1
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van Tetering L, Spies S, Wildeman QDK, Houthuijs KJ, van Outersterp RE, Martens J, Wevers RA, Wishart DS, Berden G, Oomens J. A spectroscopic test suggests that fragment ion structure annotations in MS/MS libraries are frequently incorrect. Commun Chem 2024; 7:30. [PMID: 38355930 PMCID: PMC10867025 DOI: 10.1038/s42004-024-01112-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2023] [Accepted: 01/22/2024] [Indexed: 02/16/2024] Open
Abstract
Modern untargeted mass spectrometry (MS) analyses quickly detect and resolve thousands of molecular compounds. Although features are readily annotated with a molecular formula in high-resolution small-molecule MS applications, the large majority of them remains unidentified in terms of their full molecular structure. Collision-induced dissociation tandem mass spectrometry (CID-MS2) provides a diagnostic molecular fingerprint to resolve the molecular structure through a library search. However, for de novo identifications, one must often rely on in silico generated MS2 spectra as reference. The ability of different in silico algorithms to correctly predict MS2 spectra and thus to retrieve correct molecular structures is a topic of lively debate, for instance in the CASMI contest. Underlying the predicted MS2 spectra are the in silico generated product ion structures, which are normally not used in de novo identification, but which can serve to critically assess the fragmentation algorithms. Here we evaluate in silico generated MSn product ion structures by comparison with structures established experimentally by infrared ion spectroscopy (IRIS). For a set of three dozen product ion structures from five precursor molecules, we find that virtually all fragment ion structure annotations in three major in silico MS2 libraries (HMDB, METLIN, mzCloud) are incorrect and caution the reader against their use for structure annotation of MS/MS ions.
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Affiliation(s)
- Lara van Tetering
- Radboud University, Institute for Molecules and Materials, FELIX Laboratory, Toernooiveld 7, 6525ED, Nijmegen, The Netherlands
| | - Sylvia Spies
- Radboud University, Institute for Molecules and Materials, FELIX Laboratory, Toernooiveld 7, 6525ED, Nijmegen, The Netherlands
| | - Quirine D K Wildeman
- Radboud University, Institute for Molecules and Materials, FELIX Laboratory, Toernooiveld 7, 6525ED, Nijmegen, The Netherlands
| | - Kas J Houthuijs
- Radboud University, Institute for Molecules and Materials, FELIX Laboratory, Toernooiveld 7, 6525ED, Nijmegen, The Netherlands
| | - Rianne E van Outersterp
- Radboud University, Institute for Molecules and Materials, FELIX Laboratory, Toernooiveld 7, 6525ED, Nijmegen, The Netherlands
| | - Jonathan Martens
- Radboud University, Institute for Molecules and Materials, FELIX Laboratory, Toernooiveld 7, 6525ED, Nijmegen, The Netherlands
| | - Ron A Wevers
- Department of Laboratory Medicine, Translational Metabolic Laboratory, Radboud University Medical Center, Geert Grooteplein Zuid 10, 6525GA, Nijmegen, The Netherlands
| | - David S Wishart
- Departments of Computing Science and Biological Sciences, University of Alberta, Edmonton, AB, Canada
| | - Giel Berden
- Radboud University, Institute for Molecules and Materials, FELIX Laboratory, Toernooiveld 7, 6525ED, Nijmegen, The Netherlands
| | - Jos Oomens
- Radboud University, Institute for Molecules and Materials, FELIX Laboratory, Toernooiveld 7, 6525ED, Nijmegen, The Netherlands.
- van 't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, 1098XH, Amsterdam, The Netherlands.
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2
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Mohamed A, Rana A, Perez E, Dahlmann F, Fry A, Menges FS, van Stipdonk M, Jäger S, Boyer MA, McCoy AB, Johnson MA. Characterization of the Oxazolone and Macrocyclic Motifs in the b n ( n = 2-5) Product Ions from Collision-Induced Dissociation of Protonated Oligoglycine Peptides with Isomer-Selective, Cryogenic Vibrational Spectroscopy. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2024; 35:326-332. [PMID: 38150530 DOI: 10.1021/jasms.3c00372] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2023]
Abstract
Collision-induced dissociation (CID) of small, protonated peptides leads to the formation of b-type fragment ions that can occur with several structural motifs driven by different covalent intramolecular bonding arrangements. Here, we characterize the so-called "oxazolone" and "macrocycle" bn ion structures that occur upon CID of oligoglycine peptides (Gn) ions (n = 2-6). This is determined by acquiring the vibrational band patterns of the cryogenically cooled, D2-tagged bn ions obtained using isomer-selective, two-color IR-IR photobleaching and analyzing them with predicted (DFT) harmonic spectra for the candidate structures. Both oxazolone and macrocyclic isomers are formed by b4, whereas only oxazolone species are created for b2 and b3 and the macrocycle is created for b5. As such, n = 4 corresponds to the minimum size where both Oxa and MC forms are present.
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Affiliation(s)
- Ahmed Mohamed
- Sterling Chemistry Laboratory, Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
| | - Abhijit Rana
- Sterling Chemistry Laboratory, Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
| | - Evan Perez
- Sterling Chemistry Laboratory, Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
- The University of Utah, 315 S. 1400 E. Rm 2020, Henry Eyring Bldg, Salt Lake City, Utah 84112, United States
| | - Franziska Dahlmann
- Institut for Ion Physics and Applied Physics, University of Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
| | - Allison Fry
- Center of Excellence in Mass Spectrometry, Center for Metal Ions in Biological and Chemical Systems, Department of Chemistry and Biochemistry, Duquesne University, 600 Forbes Avenue, Pittsburgh, Pennsylvania 15282, United States
| | - Fabian S Menges
- Sterling Chemistry Laboratory, Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
| | - Michael van Stipdonk
- Center of Excellence in Mass Spectrometry, Center for Metal Ions in Biological and Chemical Systems, Department of Chemistry and Biochemistry, Duquesne University, 600 Forbes Avenue, Pittsburgh, Pennsylvania 15282, United States
| | - Svenja Jäger
- Chair of Physical Chemistry II, Ruhr-University Bochum, Universitätsstraße 150, 44801 Bochum, Germany
| | - Mark A Boyer
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Anne B McCoy
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Mark A Johnson
- Sterling Chemistry Laboratory, Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
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3
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Yoshizawa K, Hirata K, Ishiuchi SI, Fujii M, Zehnacker A. Do Stereochemical Effects Overcome a Charge-Induced Perturbation in Isolated Protonated Cyclo(Tyr-Tyr)? J Phys Chem A 2022; 126:6387-6394. [PMID: 36098637 DOI: 10.1021/acs.jpca.2c03789] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Two diastereomers of the protonated diketopiperazine (DKP) dipeptide cyclo(Tyr-Tyr), namely, cyclo(LTyr-LTyr)H+ and cyclo(LTyr-DTyr)H+, are studied in a cryogenic ion trap by means of IR photodissociation spectroscopy combined with quantum chemical calculations. The two diastereomers have similar structures in which one of the rings is folded over the DKP ring and the other one is extended in a trans geometry, allowing a strong OH+···π interaction to take place. This contrasts to the observation of a stacked geometry for neutral cyclo(LTyr-LTyr) only under supersonic expansion conditions that do not exist for cyclo(LTyr-DTyr). In the protonated form, the strength of the OH+···π interaction is different for the two diastereomers, resulting in a ∼110 cm-1 difference in the ν(OH+) frequency and a smaller but clearly identifiable difference in the protonated amide ν(NH) frequency. Stereochemical effects are therefore still evidenced despite the strong perturbation due to the excess charge.
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Affiliation(s)
- Koki Yoshizawa
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259, Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan.,School of Life Science and Technology, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8503, Japan
| | - Keisuke Hirata
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259, Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan.,Department of Chemistry, School of Science, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan
| | - Shun-Ichi Ishiuchi
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259, Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan.,Department of Chemistry, School of Science, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan
| | - Masaaki Fujii
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259, Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan.,School of Life Science and Technology, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8503, Japan.,International Research Frontiers Initiative (IRFI), Institute of Innovative Research, Tokyo Institute of Technology, 4259, Nagatsuta-cho, Midori-ku, Yokohama 226-8501, Japan
| | - Anne Zehnacker
- International Research Frontiers Initiative (IRFI), Institute of Innovative Research, Tokyo Institute of Technology, 4259, Nagatsuta-cho, Midori-ku, Yokohama 226-8501, Japan.,Institut des Sciences Moléculaires d'Orsay (ISMO), CNRS, Université Paris-Saclay, Orsay F-91405, France
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4
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Le Barbu-Debus K, Pérez-Mellor A, Lepère V, Zehnacker A. How change in chirality prevents β-amyloid type interaction in a protonated cyclic dipeptide dimer. Phys Chem Chem Phys 2022; 24:19783-19791. [PMID: 35969161 DOI: 10.1039/d2cp03110h] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The protonated dimers of the diketopiperazine dipeptide cyclo (LPhe-LHis) and cyclo (LPhe-DHis) are studied by laser spectroscopy combined with mass spectrometry to shed light on the influence of stereochemistry on the clustering propensity of cyclic dipeptides. The marked spectroscopic differences experimentally observed in the hydride stretch region are well accounted for by the results of DFT calculations. Both diastereomeric protonated dimers involve a strong ionic hydrogen bond from the protonated imidazole ring of one monomer to the neutral imidazole nitrogen of the other. While this strong interaction is accompanied by a single NH⋯O hydrogen bond between the amide functions of the two moieties for the protonated dimer of cyclo (LPhe-DHis), that of cyclo (LPhe-LHis) involves two NH⋯O interactions, forming the motif of an antiparallel β sheet. Therefore, a change in chirality of the residue prevents the formation of the β sheet pattern observed in the amyloid type aggregation. These results emphasize the peculiar role of the histidine residue in peptide structure and interaction.
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Affiliation(s)
- Katia Le Barbu-Debus
- Institut des Sciences Moléculaires d'Orsay (ISMO), CNRS, Université Paris-Saclay, F-91405 Orsay, France.
| | - Ariel Pérez-Mellor
- Institut des Sciences Moléculaires d'Orsay (ISMO), CNRS, Université Paris-Saclay, F-91405 Orsay, France.
| | - Valéria Lepère
- Institut des Sciences Moléculaires d'Orsay (ISMO), CNRS, Université Paris-Saclay, F-91405 Orsay, France.
| | - Anne Zehnacker
- Institut des Sciences Moléculaires d'Orsay (ISMO), CNRS, Université Paris-Saclay, F-91405 Orsay, France.
