacancy. The fragmentation channels, triggered by triple electron detachment Auger decay are predominantly related to protonated guanine base loss and even loss of protonated guanine dimers is tentatively observed. The fragmentation is not a consequence of the initial K-shell vacancy but purely due to multiple detachment of valence electrons, as a very similar positive ion fragmentation pattern is observed in femtosecond laser-induced dissociation experiments. A K-shell vacancy in DNA that is induced by a (therapeutically relevant) soft X-ray of MeV carbon ion, decays by Auger processes accompanied by emission of at least 3 low energy electrons.![]()
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Affiliation(s)
- Wen Li
- University of Groningen, Zernike Institute for Advanced Materials Nijenborgh 4 9747AG Groningen Netherlands
| | - Oksana Kavatsyuk
- University College Groningen Hoendiep 23/24 9718BG Groningen Netherlands
| | - Wessel Douma
- University of Groningen, Zernike Institute for Advanced Materials Nijenborgh 4 9747AG Groningen Netherlands
| | - Xin Wang
- University of Groningen, Zernike Institute for Advanced Materials Nijenborgh 4 9747AG Groningen Netherlands
| | - Ronnie Hoekstra
- University of Groningen, Zernike Institute for Advanced Materials Nijenborgh 4 9747AG Groningen Netherlands
| | - Dennis Mayer
- Universität Potsdam, Institut für Physik und Astronomie 14476 Potsdam Germany
| | - Matthew S Robinson
- Universität Potsdam, Institut für Physik und Astronomie 14476 Potsdam Germany.,Centre for Free Electron Lasers (CFEL), DESY Notkestraße 85 22607 Hamburg Germany
| | - Markus Gühr
- Universität Potsdam, Institut für Physik und Astronomie 14476 Potsdam Germany
| | - Mathieu Lalande
- CIMAP UMR 6252 (CEA/CNRS/ENSICAEN/Université de Caen Normandie) Boulevard Becquerel 14070 Caen Cedex 5 France
| | - Marwa Abdelmouleh
- CIMAP UMR 6252 (CEA/CNRS/ENSICAEN/Université de Caen Normandie) Boulevard Becquerel 14070 Caen Cedex 5 France
| | - Michal Ryszka
- CIMAP UMR 6252 (CEA/CNRS/ENSICAEN/Université de Caen Normandie) Boulevard Becquerel 14070 Caen Cedex 5 France
| | - Jean Christophe Poully
- CIMAP UMR 6252 (CEA/CNRS/ENSICAEN/Université de Caen Normandie) Boulevard Becquerel 14070 Caen Cedex 5 France
| | - Thomas Schlathölter
- University of Groningen, Zernike Institute for Advanced Materials Nijenborgh 4 9747AG Groningen Netherlands
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Neidel C, Kuehn A, Schulz CP, Hertel IV, Linscheid MW, Schultz T. Femtosecond laser-induced dissociation (fs-LID) as an activation method in mass spectrometry. Chem Phys 2018. [DOI: 10.1016/j.chemphys.2018.05.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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5
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Giuliani A, Williams JP, Green MR. Extreme Ultraviolet Radiation: A Means of Ion Activation for Tandem Mass Spectrometry. Anal Chem 2018; 90:7176-7180. [DOI: 10.1021/acs.analchem.8b01789] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Alexandre Giuliani
- Synchrotron SOLEIL, L’Orme des Merisiers, Gif-sur-Yvette F-91190, France
- UAR 1008 CEPIA, INRA, Nantes F-44316, France
| | | | - Martin R. Green
- Waters Corporation, Stamford Avenue, Altrincham Road, Wilmslow SK9 4AX, U.K
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Li P, Kreft I, Jackson GP. Top-Down Charge Transfer Dissociation (CTD) of Gas-Phase Insulin: Evidence of a One-Step, Two-Electron Oxidation Mechanism. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2018; 29:284-296. [PMID: 28786096 PMCID: PMC5803485 DOI: 10.1007/s13361-017-1700-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Revised: 04/24/2017] [Accepted: 04/27/2017] [Indexed: 05/03/2023]
Abstract
