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Halin E, Hoyas S, Lemaur V, De Winter J, Laurent S, Connolly MD, Zuckermann RN, Cornil J, Gerbaux P. Backbone Cleavages of Protonated Peptoids upon Collision-Induced Dissociation: Competitive and Consecutive B-Y and A 1-Y X Reactions. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2019; 30:2726-2740. [PMID: 31755045 DOI: 10.1007/s13361-019-02342-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2019] [Revised: 09/11/2019] [Accepted: 09/11/2019] [Indexed: 06/10/2023]
Abstract
Mass spectrometric techniques and more particularly collision-induced dissociation (CID) experiments represent a powerful method for the determination of the primary sequence of (bio)molecules. However, the knowledge of the ion fragmentation patterns say the dissociation reaction mechanisms is a prerequisite to reconstitute the sequence based on fragment ions. Previous papers proposed that protonated peptoids dissociate following an oxazolone-ring mechanism starting from the O-protonation species and leading to high mass Y sequence ions. Here we revisit this backbone cleavage mechanism by performing CID and ion mobility experiments, together with computational chemistry, on tailor-made peptoids. We demonstrated that the B/Y cleavages of collisionally activated O-protonated peptoids must involve the amide nitrogen protonated structures as the dissociating species, mimicking the CID behavior of protonated peptides. Upon the nucleophilic attack of the oxygen atom of the N-terminal adjacent carbonyl group on the carbonyl carbon atom of the protonated amide, the peptoid ions directly dissociate to form an ion-neutral complex associating an oxazolone ion to the neutral truncated peptoid residue. Dissociation of the ion/neutral complex predominantly produces Y ions due to the high proton affinity of the secondary amide function characteristic of truncated peptoids. Whereas the production of Yx ions from acetylated peptoids also involves the B/Y pathway, the observation of abundant Yx ions from non-acetylated peptoid ions is shown in the present study to arise from an A1-Yx mechanism. The consecutive and competitive characters of the A1-Yx and the B/Y mechanisms are also investigated by drift time-aligned CID experiments.
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Affiliation(s)
- Emilie Halin
- Organic Synthesis & Mass Spectrometry Laboratory, Interdisciplinary Center for Mass Spectrometry (CISMa), Center of Innovation and Research in Materials and Polymers (CIRMAP), University of Mons - UMONS, 23 Place du Parc, 7000, Mons, Belgium
- Department of General, Organic Biomedical Chemistry, NMR and Molecular Imaging Laboratory, University of Mons - UMONS, 23 Place du Parc, 7000, Mons, Belgium
| | - Sébastien Hoyas
- Organic Synthesis & Mass Spectrometry Laboratory, Interdisciplinary Center for Mass Spectrometry (CISMa), Center of Innovation and Research in Materials and Polymers (CIRMAP), University of Mons - UMONS, 23 Place du Parc, 7000, Mons, Belgium
- Laboratory for Chemistry of Novel Materials, Center of Innovation and Research in Materials and Polymers, Research Institute for Science and Engineering of Materials, University of Mons, UMONS, 23 Place du Parc, 7000, Mons, Belgium
| | - Vincent Lemaur
- Laboratory for Chemistry of Novel Materials, Center of Innovation and Research in Materials and Polymers, Research Institute for Science and Engineering of Materials, University of Mons, UMONS, 23 Place du Parc, 7000, Mons, Belgium
| | - Julien De Winter
- Organic Synthesis & Mass Spectrometry Laboratory, Interdisciplinary Center for Mass Spectrometry (CISMa), Center of Innovation and Research in Materials and Polymers (CIRMAP), University of Mons - UMONS, 23 Place du Parc, 7000, Mons, Belgium
| | - Sophie Laurent
- Department of General, Organic Biomedical Chemistry, NMR and Molecular Imaging Laboratory, University of Mons - UMONS, 23 Place du Parc, 7000, Mons, Belgium
| | - Michael D Connolly
- Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA, 94720, USA
| | - Ronald N Zuckermann
- Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA, 94720, USA
| | - Jérôme Cornil
- Laboratory for Chemistry of Novel Materials, Center of Innovation and Research in Materials and Polymers, Research Institute for Science and Engineering of Materials, University of Mons, UMONS, 23 Place du Parc, 7000, Mons, Belgium
| | - Pascal Gerbaux
- Organic Synthesis & Mass Spectrometry Laboratory, Interdisciplinary Center for Mass Spectrometry (CISMa), Center of Innovation and Research in Materials and Polymers (CIRMAP), University of Mons - UMONS, 23 Place du Parc, 7000, Mons, Belgium.
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