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5
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Zhang ZC, Hales DA, Clemmer DE. Influence of N Terminus Amino Acid on Peptide Cleavage in Solution through Diketopiperazine Formation. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2022; 33:1368-1376. [PMID: 35576623 PMCID: PMC10161955 DOI: 10.1021/jasms.2c00037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Diketopiperazine (DKP) formation is an important degradation pathway for peptides and proteins. It can occur during synthesis and storage in either solution or the solid state. The kinetics of peptide cleavage through DKP formation have been analyzed for the model peptides Xaa1-Pro2-Gly4-Lys7 [Xaa = Gln, Glu, Lys, Ser, Phe, Trp, Tyr, Cha (β-cyclohexylalanine), Aib (α-aminoisobutyric acid), Gly, and Val] at multiple elevated temperatures in ethanol with ion mobility spectrometry-mass spectrometry (IMS-MS). When Xaa is an amino acid with a charged or polar side chain, degradation is relatively fast. When Xaa is an amino acid with a nonpolar alkyl side chain, the peptide is relatively stable. For these peptides, a bulky group on the α carbon speeds up dissociation, but the kinetic effects vary in a complicated manner for bulky groups on the β or γ carbon. Peptides where Xaa has a nonpolar aromatic side chain show moderate dissociation rates. The stability of these peptides is a result of multiple factors. The reaction rate is enhanced by (1) the stabilization of the late transition state through the interaction of an aromatic ring with the nascent DKP ring or lowering the activation energy of nucleophilic attack intermediate state through polar or charged residues and (2) the preference of the cis proline bond favored by the aromatic N-terminus. The number of unseen intermediates and transition state thermodynamic values are derived for each peptide by modeling the kinetics data. Most of the transition states are entropically favored (ΔS⧧ ∼ -5 to +31 J·mol-1·K-1), and all are enthalpically disfavored (ΔH⧧ ∼ 93 to 109 kJ·mol-1). The Gibbs free energy of activation is similar for all of the peptides studied here (ΔG⧧ ∼ 90-99 kJ·mol-1).
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Affiliation(s)
- Zhi-Chao Zhang
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405, United States
| | - David A Hales
- Department of Chemistry, Hendrix College, Conway, Arkansas 72032, United States
| | - David E Clemmer
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405, United States
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6
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Abstract
Protonated cyclic dipeptides undergo collision-induced dissociation, and this reaction mechanism strongly depends on the symmetry and the nature of the residues. We review the main dissociation mechanism for a series of cyclic dipeptides, obtained through chemical dynamics simulations. The systems range from the symmetrical cyclo-(glycyl-glycyl), with two possible symmetrical protonation sites located on the peptide ring, to cyclo-(tyrosyl-prolyl), where the symmetry of protonation sites on the peptide ring is broken by the dissimilar nature of the different residues. Finally, cyclo-(phenylalanyl-histidyl) shows a completely asymmetric situation, with the proton located on one of the dipeptide side chains, which explains the peculiar fragmentation mechanism induced by shuttling the proton, whose efficiency is strongly dependent on the relative chirality of the residues.
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7
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Lau JKC, Esuon F, Berden G, Oomens J, Hopkinson AC, Ryzhov V, Siu KWM. Generation, Characterization, and Dissociation of Radical Cations Derived from Prolyl-glycyl-glycine. J Phys Chem B 2021; 125:6121-6129. [PMID: 34097420 DOI: 10.1021/acs.jpcb.1c01732] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Radical cations of an aliphatic tripeptide prolyl-glycyl-glycine (PGG•+) and its sequence ions [a3 + H]•+ and [b2 - H]•+ have been generated by collision-induced dissociation of the [Cu(Phen)(PGG)]•2+ complex, where Phen = 1,10-phenanthroline. Infrared multiple photon dissociation spectroscopy, ion-molecule reaction experiments, and theoretical calculations have been used to investigate the structures of these ions. The unpaired electron in these three radical cations is located at different α-carbons. The PGG•+ radical cation has a captodative structure with the radical at the α-carbon of the proline residue and the proton on the oxygen of the first amide group. This structure is at the global minimum on the potential energy surface (PES). By contrast, the [a3 + H]•+ and [b2 - H]•+ ions are not the lowest-energy structures on their respective PESs, and their radicals are formally located at the C-terminal and second α-carbons, respectively. Density functional theory calculations on the structures of the ternary copper(II) complex ion suggest that the charge-solvated isomer of the metal complex is the precursor ion that dissociates to give the PGG•+ radical cation. The isomer of the complex in which PGG is bound as a zwitterion dissociates to give the [a3 + H]•+ and [b2 - H]•+ ions.
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Affiliation(s)
- Justin Kai-Chi Lau
- Department of Chemistry and Centre for Research in Mass Spectrometry, York University, 4700 Keele Street, Toronto, Ontario M3J 1P3, Canada.,Department of Chemistry and Biochemistry, University of Windsor, 401 Sunset Avenue, Windsor, Ontario N9B 3P4, Canada
| | - Francis Esuon
- Department of Chemistry and Biochemistry, Northern Illinois University, DeKalb, Illinois 60115, United States
| | - Giel Berden
- FELIX Laboratory, Institute for Molecules and Materials, Radboud University, Toernooiveld 7, Nijmegen 6525 ED, the Netherlands
| | - Jos Oomens
- FELIX Laboratory, Institute for Molecules and Materials, Radboud University, Toernooiveld 7, Nijmegen 6525 ED, the Netherlands
| | - Alan C Hopkinson
- Department of Chemistry and Centre for Research in Mass Spectrometry, York University, 4700 Keele Street, Toronto, Ontario M3J 1P3, Canada
| | - Victor Ryzhov
- Department of Chemistry and Biochemistry, Northern Illinois University, DeKalb, Illinois 60115, United States
| | - K W Michael Siu
- Department of Chemistry and Centre for Research in Mass Spectrometry, York University, 4700 Keele Street, Toronto, Ontario M3J 1P3, Canada.,Department of Chemistry and Biochemistry, University of Windsor, 401 Sunset Avenue, Windsor, Ontario N9B 3P4, Canada
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8
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Guan S, Bythell BJ. Size Dependent Fragmentation Chemistry of Short Doubly Protonated Tryptic Peptides. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2021; 32:1020-1032. [PMID: 33779179 DOI: 10.1021/jasms.1c00009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Tandem mass spectrometry of electrospray ionized multiply charged peptide ions is commonly used to identify the sequence of peptide(s) and infer the identity of source protein(s). Doubly protonated peptide ions are consistently the most efficiently sequenced ions following collision-induced dissociation of peptides generated by tryptic digestion. While the broad characteristics of longer (N ≥ 8 residue) doubly protonated peptides have been investigated, there is comparatively little data on shorter systems where charge repulsion should exhibit the greatest influence on the dissociation chemistry. To address this gap and further understand the chemistry underlying collisional-dissociation of doubly charged tryptic peptides, two series of analytes ([GxR+2H]2+ and [AxR+2H]2+, x = 2-5) were investigated experimentally and with theory. We find distinct differences in the preference of bond cleavage sites for these peptides as a function of size and to a lesser extent composition. Density functional calculations at two levels of theory predict that the threshold relative energies required for bond cleavages at the same site for peptides of different size are quite similar (for example, b2-yN-2). In isolation, this finding is inconsistent with experiment. However, the predicted extent of entropy change of these reactions is size dependent. Subsequent RRKM rate constant calculations provide a far clearer picture of the kinetics of the competing bond cleavage reactions enabling rationalization of experimental findings. The M06-2X data were substantially more consistent with experiment than were the B3LYP data.
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Affiliation(s)
- Shanshan Guan
- Department of Chemistry and Biochemistry, Ohio University, 307 Chemistry Building, Athens, Ohio 45701, United States
- Department of Chemistry and Biochemistry, University of Missouri-St. Louis, 1 University Boulevard, St. Louis, Missouri 63121, United States
| | - Benjamin J Bythell
- Department of Chemistry and Biochemistry, Ohio University, 307 Chemistry Building, Athens, Ohio 45701, United States
- Department of Chemistry and Biochemistry, University of Missouri-St. Louis, 1 University Boulevard, St. Louis, Missouri 63121, United States
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9
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Boles GC, Kempkes LJM, Martens J, Berden G, Oomens J, Armentrout PB. Influence of a Hydroxyl Group on the Deamidation and Dehydration Reactions of Protonated Asparagine-Serine Investigated by Combined Spectroscopic, Guided Ion Beam, and Theoretical Approaches. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2021; 32:786-805. [PMID: 33570934 DOI: 10.1021/jasms.0c00468] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Deamidation of asparaginyl (Asn) peptides is a spontaneous post-translational modification that plays a significant role in degenerative diseases and other biological processes under physiological conditions. In the gas phase, deamidation of protonated peptides is a major fragmentation channel upon activation by collision-induced dissociation. Here, we present a full description of the deamidation process from protonated asparagine-serine, [AsnSer+H]+, via infrared (IR) action spectroscopy and threshold collision-induced dissociation (TCID) experiments in combination with theoretical calculations. The IR results demonstrate that deamidation proceeds via bifurcating reaction pathways leading to furanone- and succinimide-type product ion structures, with a population analysis indicating the latter product dominates. Theory demonstrates that nucleophilic attack of the peptidyl amide oxygen onto the Asn side chain leads to furanone formation, whereas nucleophilic attack by the peptidyl amide nitrogen onto the Asn side-chain carbonyl carbon leads to the formation of the succinimide product structure. TCID experiments find that furanone formation has a threshold energy of 145 ± 12 kJ/mol and succinimide formation occurs with a threshold energy of 131 ± 12 kJ/mol, consistent with theoretical energies and with the spectroscopic results indicating that succinimide dominates. The results provide information regarding the inductive and steric effects of the Ser side chain on the deamidation process. The other major channel observed in the TCID experiments of [AsnSer+H]+ is dehydration, where a threshold energy of 104 ± 10 kJ/mol is determined. A complete IR and theoretical analysis of this pathway is also provided. As for deamidation, a bifurcating pathway is found with both dominant oxazoline and minor diketopiperazine products identified. Here, the Ser side chain is directly involved in both pathways.
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Affiliation(s)
- Georgia C Boles
- Department of Chemistry, University of Utah, 315 South 1400 East, Room 2020, Salt Lake City, Utah 84112, United States
| | - Lisanne J M Kempkes
- Radboud University, Institute for Molecules and Materials, FELIX Laboratory, Toernooiveld 7, 6525 ED Nijmegen, The Netherlands
| | - Jonathan Martens
- Radboud University, Institute for Molecules and Materials, FELIX Laboratory, Toernooiveld 7, 6525 ED Nijmegen, The Netherlands
| | - Giel Berden
- Radboud University, Institute for Molecules and Materials, FELIX Laboratory, Toernooiveld 7, 6525 ED Nijmegen, The Netherlands
| | - Jos Oomens
- Radboud University, Institute for Molecules and Materials, FELIX Laboratory, 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
| | - P B Armentrout
- Department of Chemistry, University of Utah, 315 South 1400 East, Room 2020, Salt Lake City, Utah 84112, United States
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10
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Wang J, Wang C, Zhang H, Liu Y, Shi T. Mass spectral and theoretical investigations of the transient proton-bound dimers on the cleavage processes of the peptide GHK and its analogues. RSC Adv 2021; 11:4077-4086. [PMID: 35424374 PMCID: PMC8694339 DOI: 10.1039/d0ra07600g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Accepted: 01/14/2021] [Indexed: 11/21/2022] Open
Abstract
Fragmentation mechanisms of the singly protonated peptides GHK, GHKH and HGHK have been investigated by mass spectrometry and theoretical calculations. Fragmentation behavior of the protonated H-K amide bond in GHK was changed completely when a histidinyl residue was introduced into the C-terminus of GHK. The H-K amide bond breaking was a predominant pathway in the case of GHK and GHKH. For HGHK, the histidinyl residue at the N-terminus hampered significantly breaking of the H-K amide bond resulting in a high potential energy barrier; calculations indicated that this histidinyl effect played a vital role for the H-K amide bond fragmentation. Subsequent analysis of the fragmentation mechanism revealed that recombination processes of the hydrogen bonding for the intermediate products were all exergonic. Formation of a proton-bound dimer (PBD) lowering the energy barriers from a thermodynamic perspective for all the designed fragmentation pathways was demonstrated to be feasible by our systematic calculations. Moreover, the involvement of different PBDs was further confirmed by analyses of the reduced density gradient (RDG) isosurfaces and scatter maps. A dynamically favored pathway was likely via six-membered ring or nine-membered ring structures generated by the diketopiperazine as revealed by atom-in-molecules (AIM) analyses, since the steric interaction energies in the newly formed ring were estimated to be relatively small when compared to the products generated from a lactam and/or an oxazolone pathway. This is the first feasibility investigation from a dynamic viewpoint for formation of different rings involved in the lactam, oxazolone or diketopiperazine pathways in the fragmentation mechanisms proposed.