Top-down analyses of protonated insulin cations of charge states of 4+, 5+, or 6+ were performed by exposing the isolated precursor ions to a beam of helium cations with kinetic energy of more than 6 keV, in a technique termed charge transfer dissociation (CTD). The ~100 ms charge transfer reaction resulted in approximately 20% conversion efficiency to other intact charge exchange products (CTnoD), and a range of low abundance fragment ions. To increase backbone and sulfide cleavages, and to provide better structural information than straightforward MS2 CTD, the CTnoD oxidized products were isolated and subjected to collisional activation at the MS3 level. The MS3 CTD/CID reaction effectively broke the disulfide linkages, separated the two chains, and yielded more structurally informative fragment ions within the inter-chain cyclic region. CTD also provided doubly oxidized intact product ions at the MS2 level, and resonance ejection of the singly oxidized product ion revealed that the doubly oxidized product originates directly from the isolated precursor ion and not from consecutive CTD reactions of a singly oxidized intermediate. MS4 experiments were employed to help identify potential radical cations and diradical cations, but the results were negative or inconclusive. Nonetheless, the two-electron oxidation process is a demonstration of the very large potential energy (>20 eV) available through CTD, and is a notable capability for a 3D ion trap platform. Graphical Abstract ᅟ.
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Affiliation(s)
- Pengfei Li
- C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, WV, 26506, USA
| | - Iris Kreft
- Department of Forensic and Investigative Science, West Virginia University, Morgantown, WV, 26506-6121, USA
| | - Glen P Jackson
- C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, WV, 26506, USA.
- Department of Forensic and Investigative Science, West Virginia University, Morgantown, WV, 26506-6121, USA.
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7
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Li P, Jackson GP. Charge Transfer Dissociation (CTD) Mass Spectrometry of Peptide Cations: Study of Charge State Effects and Side-Chain Losses. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2017; 28:1271-1281. [PMID: 28091811 DOI: 10.1007/s13361-016-1574-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2016] [Revised: 12/03/2016] [Accepted: 12/04/2016] [Indexed: 05/04/2023]
Abstract
1+, 2+, and 3+ precursors of substance P and bradykinin were subjected to helium cation irradiation in a 3D ion trap mass spectrometer. Charge exchange with the helium cations produces a variety of fragment ions, the number and type of which are dependent on the charge state of the precursor ions. For 1+ peptide precursors, fragmentation is generally restricted to C-CO backbone bonds (a and x ions), whereas for 2+ and 3+ peptide precursors, all three backbone bonds (C-CO, C-N, and N-Cα) are cleaved. The type of backbone bond cleavage is indicative of possible dissociation channels involved in CTD process, including high-energy, kinetic-based, and ETD-like pathways. In addition to backbone cleavages, amino acid side-chain cleavages are observed in CTD, which are consistent with other high-energy and radical-mediated techniques. The unique dissociation pattern and supplementary information available from side-chain cleavages make CTD a potentially useful activation method for the structural study of gas-phase biomolecules. Graphical Abstract ᅟ.
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Affiliation(s)
- Pengfei Li
- C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, WV, 26506, USA
| | - Glen P Jackson
- C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, WV, 26506, USA.
- Department of Forensic and Investigative Science, West Virginia University, Morgantown, WV, 26506-6121, USA.
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Schwob L, Lalande M, Egorov D, Rangama J, Hoekstra R, Vizcaino V, Schlathölter T, Poully JC. Radical-driven processes within a peptidic sequence of type I collagen upon single-photon ionisation in the gas phase. Phys Chem Chem Phys 2017; 19:22895-22904. [DOI: 10.1039/c7cp03376a] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Radical creation after single-photon ionisation of collagen peptides induces the loss of molecules from amino-acid residue side-chains.
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Affiliation(s)
- Lucas Schwob
- CIMAP
- UMP 6252 (CEA/CNRS/ENSICAEN/Université de Caen Normandie)
- Caen
- France
| | - Mathieu Lalande
- CIMAP
- UMP 6252 (CEA/CNRS/ENSICAEN/Université de Caen Normandie)
- Caen
- France
| | - Dmitrii Egorov
- Zernike Institute for Advanced Materials
- University of Groningen
- 9747AG Groningen
- The Netherlands
| | - Jimmy Rangama
- CIMAP
- UMP 6252 (CEA/CNRS/ENSICAEN/Université de Caen Normandie)
- Caen
- France
| | - Ronnie Hoekstra
- Zernike Institute for Advanced Materials
- University of Groningen
- 9747AG Groningen
- The Netherlands
| | - Violaine Vizcaino
- CIMAP
- UMP 6252 (CEA/CNRS/ENSICAEN/Université de Caen Normandie)
- Caen
- France
| | - Thomas Schlathölter
- Zernike Institute for Advanced Materials
- University of Groningen
- 9747AG Groningen
- The Netherlands
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9
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Steven RT, Dexter A, Bunch J. Investigating MALDI MSI parameters (Part 2) – On the use of a mechanically shuttered trigger system for improved laser energy stability. Methods 2016; 104:111-7. [DOI: 10.1016/j.ymeth.2016.04.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Revised: 03/01/2016] [Accepted: 04/13/2016] [Indexed: 10/21/2022] Open
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Canon F, Milosavljević AR, Nahon L, Giuliani A. Action spectroscopy of a protonated peptide in the ultraviolet range. Phys Chem Chem Phys 2015; 17:25725-33. [DOI: 10.1039/c4cp04762a] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Action spectroscopy of substance P, a model undecapeptide, has been probed from 5.2 eV to 20 eV.
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Affiliation(s)
- Francis Canon
- Synchrotron Soleil
- l'Orme des Merisiers
- 91192 Gif sur Yvette Cedex
- France
- UMR1324 Centre des Sciences du Goût et de l'Alimentation
| | | | - Laurent Nahon
- Synchrotron Soleil
- l'Orme des Merisiers
- 91192 Gif sur Yvette Cedex
- France
| | - Alexandre Giuliani
- Synchrotron Soleil
- l'Orme des Merisiers
- 91192 Gif sur Yvette Cedex
- France
- Uar1008
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11
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Konar A, Shu Y, Lozovoy VV, Jackson JE, Levine BG, Dantus M. Polyatomic molecules under intense femtosecond laser irradiation. J Phys Chem A 2014; 118:11433-50. [PMID: 25314590 DOI: 10.1021/jp505498t] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Interaction of intense laser pulses with atoms and molecules is at the forefront of atomic, molecular, and optical physics. It is the gateway to powerful new tools that include above threshold ionization, high harmonic generation, electron diffraction, molecular tomography, and attosecond pulse generation. Intense laser pulses are ideal for probing and manipulating chemical bonding. Though the behavior of atoms in strong fields has been well studied, molecules under intense fields are not as well understood and current models have failed in certain important aspects. Molecules, as opposed to atoms, present confounding possibilities of nuclear and electronic motion upon excitation. The dynamics and fragmentation patterns in response to the laser field are structure sensitive; therefore, a molecule cannot simply be treated as a "bag of atoms" during field induced ionization. In this article we present a set of experiments and theoretical calculations exploring the behavior of a large collection of aryl alkyl ketones when irradiated with intense femtosecond pulses. Specifically, we consider to what extent molecules retain their molecular identity and properties under strong laser fields. Using time-of-flight mass spectrometry in conjunction with pump-probe techniques we study the dynamical behavior of these molecules, monitoring ion yield modulation caused by intramolecular motions post ionization. The set of molecules studied is further divided into smaller sets, sorted by type and position of functional groups. The pump-probe time-delay scans show that among positional isomers the variations in relative energies, which amount to only a few hundred millielectronvolts, influence the dynamical behavior of the molecules despite their having experienced such high fields (V/Å). High level ab initio quantum chemical calculations were performed to predict molecular dynamics along with single and multiphoton resonances in the neutral and ionic states. We propose the following model of strong-field ionization and subsequent fragmentation for polyatomic molecules: Single electron ionization occurs on a suboptical cycle time scale, and the electron carries away essentially all of the energy, leaving behind little internal energy in the cation. Subsequent fragmentation of the cation takes place as a result of further photon absorption modulated by one- and two-photon resonances, which provide sufficient energy to overcome the dissociation energy. The proposed hypothesis implies the loss of a photoelectron at a rate that is faster than intramolecular vibrational relaxation and is consistent with the observation of nonergodic photofragmentation of polyatomic molecules as well as experimental results from many other research groups on different molecules and with different pulse durations and wavelengths.
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Affiliation(s)
- Arkaprabha Konar
- Department of Chemistry and ‡Department of Physics and Astronomy, Michigan State University , East Lansing, Michigan 48824, United States
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Giuliani A, Milosavljević AR, Canon F, Nahon L. Contribution of synchrotron radiation to photoactivation studies of biomolecular ions in the gas phase. MASS SPECTROMETRY REVIEWS 2014; 33:424-441. [PMID: 24375654 DOI: 10.1002/mas.21398] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Photon activation of ions in the visible and ultraviolet range attracts a growing interest, partly for its promising applications in tandem mass spectrometry. However, this task is not trivial, as it requires notably high brilliance photon sources. Hence, most of the work in that field has been performed using lasers. Synchrotron radiation is a source continuously tunable over a wide photon energy range and which possesses the necessary characteristics for ion activation. This review focuses on the array of applications of synchrotron radiation in photon activation of ions ranging from near UV to soft X-rays.
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Affiliation(s)
- Alexandre Giuliani
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint Aubin, 91192, Gif-sur-Yvette, France; UAR1008 CEPIA, INRA, 44316, Nantes, France
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Antoine R, Lemoine J, Dugourd P. Electron photodetachment dissociation for structural characterization of synthetic and bio-polymer anions. MASS SPECTROMETRY REVIEWS 2014; 33:501-22. [PMID: 24285407 DOI: 10.1002/mas.21402] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2012] [Revised: 12/21/2012] [Accepted: 01/08/2013] [Indexed: 05/25/2023]
Abstract
Tandem mass spectrometry (MS-MS) is a generic term evoking techniques dedicated to structural analysis, detection or quantification of molecules based on dissociation of a precursor ion into fragments. Searching for the most informative fragmentation patterns has led to the development of a vast array of activation modes that offer complementary ion reactivity and dissociation pathways. Collisional activation of ions using atoms, molecules or surface resulting in unimolecular dissociation of activated ions still plays a key role in tandem mass spectrometry. The discovery of electron capture dissociation (ECD) and then the development of other electron-ion or ion/ion reaction methods, constituted a significant breakthrough, especially for structural analysis of large biomolecules. Similarly, photon activation opened promising new frontiers in ion fragmentation owing to the ability of tightly controlled internal energy deposition and easy implementation on commercial instruments. Ion activation by photons includes slow heating methods such as infrared multiple photon dissociation (IRMPD) and black-body infrared radiative dissociation (BIRD) and higher energy methods like ultra-violet photodissociation (UVPD) and electron photo detachment dissociation (EPD). EPD occurs after UV irradiation of multiply negatively charged ions resulting in the formation of oxidized radical anions. The present paper reviews the hypothesis regarding the mechanisms of electron photo-detachment, radical formation and direct or activated dissociation pathways that support the observation of odd and even electron product ions. Finally, the value of EPD as a complementary structural analysis tool is illustrated through selected examples of synthetic polymers, oligonucleotides, polypeptides, lipids, and polysaccharides.
