1
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Asakawa D, Hosokai T, Nakayama Y. Experimental and Theoretical Investigation of MALDI In-Source Decay of Peptides with a Reducing Matrix: What Is the Initial Fragmentation Step? JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2022; 33:1011-1021. [PMID: 35587880 DOI: 10.1021/jasms.2c00066] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Matrix-assisted laser desorption/ionization in-source decay (MALDI-ISD) with a reducing matrix is believed to be initiated by hydrogen transfer from the matrix to the peptide. Several new matrices have recently been developed to achieve more efficient MALDI-ISD. In particular, the use of matrices containing aniline groups facilitates MALDI-ISD to a greater extent than that of matrices containing phenol groups, although the N-H bond in aniline is stronger than the O-H bond in phenol. In this study, photoelectron yield spectroscopy of matrix solids revealed that conversion of the phenol group to the aniline group decreased the ionization energy of the matrix solids. Crucially, the use of a matrix with lower ionization energy has been found to result in efficient cleavage at N-Cα and disulfide bonds by MALDI-ISD. Therefore, electron association with the peptide rather than the fragmentation mechanism involving hydrogen atom attachment is proposed as the initial step of the MALDI-ISD process. In this mechanism, electron transfer from the reducing matrix to the peptide produces a peptide anion radical, which provides either a [cn + H]/[zm]• or [an]•/[ym + H] fragment pair. Fragmentation of the peptide anion radical strongly depends on the gas-phase acidity of the matrix used. Subsequently, the resultant fragments/radicals underwent a reaction in the MALDI plume, producing observable even-electron ions. Consequently, MALDI-ISD fragments are observed as both positive and negative ions, even though MALDI-ISD with a reducing matrix involves fragmentation of peptide anion radicals. The proposed mechanism is suitable for obtaining a better understanding of the MALDI-ISD process.
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Affiliation(s)
- Daiki Asakawa
- National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 2, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568, Japan
| | - Takuya Hosokai
- National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 2, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568, Japan
- Department of Pure and Applied Chemistry, Tokyo University of Science, Noda, Chiba 278-8510, Japan
| | - Yasuo Nakayama
- National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 2, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568, Japan
- Department of Pure and Applied Chemistry; Division of Colloid and Interface Science; Research Group for Advanced Energy Conversion, Tokyo University of Science, Noda 278-8510, Japan
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2
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Asakawa D, Takahashi H, Iwamoto S, Tanaka K. Hot Hydrogen Atom Irradiation of Protonated/Deprotonated Peptide in an Ion Trap Facilitates Fragmentation through Heated Radical Formation. J Am Chem Soc 2022; 144:3020-3028. [PMID: 35138819 DOI: 10.1021/jacs.1c11081] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Tandem mass spectrometry with fragmentation involving the reaction with hydrogen atoms is expected to be useful for the analysis of peptides and proteins. In general, hydrogen atoms preferentially react with odd-electron radicals. The attachment of hydrogen atoms to even-electron peptide ions is barely observed because of their low reaction rate. To date, only the methodology developed by our group has successfully induced the fragmentation of even-electron peptide ions by reacting with hydrogen atoms. In the present study, we focused on the temperature of the peptide ions and hydrogen atoms in an ion trap mass spectrometer to understand the mechanism of the corresponding reaction. Because the reaction between even-electron peptide ions and hydrogen atoms has a significant transition state barrier, the use of hot hydrogen atoms is required to initiate the reaction. The reaction contributes to increase the internal energy of the resultant peptide radicals because the heat of reaction and kinetic energy of the hydrogen atom are converted to the internal energy of the product. The resultant oxygen- and carbon-centered peptide radicals undergo radical-induced fragmentation with sub-picosecond and sub-millisecond time scales, respectively.
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Affiliation(s)
- Daiki Asakawa
- National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 2, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568, Japan
| | - Hidenori Takahashi
- Koichi Tanaka Mass Spectrometry Research Laboratory, Shimadzu Corporation, 1 Nishinokyo-Kuwabaracho Nakagyo-ku, Kyoto 604-8511, Japan
| | - Shinichi Iwamoto
- Koichi Tanaka Mass Spectrometry Research Laboratory, Shimadzu Corporation, 1 Nishinokyo-Kuwabaracho Nakagyo-ku, Kyoto 604-8511, Japan
| | - Koichi Tanaka
- Koichi Tanaka Mass Spectrometry Research Laboratory, Shimadzu Corporation, 1 Nishinokyo-Kuwabaracho Nakagyo-ku, Kyoto 604-8511, Japan
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3
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Asakawa D, Takahashi H, Iwamoto S, Tanaka K. Gas-Phase Peptide Fragmentation Induced by Hydrogen Attachment, from Principle to Sequencing of Amide Nitrogen-Methylated Peptides. Anal Chem 2020; 92:15773-15780. [PMID: 33256396 DOI: 10.1021/acs.analchem.0c02766] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Tandem mass spectrometry (MS/MS) with radical-based fragmentation was developed recently, which involves the reaction of hydrogen atoms and peptides in a process called hydrogen attachment/abstraction dissociation (HAD). HAD mainly produces [cn + 2H]+ and [zm + 2H]+ via hydrogen attachment to the carbonyl oxygen on the peptide backbone. In addition, HAD often generates [an + 2H]+ and [xm + 2H]+. To explain the formation of [an + 2H]+ and [xm + 2H]+, hydrogen attachment to the carbonyl carbon atom on the peptide backbone is proposed to initiate Cα-C bond cleavage. The resultant hydrogen-abundant oxygen-centered radical intermediate undergoes radical-induced dissociation to give [an + H]+• and [xm + 2H]+. Subsequently, [an + 2H]+ was produced by the reaction of [an + H]+• and a hydrogen atom. The fragment ions formed by the cleavage of N-Cα and Cα-C bonds are observed in the HAD-MS/MS spectra, and the mass differences of these fragment ions correspond to the mass of peptide bonds. Consequently, HAD-MS/MS allows the identification of post-translational modifications on the peptide backbone. In addition, HAD-MS/MS provides a consecutive series of [cn + 2H]+ and [an + 2H]+ as the N-terminal fragments, as well as [zm + 2H]+ and [xm + 2H]+, which enables the sequencing of peptides with post-translational modification, including the discrimination of modifications on the side chain and backbone.
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Affiliation(s)
- Daiki Asakawa
- National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 2, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568, Japan
| | - Hidenori Takahashi
- Koichi Tanaka Mass Spectrometry Research Laboratory, Shimadzu Corporation, 1 Nishinokyo-Kuwabaracho, Nakagyo-ku, Kyoto 604-8511, Japan
| | - Shinichi Iwamoto
- Koichi Tanaka Mass Spectrometry Research Laboratory, Shimadzu Corporation, 1 Nishinokyo-Kuwabaracho, Nakagyo-ku, Kyoto 604-8511, Japan
| | - Koichi Tanaka
- Koichi Tanaka Mass Spectrometry Research Laboratory, Shimadzu Corporation, 1 Nishinokyo-Kuwabaracho, Nakagyo-ku, Kyoto 604-8511, Japan
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4
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Abstract
By using high-level ab initio methods, we examine the nature of bonding between Rydberg electrons hosted by two four-coordinate nitrogen centers embedded in a hydrocarbon scaffold. The electronic structure of these species resembles that of diradicals, yet the diffuse nature of the orbitals hosting the unpaired electrons results in unusual features. The unpaired Rydberg electrons exhibit long-range bonding interactions, leading to stabilization of the singlet state (relative to the triplet) and a reduced number of effectively unpaired electrons. However, thermochemical gains due to through-space bonding are offset by strong Coulomb repulsion between positively charged nitrogen cores. The kinetic stability of these Rydberg diradicals may be controlled by a judicious choice of the molecular scaffold, suggesting possible strategies for their experimental characterization.
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Affiliation(s)
- Maxim V Ivanov
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, United States
| | - Anna I Krylov
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, United States
| | - Shmuel Zilberg
- Department of Chemical Sciences, Ariel University, Ariel 40700, Israel
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5
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Asakawa D, Takahashi H, Iwamoto S, Tanaka K. Hydrogen attachment dissociation of peptides containing disulfide bonds. Phys Chem Chem Phys 2019; 21:26049-26057. [PMID: 31746862 DOI: 10.1039/c9cp03923f] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A combination of tandem mass spectrometry (MS/MS) and hydrogen attachment dissociation (HAD) is a useful method for peptide sequence analysis. In this study, gas-phase fragmentation induced by the attachment of hydrogen to peptides containing disulfide bonds was investigated. Hydrogen attachment induced the cleavage of either the disulfide or N-Cα bond, which competitively occurred during HAD. The disulfide bond cleavage proceeded through an intermediate, which contains a thiyl radical (-S˙) and a thiol group (-SH). In contrast, N-Cα bond cleavage produced an intermediate containing an enol-imine group and α-carbon radical. The intermediate α-carbon radical then attacked the disulfide bond, resulting in a cyclic [z]+ fragment. The counterpart, [c + H]+˙ with a thiyl radical underwent further hydrogen attachment, producing [c + 2H]+. Because both disulfide and N-Cα bonds were cleaved by a single hydrogen attachment event, HAD-MS/MS can provide sequence information for the backbone region in the disulfide loop.
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Affiliation(s)
- Daiki Asakawa
- National Institute of Advanced Industrial Science and Technology (AIST), National Metrology Institute of Japan (NMIJ), Tsukuba Central 2, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568, Japan.
| | - Hidenori Takahashi
- Koichi Tanaka Mass Spectrometry Research Laboratory, Shimadzu Corporation, 1 Nishinokyo-Kuwabaracho Nakagyo-ku, Kyoto 604-8511, Japan
| | - Shinichi Iwamoto
- Koichi Tanaka Mass Spectrometry Research Laboratory, Shimadzu Corporation, 1 Nishinokyo-Kuwabaracho Nakagyo-ku, Kyoto 604-8511, Japan
| | - Koichi Tanaka
- Koichi Tanaka Mass Spectrometry Research Laboratory, Shimadzu Corporation, 1 Nishinokyo-Kuwabaracho Nakagyo-ku, Kyoto 604-8511, Japan
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6
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Asakawa D, Takahashi H, Sekiya S, Iwamoto S, Tanaka K. Sequencing of Sulfopeptides Using Negative-Ion Tandem Mass Spectrometry with Hydrogen Attachment/Abstraction Dissociation. Anal Chem 2019; 91:10549-10556. [DOI: 10.1021/acs.analchem.9b01568] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- Daiki Asakawa
- National Institute of Advanced Industrial Science and Technology (AIST), National Metrology Institute of Japan (NMIJ), Tsukuba Central 2, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568, Japan
| | - Hidenori Takahashi
- Koichi Tanaka Mass Spectrometry Research Laboratory, Shimadzu Corporation, 1 Nishinokyo-Kuwabaracho, Nakagyo-ku, Kyoto 604-8511, Japan
| | - Sadanori Sekiya
- Koichi Tanaka Mass Spectrometry Research Laboratory, Shimadzu Corporation, 1 Nishinokyo-Kuwabaracho, Nakagyo-ku, Kyoto 604-8511, Japan
| | - Shinichi Iwamoto
- Koichi Tanaka Mass Spectrometry Research Laboratory, Shimadzu Corporation, 1 Nishinokyo-Kuwabaracho, Nakagyo-ku, Kyoto 604-8511, Japan
| | - Koichi Tanaka
- Koichi Tanaka Mass Spectrometry Research Laboratory, Shimadzu Corporation, 1 Nishinokyo-Kuwabaracho, Nakagyo-ku, Kyoto 604-8511, Japan
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7
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Kempkes LJ, Martens J, Berden G, Houthuijs KJ, Oomens J. Investigation of the position of the radical in z3-ions resulting from electron transfer dissociation using infrared ion spectroscopy. Faraday Discuss 2019; 217:434-452. [DOI: 10.1039/c8fd00202a] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The molecular structures of six open-shell z3-ions resulting from electron transfer dissociation mass spectrometry (ETD MS) were investigated using infrared ion spectroscopy in combination with density functional theory and molecular mechanics/molecular dynamics calculations.
