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Terada K, Kurita T, Gimenez-Dejoz J, Masunaga H, Tsuchiya K, Numata K. Papain-Catalyzed, Sequence-Dependent Polymerization Yields Polypeptides Containing Periodic Histidine Residues. Macromolecules 2022. [DOI: 10.1021/acs.macromol.2c01036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Kayo Terada
- Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Kyoto Daigaku Katsura, Nishikyo-ku, