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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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2
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Commodore JJ, Cassady CJ. Electron transfer dissociation mass spectrometry of acidic phosphorylated peptides cationized with trivalent praseodymium. JOURNAL OF MASS SPECTROMETRY : JMS 2018; 53:1178-1188. [PMID: 30221809 PMCID: PMC6291000 DOI: 10.1002/jms.4291] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Revised: 08/13/2018] [Accepted: 09/10/2018] [Indexed: 06/08/2023]
Abstract
The lanthanide ion praseodymium, Pr(III), was employed to study metallated ion formation and electron transfer dissociation (ETD) of 27 biological and model highly acidic phosphopeptides. All phosphopeptides investigated form metallated ions by electrospray ionization (ESI) that can be studied by ETD to yield abundant sequence information. The ions formed are [M + Pr - H]2+ , [M + Pr]3+ , and [M + Pr + H]4+ . All biological phosphopeptides with a chain length of seven or more residues generate [M + Pr]3+ . For biological phosphopeptides, [M + Pr]3+ undergoes more backbone cleavage by ETD than [M + Pr - H]2+ and, in some cases, full sequence coverage occurs. Acidic model phosphorylated hexa-peptides and octa-peptides, composed of alanine residues and one phosphorylated residue, form exclusively [M + Pr - H]2+ by ESI. Limited sequence information is obtained by ETD of [M + Pr - H]2+ with only metallated product ions being generated. For two biological phosphopeptides, [M + Pr + H]4+ is observed and may be due to the presence of at least one residue with a highly basic side chain that facilitates the addition of an extra proton. For the model phosphopeptides, more sequence coverage occurs when the phosphorylated residue is in the middle of the sequence than at either the N- or C-terminus. ETD of the metallated precursor ions formed by ESI generates exclusively metallated and nonmetallated c- and z-ions for the biological phosphopeptides, while metallated c-ions, z-ions, and a few y-ions form for the model phosphopeptides. Most of the product ions contain the phosphorylated residue indicating that the metal ion binds predominantly at the deprotonated phosphate group. The results of this study indicate that ETD is a promising tool for sequencing highly acidic phosphorylated peptides by metal adduction with Pr (III) and, by extension, all nonradioactive lanthanide metal ions.
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Affiliation(s)
| | - Carolyn J Cassady
- Department of Chemistry, The University of Alabama, Tuscaloosa, Alabama, USA
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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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Schneeberger EM, Breuker K. Replacing H + by Na + or K + in phosphopeptide anions and cations prevents electron capture dissociation. Chem Sci 2018; 9:7338-7353. [PMID: 30542537 PMCID: PMC6237128 DOI: 10.1039/c8sc02470g] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Accepted: 07/07/2018] [Indexed: 01/29/2023] Open
Abstract
By successively replacing H+ by Na+ or K+ in phosphopeptide anions and cations, we show that the efficiency of fragmentation into c and z˙ or c˙ and z fragments from N-Cα backbone bond cleavage by negative ion electron capture dissociation (niECD) and electron capture dissociation (ECD) substantially decreases with increasing number of alkali ions attached. In proton-deficient phosphopeptide ions with a net charge of 2-, we observed an exponential decrease in electron capture efficiency with increasing number of Na+ or K+ ions attached, suggesting that electrons are preferentially captured at protonated sites. In proton-abundant phosphopeptide ions with a net charge of 3+, the electron capture efficiency was not affected by replacing up to four H+ ions with Na+ or K+ ions, but the yield of c, z˙ and c˙, z fragments from N-Cα backbone bond cleavage generally decreased next to Na+ or K+ binding sites. We interpret the site-specific decrease in fragmentation efficiency as Na+ or K+ binding to backbone amide oxygen in competition with interactions of protonated sites that would otherwise lead to backbone cleavage into c, z˙ or c˙, z fragments. Our findings seriously challenge the hypothesis that the positive charge responsible for ECD into c, z˙ or c˙, z fragments can generally be a sodium or other metal ion instead of a proton.
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Affiliation(s)
- Eva-Maria Schneeberger
- Institute of Organic Chemistry , Center for Molecular Biosciences Innsbruck (CMBI) , University of Innsbruck , Innrain 80/82 , 6020 Innsbruck , Austria . ; http://www.bioms-breuker.at/
| | - Kathrin Breuker
- Institute of Organic Chemistry , Center for Molecular Biosciences Innsbruck (CMBI) , University of Innsbruck , Innrain 80/82 , 6020 Innsbruck , Austria . ; http://www.bioms-breuker.at/
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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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Halim MA, MacAleese L, Lemoine J, Antoine R, Dugourd P, Girod M. Ultraviolet, Infrared, and High-Low Energy Photodissociation of Post-Translationally Modified Peptides. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2018; 29:270-283. [PMID: 28980177 DOI: 10.1007/s13361-017-1794-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Revised: 08/17/2017] [Accepted: 08/18/2017] [Indexed: 06/07/2023]
Abstract
Mass spectrometry-based methods have made significant progress in characterizing post-translational modifications in peptides and proteins; however, certain aspects regarding fragmentation methods must still be improved. A good technique is expected to provide excellent sequence information, locate PTM sites, and retain the labile PTM groups. To address these issues, we investigate 10.6 μm IRMPD, 213 nm UVPD, and combined UV and IR photodissociation, known as HiLoPD (high-low photodissociation), for phospho-, sulfo-, and glyco-peptide cations. IRMPD shows excellent backbone fragmentation and produces equal numbers of N- and C-terminal ions. The results reveal that 213 nm UVPD and HiLoPD methods can provide diverse backbone fragmentation producing a/x, b/y, and c/z ions with excellent sequence coverage, locate PTM sites, and offer reasonable retention efficiency for phospho- and glyco-peptides. Excellent sequence coverage is achieved for sulfo-peptides and the position of the SO3 group can be pinpointed; however, widespread SO3 losses are detected irrespective of the methods used herein. Based on the overall performance achieved, we believe that 213 nm UVPD and HiLoPD can serve as alternative options to collision activation and electron transfer dissociations for phospho- and glyco-proteomics. Graphical Abstract ᅟ.
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Affiliation(s)
- Mohammad A Halim
- Université de Lyon, Université Claude Bernard Lyon 1, CNRS, Institut Lumière Matière, F-69622, Lyon, France
| | - Luke MacAleese
- Université de Lyon, Université Claude Bernard Lyon 1, CNRS, Institut Lumière Matière, F-69622, Lyon, France
| | - Jérôme Lemoine
- Université de Lyon, Institut des Sciences Analytiques, UMR 5280, CNRS, Université Lyon 1, ENS Lyon, 69622, Villeurbanne, Cedex, France
| | - Rodolphe Antoine
- Université de Lyon, Université Claude Bernard Lyon 1, CNRS, Institut Lumière Matière, F-69622, Lyon, France
| | - Philippe Dugourd
- Université de Lyon, Université Claude Bernard Lyon 1, CNRS, Institut Lumière Matière, F-69622, Lyon, France.
| | - Marion Girod
- Université de Lyon, Institut des Sciences Analytiques, UMR 5280, CNRS, Université Lyon 1, ENS Lyon, 69622, Villeurbanne, Cedex, France
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Commodore JJ, Cassady CJ. Effects of acidic peptide size and sequence on trivalent praseodymium adduction and electron transfer dissociation mass spectrometry. JOURNAL OF MASS SPECTROMETRY : JMS 2017; 52:218-229. [PMID: 28170125 PMCID: PMC5407459 DOI: 10.1002/jms.3919] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Revised: 01/31/2017] [Accepted: 02/02/2017] [Indexed: 05/05/2023]
Abstract
Using the lanthanide ion praseodymium, Pr(III), metallated ion formation and electron transfer dissociation (ETD) were studied for 25 biological and model acidic peptides. For chain lengths of seven or more residues, even highly acidic peptides that can be difficult to protonate by electrospray ionization will metallate and undergo abundant ETD fragmentation. Peptides composed of predominantly acidic residues form only the deprotonated ion, [M + Pr - H]2+ ; this ion yields near complete ETD sequence coverage for larger peptides. Peptides with a mixture of acidic and neutral residues generate [M + Pr]3+ , which cleaves between every residue for many peptides. Acidic peptides that contain at least one residue with a basic side chain also produce the protonated ion, [M + Pr + H]4+ ; this ion undergoes the most extensive sequence coverage by ETD. Primarily metallated and non-metallated c- and z-ions form for all peptides investigated. Metal adducted product ions are only present when at least half of the peptide sequence can be incorporated into the ion; this suggests that the metal ion simultaneously attaches to more than one acidic site. The only site consistently lacking dissociation is at the N-terminal side of a proline residue. Increasing peptide chain length generates more backbone cleavage for metal-peptide complexes with the same charge state. For acidic peptides with the same length, increasing the precursor ion charge state from 2+ to 3+ also leads to more cleavage. The results of this study indicate that highly acidic peptides can be sequenced by ETD of complexes formed with Pr(III). Copyright © 2017 John Wiley & Sons, Ltd.
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Affiliation(s)
| | - Carolyn J. Cassady
- Department of Chemistry, The University of Alabama, Tuscaloosa, AL 35487
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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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Commodore JJ, Cassady CJ. The Effects of Trivalent Lanthanide Cationization on the Electron Transfer Dissociation of Acidic Fibrinopeptide B and its Analogs. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2016; 27:1499-509. [PMID: 27294379 PMCID: PMC4974135 DOI: 10.1007/s13361-016-1428-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Revised: 05/22/2016] [Accepted: 05/23/2016] [Indexed: 05/08/2023]
Abstract
Electrospray ionization (ESI) on mixtures of acidic fibrinopeptide B and two peptide analogs with trivalent lanthanide salts generates [M + Met + H](4+), [M + Met](3+), and [M + Met -H](2+), where M = peptide and Met = metal (except radioactive promethium). These ions undergo extensive and highly efficient electron transfer dissociation (ETD) to form metallated and non-metallated c- and z-ions. All metal adducted product ions contain at least two acidic sites, which suggest attachment of the lanthanide cation at the side chains of one or more acidic residues. The three peptides undergo similar fragmentation. ETD on [M + Met + H](4+) leads to cleavage at every residue; the presence of both a metal ion and an extra proton is very effective in promoting sequence-informative fragmentation. Backbone dissociation of [M + Met](3+) is also extensive, although cleavage does not always occur between adjacent glutamic acid residues. For [M + Met - H ](2+), a more limited range of product ions form. All lanthanide metal peptide complexes display similar fragmentation except for europium (Eu). ETD on [M + Eu - H](2+) and [M + Eu](3+) yields a limited amount of peptide backbone cleavage; however, [M + Eu + H](4+) dissociates extensively with cleavage at every residue. With the exception of the results for Eu(III), metallated peptide ion formation by ESI, ETD fragmentation efficiencies, and product ion formation are unaffected by the identity of the lanthanide cation. Adduction with trivalent lanthanide metal ions is a promising tool for sequence analysis of acidic peptides by ETD. Graphical Abstract ᅟ.
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Affiliation(s)
| | - Carolyn J Cassady
- Department of Chemistry, The University of Alabama, Tuscaloosa, AL, 35487, USA.
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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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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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Asakawa D, Wada Y. Electron transfer dissociation mass spectrometry of peptides containing free cysteine using group XII metals as a charge carrier. J Phys Chem B 2014; 118:12318-25. [PMID: 25271566 DOI: 10.1021/jp502818u] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Electron transfer dissociation (ETD) has been used for peptide sequencing. Since ETD preferentially produces the c'/z(•) fragment pair, peptide sequencing is generally performed by interpretation of mass differences between series of consecutive c' and z(•) ions. However, the presence of free cysteine residues in a precursor promotes peptide bond cleavage, hindering interpretation of the ETD spectrum. In the present study, the divalent group XII metals, such as Zn(2+), Cd(2+) and Hg(2+), were used as charge carriers to produce metal-peptide complexes. The thiol group is deprotonated by complexation with the group XII metal. The formation of b and y' ions was successfully suppressed by using the zinc-peptide complex as a precursor, indicating Zn(2+)-aided ETD to be a useful method for sequencing of cysteine-containing peptides. By contrast, ETD of Cd(2+)- and Hg(2+)-peptide complexes mainly led to SH2 loss and radical cation formation, respectively. These processes were mediated by recombination energy between the metal cation and an electron. The presence of monovalent cadmium and neutral mercury in ETD products was confirmed by MS(3) analysis with collision-induced dissociation.
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Affiliation(s)
- Daiki Asakawa
- Department of Molecular Medicine, Osaka Medical Center and Research Institute for Maternal and Child Health , 840 Murodo-cho, Izumi, Osaka 594-1101, Japan
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