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Affiliation(s)
| | - Jonathan Martens
- Radboud University
- FELIX Laboratory
- 6525 ED Nijmegen
- The Netherlands
| | - Giel Berden
- Radboud University
- FELIX Laboratory
- 6525 ED Nijmegen
- The Netherlands
| | - Kas J. Houthuijs
- Radboud University
- FELIX Laboratory
- 6525 ED Nijmegen
- The Netherlands
| | - Jos Oomens
- Radboud University
- FELIX Laboratory
- 6525 ED Nijmegen
- The Netherlands
- Van’t Hoff Institute for Molecular Sciences
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8
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Asakawa D, Takahashi H, Iwamoto S, Tanaka K. Hydrogen atom attachment to histidine and tryptophan containing peptides in the gas phase. Phys Chem Chem Phys 2019; 21:11633-11641. [DOI: 10.1039/c9cp00083f] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
In this study, we focus on the gas-phase fragmentation induced by the attachment of hydrogen atoms to the histidine and tryptophan residue side-chains in the peptide that provides the fragment ions due to Cα–Cβ bond cleavage.
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Affiliation(s)
- Daiki Asakawa
- National Institute of Advanced Industrial Science and Technology (AIST)
- National Metrology Institute of Japan (NMIJ)
- Tsukuba
- Japan
| | - Hidenori Takahashi
- Koichi Tanaka Mass Spectrometry Research Laboratory
- Shimadzu Corporation
- Kyoto 604-8511
- Japan
| | - Shinichi Iwamoto
- Koichi Tanaka Mass Spectrometry Research Laboratory
- Shimadzu Corporation
- Kyoto 604-8511
- Japan
| | - Koichi Tanaka
- Koichi Tanaka Mass Spectrometry Research Laboratory
- Shimadzu Corporation
- Kyoto 604-8511
- Japan
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9
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Kempkes LM, Martens J, Berden G, Oomens J. Spectroscopic Characterization of an Extensive Set of c-Type Peptide Fragment Ions Formed by Electron Transfer Dissociation Suggests Exclusive Formation of Amide Isomers. J Phys Chem Lett 2018; 9:6404-6411. [PMID: 30343579 PMCID: PMC6240889 DOI: 10.1021/acs.jpclett.8b02850] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2018] [Accepted: 10/18/2018] [Indexed: 06/08/2023]
Abstract
Electron attachment dissociation (electron capture dissociation (ECD) and electron transfer dissociation (ETD)) applied to gaseous multiply protonated peptides leads predominantly to backbone N-Cα bond cleavages and the formation of c- and z-type fragment ions. The mechanisms involved in the formation of these ions have been the subject of much discussion. Here, we determine the molecular structures of an extensive set of c-type ions produced by ETD using infrared ion spectroscopy. Nine c3- and c4-ions are investigated to establish their C-terminal structure as either enol-imine or amide isomers by comparison of the experimental infrared spectra with quantum-chemically predicted spectra for both structural variants. The spectra suggest that all c-ions investigated possess an amide structure; the absence of the NH bending mode at approximately 1000-1200 cm-1 serves as an important diagnostic feature.
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Affiliation(s)
- Lisanne
J. M. Kempkes
- FELIX
Laboratory, Institute for Molecules and Materials, Radboud University, Toernooiveld 7, 6525 ED Nijmegen, The Netherlands
| | - Jonathan Martens
- FELIX
Laboratory, Institute for Molecules and Materials, Radboud University, Toernooiveld 7, 6525 ED Nijmegen, The Netherlands
| | - Giel Berden
- FELIX
Laboratory, Institute for Molecules and Materials, Radboud University, Toernooiveld 7, 6525 ED Nijmegen, The Netherlands
| | - Jos Oomens
- FELIX
Laboratory, Institute for Molecules and Materials, Radboud University, Toernooiveld 7, 6525 ED Nijmegen, The Netherlands
- Van’t
Hoff Institute for Molecular Sciences, University
of Amsterdam, Science
Park 904, 1098 XH Amsterdam, The Netherlands
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10
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Asakawa D, Miyazato A, Rosu F, Gabelica V. Influence of the metals and ligands in dinuclear complexes on phosphopeptide sequencing by electron-transfer dissociation tandem mass spectrometry. Phys Chem Chem Phys 2018; 20:26597-26607. [PMID: 30310898 DOI: 10.1039/c8cp04516j] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Phosphorylation is one of the most important protein modifications, and electron-transfer dissociation tandem mass spectrometry (ETD-MS/MS) is a potentially useful method for the sequencing of phosphopeptides, including determination of the phosphorylation site. Notably, ETD-MS/MS typically provides useful information when the precursor contains more than three positive charges. It is not yet used as an analysis method for large-scale phosphopeptide production due to difficulties occurring in the production of acidic phosphopeptides having more than three positive charges. To increase the charge state of phosphopeptides, we used dinuclear metal complexes, which selectively bind to the phosphate group in phosphopeptides with the addition of positive charge(s). Dinuclear copper, zinc, and gallium complexes were tested and it was found that the type of metal present in the complex strongly affected the affinity of the phosphorylated compounds and their ETD fragmentation. The dinuclear copper complex interacted weakly with the phosphate groups and ETD-induced peptide fragmentation was largely suppressed by the presence of Cu2+, which worked as an electron trap. The dinuclear gallium complex was strongly bound to a phosphate group. However, the ligand binding to gallium acted as an electron trap and the presence of dinuclear gallium complex in the precursor for ETD-MS/MS hampered the sequencing of the phosphopeptides, as in the case of dinuclear copper complexes. In contrast, dinuclear zinc complexes efficiently bind to phosphopeptides with an increase in the charge state, facilitating phosphopeptide sequencing by ETD-MS/MS. The fragmentation of the ligand and peptide backbone in the dinuclear zinc-phosphopeptide complex were competitively induced by ETD. These processes are influenced by the ligand structure and so the detailed ETD fragmentation pathways were investigated using density functional theory calculations.
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Affiliation(s)
- Daiki Asakawa
- National Institute of Advanced Industrial Science and Technology (AIST), National Metrology Institute of Japan (NMIJ), Tsukuba Central 2, 1-1-1 Umezono, Tsukuba, Ibaraki, 305-8568, Japan.
| | - Akio Miyazato
- Center for Nano Materials and Technology, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi, Ishikawa, Japan
| | - Frédéric Rosu
- CNRS, INSERM, Univ. Bordeaux, Institut Européen de Chimie et Biologie (IECB, UMS3033, US001), 2 rue Robert Escarpit, 33607 Pessac, France
| | - Valérie Gabelica
- Univ. Bordeaux, INSERM, CNRS, Laboratoire Acides Nucléiques Régulations Naturelle et Artificielle (ARNA, U1212, UMR5320), IECB, 2 rue Robert Escarpit, 33607 Pessac, France
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11
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Chen X, Wang Z, Wong YLE, Wu R, Zhang F, Chan TWD. Electron-ion reaction-based dissociation: A powerful ion activation method for the elucidation of natural product structures. MASS SPECTROMETRY REVIEWS 2018; 37:793-810. [PMID: 29603345 DOI: 10.1002/mas.21563] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Accepted: 02/12/2018] [Indexed: 05/16/2023]
Abstract
The structural elucidation of natural products (NPs) remains a challenge due to their structurally diversities and unpredictable functionalities, motifs, and scaffolds. Tandem mass spectrometry (MS/MS) is an effective method that assists the full elucidation of complicated NP structures. Ion activation methods play a key role in determining the fragmentation pathways and the structural information obtained from MS/MS. Electron-ion reaction-based dissociation (ExD) methods, including electron capture dissociation (ECD), electron transfer dissociation (ETD), electron-induced dissociation (EID), and electron detachment dissociation (EDD), can induce the breakage of specific chemical bonds and the generation of distinct fragment ions. This review article provides an overview of the mechanisms, instrumentation, and typical applications related to ExD MS/MS in the structural elucidation of NPs, primarly including lipids, oligosaccharides, glycoconjugates, metabolites, and pharmaceutical drugs. This work aims to reveal the capacity and potential of ExD mass spectrometry in analyzing NPs and consequently helping the NP communities to utilize the modern capabilities of MS/MS in the discovery and evaluation of novel NPs.
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Affiliation(s)
- Xiangfeng Chen
- Key Laboratory for Applied Technology of Sophisticated Analytical Instruments, Shandong Analysis and Test Centre, Qilu University of Technology (Shandong Academy of Science), Shandong, P.R. China
- Department of Chemistry, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong SAR, P.R. China
| | - Ze Wang
- Department of Chemistry, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong SAR, P.R. China
| | - Y-L Elaine Wong
- Department of Chemistry, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong SAR, P.R. China
| | - Ri Wu
- Department of Chemistry, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong SAR, P.R. China
| | - Feng Zhang
- Chinese Academy of Inspection and Quarantine, Beijing, P. R. China
| | - T-W Dominic Chan
- Department of Chemistry, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong SAR, P.R. China
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12
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Imaoka N, Houferak C, Murphy MP, Nguyen HTH, Dang A, Tureček F. Spontaneous Isomerization of Peptide Cation Radicals Following Electron Transfer Dissociation Revealed by UV-Vis Photodissociation Action Spectroscopy. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2018; 29:1768-1780. [PMID: 29340957 DOI: 10.1007/s13361-017-1871-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2017] [Revised: 12/06/2017] [Accepted: 12/14/2017] [Indexed: 06/07/2023]
Abstract
Peptide cation radicals of the z-type were produced by electron transfer dissociation (ETD) of peptide dications and studied by UV-Vis photodissociation (UVPD) action spectroscopy. Cation radicals containing the Asp (D), Asn (N), Glu (E), and Gln (Q) residues were found to spontaneously isomerize by hydrogen atom migrations upon ETD. Canonical N-terminal [z4 + H]+● fragment ion-radicals of the R-C●H-CONH- type, initially formed by N-Cα bond cleavage, were found to be minor components of the stable ion fraction. Vibronically broadened UV-Vis absorption spectra were calculated by time-dependent density functional theory for several [●DAAR + H]+ isomers and used to assign structures to the action spectra. The potential energy surface of [●DAAR + H]+ isomers was mapped by ab initio and density functional theory calculations that revealed multiple isomerization pathways by hydrogen atom migrations. The transition-state energies for the isomerizations were found to be lower than the dissociation thresholds, accounting for the isomerization in non-dissociating ions. The facile isomerization in [●XAAR + H]+ ions (X = D, N, E, and Q) was attributed to low-energy intermediates having the radical defect in the side chain that can promote hydrogen migration along backbone Cα positions. A similar side-chain mediated mechanism is suggested for the facile intermolecular hydrogen migration between the c- and [z + H]●-ETD fragments containing Asp, Asn, Glu, and Gln residues. Graphical Abstract ᅟ.
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Affiliation(s)
- Naruaki Imaoka
- Department of Physics, Graduate School of Science, Osaka University, Toyonaka, Osaka, Japan
| | - Camille Houferak
- Department of Chemistry, University of Washington, Box 351700, Seattle, WA, 98195-1700, USA
| | - Megan P Murphy
- Department of Chemistry, University of Washington, Box 351700, Seattle, WA, 98195-1700, USA
| | - Huong T H Nguyen
- Department of Chemistry, University of Washington, Box 351700, Seattle, WA, 98195-1700, USA
| | - Andy Dang
- Department of Chemistry, University of Washington, Box 351700, Seattle, WA, 98195-1700, USA
| | - František Tureček
- Department of Chemistry, University of Washington, Box 351700, Seattle, WA, 98195-1700, USA.
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13
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Ranka K, Zhao N, Yu L, Stanton JF, Polfer NC. Radical Rearrangement Chemistry in Ultraviolet Photodissociation of Iodotyrosine Systems: Insights from Metastable Dissociation, Infrared Ion Spectroscopy, and Reaction Pathway Calculations. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2018; 29:1791-1801. [PMID: 29845561 DOI: 10.1007/s13361-018-1959-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Revised: 03/21/2018] [Accepted: 04/01/2018] [Indexed: 06/08/2023]
Abstract
We report on the ultraviolet photodissociation (UVPD) chemistry of protonated tyrosine, iodotyrosine, and diiodotyrosine. Distonic loss of the iodine creates a high-energy radical at the aromatic ring that engages in hydrogen/proton rearrangement chemistry. Based on UVPD kinetics measurements, the appearance of this radical is coincident with the UV irradiation pulse (8 ns). Conversely, sequential UVPD product ions exhibit metastable decay on ca. 100 ns timescales. Infrared ion spectroscopy is capable of confirming putative structures of the rearrangement products as proton transfers from the imine and β-carbon hydrogens. Potential energy surfaces for the various reaction pathways indicate that the rearrangement chemistry is highly complex, compatible with a cascade of rearrangements, and that there is no preferred rearrangement pathway even in small molecular systems like these. Graphical Abstract.
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Affiliation(s)
- Karnamohit Ranka
- Quantum Theory Project, Department of Chemistry, University of Florida, P.O. Box 117200, Gainesville, FL, 32611-7200, USA
- Quantum Theory Project, Department of Physics, University of Florida, P.O. Box 118435, Gainesville, FL, 32611-8435, USA
| | - Ning Zhao
- Department of Chemistry and Center for Chemical Physics, University of Florida, P.O. Box 117200, Gainesville, FL, 32611-7200, USA
| | - Long Yu
- Department of Chemistry and Center for Chemical Physics, University of Florida, P.O. Box 117200, Gainesville, FL, 32611-7200, USA
| | - John F Stanton
- Quantum Theory Project, Department of Chemistry, University of Florida, P.O. Box 117200, Gainesville, FL, 32611-7200, USA
- Quantum Theory Project, Department of Physics, University of Florida, P.O. Box 118435, Gainesville, FL, 32611-8435, USA
| | - Nicolas C Polfer
- Department of Chemistry and Center for Chemical Physics, University of Florida, P.O. Box 117200, Gainesville, FL, 32611-7200, USA.
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14
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Abstract
Disulfide linkage is critical to protein folding and structural stability. The location of disulfide linkages for antibodies is routinely discovered by comparing the chromatograms of the reduced and non-reduced peptide mapping with location identification confirmed by collision-induced dissociation (CID) mass spectrometry (MS)/MS. However, CID product spectra of disulfide-linked peptides can be difficult to interpret, and provide limited information on the backbone region within the disulfide loop. Here, we applied an electron-transfer dissociation (ETD)/CID combined fragmentation method that identifies the disulfide linkage without intensive LC comparison, and yet maps the disulfide location accurately. The native protein samples were digested using trypsin for proteolysis. The method uses RapiGest SF Surfactant and obviates the need for reduction/alkylation and extensive sample manipulation. An aliquot of the digest was loaded onto a C4 analytical column. Peptides were gradient-eluted and analyzed using a Thermo Scientific LTQ Orbitrap Elite mass spectrometer for the ETD-triggered CID MS3 experiment. Survey MS scans were followed by data-dependent scans consisting of ETD MS2 scans on the most intense ion in the survey scan, followed by 5 MS3 CID scans on the 5 most intense ions in the ETD MS2 scan. We were able to identify the disulfide-mediated structural variants A and A/B forms and their corresponding disulfide linkages in an immunoglobulin G2 monoclonal antibody with λ light chain (IgG2λ), where the location of cysteine linkages were unambiguously determined.
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Affiliation(s)
- Xiaoyan Guan
- a Process Development, Amgen Inc. , Thousand Oaks , CA , United States
| | - Le Zhang
- a Process Development, Amgen Inc. , Thousand Oaks , CA , United States
| | - Jette Wypych
- a Process Development, Amgen Inc. , Thousand Oaks , CA , United States
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15
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Asakawa D, Takahashi H, Iwamoto S, Tanaka K. De Novo Sequencing of Tryptic Phosphopeptides Using Matrix-Assisted Laser Desorption/Ionization Based Tandem Mass Spectrometry with Hydrogen Atom Attachment. Anal Chem 2018; 90:2701-2707. [DOI: 10.1021/acs.analchem.7b04635] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- Daiki Asakawa
- National
Metrology Institute of Japan, National Institute of Advanced Industrial Science and Technology, Tsukuba Central 2, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568, Japan
| | - Hidenori Takahashi
- Koichi
Tanaka Mass Spectrometry Research Laboratory, Shimadzu Corporation, 1 Nishinokyo-Kuwabaracho, Nakagyo-ku, Kyoto, 604-8511, Japan
| | - Shinichi Iwamoto
- Koichi
Tanaka Mass Spectrometry Research Laboratory, Shimadzu Corporation, 1 Nishinokyo-Kuwabaracho, Nakagyo-ku, Kyoto, 604-8511, Japan
| | - Koichi Tanaka
- Koichi
Tanaka Mass Spectrometry Research Laboratory, Shimadzu Corporation, 1 Nishinokyo-Kuwabaracho, Nakagyo-ku, Kyoto, 604-8511, Japan
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16
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Marek A, Nguyen HTH, Brož B, Tureček F. Stereospecific control of peptide gas-phase ion chemistry with cis and trans cyclo ornithine residues. JOURNAL OF MASS SPECTROMETRY : JMS 2018; 53:124-137. [PMID: 29150896 DOI: 10.1002/jms.4047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2017] [Revised: 11/02/2017] [Accepted: 11/06/2017] [Indexed: 06/07/2023]
Abstract
We report non-chiral amino acid residues cis- and trans-1,4-diaminocyclohexane-1-carboxylic acid (cyclo-ornithine, cO) that exhibit unprecedented stereospecific control of backbone dissociations of singly charged peptide cations and hydrogen-rich cation radicals produced by electron-transfer dissociation. Upon collision-induced dissociation (CID) in the slow heating regime, peptide cations containing trans-cO residues undergo facile backbone cleavages of amide bonds C-terminal to trans-cO. By contrast, peptides with cis-cO residues undergo dissociations at several amide bonds along the peptide ion backbone. Diastereoisomeric cO-containing peptides thus provide remarkably distinct tandem mass spectra. The stereospecific effect in CID of the trans-cO residue is explained by syn-facially directed proton transfer from the 4-ammonium group at cO to the C-terminal amide followed by neighboring group participation in the cleavage of the CO-NH bond, analogous to the aspartic acid and ornithine effects. Backbone dissociations of diastereoisomeric cO-containing peptide ions generate distinct [bn ]+ -type fragment ions that were characterized by CID-MS3 spectra. Stereospecific control is also reported for electron-transfer dissociation of cis- and trans-cO containing doubly charged peptide ions. The stereospecific effect upon electron transfer is related to the different conformations of doubly charged peptide ions that affect the electron attachment sites and ensuing N-Cα bond dissociations.
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Affiliation(s)
- Aleš Marek
- Department of Chemistry, University of Washington, Bagley Hall, Box 351700, Seattle, WA, 98195-1700, USA
- Czech Academy of Sciences, Institute of Organic Chemistry and Biochemistry, Prague, Czech Republic
| | - Huong T H Nguyen
- Department of Chemistry, University of Washington, Bagley Hall, Box 351700, Seattle, WA, 98195-1700, USA
| | - Břetislav Brož
- Czech Academy of Sciences, Institute of Organic Chemistry and Biochemistry, Prague, Czech Republic
| | - František Tureček
- Department of Chemistry, University of Washington, Bagley Hall, Box 351700, Seattle, WA, 98195-1700, USA
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17
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Asakawa D, Takahashi H, Iwamoto S, Tanaka K. Fundamental study of hydrogen-attachment-induced peptide fragmentation occurring in the gas phase and during the matrix-assisted laser desorption/ionization process. Phys Chem Chem Phys 2018; 20:13057-13067. [DOI: 10.1039/c8cp00733k] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Mass spectrometry with hydrogen-radical-mediated fragmentation techniques has been used for the sequencing of proteins/peptides.
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Affiliation(s)
- Daiki Asakawa
- National Institute of Advanced Industrial Science and Technology (AIST)
- Ibaraki
- Japan
| | - Hidenori Takahashi
- Koichi Tanaka Mass Spectrometry Research Laboratory
- Shimadzu Corporation
- Kyoto 604-8511
- Japan
| | - Shinichi Iwamoto
- Koichi Tanaka Mass Spectrometry Research Laboratory
- Shimadzu Corporation
- Kyoto 604-8511
- Japan
| | - Koichi Tanaka
- Koichi Tanaka Mass Spectrometry Research Laboratory
- Shimadzu Corporation
- Kyoto 604-8511
- Japan
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18
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Qi Y, Volmer DA. Electron-based fragmentation methods in mass spectrometry: An overview. MASS SPECTROMETRY REVIEWS 2017; 36:4-15. [PMID: 26445267 DOI: 10.1002/mas.21482] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2015] [Revised: 07/03/2015] [Accepted: 07/03/2015] [Indexed: 05/21/2023]
Abstract
Tandem mass spectrometry (MS/MS) provides detailed information for structural characterization of biomolecules. The combination of electron capture dissociation (ECD) techniques with Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) often provides unique ion-electron reactions and fragmentation channels in MS/MS. ECD is often a complimentary, sometimes even a superior tool to conventional MS/MS techniques. This article is aimed at providing a short overview of ECD-based fragmentation techniques (ExD) and optimization of ECD experiments for FTICR mass analyzers. Most importantly, it is meant to pique the interest of potential users for this exciting research field. © 2015 Wiley Periodicals, Inc. Mass Spec Rev 36:4-15, 2017.
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Affiliation(s)
- Yulin Qi
- Institute of Bioanalytical Chemistry, Saarland University, Campus B2.2, Saarbrücken, 66123, Germany
| | - Dietrich A Volmer
- Institute of Bioanalytical Chemistry, Saarland University, Campus B2.2, Saarbrücken, 66123, Germany
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19
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Pepin R, Layton ED, Liu Y, Afonso C, Tureček F. Where Does the Electron Go? Stable and Metastable Peptide Cation Radicals Formed by Electron Transfer. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2017; 28:164-181. [PMID: 27709510 DOI: 10.1007/s13361-016-1512-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Revised: 09/12/2016] [Accepted: 09/15/2016] [Indexed: 06/06/2023]
Abstract
Electron transfer to doubly and triply charged heptapeptide ions containing polar residues Arg, Lys, and Asp in combination with nonpolar Gly, Ala, and Pro or Leu generates stable and metastable charge-reduced ions, (M + 2H)+●, in addition to standard electron-transfer dissociation (ETD) fragment ions. The metastable (M + 2H)+● ions spontaneously dissociate upon resonant ejection from the linear ion trap, giving irregularly shaped peaks with offset m/z values. The fractions of stable and metastable (M + 2H)+● ions and their mass shifts depend on the presence of Pro-4 and Leu-4 residues in the peptides, with the Pro-4 sequences giving larger fractions of the stable ions while showing smaller mass shifts for the metastables. Conversion of the Asp and C-terminal carboxyl groups to methyl esters further lowers the charge-reduced ion stability. Collisional activation and photodissociation at 355 nm of mass-selected (M + 2H)+● results in different dissociations that give sequence specific MS3 spectra. With a single exception of charge-reduced (LKGLADR + 2H)+●, the MS3 spectra do not produce ETD sequence fragments of the c and z type. Hence, these (M + 2H)+● ions are covalent radicals, not ion-molecule complexes, undergoing dramatically different dissociations in the ground and excited electronic states. The increased stability of the Pro-4 containing (M + 2H)+● ions is attributed to radicals formed by opening of the Pro ring and undergoing further stabilization by hydrogen atom migrations. UV-VIS photodissociation action spectroscopy and time-dependent density functional theory calculations are used in a case in point study of the stable (LKGPADR + 2H)+● ion produced by ETD. In contrast to singly-reduced peptide ions, doubly reduced (M + 3H)+ ions are stable only when formed from the Pro-4 precursors and show all characteristics of even electron ions regarding no photon absorption at 355 nm or ion-molecule reactions, and exhibiting proton driven collision induced dissociations. Graphical Abstract ᅟ.
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Affiliation(s)
- Robert Pepin
- Department of Chemistry, University of Washington, Bagley Hall, Box 351700, Seattle, WA, 98195-1700, USA
| | - Erik D Layton
- Department of Chemistry, University of Washington, Bagley Hall, Box 351700, Seattle, WA, 98195-1700, USA
| | - Yang Liu
- Department of Chemistry, University of Washington, Bagley Hall, Box 351700, Seattle, WA, 98195-1700, USA
| | - Carlos Afonso
- INSA Rouen, UNIROUEN, CNRS, COBRA, Normandie University, 76000, Rouen, France
| | - František Tureček
- Department of Chemistry, University of Washington, Bagley Hall, Box 351700, Seattle, WA, 98195-1700, USA.
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20
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Asakawa D, Osaka I. High-Confidence Sequencing of Phosphopeptides by Electron Transfer Dissociation Mass Spectrometry Using Dinuclear Zinc(II) Complex. Anal Chem 2016; 88:12393-12402. [PMID: 28193068 DOI: 10.1021/acs.analchem.6b03645] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Phosphorylation is the most abundant protein modification, and tandem mass spectrometry (MS2) with electron transfer dissociation (ETD) has proven to be a promising method for phosphoproteomic applications owing to its ability to determine phosphorylation sites on proteins. However, low precursor charge states hinder the ability to obtain useful information through peptide sequencing by ETD, and the presence of acidic phosphate groups contributes to a low charge state of peptide ions. In the present report, we used a dinuclear zinc complex, (Zn2L)3+ (L = alkoxide form of 1,3-bis[bis(pyridin-2-ylmethyl)amino]propan-2-ol) for electrospray ionization (ESI), followed by ETD-MS2 analysis. Since (Zn2L)3+ selectively bound to phosphopeptide with addition of a positive charge per phosphate group, the use of (Zn2L)3+ for ESI improved the ionization yield of phosphopeptides in phosphoprotein digest. Additionally, an increase in the charge state of phosphopeptides were observed by addition of (Zn2L)3+, facilitating phosphopeptide sequencing by ETD-MS2. Since the binding between (Zn2L)3+ and the phosphate group was retained during the ETD process, a comparison between the ETD mass spectra obtained using two dinuclear zinc complex derivatives containing different zinc isotopes, namely (64Zn2L)3+ and (68Zn2L)3+, provided information about the number of phosphate groups in each fragment ion, allowing the phosphorylation site to be unambiguously determined. The details of the fragmentation processes of the (Zn2L)3+-phosphopeptide complex were investigated using a density functional theory calculation. As in the case of protonated peptides, ETD induced peptide backbone dissociation in the (Zn2L)3+-phosphopeptide complex proceeded through an aminoketyl radical intermediate.
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Affiliation(s)
- Daiki Asakawa
- National Institute of Advanced Industrial Science and Technology (AIST) , Tsukuba Central 2, 1-1-1 Umezono, Tsukuba, Ibaraki, 305-8568 Japan
| | - Issey Osaka
- Center for Nano Materials and Technology, Japan Advanced Institute of Science and Technology , 1-1 Asahidai, Nomi, Ishikawa, Japan
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21
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Viglino E, Lai CK, Mu X, Chu IK, Tureček F. Ground and Excited-Electronic-State Dissociations of Hydrogen-Rich and Hydrogen-Deficient Tyrosine Peptide Cation Radicals. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2016; 27:1454-1467. [PMID: 27278824 DOI: 10.1007/s13361-016-1425-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Revised: 05/10/2016] [Accepted: 05/20/2016] [Indexed: 06/06/2023]
Abstract
We report a comprehensive study of collision-induced dissociation (CID) and near-UV photodissociation (UVPD) of a series of tyrosine-containing peptide cation radicals of the hydrogen-rich and hydrogen-deficient types. Stable, long-lived, hydrogen-rich peptide cation radicals, such as [AAAYR + 2H](+●) and several of its sequence and homology variants, were generated by electron transfer dissociation (ETD) of peptide-crown-ether complexes, and their CID-MS(3) dissociations were found to be dramatically different from those upon ETD of the respective peptide dications. All of the hydrogen-rich peptide cation radicals contained major (77%-94%) fractions of species having radical chromophores created by ETD that underwent photodissociation at 355 nm. Analysis of the CID and UVPD spectra pointed to arginine guanidinium radicals as the major components of the hydrogen-rich peptide cation radical population. Hydrogen-deficient peptide cation radicals were generated by intramolecular electron transfer in Cu(II)(2,2':6',2″-terpyridine) complexes and shown to contain chromophores absorbing at 355 nm and undergoing photodissociation. The CID and UVPD spectra showed major differences in fragmentation for [AAAYR](+●) that diminished as the Tyr residue was moved along the peptide chain. UVPD was found to be superior to CID in localizing Cα-radical positions in peptide cation radical intermediates. Graphical Abstract ᅟ.
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Affiliation(s)
- Emilie Viglino
- Department of Chemistry, University of Washington, Bagley Hall, Box 351700, Seattle, WA, 981915-1700, USA
| | - Cheuk Kuen Lai
- Department of Chemistry, University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Xiaoyan Mu
- Department of Chemistry, University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Ivan K Chu
- Department of Chemistry, University of Hong Kong, Pokfulam Road, Hong Kong, China.
| | - František Tureček
- Department of Chemistry, University of Washington, Bagley Hall, Box 351700, Seattle, WA, 981915-1700, USA.
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22
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Asakawa D. Principles of hydrogen radical mediated peptide/protein fragmentation during matrix-assisted laser desorption/ionization mass spectrometry. MASS SPECTROMETRY REVIEWS 2016; 35:535-556. [PMID: 25286767 DOI: 10.1002/mas.21444] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2014] [Revised: 06/30/2014] [Accepted: 06/30/2014] [Indexed: 06/03/2023]
Abstract
Matrix-assisted laser desorption/ionization in-source decay (MALDI-ISD) is a very easy way to obtain large sequence tags and, thereby, reliable identification of peptides and proteins. Recently discovered new matrices have enhanced the MALDI-ISD yield and opened new research avenues. The use of reducing and oxidizing matrices for MALDI-ISD of peptides and proteins favors the production of fragmentation pathways involving "hydrogen-abundant" and "hydrogen-deficient" radical precursors, respectively. Since an oxidizing matrix provides information on peptide/protein sequences complementary to that obtained with a reducing matrix, MALDI-ISD employing both reducing and oxidizing matrices is a potentially useful strategy for de novo peptide sequencing. Moreover, a pseudo-MS(3) method provides sequence information about N- and C-terminus extremities in proteins and allows N- and C-terminal side fragments to be discriminated within the complex MALDI-ISD mass spectrum. The combination of high mass resolution of a Fourier transform-ion cyclotron resonance (FTICR) analyzer and the software suitable for MALDI-ISD facilitates the interpretation of MALDI-ISD mass spectra. A deeper understanding of the MALDI-ISD process is necessary to fully exploit this method. Thus, this review focuses first on the mechanisms underlying MALDI-ISD processes, followed by a discussion of MALDI-ISD applications in the field of proteomics. © 2014 Wiley Periodicals, Inc., Mass Spec Rev 35:535-556, 2016.
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Affiliation(s)
- Daiki Asakawa
- Quantitative Biology Center (QBiC), RIKEN, 6-2-3 Furuedai, Suita, Osaka, 565-0874, Japan
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23
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Asakawa D, De Pauw E. Difference of Electron Capture and Transfer Dissociation Mass Spectrometry on Ni(2+)-, Cu(2+)-, and Zn(2+)-Polyhistidine Complexes in the Absence of Remote Protons. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2016; 27:1165-1175. [PMID: 27098412 DOI: 10.1007/s13361-016-1395-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2016] [Revised: 03/18/2016] [Accepted: 03/22/2016] [Indexed: 06/05/2023]
Abstract
Electron capture dissociation (ECD) and electron transfer dissociation (ETD) in metal-peptide complexes are dependent on the metal cation in the complex. The divalent transition metals Ni(2+), Cu(2+), and Zn(2+) were used as charge carriers to produce metal-polyhistidine complexes in the absence of remote protons, since these metal cations strongly bind to neutral histidine residues in peptides. In the case of the ECD and ETD of Cu(2+)-polyhistidine complexes, the metal cation in the complex was reduced and the recombination energy was redistributed throughout the peptide to lead a zwitterionic peptide form having a protonated histidine residue and a deprotonated amide nitrogen. The zwitterion then underwent peptide bond cleavage, producing a and b fragment ions. In contrast, ECD and ETD induced different fragmentation processes in Zn(2+)-polyhistidine complexes. Although the N-Cα bond in the Zn(2+)-polyhistidine complex was cleaved by ETD, ECD of Zn(2+)-polyhistidine induced peptide bond cleavage accompanied with hydrogen atom release. The different fragmentation modes by ECD and ETD originated from the different electronic states of the charge-reduced complexes resulting from these processes. The details of the fragmentation processes were investigated by density functional theory. Graphical Abstract ᅟ.
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Affiliation(s)
- Daiki Asakawa
- National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki, Japan.
| | - Edwin De Pauw
- Mass Spectrometry Laboratory, Department of Chemistry, and GIGA-Research, University of Liège, B-4000, Liège (Sart-Tilman), Belgium
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24
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Martens J, Grzetic J, Berden G, Oomens J. Structural identification of electron transfer dissociation products in mass spectrometry using infrared ion spectroscopy. Nat Commun 2016; 7:11754. [PMID: 27277826 PMCID: PMC4906228 DOI: 10.1038/ncomms11754] [Citation(s) in RCA: 71] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Accepted: 04/27/2016] [Indexed: 12/04/2022] Open
Abstract
Tandem mass spectrometry occupies a principle place among modern analytical methods and drives many developments in the ‘omics' sciences. Electron attachment induced dissociation methods, as alternatives for collision-induced dissociation have profoundly influenced the field of proteomics, enabling among others the top-down sequencing of entire proteins and the analysis of post-translational modifications. The technique, however, produces more complex mass spectra and its radical-driven reaction mechanisms remain incompletely understood. Here we demonstrate the facile structural characterization of electron transfer dissociation generated peptide fragments by infrared ion spectroscopy using the tunable free-electron laser FELIX, aiding the elucidation of the underlying dissociation mechanisms. We apply this method to verify and revise previously proposed product ion structures for an often studied model tryptic peptide, [AlaAlaHisAlaArg+2H]2+. Comparing experiment with theory reveals that structures that would be assigned using only theoretical thermodynamic considerations often do not correspond to the experimentally sampled species. Mass spectrometry is a leading method used for sequencing peptides and proteins by fragmentation followed by analysis of the sequence fragments. Here, the authors use infrared spectroscopy to characterize the structures of peptide fragments formed during electron transfer dissociation.
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Affiliation(s)
- Jonathan Martens
- Radboud University, Institute for Molecules and Materials, FELIX Laboratory, Toernooiveld 7c, 6525ED Nijmegen, The Netherlands
| | - Josipa Grzetic
- Radboud University, Institute for Molecules and Materials, FELIX Laboratory, Toernooiveld 7c, 6525ED Nijmegen, The Netherlands
| | - Giel Berden
- Radboud University, Institute for Molecules and Materials, FELIX Laboratory, Toernooiveld 7c, 6525ED Nijmegen, The Netherlands
| | - Jos Oomens
- Radboud University, Institute for Molecules and Materials, FELIX Laboratory, Toernooiveld 7c, 6525ED Nijmegen, The Netherlands.,Van 't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 908, 1098XH Amsterdam, The Netherlands
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25
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Asakawa D, Yamashita A, Kawai S, Takeuchi T, Wada Y. N-Cα Bond Cleavage of Zinc-Polyhistidine Complexes in Electron Transfer Dissociation Mediated by Zwitterion Formation: Experimental Evidence and Theoretical Analysis of the Utah-Washington Model. J Phys Chem B 2016; 120:891-901. [PMID: 26673038 DOI: 10.1021/acs.jpcb.5b11118] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Electron capture dissociation (ECD) and electron transfer dissociation (ETD) of gas-phase ions are widely used for peptide/protein sequencing by mass spectrometry. To understand the general mechanism of ECD/ETD of peptides, we focused on the ETD fragmentation of metal-peptide complexes in the absence of remote protons. Since Zn(2+) strongly binds to neutral histidine residues in peptides, Zn(2+)-polyhistidine complexation does not generate any remote protons. However, in the absence of remote protons, electron transfer to the Zn(2+)-polyhistidine complex induced the N-Cα bond cleavage. The formation pathway for the ETD products was investigated by density functional theory calculations. The calculations showed that the charge-reduced zinc-peptide radical, [M + Zn](•+), can exist in the low-energy zwitterionic amide π* states, which underwent homolytic N-Cα bond dissociation. The homolytic cleavage resulted in the donation of an electron from the N-Cα bond to the nitrogen atom, producing an iminoenol c' anion. The counterpart z(•) radical contained a radical site on the α-carbon atom. The iminoenol c' anion then abstracted a proton to presumably form the more stable amide c' fragment. The current experimental and computational joint study strongly suggested that the N-Cα bond cleavage occurred through the aminoketyl radical-anion formation for Zn(2+)-polyhistidine complexes in ETD.
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Affiliation(s)
- Daiki Asakawa
- National Metrology Institute of Japan (NMIJ), Research Institute for Measurement and Analytical Instrumentation, National Institute of Advanced Industrial Science and Technology (AIST) , Tsukuba Central 2, Umezono 1-1-1, Tsukuba, Ibaraki, 305-8568, Japan
| | - Asuka Yamashita
- Department of Chemistry, Faculty of Science, Nara Women's University , Kitauoyanishi-machi, Nara, 630-8506, Japan
| | - Shikiho Kawai
- Department of Chemistry, Faculty of Science, Nara Women's University , Kitauoyanishi-machi, Nara, 630-8506, Japan
| | - Takae Takeuchi
- Department of Chemistry, Faculty of Science, Nara Women's University , Kitauoyanishi-machi, Nara, 630-8506, Japan
| | - Yoshinao Wada
- Department of Molecular Medicine, Osaka Medical Center and Research Institute for Maternal and Child Health , Murodo-cho 840, Izumi, Osaka, 594-1101, Japan
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26
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Shaffer CJ, Marek A, Nguyen HTH, Tureček F. Combining Near-UV Photodissociation with Electron Transfer. Reduction of the Diazirine Ring in a Photomethionine-Labeled Peptide Ion. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2015; 26:1367-1381. [PMID: 25904063 DOI: 10.1007/s13361-015-1139-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2015] [Revised: 02/26/2015] [Accepted: 03/12/2015] [Indexed: 06/04/2023]
Abstract
Electron transfer dissociation of peptide ions with the diazirine-containing residue photomethionine (M*) results in side-chain dissociations by loss of C3H7N2 radicals in addition to standard backbone cleavages. The side-chain dissociations are particularly prominent upon activation of long-lived, charge-reduced, cation radicals (GM*GGR + 2H)(+•). Investigation of these cation radicals by near-UV photodissociation and collisional activation revealed different fragmentation products and mechanisms resulting from these ion activation modes. The dissociations observed for photomethionine were dramatically different from those previously reported for the lower homologue photoleucine; here, a difference by a single methylene group in the side chain had a large effect on the chemistries of the cation radicals upon ETD and further activation. ETD intermediates and products were probed by tandem 355-nm UV photodissociation-collision induced dissociation and found to contain chromophores that resulted from electron attachment to the diazirine ring. The nature of the newly formed chromophores and ion energetics and kinetics were investigated by electron structure calculations combining ab initio and density functional theory methods and Rice-Ramsperger-Kassel-Marcus (RRKM) theory. The dramatic difference between the dissociations of L* and M* containing peptide cation radicals is explained by electronic effects that play a role in stabilizing critical reaction intermediates and steer the dissociations into kinetically favored reaction channels. In addition, a new alternating UVPD-ETD-UVPD MS(4) experiment is introduced and utilized for ion structure elucidation.
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Affiliation(s)
- Christopher J Shaffer
- Department of Chemistry, University of Washington, Bagley Hall, Box 351700, Seattle, WA, 98195-1700, USA
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27
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Nguyen HTH, Shaffer CJ, Tureček F. Probing peptide cation-radicals by near-UV photodissociation in the gas phase. Structure elucidation of histidine radical chromophores formed by electron transfer reduction. J Phys Chem B 2015; 119:3948-61. [PMID: 25688483 DOI: 10.1021/jp511717c] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Electron transfer reduction of gas-phase ions generated from histidine-containing peptides forms stable cation-radicals that absorb light at 355 nm, as studied for AAHAR, AAHAK, DSHAK, FHEK, HHGYK, and HHSHR. Laser photodissociation of mass-selected cation-radicals chiefly resulted in loss of H atoms, contrasting dissociations induced by slow collisional heating. The 355 nm absorption was due to new chromophores created by electron transfer and radical rearrangements in the cation-radicals. The chromophores were identified by time-dependent density functional theory calculations as 2H,3H-imidazoline and 2H-dihydrophenol radicals, formed by hydrogen atom transfer to the histidine and tyrosine side chain groups, respectively. These radicals undergo facile C-H bond dissociations upon photon absorption. In contrast, dissociations of histidine peptide cation-radicals containing the 1H,3H-imidazoline ring prefer loss of 4-methylimidazole via a multistep reaction pathway. The isomeric cation-radicals can be distinguished by a combination of collision-induced dissociation and near-UV photodissociation. The TD-DFT excitation energies in model imidazoline radicals were benchmarked on EOM-CCSD energies, and a satisfactory agreement was found for the M06-2X and ωB97XD functionals. The combination of electron transfer, photodissociation, collisional activation, and theory is presented as a powerful tool for studying structures and electronic properties of peptide cation-radicals in the gas phase.
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Affiliation(s)
- Huong T H Nguyen
- Department of Chemistry, University of Washington , Bagley Hall, Box 351700, Seattle, Washington 98195-1700, United States
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28
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Feng WL, Tian SX. Ab Initio Molecular Dynamics Simulation Study of Dissociative Electron Attachment to Dialanine Conformers. J Phys Chem A 2015; 119:1838-45. [DOI: 10.1021/jp512173z] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Wen-Ling Feng
- Hefei
National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Shan Xi Tian
- Hefei
National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026, China
- Department
of Chemical Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
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29
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Bythell BJ. Cα hydrogen atom transfer in post-cleavage radical-cation complexes: short and steep versus long winding road. J Phys Chem A 2014; 118:10797-803. [PMID: 25329622 DOI: 10.1021/jp507865h] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Recently, I explored structurally straightforward pathways to Cα hydrogen atom, H(•), transfer reactions in the radical cation complex following electron capture/transfer of a series of polyprotonated peptides (J. Phys. Chem. A 2013, 117, 1189-1196). Here, I extend my analysis to incorporate detailed rearrangement processes potentially occurring prior to H(•) transfer. This comprises intracomplex isomerization of the initial iminol-terminated (-C(OH)═NH) form of the cn' species to the energetically more favorable, amide-terminated form (-C(O)-NH2) prior to Cα H(•) abstraction by the zm(•) species. The data indicate that the previously published H(•) transfer barriers are more energetically demanding than those of this multistep alternative. The rate-determining step is typically the intracomplex iminol isomerization, consistent with the substantial energetic favorability of the amide form of the cn species. The barriers to H(•) transfer still rise steeply as a function of the charge state. In agreement with experiment, evidence for product separation without H(•) transfer at a higher charge state is also provided.
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Affiliation(s)
- Benjamin J Bythell
- Department of Chemistry and Biochemistry, University of Missouri-St. Louis , St. Louis, Missouri 63121, United States
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30
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Huang Y, Pu Y, Yu X, Costello CE, Lin C. Mechanistic study on electron capture dissociation of the oligosaccharide-Mg²⁺ complex. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2014; 25:1451-60. [PMID: 24845360 PMCID: PMC4108535 DOI: 10.1007/s13361-014-0921-0] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2014] [Revised: 04/22/2014] [Accepted: 04/22/2014] [Indexed: 05/04/2023]
Abstract
Electron capture dissociation (ECD) has shown great potential in structural characterization of glycans. However, our current understanding of the glycan ECD process is inadequate for accurate interpretation of the complex glycan ECD spectra. Here, we present the first comprehensive theoretical investigation on the ECD fragmentation behavior of metal-adducted glycans, using the cellobiose-Mg²⁺ complex as the model system. Molecular dynamics simulation was carried out to determine the typical glycan-Mg²⁺ binding patterns and the lowest-energy conformer identified was used as the initial geometry for density functional theory-based theoretical modeling. It was found that the electron is preferentially captured by Mg²⁺ and the resultant Mg⁺• can abstract a hydroxyl group from the glycan moiety to form a carbon radical. Subsequent radical migration and α-cleavage(s) result in the formation of a variety of product ions. The proposed hydroxyl abstraction mechanism correlates well with the major features in the ECD spectrum of the Mg²⁺-adducted cellohexaose. The mechanism presented here also predicts the presence of secondary, radical-induced fragmentation pathways. These secondary fragment ions could be misinterpreted, leading to erroneous structural determination. The present study highlights an urgent need for continuing investigation of the glycan ECD mechanism, which is imperative for successful development of bioinformatics tools that can take advantage of the rich structural information provided by ECD of metal-adducted glycans.
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Affiliation(s)
- Yiqun Huang
- Mass Spectrometry Resource, Boston University School of Medicine, Boston, MA 02118
- Department of Biochemistry, Boston University School of Medicine, Boston, MA 02118
| | - Yi Pu
- Mass Spectrometry Resource, Boston University School of Medicine, Boston, MA 02118
- Department of Chemistry, Boston University, Boston, MA 02215
| | - Xiang Yu
- Mass Spectrometry Resource, Boston University School of Medicine, Boston, MA 02118
- Department of Biochemistry, Boston University School of Medicine, Boston, MA 02118
| | - Catherine E. Costello
- Mass Spectrometry Resource, Boston University School of Medicine, Boston, MA 02118
- Department of Biochemistry, Boston University School of Medicine, Boston, MA 02118
- Department of Chemistry, Boston University, Boston, MA 02215
| | - Cheng Lin
- Mass Spectrometry Resource, Boston University School of Medicine, Boston, MA 02118
- Department of Biochemistry, Boston University School of Medicine, Boston, MA 02118
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31
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Riffet V, Jacquemin D, Cauët E, Frison G. Benchmarking DFT and TD-DFT Functionals for the Ground and Excited States of Hydrogen-Rich Peptide Radicals. J Chem Theory Comput 2014; 10:3308-18. [DOI: 10.1021/ct5004912] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Vanessa Riffet
- Laboratoire
de Chimie Moléculaire, Département de Chimie, Ecole
polytechnique and CNRS, 91128 Palaiseau cedex, France
| | - Denis Jacquemin
- Laboratoire
CEISAM, UMR CNRS 6230, Université de Nantes, 2 rue de la
Houssinière - BP 92208, 44322 Nantes cedex 3, France
- Institut Universitaire
de France, 103 bd Saint-Michel, F-75005 Paris Cedex 05, France
| | - Emilie Cauët
- Service
de Chimie quantique et Photophysique, Université Libre de Bruxelles, CP160/09, 50 av. F.D. Roosevelt, 1050 Bruxelles, Belgium
| | - Gilles Frison
- Laboratoire
de Chimie Moléculaire, Département de Chimie, Ecole
polytechnique and CNRS, 91128 Palaiseau cedex, France
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32
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Vasil’ev YV, Tzeng SC, Huang L, Maier CS. Protein modifications by electrophilic lipoxidation products: adduct formation, chemical strategies and tandem mass spectrometry for their detection and identification. MASS SPECTROMETRY REVIEWS 2014; 33:157-82. [PMID: 24818247 PMCID: PMC4138024 DOI: 10.1002/mas.21389] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
The post-translational modification of proteins by electrophilic oxylipids is emerging as an important mechanism that contributes to the complexity of proteomes. Enzymatic and non-enzymatic oxidation of biological lipids results in the formation of chemically diverse electrophilic carbonyl compounds, such as 2-alkenals and 4-hydroxy alkenals, epoxides, and eicosanoids with reactive cyclopentenone structures. These lipoxidation products are capable of modifying proteins. Originally considered solely as markers of oxidative insult, more recently the modifications of proteins by lipid peroxidation products are being recognized as a new mechanism of cell signaling with relevance to redox homeostasis, adaptive response and inflammatory resolution. The growing interest in protein modifications by reactive oxylipid species necessitates the availability of methods that are capable of detecting, identifying and characterizing these protein adducts in biological samples with high complexity. However, the efficient analysis of these chemically diverse protein adducts presents a considerable analytical challenge. We first provide an introduction into the chemistry and biological relevance of protein adductions by electrophilic lipoxidation products. We then provide an overview of tandem mass spectrometry approaches that have been developed in recent years for the interrogation of protein modifications by electrophilic oxylipid species.
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Affiliation(s)
| | | | | | - Claudia S. Maier
- Corresponding author: Department of Chemistry, Oregon State University, 153 Gilbert Hall Phone: 541-737-9533 Fax: 541-737-2062
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33
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Thomas DA, Sohn CH, Gao J, Beauchamp JL. Hydrogen Bonding Constrains Free Radical Reaction Dynamics at Serine and Threonine Residues in Peptides. J Phys Chem A 2014; 118:8380-92. [DOI: 10.1021/jp501367w] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
- Daniel A. Thomas
- Arthur Amos Noyes Laboratory
of Chemical Physics, California Institute of Technology, Pasadena, California 91125, United States
| | - Chang Ho Sohn
- Arthur Amos Noyes Laboratory
of Chemical Physics, California Institute of Technology, Pasadena, California 91125, United States
| | - Jinshan Gao
- Arthur Amos Noyes Laboratory
of Chemical Physics, California Institute of Technology, Pasadena, California 91125, United States
| | - J. L. Beauchamp
- Arthur Amos Noyes Laboratory
of Chemical Physics, California Institute of Technology, Pasadena, California 91125, United States
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34
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Anusiewicz I, Skurski P, Simons J. Refinements to the Utah–Washington Mechanism of Electron Capture Dissociation. J Phys Chem B 2014; 118:7892-901. [DOI: 10.1021/jp5004819] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Iwona Anusiewicz
- Department
of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308 Gdańsk, Poland
| | - Piotr Skurski
- Department
of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308 Gdańsk, Poland
| | - Jack Simons
- Chemistry
Department and Henry Eyring Center for Theoretical Chemistry, University of Utah, Salt Lake City, Utah 84112, United States
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35
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Wodrich MD, Zhurov KO, Corminboeuf C, Tsybin YO. On the viability of heterolytic peptide N-C(α) bond cleavage in electron capture and transfer dissociation mass spectrometry. J Phys Chem B 2014; 118:2985-92. [PMID: 24559292 DOI: 10.1021/jp500512a] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
While frequently employed as an experimental technique, the mechanistic picture surrounding the gas-phase dissociation of peptides carrying multiple positive charges during electron capture and electron transfer dissociation tandem mass spectrometry remains incomplete. Despite this mechanistic uncertainty, most proposals agree that the peptide backbone N-Cα bond located to the C-terminal (right) side of an aminoketyl radical formed in a peptide backbone during the electron capture process is homolytically cleaved. Recently, we introduced the "enol" mechanism, which proposes that a backbone N-Cα bond located to the N-terminal (left) side of an aminoketyl radical is cleaved heterolytically. Here, we further validate this mechanism using replica-exchange molecular dynamics to create unbiased representative sets of low-energy conformers for several model tryptic peptide systems (H-Alax-Lys-OH(2+), x = 3-5). Transition state barrier enthalpies for the cleavage of N-Cα bonds proceeding via the homolytic (right-side) and heterolytic (left-side) pathways, determined by density functional computations, identify the preferred cleavage route for each conformer. These findings support our original hypothesis that heterolytic N-Cα cleavage can exist in a competitive balance with homolytic cleavages, independent of the relative energy of the precursor dication species. Smaller peptide systems see decreased heterolytic N-Cα cleavage probabilities, likely resulting from an insufficient hydrogen-bonding network needed to stabilize and ultimately annihilate the transition state zwitterion. This observation may explain the early dismissal of left-side cleavage pathways based on computational studies employing small model systems.
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Affiliation(s)
- Matthew D Wodrich
- Biomolecular Mass Spectrometry Laboratory, Ecole Polytechnique Fédérale de Lausanne , 1015 Lausanne, Switzerland
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36
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Zhurov KO, Wodrich MD, Corminboeuf C, Tsybin YO. Ping-pong protons: how hydrogen-bonding networks facilitate heterolytic bond cleavage in peptide radical cations. J Phys Chem B 2014; 118:2628-37. [PMID: 24555737 DOI: 10.1021/jp412123h] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Electron capture and electron transfer dissociation (ECD/ETD) tandem mass spectrometry (MS/MS) are commonly employed techniques for biomolecular analysis. The ECD/ETD process predominately cleaves N-Cα peptide backbone bonds, leading to primary sequence information complementary to other mass spectrometry techniques. Despite frequent laboratory use, the mechanistic underpinnings surrounding N-Cα bond cleavage remain debated. While the majority of mechanisms assume a homolytic bond rupture, we recently showed that heterolytic cleavage is also thermodynamically viable. For a cleavage of this type to be feasible, the charge separation created upon breaking of the N-Cα backbone bond must be quickly annihilated. In this work, we show, using density functional computations, that specific hydrogen-bonding motifs and structural rearrangements involving proton transfers stabilize the transition state associated with heterolytic cleavage and eliminate the ensuing charge separation from the final product fragments. The movement of protons can occur either directly from the z- to c-fragment or in a more complex manner including a ping-pong-type mechanism. The nature of these diverse hydrogen-bonding motifs reveals that not only those functional groups proximate to the bond rupture site, but also the entire global chemical environment, play important roles in backbone cleavage characteristic of ECD/ETD MS/MS. For doubly charged systems, both conformation and electron localization site dictate which of the two fragments retains the final positive charge.
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Affiliation(s)
- Konstantin O Zhurov
- Biomolecular Mass Spectrometry Laboratory and ‡Laboratory for Computational Molecular Design, Ecole Polytechnique Fédérale de Lausanne , 1015 Lausanne, Switzerland
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37
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Le TN, Poully JC, Lecomte F, Nieuwjaer N, Manil B, Desfrançois C, Chirot F, Lemoine J, Dugourd P, van der Rest G, Grégoire G. Gas-phase structure of amyloid-β (12-28) peptide investigated by infrared spectroscopy, electron capture dissociation and ion mobility mass spectrometry. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2013; 24:1937-49. [PMID: 24043520 DOI: 10.1007/s13361-013-0722-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2013] [Revised: 07/22/2013] [Accepted: 07/30/2013] [Indexed: 05/11/2023]
Abstract
The gas-phase structures of doubly and triply protonated Amyloid-β12-28 peptides have been investigated through the combination of ion mobility (IM), electron capture dissociation (ECD) mass spectrometry, and infrared multi-photon dissociation (IRMPD) spectroscopy together with theoretical modeling. Replica-exchange molecular dynamics simulations were conducted to explore the conformational space of these protonated peptides, from which several classes of structures were found. Among the low-lying conformers, those with predicted diffusion cross-sections consistent with the ion mobility experiment were further selected and their IR spectra simulated using a hybrid quantum mechanical/semiempirical method at the ONIOM DFT/B3LYP/6-31 g(d)/AM1 level. In ECD mass spectrometry, the c/z product ion abundance (PIA) has been analyzed for the two charge states and revealed drastic differences. For the doubly protonated species, N - Cα bond cleavage occurs only on the N and C terminal parts, while a periodic distribution of PIA is clearly observed for the triply charged peptides. These PIA distributions have been rationalized by comparison with the inverse of the distances from the protonated sites to the carbonyl oxygens for the conformations suggested from IR and IM experiments. Structural assignment for the amyloid peptide is then made possible by the combination of these three experimental techniques that provide complementary information on the possible secondary structure adopted by peptides. Although globular conformations are favored for the doubly protonated peptide, incrementing the charge state leads to a conformational transition towards extended structures with 310- and α-helix motifs.
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Affiliation(s)
- Thi Nga Le
- Université Paris 13, Sorbonne Paris Cité, Laboratoire de Physique des Lasers, CNRS UMR 7538, F-93430, Villetaneuse, France
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38
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Mentinova M, Crizer DM, Baba T, McGee WM, Glish GL, McLuckey SA. Cation recombination energy/coulomb repulsion effects in ETD/ECD as revealed by variation of charge per residue at fixed total charge. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2013; 24:1676-89. [PMID: 23568028 PMCID: PMC3795911 DOI: 10.1007/s13361-013-0606-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2013] [Revised: 02/25/2013] [Accepted: 02/28/2013] [Indexed: 05/11/2023]
Abstract
Electron capture dissociation (ECD) and electron transfer dissociation (ETD) experiments in electrodynamic ion traps operated in the presence of a bath gas in the 1-10 mTorr range have been conducted on a common set of doubly protonated model peptides of the form X(AG)nX (X = lysine, arginine, or histidine, n = 1, 2, or 4). The partitioning of reaction products was measured using thermal electrons, anions of azobenzene, and anions of 1,3-dinitrobenzene as reagents. Variation of n alters the charge per residue of the peptide cation, which affects recombination energy. The ECD experiments showed that H-atom loss is greatest for the n = 1 peptides and decreases as n increases. Proton transfer in ETD, on the other hand, is expected to increase as charge per residue decreases (i.e., as n increases). These opposing tendencies were apparent in the data for the K(AG)nK peptides. H-atom loss appeared to be more prevalent in ECD than in ETD and is rationalized on the basis of either internal energy differences, differences in angular momentum transfer associated with the electron capture versus electron transfer processes, or a combination of the two. The histidine peptides showed the greatest extent of charge reduction without dissociation, the arginine peptides showed the greatest extent of side-chain cleavages, and the lysine peptides generally showed the greatest extent of partitioning into the c/z•-product ion channels. The fragmentation patterns for the complementary c- and z•-ions for ETD and ECD were found to be remarkably similar, particularly for the peptides with X = lysine.
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Affiliation(s)
- Marija Mentinova
- Department of Chemistry, Purdue University, West Lafayette, IN 47907-2084, USA
| | - David M. Crizer
- Department of Chemistry, Purdue University, West Lafayette, IN 47907-2084, USA
- Department of Chemistry, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Takashi Baba
- Department of Chemistry, University of North Carolina, Chapel Hill, NC 27599, USA
| | - William M. McGee
- Department of Chemistry, Purdue University, West Lafayette, IN 47907-2084, USA
| | - Gary L. Glish
- Department of Chemistry, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Scott A. McLuckey
- Department of Chemistry, Purdue University, West Lafayette, IN 47907-2084, USA
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39
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Kaczorowska MA, Cooper HJ. Electron capture dissociation and collision induced dissociation of S-dipalmitoylated peptides. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2013; 24:1224-1227. [PMID: 23728547 DOI: 10.1007/s13361-013-0662-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2013] [Revised: 04/18/2013] [Accepted: 04/29/2013] [Indexed: 06/02/2023]
Abstract
Here we investigate the effect of S-dipalmitoylation on the electron capture dissociation (ECD) behavior of peptides. The ECD and collision induced dissociation (CID) of peptides modified by covalent attachment of [(RS)-2,3-di(palmitoyloxy)-propyl] (PAM2) group to cysteine residues [C(PAM2)LEYDTGFK and RPPGC(PAM2)SPFK] were examined. The results suggest that ECD of S-dipalmitoylated peptides can provide both primary sequence information and structural information regarding the modification. The structural information provided by CID is complementary to that provided by ECD.
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Affiliation(s)
- Małgorzata A Kaczorowska
- Faculty of Chemical Technology and Engineering, University of Technology and Life Sciences in Bydgoszcz, Seminaryjna 3, Bydgoszcz, Poland.
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40
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Affiliation(s)
- František Tureček
- Department of Chemistry, Bagley Hall, University of Washington , Seattle, Washington 98195-1700, United States
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41
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Tureček F. Renaissance of cation-radicals in mass spectrometry. Mass Spectrom (Tokyo) 2013; 2:S0003. [PMID: 24349922 PMCID: PMC3810458 DOI: 10.5702/massspectrometry.s0003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2012] [Accepted: 11/08/2012] [Indexed: 11/23/2022] Open
Abstract
This brief overview addresses the topic that was presented in the Thomson Medal Award session at the 19th International Mass Spectrometry Conference in Kyoto, Japan. Mass spectrometry of cation-radicals has enjoyed a remarkable renaissance thanks to the development of new methods for electron attachment to multiply charged peptide ions. The charge-reduced ions that are odd-electron species exhibit interesting reactivity that is useful for peptide and protein sequencing. The paper briefly reviews the fundamental aspects of the formation, energetics, and backbone dissociations of peptide cation-radicals.
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42
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Bouchoux G. From the mobile proton to wandering hydride ion: mechanistic aspects of gas-phase ion chemistry. JOURNAL OF MASS SPECTROMETRY : JMS 2013; 48:505-518. [PMID: 23584944 DOI: 10.1002/jms.3204] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2013] [Revised: 03/06/2013] [Accepted: 03/06/2013] [Indexed: 06/02/2023]
Abstract
Structural characterization of molecular species by mass spectrometry supposes the knowledge of the type of ions generated and the mechanism by which they dissociate. In this context, a need for a rationalization of electrospray ionization(+)(-) mass spectra of small molecules has been recently expressed. Similarly, at the other end of the mass scale, efforts are currently made to interpret the major fragmentation processes of protonated and deprotonated peptides and their reduced forms produced in electron capture or electron transfer experiments. Most fragmentation processes of molecular and pseudo-molecular ions produced in the ion source of a mass spectrometer may be described by a combination of several key mechanistic steps: simple bond dissociation, formation of ion-neutral complex intermediates, hydrogen atom, hydride ion or proton migrations and nucleophilic attack. Selected crucial aspects of these elementary reactions, occurring inside positively charged ions, will be recalled and illustrated by examples taken in recent mass spectrometry literature. Emphasis will be given on the protonation process and its consequence in terms of structure and energetic.
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Affiliation(s)
- Guy Bouchoux
- Laboratoire des Mécanismes Réactionnels. Ecole Polytechnique. CNRS, Université Paris-sud, 91128, Palaiseau, France.
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43
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Puschnigg B, Huber SE, Probst M, Tanzer K, Vizcaino V, Ferreira da Silva F, Scheier P, Limão-Vieira P, Denifl S. Electron attachment to the dipeptide dialanine: influence of methylation on site selective dissociation reactions. Phys Chem Chem Phys 2013; 15:3834-40. [DOI: 10.1039/c3cp44230f] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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44
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Liu J, McLuckey SA. Electron Transfer Dissociation: Effects of Cation Charge State on Product Partitioning in Ion/Ion Electron Transfer to Multiply Protonated Polypeptides. INTERNATIONAL JOURNAL OF MASS SPECTROMETRY 2012; 330-332:174-181. [PMID: 23264749 PMCID: PMC3525064 DOI: 10.1016/j.ijms.2012.07.013] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
The effect of cation charge state on product partitioning in the gas-phase ion/ion electron transfer reactions of multiply protonated tryptic peptides, model peptides, and relatively large peptides with singly charged radical anions has been examined. In particular, partitioning into various competing channels, such as proton transfer (PT) versus electron transfer (ET), electron transfer with subsequent dissociation (ETD) versus electron transfer with no dissociation (ET,noD), and fragmentation of backbone bonds versus fragmentation of side chains, was measured quantitatively as a function of peptide charge state to allow insights to be drawn about the fundamental aspects of ion/ion reactions that lead to ETD. The ET channel increases relative to the PT channel, ETD increases relative to ET,noD, and fragmentation at backbone bonds increases relative to side-chain cleavages as cation charge state increases. The increase in ET versus PT with charge state is consistent with a Landau-Zener based curve-crossing model. An optimum charge state for ET is predicted by the model for the ground state-to-ground state reaction. However, when the population of excited product ion states is considered, it is possible that a decrease in ET efficiency as charge state increases will not be observed due to the possibility of the population of excited electronic states of the products. Several factors can contribute to the increase in ETD versus ET,noD and backbone cleavage versus side-chain losses. These factors include an increase in reaction exothermicity and charge state dependent differences in precursor and product ion structures, stabilities, and sites of protonation.
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Affiliation(s)
| | - Scott A. McLuckey
- Address reprint requests to: Dr. S.A. McLuckey, 560 Oval Drive, Department of Chemistry, Purdue University, West Lafayette, IN, USA 47907-2084, Phone: (765) 494-5270, Fax: (765) 494-0239,
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45
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Jones AW, Winn PJ, Cooper HJ. The radical ion chemistry of S-nitrosylated peptides. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2012; 23:2063-2074. [PMID: 23055078 DOI: 10.1007/s13361-012-0492-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2012] [Revised: 07/11/2012] [Accepted: 07/20/2012] [Indexed: 06/01/2023]
Abstract
The radical ion chemistry of a suite of S-nitrosopeptides has been investigated. Doubly and triply-protonated ions of peptides NYCGLPGEYWLGNDK, NYCGLPGEYWLGNDR, NYCGLPGERWLGNDR, NACGAPGEKWAGNDK, NYCGLPGEKYLGNDK, NYGLPGCEKWYGNDK and NYGLPGEKWYGCNDK were subjected to electron capture dissociation (ECD), and collision-induced dissociation (CID). The peptide sequences were selected such that the effect of the site of S-nitrosylation, the nature and position of the basic amino acid residues, and the nature of the other amino acid side chains, could be interrogated. The ECD mass spectra were dominated by a peak corresponding to loss of (•)NO from the charge-reduced precursor, which can be explained by a modified Utah-Washington mechanism. Some backbone fragmentation in which the nitrosyl modification was preserved was also observed in the ECD of some peptides. Molecular dynamics simulations of peptide ion structure suggest that the ECD behavior was dependent on the surface accessibility of the protonated residue. CID of the S-nitrosylated peptides resulted in homolysis of the S-N bond to form a long-lived radical with loss of (•)NO. The radical peptide ions were isolated and subjected to ECD and CID. ECD of the radical peptide ions provided an interesting comparison to ECD of the unmodified peptides. The dominant process was electron capture without further dissociation (ECnoD). CID of the radical peptide ions resulted in cysteine, leucine, and asparagine side chain losses, and radical-induced backbone fragmentation at tryptophan, tyrosine, and asparagine residues, in addition to charge-directed backbone fragmentation.
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Affiliation(s)
- Andrew W Jones
- School of Biosciences, College of Life and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, United Kingdom
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46
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Hurtado PP, O'Connor PB. Differentiation of isomeric amino acid residues in proteins and peptides using mass spectrometry. MASS SPECTROMETRY REVIEWS 2012; 31:609-25. [PMID: 22322410 DOI: 10.1002/mas.20357] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Characterization and differentiation of isomers in biological macromolecules using mass spectrometry is one of the most significant challenges facing scientists in the field. The capability of high-resolution MS instruments along with the development of new fragmentation methods now provides the ability to indirectly differentiate between some isomers. This ability has enabled mass spectrometry to evolve into a multidisciplinary technique incorporating areas such as pharmaceutical research, proteomics, polymer science, medicine, environmental chemistry, and recently archeology. This article aims to review recent developments in mass spectrometry methodologies in the identification of structural and spatial isomers in biological macromolecules, such as aspartic acid and isoaspartic acid (Asp/IsoAsp), leucine and isoleucine (Leu/Ile), glutamic acid and γ-glutamic acid, and D/L enantiomers.
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47
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Kalli A, Hess S. Electron capture dissociation of hydrogen-deficient peptide radical cations. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2012; 23:1729-1740. [PMID: 22855421 DOI: 10.1007/s13361-012-0433-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2012] [Revised: 06/05/2012] [Accepted: 06/12/2012] [Indexed: 06/01/2023]
Abstract
Hydrogen-deficient peptide radical cations exhibit fascinating gas phase chemistry, which is governed by radical driven dissociation and, in many cases, by a combination of radical and charge driven fragmentation. Here we examine electron capture dissociation (ECD) of doubly, [M + H](2+•), and triply, [M + 2H](3+•), charged hydrogen-deficient species, aiming to investigate the effect of a hydrogen-deficient radical site on the ECD outcome and characterize the dissociation pathways of hydrogen-deficient species in ECD. ECD of [M + H](2+•) and [M + 2H](3+•) precursor ions resulted in efficient electron capture by the hydrogen-deficient species. However, the intensities of c- and z-type product ions were reduced, compared with those observed for the even electron species, indicating suppression of N-C(α) backbone bond cleavages. We postulate that radical recombination occurs after the initial electron capture event leading to a stable even electron intermediate, which does not trigger N-C(α) bond dissociations. Although the intensities of c- and z-type product ions were reduced, the number of backbone bond cleavages remained largely unaffected between the ECD spectra of the even electron and hydrogen-deficient species. We hypothesize that a small ion population exist as a biradical, which can trigger N-C(α) bond cleavages. Alternatively, radical recombination and N-C(α) bond cleavages can be in competition, with radical recombination being the dominant pathway and N-C(α) cleavages occurring to a lesser degree. Formation of b- and y-type ions observed for two of the hydrogen-deficient peptides examined is also discussed.
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Affiliation(s)
- Anastasia Kalli
- Proteome Exploration Laboratory, Division of Biology, Beckman Institute, California Institute of Technology, Pasadena, 91125, USA
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48
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Wodrich MD, Zhurov KO, Vorobyev A, Ben Hamidane H, Corminboeuf C, Tsybin YO. Heterolytic N–Cα Bond Cleavage in Electron Capture and Transfer Dissociation of Peptide Cations. J Phys Chem B 2012; 116:10807-15. [DOI: 10.1021/jp306703f] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Matthew D. Wodrich
- Biomolecular
Mass Spectrometry
Laboratory, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
- Laboratory for Computational
Molecular Design, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | - Konstantin O. Zhurov
- Biomolecular
Mass Spectrometry
Laboratory, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | - Aleksey Vorobyev
- Biomolecular
Mass Spectrometry
Laboratory, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | - Hisham Ben Hamidane
- Biomolecular
Mass Spectrometry
Laboratory, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | - Clémence Corminboeuf
- Laboratory for Computational
Molecular Design, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | - Yury O. Tsybin
- Biomolecular
Mass Spectrometry
Laboratory, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
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49
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Zimnicka M, Chung TW, Moss CL, Tureček F. Perturbing Peptide Cation-Radical Electronic States by Thioxoamide Groups: Formation, Dissociations, and Energetics of Thioxopeptide Cation-Radicals. J Phys Chem A 2012; 117:1265-75. [DOI: 10.1021/jp305865q] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Magdalena Zimnicka
- Department of Chemistry, Bagley Hall, Box
351700, University of Washington, Seattle,
Washington 98195-1700,
United States
| | - Thomas W. Chung
- Department of Chemistry, Bagley Hall, Box
351700, University of Washington, Seattle,
Washington 98195-1700,
United States
| | - Christopher L. Moss
- Department of Chemistry, Bagley Hall, Box
351700, University of Washington, Seattle,
Washington 98195-1700,
United States
| | - František Tureček
- Department of Chemistry, Bagley Hall, Box
351700, University of Washington, Seattle,
Washington 98195-1700,
United States
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50
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Gschliesser D, Vizcaino V, Probst M, Scheier P, Denifl S. Formation and decay of the dehydrogenated parent anion upon electron attachment to dialanine. Chemistry 2012; 18:4613-9. [PMID: 22374822 PMCID: PMC3482929 DOI: 10.1002/chem.201102433] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2011] [Indexed: 11/24/2022]
Abstract
The dehydrogenated parent anion [M-H](-) is one of the most dominant anions formed in dissociative electron attachment to various small biomolecules like nucleobases and single amino acids. In the present study, we investigate the [M-H](-) channel for the dipeptide dialanine by utilizing an electron monochromator and a two-sector-field mass spectrometer. At electron energies below 2 eV, the measured high-resolution ion-efficiency curve has a different shape to that for the single amino acid alanine, which is explained by the altered threshold energies for formation of [M-H](-) determined in quantum chemical calculations. Moreover, the structure of the formed [M-H](-) anion is further studied by investigating the unimolecular and collision-induced decay of this anion. Trajectory calculations have been carried out to aid the interpretation of the experimentally observed fragmentation patterns.
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Affiliation(s)
- David Gschliesser
- Institut für Ionenphysik und Angewandte Physik and Center for Molecular Biosciences Innsbruck, Leopold-Franzens-Universität Innsbruck, Technikerstrasse 256020 Innsbruck (Austria)
| | - Violaine Vizcaino
- Institut für Ionenphysik und Angewandte Physik and Center for Molecular Biosciences Innsbruck, Leopold-Franzens-Universität Innsbruck, Technikerstrasse 256020 Innsbruck (Austria)
| | - Michael Probst
- Institut für Ionenphysik und Angewandte Physik and Center for Molecular Biosciences Innsbruck, Leopold-Franzens-Universität Innsbruck, Technikerstrasse 256020 Innsbruck (Austria)
| | - Paul Scheier
- Institut für Ionenphysik und Angewandte Physik and Center for Molecular Biosciences Innsbruck, Leopold-Franzens-Universität Innsbruck, Technikerstrasse 256020 Innsbruck (Austria)
| | - Stephan Denifl
- Institut für Ionenphysik und Angewandte Physik and Center for Molecular Biosciences Innsbruck, Leopold-Franzens-Universität Innsbruck, Technikerstrasse 256020 Innsbruck (Austria)
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