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Affiliation(s)
- Jinhu Wang
- College of Chemistry, Chemical Engineering and Materials Science, Zaozhuang University Zaozhuang 277160 Shandong Province P. R. China
| | - Cheng Wang
- Department of Traditional Chinese Medicine, Zaozhuang Municipal Hospital Zaozhuang 277102 Shandong Province P. R. China
| | - Han Zhang
- College of Chemistry, Chemical Engineering and Materials Science, Zaozhuang University Zaozhuang 277160 Shandong Province P. R. China
| | - Yang Liu
- College of Chemistry, Chemical Engineering and Materials Science, Zaozhuang University Zaozhuang 277160 Shandong Province P. R. China
| | - Tiesheng Shi
- College of Chemistry, Chemical Engineering and Materials Science, Zaozhuang University Zaozhuang 277160 Shandong Province P. R. China
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11
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Oomens J, Kempkes LJM, Geurts TPJ, van Dijk L, Martens J, Berden G, Armentrout PB. Water Loss from Protonated XxxSer and XxxThr Dipeptides Gives Oxazoline-Not Oxazolone-Product Ions. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2020; 31:2111-2123. [PMID: 32876444 PMCID: PMC7552115 DOI: 10.1021/jasms.0c00239] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Revised: 08/31/2020] [Accepted: 09/02/2020] [Indexed: 06/11/2023]
Abstract
Neutral loss of water and ammonia are often significant fragmentation channels upon collisional activation of protonated peptides. Here, we deploy infrared ion spectroscopy to investigate the dehydration reactions of protonated AlaSer, AlaThr, GlySer, GlyThr, PheSer, PheThr, ProSer, ProThr, AsnSer, and AsnThr, focusing on the question of the structure of the resulting [M + H - H2O]+ fragment ion and the site from which H2O is expelled. In all cases, the second residue of the selected peptides contains a hydroxyl moiety, so that H2O loss can potentially occur from this side-chain, as an alternative to loss from the C-terminal free acid of the dipeptide. Infrared action spectra of the product ions along with quantum-chemical calculations unambiguously show that dehydration consistently produces fragment ions containing an oxazoline moiety. This contrasts with the common oxazolone structure that would result from dehydration at the C-terminus analogous to the common b/y dissociation forming regular b2-type sequence ions. The oxazoline product structure suggests a reaction mechanism involving water loss from the Ser/Thr side-chain with concomitant nucleophilic attack of the amide carbonyl oxygen at its β-carbon, forming an oxazoline ring. However, an extensive quantum-chemical investigation comparing the potential energy surfaces for three entirely different dehydration reaction pathways indicates that it is actually the backbone amide oxygen atom that leaves as the water molecule.
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Affiliation(s)
- Jos Oomens
- FELIX Laboratory, Institute of 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
| | - Lisanne J. M. Kempkes
- FELIX Laboratory, Institute of Molecules and
Materials, Radboud University, Toernooiveld 7, 6525 ED
Nijmegen, The Netherlands
| | - Thijs P. J. Geurts
- FELIX Laboratory, Institute of Molecules and
Materials, Radboud University, Toernooiveld 7, 6525 ED
Nijmegen, The Netherlands
| | - Luuk van Dijk
- FELIX Laboratory, Institute of Molecules and
Materials, Radboud University, Toernooiveld 7, 6525 ED
Nijmegen, The Netherlands
| | - Jonathan Martens
- FELIX Laboratory, Institute of Molecules and
Materials, Radboud University, Toernooiveld 7, 6525 ED
Nijmegen, The Netherlands
| | - Giel Berden
- FELIX Laboratory, Institute of Molecules and
Materials, Radboud University, Toernooiveld 7, 6525 ED
Nijmegen, The Netherlands
| | - P. B. Armentrout
- Department of Chemistry, University of
Utah, 315 South 1400 East, Room 2020, Salt Lake City, Utah 84112,
United States
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12
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Thermal dissociation of the singly protonated Arginine: Competition between side-chain and backbone fragmentation. Chem Phys 2020. [DOI: 10.1016/j.chemphys.2020.110890] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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13
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Cautereels J, Giribaldi J, Enjalbal C, Blockhuys F. Quantum chemical mass spectrometry: Ab initio study of b 2 -ion formation mechanisms for the singly protonated Gln-His-Ser tripeptide. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2020; 34:e8778. [PMID: 32144813 DOI: 10.1002/rcm.8778] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Revised: 02/28/2020] [Accepted: 03/05/2020] [Indexed: 06/10/2023]
Abstract
RATIONALE Both amide bond protonation triggering peptide fragmentations and the controversial b2 -ion structures have been subjects of intense research. The involvement of histidine (H), with its imidazole side chain that induces specific dissociation patterns involving inter-side-chain (ISC) interactions, in b2 -ion formation was investigated, focusing on the QHS model tripeptide. METHODS To identify the effect of histidine on fragmentations issued from ISC interactions, QHS was selected for a comprehensive analysis of the pathways leading to the three possible b2 -ion structures, using quantum chemical calculations performed at the DFT/B3LYP/6-311+G* level of theory. Electrospray ionization ion trap mass spectrometry allowed the recording of MS2 and MS3 tandem mass spectra, whereas the Quantum Chemical Mass Spectrometry for Materials Science (QCMS2 ) method was used to predict fragmentation patterns. RESULTS Whereas it is very difficult to differentiate among protonated oxazolone, diketopiperazine, or lactam b2 -ions using MS2 and MS3 mass spectra, the calculations indicated that the QH b2 -ion (detected at m/z 266) is probably a mixture of the lactam and oxazolone structures formed after amide nitrogen protonation, making the formation of diketopiperazine less likely as it requires an additional step for its formation. CONCLUSIONS In contrast to glycine-histidine-containing b2 -ions, known to be issued from the backbone-imidazole cyclization, we found that interactions between the side chains were not obvious to perceive, neither from a thermodynamics nor from a fragmentation perspective, emphasizing the importance of the whole sequence on the dissociation behavior usually demonstrated from simple glycine-containing tripeptides.
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Affiliation(s)
- Julie Cautereels
- Department of Chemistry, University of Antwerp, Antwerp, Belgium
| | | | | | - Frank Blockhuys
- Department of Chemistry, University of Antwerp, Antwerp, Belgium
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14
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Smith ZM, Wang X, Scheerer JR, Martens J, Berden G, Oomens J, Steinmetz V, Somogyi A, Wysocki V, Poutsma JC. Spectroscopic Evidence for Lactam Formation in Terminal Ornithine b 2+ and b 3+ Fragment Ions. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2019; 30:1565-1577. [PMID: 31183839 PMCID: PMC6697629 DOI: 10.1007/s13361-019-02244-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Revised: 04/24/2019] [Accepted: 04/26/2019] [Indexed: 06/09/2023]
Abstract
Infrared multiple photon dissociation action spectroscopy was performed on the AlaOrn b2+ and AlaAlaOrn b3+ fragment ions from ornithine-containing tetrapeptides. Infrared spectra were obtained in the fingerprint region (1000-2000 cm-1) using the infrared free electron lasers at the Centre Laser Infrarouge d'Orsay (CLIO) facility in Orsay, France, and the free electron lasers for infrared experiments (FELIX) facility in Nijmegen, the Netherlands. A novel terminal ornithine lactam AO+ b2+ structure was synthesized for experimental comparison and spectroscopy confirms that the b2+ fragment ion from AOAA forms a lactam structure. Comparison of experimental spectra with scaled harmonic frequencies at the B3LYP/6-31+G(d,p) level of theory shows that AO+ b2+ forms a terminal lactam protonated either on the lactam carbonyl oxygen or the N-terminal nitrogen atom. Several low-lying conformers of these isomers are likely populated following IRMPD dissociation. Similarly, a comparison of the experimental IRMPD spectrum with calculated spectra shows that AAO+ b3+-ions also adopt a lactam structure, again with multiple different protonation sites, during fragmentation. This study provides spectroscopic confirmation for the lactam cyclization proposed for the "ornithine effect" and represents an alternative bn+ structure to the oxazolone and diketopiperazine/macrocycle structures most often formed.
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Affiliation(s)
- Zachary M Smith
- Department of Chemistry, The College of William & Mary, Williamsburg, VA, 23187-8795, USA
| | - Xiye Wang
- Department of Chemistry, The College of William & Mary, Williamsburg, VA, 23187-8795, USA
| | - Jonathan R Scheerer
- Department of Chemistry, The College of William & Mary, Williamsburg, VA, 23187-8795, USA
| | - Jonathan Martens
- Institute for Molecules and Materials, FELIX Laboratory, Radboud University, Nijmegen, The Netherlands
| | - Giel Berden
- Institute for Molecules and Materials, FELIX Laboratory, Radboud University, Nijmegen, The Netherlands
| | - Jos Oomens
- Institute for Molecules and Materials, FELIX Laboratory, Radboud University, Nijmegen, The Netherlands
| | - Vincent Steinmetz
- Laboratorie de Chimie Physique, CNRS UMR 8000, Université Paris, 91405, Orsay, France
| | - Arpad Somogyi
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, 43210-1173, USA
| | - Vicki Wysocki
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, 43210-1173, USA
| | - John C Poutsma
- Department of Chemistry, The College of William & Mary, Williamsburg, VA, 23187-8795, USA.