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Affiliation(s)
- Rodolphe Antoine
- University of Lyon, F-69622, Lyon, France; CNRS et Université Lyon 1, UMR5306, Institut Lumière Matière, Villeurbanne, France
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Smith SA, Kalcic CL, Cui L, Reid GE. Femtosecond laser-induced ionization/dissociation tandem mass spectrometry (fsLID-MS/MS) of deprotonated phosphopeptide anions. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2013; 27:2807-2817. [PMID: 24214867 DOI: 10.1002/rcm.6750] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2013] [Revised: 09/24/2013] [Accepted: 09/25/2013] [Indexed: 06/02/2023]
Abstract
RATIONALE Radical-directed dissociation techniques provide structural information which is complementary to that from conventional collision-induced dissociation (CID). The analysis of phosphopeptide anions is warranted due to their relatively acidic character. As femtosecond laser-induced ionization/dissociation tandem mass spectrometry (fsLID-MS/MS) is uniquely initiated by field ionization, an investigation is warranted to determine whether fsLID may provide novel analytical utility for phosphopeptide anions. METHODS Twenty-three synthetic deprotonated phosphopeptide anions were introduced into a three-dimensional quadrupole ion trap mass spectrometer via electrospray ionization. The ion trap was interfaced with a near-IR (802 nm) ultrashort-pulsed (35 fs FWHM) ultrahigh-powered (peak power ~10(14) W/cm(2)) laser system. Performance comparisons are made with other techniques applied to phosphopeptide anion analysis, including CID, electron detachment dissociation (EDD), negative electron transfer dissociation (NETD), activated electron photodetachment dissociation (activated-EPD), and ultraviolet photodissociation (UVPD). RESULTS FsLID-MS/MS of multiply deprotonated phosphopeptide anions provides sequence information via phosphorylation-intact a/x ions in addition to other sequence ions, satellite ions, and side-chain losses. Novel fragmentation processes include selective c-ion formation N-terminal to Ser/Thr and a phosphorylation-specific correlation between xn -98 ion abundances and phosphorylation at the n(th) residue. Sequencing-quality data required about 30 s of signal averaging. fsLID-MS/MS of singly deprotonated phosphopeptides did not yield product anions with stable trajectories, despite significant depletion of the precursor. CONCLUSIONS Multiply deprotonated phosphopeptide anions were sequenced via negative-mode fsLID-MS/MS, with phosphosite localization facilitated by a/x ion series in addition to diagnostic x(n)-98 ions. fsLID-MS/MS is qualitatively competitive with other techniques. Further efficiency enhancements (e.g., implementation on a linear trap or/and higher pulse frequencies) may permit sequence analyses on chromatographic timescales.
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Affiliation(s)
- Scott A Smith
- RTSF Mass Spectrometry & Metabolomics Core, Michigan State University, East Lansing, MI, 48824, USA
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Duffy MJ, Kelly O, Calvert CR, King RB, Belshaw L, Kelly TJ, Costello JT, Timson DJ, Bryan WA, Kierspel T, Turcu ICE, Cacho CM, Springate E, Williams ID, Greenwood JB. Fragmentation of neutral amino acids and small peptides by intense, femtosecond laser pulses. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2013; 24:1366-1375. [PMID: 23817831 DOI: 10.1007/s13361-013-0653-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2013] [Revised: 04/15/2013] [Accepted: 04/16/2013] [Indexed: 06/02/2023]
Abstract
High power femtosecond laser pulses have unique properties that could lead to their application as ionization or activation sources in mass spectrometry. By concentrating many photons into pulse lengths approaching the timescales associated with atomic motion, very strong electric field strengths are generated, which can efficiently ionize and fragment molecules without the need for resonant absorption. However, the complex interaction between these pulses and biomolecular species is not well understood. To address this issue, we have studied the interaction of intense, femtosecond pulses with a number of amino acids and small peptides. Unlike previous studies, we have used neutral forms of these molecular targets, which allowed us to investigate dissociation of radical cations without the spectra being complicated by the action of mobile protons. We found fragmentation was dominated by fast, radical-initiated dissociation close to the charge site generated by the initial ionization or from subsequent ultrafast migration of this charge. Fragments with lower yields, which are useful for structural determinations, were also observed and attributed to radical migration caused by hydrogen atom transfer within the molecule.
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Affiliation(s)
- Martin J Duffy
- Centre for Plasma Physics, School of Mathematics and Physics, Queen's University Belfast, Belfast, UK
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