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15
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Martin-Somer A, Martens J, Grzetic J, Hase WL, Oomens J, Spezia R. Unimolecular Fragmentation of Deprotonated Diproline [Pro2-H]− Studied by Chemical Dynamics Simulations and IRMPD Spectroscopy. J Phys Chem A 2018; 122:2612-2625. [DOI: 10.1021/acs.jpca.7b11873] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Ana Martin-Somer
- Laboratoire Analyse et Modélisation pour la Biologie et l’Environnement, CEA-CNRS, Université Paris Saclay, Evry 91025, France
- Departamento de Química, Facultad de Ciencias, Módulo
13, Universidad Autónoma de Madrid, Campus de Excelencia UAM-CSIC, Cantoblanco, 28049 Madrid, Spain
| | - 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
| | - William L. Hase
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409, United States
| | - 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
| | - Riccardo Spezia
- Laboratoire Analyse et Modélisation pour la Biologie et l’Environnement, CEA-CNRS, Université Paris Saclay, Evry 91025, France
- Laboratoire de Chimie Théorique, LCT, Sorbonne Université, CNRS, F. 75005 Paris, France
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16
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Bythell BJ. Comment on: "Quantum Chemical Mass Spectrometry: Verification and Extension of the Mobile Proton Model for Histidine" by Julie Cautereels and Frank Blockhuys, J. Am. Soc. Mass Spectrom. 28, 1227-1235 (2017). JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2017; 28:2728-2730. [PMID: 28952060 DOI: 10.1007/s13361-017-1804-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Affiliation(s)
- Benjamin J Bythell
- Department of Chemistry and Biochemistry, University of Missouri-St. Louis, St. Louis, MO, 63121, USA.
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17
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Alata I, Pérez-Mellor A, Ben Nasr F, Scuderi D, Steinmetz V, Gobert F, Jaïdane NE, Zehnacker-Rentien A. Does the Residues Chirality Modify the Conformation of a Cyclo-Dipeptide? Vibrational Spectroscopy of Protonated Cyclo-diphenylalanine in the Gas Phase. J Phys Chem A 2017; 121:7130-7138. [DOI: 10.1021/acs.jpca.7b06159] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Ivan Alata
- Institut
des Sciences Moléculaires d’Orsay, CNRS, Univ. Paris-Sud, Université Paris-Saclay, F-91405 Orsay, France
| | - Ariel Pérez-Mellor
- Institut
des Sciences Moléculaires d’Orsay, CNRS, Univ. Paris-Sud, Université Paris-Saclay, F-91405 Orsay, France
| | - Feriel Ben Nasr
- Institut
des Sciences Moléculaires d’Orsay, CNRS, Univ. Paris-Sud, Université Paris-Saclay, F-91405 Orsay, France
- Laboratoire
de Spectroscopie Atomique Moléculaire et Applications, Université de Tunis El Manar, Tunis 1060, Tunisia
| | - Debora Scuderi
- Laboratoire
de Chimie Physique, CNRS, UMR8000, Univ. Paris-Sud, Orsay F-91405, France
| | - Vincent Steinmetz
- Laboratoire
de Chimie Physique, CNRS, UMR8000, Univ. Paris-Sud, Orsay F-91405, France
| | - Fabrice Gobert
- Laboratoire
de Chimie Physique, CNRS, UMR8000, Univ. Paris-Sud, Orsay F-91405, France
| | - Nejm-Eddine Jaïdane
- Laboratoire
de Spectroscopie Atomique Moléculaire et Applications, Université de Tunis El Manar, Tunis 1060, Tunisia
| | - Anne Zehnacker-Rentien
- Institut
des Sciences Moléculaires d’Orsay, CNRS, Univ. Paris-Sud, Université Paris-Saclay, F-91405 Orsay, France
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18
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Koirala D, Mistry S, Wenthold PG. Participation of C-H Protons in the Dissociation of a Proton Deficient Dipeptide. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2017; 28:1313-1323. [PMID: 28429299 DOI: 10.1007/s13361-017-1662-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Revised: 03/13/2017] [Accepted: 03/14/2017] [Indexed: 06/07/2023]
Abstract
The dissociation of anionic dipeptides Phe*Gly and GlyPhe*, where Phe* refers to sulfonated phenyl alanine, has been investigated by using ion trap mass spectrometry. The dipeptides undergo collision-induced dissociation (CID) to give the same products, indicating that they rearrange to a common structure before dissociation. The rearrangement does not occur with the dipeptide methyl esters. The structures of the b2 ions were investigated to determine the effect that having a remote, anionic site has on product formation. Comparison with the CID spectra for authentic structures shows that the b2 ion obtained from GlyPhe* has predominantly a diketopiperazine structure. The CID spectra for the Phe*Gly b2 ion and the authentic oxazolone are similar, but differences in intensity suggest a two-component mixture. Isotopic labeling studies are consistent with the formation of two products, with one resulting from loss of a non-mobile proton on the Gly α-carbon. The results are attributed to the formation of an oxazole and oxazolone enol product. Electronic structure calculations predict that the enol structure of the Phe*Gly b2 ion is lower in energy than the keto version due to intramolecular hydrogen bonding with the sulfonate group. Graphical Abstract ᅟ.
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Affiliation(s)
- Damodar Koirala
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, IN, 47906, USA
| | - Sabyasachy Mistry
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, IN, 47906, USA
| | - Paul G Wenthold
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, IN, 47906, USA.
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19
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Molecular identification in metabolomics using infrared ion spectroscopy. Sci Rep 2017; 7:3363. [PMID: 28611404 PMCID: PMC5469762 DOI: 10.1038/s41598-017-03387-4] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2017] [Accepted: 04/27/2017] [Indexed: 11/25/2022] Open
Abstract
Small molecule identification is a continually expanding field of research and represents the core challenge in various areas of (bio)analytical science, including metabolomics. Here, we unequivocally differentiate enantiomeric N-acetylhexosamines in body fluids using infrared ion spectroscopy, providing orthogonal identification of molecular structure unavailable by standard liquid chromatography/high-resolution tandem mass spectrometry. These results illustrate the potential of infrared ion spectroscopy for the identification of small molecules from complex mixtures.
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20
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Kempkes LJM, Martens J, Grzetic J, Berden G, Oomens J. Deamidation Reactions of Asparagine- and Glutamine-Containing Dipeptides Investigated by Ion Spectroscopy. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2016; 27:1855-1869. [PMID: 27624159 PMCID: PMC5059420 DOI: 10.1007/s13361-016-1462-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Revised: 07/21/2016] [Accepted: 07/22/2016] [Indexed: 05/27/2023]
Abstract
Deamidation is a major fragmentation channel upon activation by collision induced dissociation (CID) for protonated peptides containing glutamine (Gln) and asparagine (Asn) residues. Here, we investigate these NH3-loss reactions for four Asn- and Gln-containing protonated peptides in terms of the resulting product ion structures using infrared ion spectroscopy with the free electron laser FELIX. The influence of the side chain length (Asn versus Gln) and of the amino acid sequence on the deamidation reaction has been examined. Molecular structures for the product ions are determined by comparison of experimental IR spectra with spectra predicted by density functional theory (DFT). The reaction mechanisms identified for the four dipeptides AlaAsn, AsnAla, AlaGln, and GlnAla are not the same. For all four dipeptides, primary deamidation takes place from the amide side chain (and not from the N-terminus) and, in most cases, resembles the mechanisms previously identified for the protonated amino acids asparagine and glutamine. Secondary fragmentation reactions of the deamidation products have also been characterized and provide further insight in - and confirmation of - the identified mechanisms. Overall, this study provides a comprehensive molecular structure map of the deamidation chemistry of this series of dipeptides. Graphical Abstract ᅟ.
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Affiliation(s)
- Lisanne J M Kempkes
- FELIX Laboratory, Institute for Molecules and Materials, Radboud University, Toernooiveld 7c, 6525 ED, Nijmegen, The Netherlands
| | - Jonathan Martens
- FELIX Laboratory, Institute for Molecules and Materials, Radboud University, Toernooiveld 7c, 6525 ED, Nijmegen, The Netherlands
| | - Josipa Grzetic
- FELIX Laboratory, Institute for Molecules and Materials, Radboud University, Toernooiveld 7c, 6525 ED, Nijmegen, The Netherlands
| | - Giel Berden
- FELIX Laboratory, Institute for Molecules and Materials, Radboud University, Toernooiveld 7c, 6525 ED, Nijmegen, The Netherlands
| | - Jos Oomens
- FELIX Laboratory, Institute for Molecules and Materials, Radboud University, Toernooiveld 7c, 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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21
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Homayoon Z, Pratihar S, Dratz E, Snider R, Spezia R, Barnes GL, Macaluso V, Martin Somer A, Hase WL. Model Simulations of the Thermal Dissociation of the TIK(H+)2 Tripeptide: Mechanisms and Kinetic Parameters. J Phys Chem A 2016; 120:8211-8227. [DOI: 10.1021/acs.jpca.6b05884] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Zahra Homayoon
- Department
of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409-1061, United States
| | - Subha Pratihar
- Department
of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409-1061, United States
| | | | | | - Riccardo Spezia
- Laboratoire
Analyse et Modélisation pour la Biologie et l’Environnement, Université d’Evry Val d’Essonne UMR 8587 CNRS-CEA-UEVE, Bd. F. Mitterrand, 91025 Evry Cedex, France
| | - George L. Barnes
- Department
of Chemistry and Biochemistry, Siena College, Loudonville, New York 12211, United States
| | - Veronica Macaluso
- Laboratoire
Analyse et Modélisation pour la Biologie et l’Environnement, Université d’Evry Val d’Essonne UMR 8587 CNRS-CEA-UEVE, Bd. F. Mitterrand, 91025 Evry Cedex, France
| | - Ana Martin Somer
- Laboratoire
Analyse et Modélisation pour la Biologie et l’Environnement, Université d’Evry Val d’Essonne UMR 8587 CNRS-CEA-UEVE, Bd. F. Mitterrand, 91025 Evry Cedex, France
| | - William L. Hase
- Department
of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409-1061, United States
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22
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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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23
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Cismesia AP, Bailey LS, Bell MR, Tesler LF, Polfer NC. Making Mass Spectrometry See the Light: The Promises and Challenges of Cryogenic Infrared Ion Spectroscopy as a Bioanalytical Technique. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2016; 27:757-66. [PMID: 26975370 PMCID: PMC4841727 DOI: 10.1007/s13361-016-1366-4] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Revised: 02/11/2016] [Accepted: 02/12/2016] [Indexed: 05/31/2023]
Abstract
The detailed chemical information contained in the vibrational spectrum of a cryogenically cooled analyte ion would, in principle, make infrared (IR) ion spectroscopy a gold standard technique for molecular identification in mass spectrometry. Despite this immense potential, there are considerable challenges in both instrumentation and methodology to overcome before the technique is analytically useful. Here, we discuss the promise of IR ion spectroscopy for small molecule analysis in the context of metabolite identification. Experimental strategies to address sensitivity constraints, poor overall duty cycle, and speed of the experiment are intimately tied to the development of a mass-selective cryogenic trap. Therefore, the most likely avenues for success, in the authors' opinion, are presented here, alongside alternative approaches and some thoughts on data interpretation.
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Affiliation(s)
- Adam P Cismesia
- Department of Chemistry, University of Florida, P.O. Box 117200, Gainesville, FL, 32611-7200, USA
| | - Laura S Bailey
- Department of Chemistry, University of Florida, P.O. Box 117200, Gainesville, FL, 32611-7200, USA
| | - Matthew R Bell
- Department of Chemistry, University of Florida, P.O. Box 117200, Gainesville, FL, 32611-7200, USA
| | - Larry F Tesler
- Department of Chemistry, University of Florida, P.O. Box 117200, Gainesville, FL, 32611-7200, USA
| | - Nicolas C Polfer
- Department of Chemistry, University of Florida, P.O. Box 117200, Gainesville, FL, 32611-7200, USA.
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24
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Nelson CR, Abutokaikah MT, Harrison AG, Bythell BJ. Proton Mobility in b₂ Ion Formation and Fragmentation Reactions of Histidine-Containing Peptides. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2016; 27:487-497. [PMID: 26602904 DOI: 10.1007/s13361-015-1298-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Revised: 10/13/2015] [Accepted: 10/19/2015] [Indexed: 06/05/2023]
Abstract
A detailed energy-resolved study of the fragmentation reactions of protonated histidine-containing peptides and their b2 ions has been undertaken. Density functional theory calculations were utilized to predict how the fragmentation reactions occur so that we might discern why the mass spectra demonstrated particular energy dependencies. We compare our results to the current literature and to synthetic b2 ion standards. We show that the position of the His residue does affect the identity of the subsequent b2 ion (diketopiperazine versus oxazolone versus lactam) and that energy-resolved CID can distinguish these isomeric products based on their fragmentation energetics. The histidine side chain facilitates every major transformation except trans-cis isomerization of the first amide bond, a necessary prerequisite to diketopiperazine b2 ion formation. Despite this lack of catalyzation, trans-cis isomerization is predicted to be facile. Concomitantly, the subsequent amide bond cleavage reaction is rate-limiting.
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Affiliation(s)
- Carissa R Nelson
- Department of Chemistry and Biochemistry, University of Missouri, St. Louis, MO, 63121, USA
| | - Maha T Abutokaikah
- Department of Chemistry and Biochemistry, University of Missouri, St. Louis, MO, 63121, USA
| | - Alex G Harrison
- Department of Chemistry, University of Toronto, Toronto, ON, M5S 1A1, Canada
| | - Benjamin J Bythell
- Department of Chemistry and Biochemistry, University of Missouri, St. Louis, MO, 63121, USA.
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25
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Aseev O, Perez MAS, Rothlisberger U, Rizzo TR. Cryogenic Spectroscopy and Quantum Molecular Dynamics Determine the Structure of Cyclic Intermediates Involved in Peptide Sequence Scrambling. J Phys Chem Lett 2015; 6:2524-2529. [PMID: 26266729 DOI: 10.1021/acs.jpclett.5b01088] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Collision-induced dissociation (CID) is a key technique used in mass spectrometry-based peptide sequencing. Collisionally activated peptides undergo statistical dissociation, forming a series of backbone fragment ions that reflect their amino acid (AA) sequence. Some of these fragments may experience a "head-to-tail" cyclization, which after proton migration, can lead to the cyclic structure opening in a different place than the initially formed bond. This process leads to AA sequence scrambling that may hinder sequencing of the initial peptide. Here we combine cryogenic ion spectroscopy and ab initio molecular dynamics simulations to isolate and characterize the precise structures of key intermediates in the scrambling process. The most stable peptide fragments show intriguing symmetric cyclic structures in which the proton is situated on a C2 symmetry axis and forms exceptionally short H-bonds (1.20 Å) with two backbone oxygens. Other nonsymmetric cyclic structures also exist, one of which is protonated on the amide nitrogen, where ring opening is likely to occur.
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Affiliation(s)
- Oleg Aseev
- †Laboratoire de Chimie Physique Moléculaire, École Polytechnique Fédérale de Lausanne, EPFL SB ISIC LCPM, Station 6, CH-1015 Lausanne, Switzerland
| | - Marta A S Perez
- ‡Laboratory of Computational Chemistry and Biochemistry, École Polytechnique Fédérale de Lausanne, EPFL SB ISIC LCBC, Station 6, CH-1015 Lausanne, Switzerland
| | - Ursula Rothlisberger
- ‡Laboratory of Computational Chemistry and Biochemistry, École Polytechnique Fédérale de Lausanne, EPFL SB ISIC LCBC, Station 6, CH-1015 Lausanne, Switzerland
| | - Thomas R Rizzo
- †Laboratoire de Chimie Physique Moléculaire, École Polytechnique Fédérale de Lausanne, EPFL SB ISIC LCPM, Station 6, CH-1015 Lausanne, Switzerland
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26
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Bythell BJ, Harrison AG. Formation of a(1) ions directly from oxazolone b(2) ions: an energy-resolved and computational study. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2015; 26:774-781. [PMID: 25810075 DOI: 10.1007/s13361-015-1080-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2014] [Revised: 01/13/2015] [Accepted: 01/13/2015] [Indexed: 06/04/2023]
Abstract
It is well-known that oxazolone b2 ions fragment extensively by elimination of CO to form a2 ions, which often fragment further to form a1 ions. Less well-known is that some oxazolone b2 ions may fragment directly to form a1 ions. The present study uses energy-resolved collision-induced dissociation experiments to explore the occurrence of the direct b2→a1 fragmentation reaction. The experimental results show that the direct b2→a1 reaction is generally observed when Gly is the C-terminal residue of the oxazolone. When the C-terminal residue is more complex, it is able to provide increased stability of the a2 product in the b2→a2 fragmentation pathway. Our computational studies of the relative critical reaction energies for the b2→a2 reaction compared with those for the b2→a1 reaction provide support that the critical reaction energies are similar for the two pathways when the C-terminal residue of the oxazolone is Gly. By contrast, when the nitrogen of the oxazolone ring in the b2 ion does not bear a hydrogen, as in the Ala-Sar and Tyr-Sar (Sar = N-methylglycine) oxazolone b2 ions, a1 ions are not formed but rather neutral imine elimination from the N-terminus of the b2 ion becomes a dominant fragmentation reaction. The M06-2X/6-31+G(d,p) density functional theory calculations are in general agreement with the experimental data for both types of reaction. In contrast, the B3LYP/6-31+G(d,p) model systematically underestimates the barriers of these SN2-like b2→a1 reaction. The difference between the two methods of barrier calculation are highly significant (P < 0.001) for the b2→a1 reaction, but only marginally significant (P = 0.05) for the b2→a2 reaction. The computations provide further evidence of the limitations of the B3LYP functional when describing SN2-like reactions.
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Affiliation(s)
- Benjamin J Bythell
- Department of Chemistry and Biochemistry, University of Missouri-St. Louis, St. Louis, MO, 63131, USA,
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Chawner R, Holman SW, Gaskell SJ, Eyers CE. Peptide scrambling during collision-induced dissociation is influenced by N-terminal residue basicity. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2014; 25:1927-1938. [PMID: 25135610 PMCID: PMC4197365 DOI: 10.1007/s13361-014-0968-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/17/2014] [Revised: 07/14/2014] [Accepted: 07/16/2014] [Indexed: 06/03/2023]
Abstract
'Bottom up' proteomic studies typically use tandem mass spectrometry data to infer peptide ion sequence, enabling identification of the protein whence they derive. The majority of such studies employ collision-induced dissociation (CID) to induce fragmentation of the peptide structure giving diagnostic b-, y-, and a- ions. Recently, rearrangement processes that result in scrambling of the original peptide sequence during CID have been reported for these ions. Such processes have the potential to adversely affect ion accounting (and thus scores from automated search algorithms) in tandem mass spectra, and in extreme cases could lead to false peptide identification. Here, analysis of peptide species produced by Lys-N proteolysis of standard proteins is performed and sequences that exhibit such rearrangement processes identified. The effect of increasing the gas-phase basicity of the N-terminal lysine residue through derivatization to homoarginine toward such sequence scrambling is then assessed. The presence of a highly basic homoarginine (or arginine) residue at the N-terminus is found to disfavor/inhibit sequence scrambling with a coincident increase in the formation of b(n-1)+H(2)O product ions. Finally, further analysis of a sequence produced by Lys-C proteolysis provides evidence toward a potential mechanism for the apparent inhibition of sequence scrambling during resonance excitation CID.
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Affiliation(s)
- Ross Chawner
- Michael Barber Centre for Mass Spectrometry, School of Chemistry, Manchester Institute of Biotechnology, University of Manchester, Manchester, M1 7DN UK
- Waters Corporation, Stamford Avenue, Wilmslow, SK9 4AX UK
| | - Stephen W. Holman
- Michael Barber Centre for Mass Spectrometry, School of Chemistry, Manchester Institute of Biotechnology, University of Manchester, Manchester, M1 7DN UK
- Department of Biochemistry, Institute of Integrative Biology, University of Liverpool, Liverpool, L69 7ZB UK
| | | | - Claire E. Eyers
- Michael Barber Centre for Mass Spectrometry, School of Chemistry, Manchester Institute of Biotechnology, University of Manchester, Manchester, M1 7DN UK
- Department of Biochemistry, Institute of Integrative Biology, University of Liverpool, Liverpool, L69 7ZB UK
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Harper B, Miladi M, Solouki T. Loss of internal backbone carbonyls: additional evidence for sequence-scrambling in collision-induced dissociation of y-type ions. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2014; 25:1716-1729. [PMID: 25070583 DOI: 10.1007/s13361-014-0955-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2014] [Revised: 05/14/2014] [Accepted: 06/19/2014] [Indexed: 06/03/2023]
Abstract
It is shown that y-type ions, after losing C-terminal H2O or NH3, can lose an internal backbone carbonyl (CO) from different peptide positions and yield structurally different product fragment ions upon collision-induced dissociation (CID). Such CO losses from internal peptide backbones of y-fragment ions are not unique to a single peptide and were observed in four of five model peptides studied herein. Experimental details on examples of CO losses from y-type fragment ions for an isotopically labeled AAAAHAA-NH2 heptapeptide and des-acetylated-α-melanocyte-stimulating hormone (dα-MSH) (SYSMEHFRWGKPV-NH2) are reported. Results from isotope labeling, tandem mass spectrometry (MS(n)), and ion mobility-mass spectrometry (IM-MS) confirm that CO losses from different amino acids of m/z-isolated y-type ions yield structurally different ions. It is shown that losses of internal backbone carbonyls (as CID products of m/z-isolated y-type ions) are among intermediate steps towards formation of rearranged or permutated product fragment ions. Possible mechanisms for generation of the observed sequence-scrambled a-"like" ions, as intermediates in sequence-scrambling pathways of y-type ions, are proposed and discussed.
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Affiliation(s)
- Brett Harper
- Institute of Biomedical Studies, Baylor University, Waco, TX, 76798, USA
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29
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Morrison LJ, Wysocki VH. Gas-Phase Helical Peptides Mimic Solution-Phase Behavior. J Am Chem Soc 2014; 136:14173-83. [PMID: 25203898 DOI: 10.1021/ja507298e] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Lindsay J. Morrison
- Ohio State University, 484
West 12th Avenue, Columbus, Ohio 43210, United States
| | - Vicki H. Wysocki
- Ohio State University, 484
West 12th Avenue, Columbus, Ohio 43210, United States
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30
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Morrison LJ, Chamot-Rooke J, Wysocki VH. IR action spectroscopy shows competitive oxazolone and diketopiperazine formation in peptides depends on peptide length and identity of terminal residue in the departing fragment. Analyst 2014; 139:2137-43. [PMID: 24618890 PMCID: PMC6467643 DOI: 10.1039/c4an00064a] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The interplay between the entropically and enthalpically favored products of peptide fragmentation is probed using a combined experimental and theoretical approach. These b2 ion products can take either an oxazolone or diketopiperazine structure. Cleavage after the second amide bond is often a favorable process because the products are small ring structures that are particularly stable. These structures are structurally characterized by action IRMPD spectroscopy and semi-quantified using gas-phase hydrogen-deuterium exchange. The formation of the oxazolone and diketopiperazine has been thought to be largely governed by the identity of the first two residues at the N-terminus of the peptide. We show here that the length of the precursor peptide and identity of the third residue play a significant role in the formation of the diketopiperazine structure in peptides containing an N-terminal asparagine residue. This is additionally the first instance showing an N-terminal residue with an amide side chain can promote formation of the diketopiperazine b2 ion structure.
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Affiliation(s)
- L J Morrison
- Department of Chemistry and Biochemistry, The Ohio State University, 484 W. 12th Ave, Columbus, OH 43210, USA.
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31
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Marek A, Tureček F. Collision-induced dissociation of diazirine-labeled peptide ions. Evidence for Brønsted-acid assisted elimination of nitrogen. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2014; 25:778-789. [PMID: 24549894 DOI: 10.1007/s13361-014-0832-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2013] [Revised: 12/26/2013] [Accepted: 01/09/2014] [Indexed: 06/03/2023]
Abstract
Gas-phase dissociations were investigated for several peptide ions containing the Gly-Leu* N-terminal motif where Leu* was a modified norleucine residue containing the photolabile diazirine ring. Collisional activation of gas-phase peptide cations resulted in facile N₂ elimination that competed with backbone dissociations. A free lysine ammonium group can act as a Brønsted acid to facilitate N₂ elimination. This dissociation was accompanied by insertion of a lysine proton in the side chain of the photoleucine residue, as established by deuterium labeling and gas-phase sequencing of the products. Electron structure calculations were used to provide structures and energies of reactants, intermediates, and transition states for Gly-Leu*-Gly-Gly-Lys amide ions that were combined with RRKM calculations of unimolecular rate constants. The calculations indicated that Brønsted acid-catalyzed eliminations were kinetically preferred over direct loss of N₂ from the diazirine ring. Mechanisms are proposed to explain the proton-initiated reactions and discuss the reaction products. The non-catalyzed diazirine ring cleavage and N₂ loss is proposed as a thermometer dissociation for peptide ion dissociations.
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Affiliation(s)
- Aleš Marek
- Department of Chemistry, University of Washington, Bagley Hall, Seattle, WA, 98195-1700, USA
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32
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Zekavat B, Miladi M, Al-Fdeilat AH, Somogyi A, Solouki T. Evidence for sequence scrambling and divergent H/D exchange reactions of doubly-charged isobaric b-type fragment ions. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2014; 25:226-236. [PMID: 24346960 DOI: 10.1007/s13361-013-0768-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2012] [Revised: 10/07/2013] [Accepted: 10/08/2013] [Indexed: 06/03/2023]
Abstract
To date, only a limited number of reports are available on structural variants of multiply-charged b-fragment ions. We report on observed bimodal gas-phase hydrogen/deuterium exchange (HDX) reaction kinetics and patterns for substance P b10(2+) that point to presence of isomeric structures. We also compare HDX reactions, post-ion mobility/collision-induced dissociation (post-IM/CID), and sustained off-resonance irradiation-collision induced dissociation (SORI-CID) of substance P b10(2+) and a cyclic peptide with an identical amino acid (AA) sequence order to substance P b10. The observed HDX patterns and reaction kinetics and SORI-CID pattern for the doubly charged head-to-tail cyclized peptide were different from either of the presumed isomers of substance P b10(2+), suggesting that b10(2+) may not exist exclusively as a head-to-tail cyclized structure. Ultra-high mass measurement accuracy was used to assign identities of the observed SORI-CID fragment ions of substance P b10(2+); over 30% of the observed SORI-CID fragment ions from substance P b10(2+) had rearranged (scrambled) AA sequences. Moreover, post-IM/CID experiments revealed the presence of two conformer types for substance P b10(2+), whereas only one conformer type was observed for the head-to-tail cyclized peptide. We also show that AA sequence scrambling from CID of doubly-charged b-fragment ions is not unique to substance P b10(2+).
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Affiliation(s)
- Behrooz Zekavat
- Department of Chemistry and Biochemistry, Baylor University, Waco, TX, 76798, USA
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Miladi M, Harper B, Solouki T. Evidence for sequence scrambling in collision-induced dissociation of y-type fragment ions. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2013; 24:1755-1766. [PMID: 23982935 DOI: 10.1007/s13361-013-0714-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: 02/10/2013] [Revised: 06/19/2013] [Accepted: 06/28/2013] [Indexed: 06/02/2023]
Abstract
Sequence scrambling from y-type fragment ions has not been previously reported. In a study designed to probe structural variations among b-type fragment ions, it was noted that y fragment ions might also yield sequence-scrambled ions. In this study, we examined the possibility and extent of sequence-scrambled fragment ion generation from collision-induced dissociation (CID) of y-type ions from four peptides (all containing basic residues near the C-terminus) including: AAAAHAA-NH2 (where "A" denotes carbon thirteen ((13)C1) isotope on the alanine carbonyl group), des-acetylated-α-melanocyte (SYSMEHFRWGKPV-NH2), angiotensin II antipeptide (EGVYVHPV), and glu-fibrinopeptide b (EGVNDNEEGFFSAR). We investigated fragmentation patterns of 32 y-type fragment ions, including y fragment ions with different charge states (+1 to +3) and sizes (3 to 12 amino acids). Sequence-scrambled fragment ions were observed from ~50 % (16 out of 32) of the studied y-type ions. However, observed sequence-scrambled ions had low relative intensities from ~0.1 % to a maximum of ~12 %. We present and discuss potential mechanisms for generation of sequence-scrambled fragment ions. To the best of our knowledge, results on y fragment dissociation presented here provide the first experimental evidence for generation of sequence-scrambled fragments from CID of y ions through intermediate cyclic "b-type" ions.
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Affiliation(s)
- Mahsan Miladi
- Department of Chemistry and Biochemistry, Baylor University, Waco, TX, 76798, USA
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34
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Harrison AG. Fragmentation reactions of methionine-containing protonated octapeptides and fragment ions therefrom: an energy-resolved study. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2013; 24:1555-1564. [PMID: 23943431 DOI: 10.1007/s13361-013-0706-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2012] [Revised: 05/27/2013] [Accepted: 06/03/2013] [Indexed: 06/02/2023]
Abstract
The fragmentation reactions of the MH(+) ions as well as the b7, a7, and a7* ions derived therefrom have been studied in detail for the octapeptides MAAAAAAA, AAMAAAAA, AAAAMAAA, and AAAAAAMA. Ionization was by electrospray using a QqToF mass spectrometer, which allowed a study of the evolution of the fragmentation channels as a function of the collision energy. Not surprisingly, the product ion mass spectra for the b7 ions are independent of the original precursor sequence, indicating macrocyclization and reopening to the same mixture of protonated oxazolones prior to fragmentation. The results show that this sequence scrambling results in a distinct preference to place the Met residue in the C-terminal position of the protonated oxazolones. The a7 and a7* ions also produce product ion mass spectra independent of the original peptide sequence. The results for the a7 ions indicate that fragmentation occurs primarily from an amide structure analogous to that observed for a4 ions (Bythell et al. in J Am Chem Soc 132:14766-14779, 2010). Clearly, the rearrangement reaction they have proposed applies equally well to an ions as large as a7. The major fragmentation modes of the MH(+) ions at low collision energies produce b7, b6, and b5 ions. As the collision energy is increased further fragmentation of these primary products produces, in part, non-direct sequence ions, which become prominent at lower m/z values, particularly for the peptides with the Met residue near the N-terminus.
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Affiliation(s)
- Alex G Harrison
- Department of Chemistry, University of Toronto, Toronto, ON, M5S 3H6, Canada,
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35
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Zekavat B, Miladi M, Becker C, Munisamy SM, Solouki T. Combined use of post-ion mobility/collision-induced dissociation and chemometrics for b fragment ion analysis. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2013; 24:1355-1365. [PMID: 23836377 DOI: 10.1007/s13361-013-0673-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2012] [Revised: 05/01/2013] [Accepted: 05/06/2013] [Indexed: 06/02/2023]
Abstract
Although structural isomers may yield indistinguishable ion mobility (IM) arrival times and similar fragment ions in tandem mass spectrometry (MS), it is demonstrated that post-IM/collision-induced dissociation MS (post-IM/CID MS) combined with chemometrics can enable independent study of the IM-overlapped isomers. The new approach allowed us to investigate the propensity of selected b type fragment ions from AlaAlaAlaHisAlaAlaAla-NH2 (AAA(His)AAA) heptapeptide to form different isomers. Principle component analysis (PCA) of the unresolved post-IM/CID profiles indicated the presence of two different isomer types for b4(+), b5(+), and b6(+) and a single isomer type for b7(+) fragments of AAA(His)AAA. We employed a simple-to-use interactive self-modeling mixture analysis (SIMPLISMA) to calculate the total IM profiles and CID mass spectra of b fragment isomers. The deconvoluted CID mass spectra showed discernible fragmentation patterns for the two isomers of b4(+), b5(+), and b6(+) fragments. Under our experimental conditions, calculated percentages of the "cyclic" isomers (at the 95% confidence level for n = 3) for b4(+), b5(+), and b6(+) were 61 (± 5)%, 36 (± 5)%, and 48 (± 2)%, respectively. Results from the SIMPLISMA deconvolution of b5(+) species resembled the CID MS patterns of fully resolved IM profiles for the two b5(+) isomers. The "cyclic" isomers for each of the two-component b fragment ions were less susceptible to ion fragmentation than their "linear" counterparts.
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Affiliation(s)
- Behrooz Zekavat
- Department of Chemistry and Biochemistry, Baylor University Sciences Building, Waco, TX 76798, USA
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36
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Grzetic J, Oomens J. Spectroscopic identification of cyclic imide b2-ions from peptides containing Gln and Asn residues. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2013; 24:1228-1241. [PMID: 23722727 DOI: 10.1007/s13361-013-0661-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2013] [Revised: 04/16/2013] [Accepted: 04/29/2013] [Indexed: 06/02/2023]
Abstract
In mass-spectrometry based peptide sequencing, formation of b- and y-type fragments by cleavage of the amide C-N bond constitutes the main dissociation pathway of protonated peptides under low-energy collision induced dissociation (CID). The structure of the b2 fragment ion from peptides containing glutamine (Gln) and asparagine (Asn) residues is investigated here by infrared ion spectroscopy using the free electron laser FELIX. The spectra are compared with theoretical spectra calculated using density functional theory for different possible isomeric structures as well as to experimental spectra of synthesized model systems. The spectra unambiguously show that the b2-ions do not possess the common oxazolone structure, nor do they possess the alternative diketopiperazine structure. Instead, cyclic imide structures are formed through nucleophilic attack by the amide nitrogen atom of the Gln and Asn side chains. The alternative pathway involving nucleophilic attack from the side-chain amide oxygen atom leading to cyclic isoimide structures, which had been suggested by several authors, can clearly be excluded based on the present IR spectra. This mechanism is perhaps surprising as the amide oxygen atom is considered to be the better nucleophile; however, computations show that the products formed via attack by the amide nitrogen are considerably lower in energy. Hence, b2-ions with Asn or Gln in the second position form structures with a five-membered succinimide or a six-membered glutarimide ring, respectively. b2-Ions formed from peptides with Asn in the first position are spectroscopically shown to possess the classical oxazolone structure.
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Affiliation(s)
- Josipa Grzetic
- Radboud University Nijmegen, Institute for Molecules and Materials, FELIX Facility, 6525ED, Nijmegen, The Netherlands
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37
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Durand S, Rossa M, Hernandez O, Paizs B, Maître P. IR Spectroscopy of b4 Fragment Ions of Protonated Pentapeptides in the X–H (X = C, N, O) Region. J Phys Chem A 2013; 117:2508-16. [DOI: 10.1021/jp400634t] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- Sylvère Durand
- Laboratoire de Chimie Physique,
Université Paris Sud, UMR8000 CNRS, Faculté des Sciences,
Bât. 350, 91405 Orsay Cedex, France
| | - Maximiliano Rossa
- Laboratoire de Chimie Physique,
Université Paris Sud, UMR8000 CNRS, Faculté des Sciences,
Bât. 350, 91405 Orsay Cedex, France
| | - Oscar Hernandez
- Laboratoire de Chimie Physique,
Université Paris Sud, UMR8000 CNRS, Faculté des Sciences,
Bât. 350, 91405 Orsay Cedex, France
| | - Béla Paizs
- Computational Proteomics Group, German Cancer Research Center, Im Neuenheimer Feld
580, 69120 Heidelberg, Germany
- School of Chemistry, Bangor University, Bangor, Gwynedd LL57 2UW,
U.K
| | - Philippe Maître
- Laboratoire de Chimie Physique,
Université Paris Sud, UMR8000 CNRS, Faculté des Sciences,
Bât. 350, 91405 Orsay Cedex, France
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Gucinski AC, Chamot-Rooke J, Steinmetz V, Somogyi Á, Wysocki VH. Influence of N-terminal residue composition on the structure of proline-containing b2+ ions. J Phys Chem A 2013; 117:1291-8. [PMID: 23312013 PMCID: PMC3641857 DOI: 10.1021/jp306759f] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
To probe the structural implications of the proline residue on its characteristic peptide fragmentation patterns, in particular its unusual cleavage at its C-terminus in formation of a b(2) ion in XxxProZzz sequences, the structures of a series of proline-containing b(2)(+) ions were studied by using action infrared multiphoton dissociation (IRMPD) spectroscopy and fragment ion hydrogen-deuterium exchange (HDX). Five different Xxx-Pro b(2)(+) ions were studied, with glycine, alanine, isoleucine, valine, or histidine in the N-terminal position. The residues selected feature different sizes, chain lengths, and gas phase basicities to explore whether the structure of the N-terminal residue influences the Xxx-Pro b(2)(+) ion structure. In proteins, the proline side chain-to-backbone attachment causes its peptide bonds to be in the cis conformation more than any other amino acid, although trans is still favored over cis. However, HP is the only b(2)(+) ion studied here that forms the diketopiperazine exclusively. The GP, AP, IP, and VP b(2)(+) ions formed from protonated tripeptide precursors predominantly featured oxazolone structures with small diketopiperazine contributions. In contrast to the b(2)(+) ions generated from tripeptides, synthetic cyclic dipeptides VP and HP were confirmed to have exclusive diketopiperazine structures.
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Affiliation(s)
- Ashley C Gucinski
- Department of Chemistry and Biochemistry, The University of Arizona, 1306 East University Boulevard, P.O. Box 210041, Tucson, Arizona 85721-0041, USA.
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Michalski A, Neuhauser N, Cox J, Mann M. A systematic investigation into the nature of tryptic HCD spectra. J Proteome Res 2012; 11:5479-91. [PMID: 22998608 DOI: 10.1021/pr3007045] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Modern mass spectrometry-based proteomics can produce millions of peptide fragmentation spectra, which are automatically identified in databases using sequence-specific b- or y-ions. Proteomics projects have mainly been performed with low resolution collision-induced dissociation (CID) in ion traps and beam-type fragmentation on triple quadrupole and QTOF instruments. Recently, the latter has also become available with Orbitrap instrumentation as higher energy collisional dissociation (HCD), routinely providing full mass range fragmentation with high mass accuracy. To systematically study the nature of HCD spectra, we made use of a large scale data set of tryptic peptides identified with an FDR of 0.0001, from which we extract a subset of more than 16,000 that have little or no contribution from cofragmented precursors. We employed a newly developed computer-assisted "Expert System", which distills our experience and literature knowledge about fragmentation pathways. It aims to automatically annotate the peaks in high mass accuracy fragment spectra while strictly controlling the false discovery rate. Using this Expert System we determined that sequence specific regular ions covering the entire sequence were present for almost all peptides with up to 10 amino acids (median 100%). Peptides up to 20 amino acid length contained sufficient fragmentation to cover 80% of the sequence. Internal fragments are common in HCD spectra but not in high resolution CID spectra (10% vs 1%). The low mass region contains abundant immonium ions (6% of fragment ion intensity), the characteristic a(2), b(2) ion pair (72% of spectra), side chain fragments and reporter ions for peptide modifications such as tyrosine phosphorylation. B- and y-ions account for only 20% of fragment ions by number but 53% by ion intensity. Overall, 84% of the fragment ion intensity was unambiguously explainable. Thus high mass accuracy HCD and CID data are near comprehensively and automatically interpretable.
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Affiliation(s)
- Annette Michalski
- Department of Proteomics and Signal Transduction, Max-Planck Institute of Biochemistry, Martinsried, Germany
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40
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Yang H, Good DM, van der Spoel D, Zubarev RA. Carbonyl charge solvation patterns may relate to fragmentation classes in collision-activated dissociation. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2012; 23:1319-1325. [PMID: 22689324 DOI: 10.1007/s13361-012-0418-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2012] [Revised: 05/12/2012] [Accepted: 05/13/2012] [Indexed: 06/01/2023]
Abstract
Here, we investigate the hypothesis that the origin of Class I fragmentation in tryptic peptide dications corresponding to the cleavage of the first two amino acids from the N-terminus is due to a dominant charge solvation pattern. Molecular dynamics simulations (MDS) of model A(n)R dications confirmed the existence of a persistent solvation of the protonated N-terminus on the second backbone carbonyl. Additionally, MDS predicted a new distinct fragmentation class corresponding to the loss of two amino acids from the C-terminus. This prediction was confirmed experimentally at very low excitation levels. The pattern produced by electron transfer dissociation of the same dications gave markedly decreased cleavage frequencies at the second peptide bond, which, within the non-local fragmentation mechanism, supports the preferential charge solvation on the second carbonyl. Taken together, these results confirm the role of a charge solvation pattern in the origin of fragmentation classes.
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Affiliation(s)
- Hongqian Yang
- Division of Physiological Chemistry I, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
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Wassermann TN, Boyarkin OV, Paizs B, Rizzo TR. Conformation-specific spectroscopy of peptide fragment ions in a low-temperature ion trap. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2012; 23:1029-1045. [PMID: 22460621 DOI: 10.1007/s13361-012-0368-0] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2011] [Revised: 02/17/2012] [Accepted: 02/23/2012] [Indexed: 05/31/2023]
Abstract
We have applied conformer-selective infrared-ultraviolet (IR-UV) double-resonance photofragment spectroscopy at low temperatures in an ion trap mass spectrometer for the spectroscopic characterization of peptide fragment ions. We investigate b- and a-type ions formed by collision-induced dissociation from protonated leucine-enkephalin. The vibrational analysis and assignment are supported by nitrogen-15 isotopic substitution of individual amino acid residues and assisted by density functional theory calculations. Under such conditions, b-type ions of different size are found to appear exclusively as linear oxazolone structures with protonation on the N-terminus, while a rearrangement reaction is confirmed for the a (4) ion in which the side chain of the C-terminal phenylalanine residue is transferred to the N-terminal side of the molecule. The vibrational spectra that we present here provide a particularly stringent test for theoretical approaches.
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Affiliation(s)
- Tobias N Wassermann
- Laboratoire de Chimie Physique Moléculaire, École Polytechnique Fédérale de Lausanne, 1015, Lausanne, Switzerland
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42
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Tirado M, Polfer NC. Defying entropy: forming large head-to-tail macrocycles in the gas phase. Angew Chem Int Ed Engl 2012; 51:6436-8. [PMID: 22615257 DOI: 10.1002/anie.201202405] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2012] [Indexed: 11/08/2022]
Abstract
Spectral fingerprints: Collision-induced dissociation (CID) of protonated peptides in the gas phase results in linear fragment ions with a five-membered oxazolone ring on their C-terminal side. Infrared spectroscopy confirms that smaller fragments adopt oxazolone structures. Conversely, in mid-sized and larger fragments an isomerization to "head-to-tail" macrocycles is observed (see picture).
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Affiliation(s)
- Marcus Tirado
- Department of Chemistry, University of Florida, Buckman Drive, P.O. Box 117200, Gainesville, FL 32611, USA
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43
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Tirado M, Polfer NC. Defying Entropy: Forming Large Head-to-Tail Macrocycles in the Gas Phase. Angew Chem Int Ed Engl 2012. [DOI: 10.1002/ange.201202405] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Gucinski AC, Chamot-Rooke J, Nicol E, Somogyi Á, Wysocki VH. Structural influences on preferential oxazolone versus diketopiperazine b(2+) ion formation for histidine analogue-containing peptides. J Phys Chem A 2012; 116:4296-304. [PMID: 22448972 PMCID: PMC3523341 DOI: 10.1021/jp300262d] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Studies of peptide fragment ion structures are important to aid in the accurate kinetic modeling and prediction of peptide fragmentation pathways for a given sequence. Peptide b(2)(+) ion structures have been of recent interest. While previously studied b(2)(+) ions that contain only aliphatic or simple aromatic residues are oxazolone structures, the HA b(2)(+) ion consists of both oxazolone and diketopiperazine structures. The structures of a series of histidine-analogue-containing Xxx-Ala b(2)(+) ions were studied by using action infrared multiphoton dissociation (IRMPD) spectroscopy, fragment ion hydrogen-deuterium exchange (HDX), and density functional theory (DFT) calculations to systematically probe the influence of different side chain structural elements on the resulting b(2)(+) ion structures formed. The b(2)(+) ions studied include His-Ala (HA), methylated histidine analogues, including π-methyl-HA and τ-methyl-HA, pyridylalanine (pa) analogues, including 2-(pa)A, 3-(pa)A, and 4-(pa)A, and linear analogues, including diaminobutanoic acid-Ala (DabA) and Lys-Ala (KA). The location and accessibility of the histidine π-nitrogen, or an amino nitrogen on an aliphatic side chain, were seen to be essential for diketopiperazine formation in addition to the more typical oxazolone structure formation, while blocking or removal of the τ-nitrogen did not change the b(2)(+) ion structures formed. Linear histidine analogues, DabA and KA, formed only diketopiperazine structures, suggesting that a steric interaction in the HisAla case may interfere with the complete trans-cis isomerization of the first amide bond that is necessary for diketopiperazine formation.
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Affiliation(s)
- Ashley C Gucinski
- Department of Chemistry and Biochemistry, The University of Arizona, 1306 East University Boulevard, Tucson, Arizona 85721, USA.
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45
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Obolensky OI, Wu WW, Shen RF, Yu YK. Using dissociation energies to predict observability of b- and y-peaks in mass spectra of short peptides. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2012; 26:915-20. [PMID: 22396027 PMCID: PMC3468955 DOI: 10.1002/rcm.6180] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
RATIONALE Peptide identification reliability can be improved by excluding from analysis those m/z peaks of candidate peptides which cannot be observed in practice due to various physical, chemical or thermodynamic considerations. We propose using dissociation energies (as opposed to proton affinities) as a predictor of observability of different m/z peaks in spectra of short peptides. METHODS Mass spectra of the tetrapeptides AAAA, AAFA, AAVA, AFAA, AVAA, AFFA, and AVVA were measured in the collision-induced dissociation (CID) activation mode on a grid of activation times 0.05 to 100 ms and normalized collision energy 10 to 35%. The lowest energy geometries and vibrational spectra were calculated for the precursor ions and their charged and neutral fragments using density functional theory (DFT) at the TPSS/6-31G(d,p) level. Dissociation energies were calculated for all fragmentation channels leading to b- or y-fragments. RESULTS It is demonstrated that m/z peaks observed in the mass spectra correspond to the fragmentation channels with the lowest dissociation energies. Using 50 kcal/mol as the cut-off value of dissociation energy, it was predicted that 28 out of 42 possible peaks in the b- and y-series of the seven tetrapeptides can be observed in mass spectra. In the experiments, 26 b- or y-peaks were observed, all of which are among the 28 predicted ones. CONCLUSIONS The use of dissociation energies generalizes the use of proton affinities for semi-quantitative predictions of relative intensities of different m/z peaks of short peptides. Further advances in this direction will pave the way for reliable quantitative predictions and, hence, for a significant improvement in robustness and accuracy of peptide and protein identification tools.
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Affiliation(s)
- O I Obolensky
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD, USA.
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46
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Bythell BJ, Hendrickson CL, Marshall AG. Relative stability of peptide sequence ions generated by tandem mass spectrometry. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2012; 23:644-654. [PMID: 22354685 DOI: 10.1007/s13361-012-0357-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2011] [Revised: 02/01/2012] [Accepted: 02/01/2012] [Indexed: 05/31/2023]
Abstract
We report the use of unimolecular dissociation by infrared radiation for gaseous multiphoton energy transfer to determine relative activation energy (E(a,laser)) for dissociation of peptide sequence ions. The sequence ions of interest are mass-isolated; the entire ion cloud is then irradiated with a continuous wave CO(2) laser, and the first order rate constant, k(d), is determined for each of a series of laser powers. Provided these conditions are met, a plot of the natural logarithm of k(d) versus the natural logarithm of laser power yields a straight line, whose slope provides a measure of E(a,laser). This method reproduces the E(a) values from blackbody radiative dissociation (BIRD) for the comparatively large, singly and doubly protonated bradykinin ions (nominally y ( 9 ) and y ( 9 ) ( 2+ )). The comparatively small sequence ion systems produce E(a,laser) values that are systematic underestimates of theoretical barriers calculated with density functional theory (DFT). However, the relative E(a,laser) values are in qualitative agreement with the mobile proton model and available theory. Additionally, novel protonated cyclic-dipeptide (diketopiperazine) fragmentation reactions are analyzed with DFT. FT-ICR MS provides access to sequence ions generated by electron capture dissociation, infrared multiphoton dissociation, and collisional activation methods (i.e., b ( n ), y ( m ) , c ( n ), z ( m ) ( • ) ions).
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Affiliation(s)
- Benjamin J Bythell
- Ion Cyclotron Resonance Program, National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL, USA
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47
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Tirado M, Rutters J, Chen X, Yeung A, van Maarseveen J, Eyler JR, Berden G, Oomens J, Polfer NC. Disfavoring macrocycle b fragments by constraining torsional freedom: the "twisted" case of QWFGLM b6. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2012; 23:475-482. [PMID: 22219043 DOI: 10.1007/s13361-011-0315-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2011] [Revised: 12/02/2011] [Accepted: 12/04/2011] [Indexed: 05/31/2023]
Abstract
While recent studies have shown that for some peptides, such as oligoglycines and Leu-enkephalin, mid-sized b fragment ions exist as a mixture of oxazolone and macrocycle structures, other primary structure motifs, such as QWFGLM, are shown to exclusively give rise to macrocycle structures. The aim of this study was to determine if certain amino acid residues are capable of suppressing macrocycle formation in the corresponding b fragment. The residues proline and 4-aminomethylbenzoic acid (4AMBz) were chosen because of their intrinsic rigidity, in the expectation that limited torsional flexibility may impede "head-to-tail" macrocycle formation. The presence of oxazolone versus macrocycle b(6) fragment structures was validated by infrared multiple photon dissociation (IRMPD) spectroscopy, using the free electron laser FELIX. It is confirmed that proline disfavors macrocycle formation in the cases of QPWFGLM b(7) and in QPFGLM b(6). The 4AMBz substitution experiments show that merely QWFG(4AMBz)M b(6), with 4AMBz in the fifth position, exhibits a weak oxazolone band. This effect is likely ascribed to a stabilization of the oxazolone structure, due to an extended oxazolone ring-phenyl π-electron system, not due to the rigidity of the 4AMBz residue. These results show that some primary structures have an intrinsic propensity to form macrocycle structures, which is difficult to disrupt, even using residues with limited torsional flexibility.
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Affiliation(s)
- Marcus Tirado
- Department of Chemistry, University of Florida, P.O. Box 117200, Gainesville, FL, 32611-7200, USA
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48
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Grzetic J, Oomens J. Spectroscopic evidence for an oxazolone structure in anionic b-type peptide fragments. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2012; 23:290-300. [PMID: 22170467 PMCID: PMC3264858 DOI: 10.1007/s13361-011-0297-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/03/2011] [Revised: 10/31/2011] [Accepted: 11/02/2011] [Indexed: 05/31/2023]
Abstract
Infrared spectra of anionic b-type fragments generated by collision induced dissociation (CID) from deprotonated peptides are reported. Spectra of the b(2) fragments of deprotonated AlaAlaAla and AlaTyrAla have been recorded over the 800-1800 cm(-1) spectral range by multiple-photon dissociation (MPD) spectroscopy using an FTICR mass spectrometer in combination with the free electron laser FELIX. Structural characterization of the b-type fragments is accomplished by comparison with density functional theory calculated spectra at the B3LYP/6-31++G(d,p) level for different isomeric structures. Although diketopiperazine structures represent the energetically lowest isomers, the IR spectra suggest an oxazolone structure for the b(2) fragments of both peptides. Deprotonation is shown to occur on the oxazolone α-carbon, which leads to a conjugated structure in which the negative charge is practically delocalized over the entire oxazolone ring, providing enhanced gas-phase stability.
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Affiliation(s)
- Josipa Grzetic
- FOM Institute for Plasma Physics Rijnhuizen, Edisonbaan 14, 3439MN Nieuwegein, The Netherlands
| | - Jos Oomens
- FOM Institute for Plasma Physics Rijnhuizen, Edisonbaan 14, 3439MN Nieuwegein, The Netherlands
- van’t Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, 1098XH Amsterdam, The Netherlands
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49
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Wang J, Zhang J, Arbogast B, Maier CS. Tandem mass spectrometric characterization of thiol peptides modified by the chemoselective cationic sulfhydryl reagent (4-iodobutyl)triphenylphosphonium--effects of a cationic thiol derivatization on peptide fragmentation. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2011; 22:1771-83. [PMID: 21952891 PMCID: PMC3187551 DOI: 10.1007/s13361-011-0192-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2011] [Revised: 05/18/2011] [Accepted: 06/08/2011] [Indexed: 05/24/2023]
Abstract
Fixed charge chemical modifications on peptides and proteins can impact fragmentation behaviors in tandem mass spectrometry (MS/MS). In this study, we employed a thiol-specific cationic alkylation reagent, (4-iodobutyl)triphenylphosphonium (IBTP), to selectively modify cysteine thiol groups in mitochondrial proteome samples. Tandem mass spectrometric characteristics of butyltriphenylphosphonium (BTP)-modified peptides were evaluated by comparison to their carbamidomethylated (CAM) analogues using a quadrupole time-of-flight (Q-TOF) instrument under low energy collision-induced dissociation (CID) conditions. Introduction of the fixed charge modification resulted in the observation of peptide and fragment (b(n) and y(n)) ions with higher charge states than those observed for CAM-modified analogues. The charged BTP moiety had a significant effect on the neighboring amide bond fragmentation products. A decrease in relative abundances of the product ions at the corresponding cleavage sites was observed compared with those from the CAM-modified derivatives. This effect was particularly noticeable when an Xxx-Pro bond was in the vicinity of a BTP group. We hypothesized that the presence of a phosphonium moiety will reduce the tendency for protonation of the proximal amide bonds in the peptide backbone. Indeed, calculations indicated that proton affinities of backbone amide bonds close to the modified cysteine residues were generally 20-50 kcal/mol lower for BTP-modified peptides than for the unmodified or CAM-modified analogues with the sequence motif -Ala-Cys-Ala(n)-Ala(2)-, -Ala-Cys-Ala(n)-Pro-Ala-, and -Ala-Pro-Ala(n)-Cys-Ala-, n=0-3.
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Affiliation(s)
- Jing Wang
- Department of Chemistry, Oregon State University, Corvallis, OR 97331
| | - Jie Zhang
- Department of Chemistry, Oregon State University, Corvallis, OR 97331
| | | | - Claudia S. Maier
- Department of Chemistry, Oregon State University, Corvallis, OR 97331
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50
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Chen X, Tirado M, Steill JD, Oomens J, Polfer NC. Cyclic peptide as reference system for b ion structural analysis in the gas phase. JOURNAL OF MASS SPECTROMETRY : JMS 2011; 46:1011-1015. [PMID: 22012667 DOI: 10.1002/jms.1982] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Infrared multiple photon dissociation spectroscopy and hydrogen/deuterium exchange methods are used to confirm the macrocylic structure of a b(6) peptide fragment by direct comparison with a synthetically made cyclic peptide. The acetylation of the peptide N-terminus results in the inhibition of the macrocyclic formation, supporting the "head-to-tail" cyclization mechanism. Differences in hydrogen/deuterium exchange rates for macrocyclic and oxazalone structure peptide fragments are interpreted to be a result of the complex interplay of multiple basic sites in the peptide fragment, supporting the relay mechanism for deuterium exchange with CH(3)OD.
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Affiliation(s)
- Xian Chen
- Department of Chemistry, University of Florida, Gainesville, Florida 32611, United States
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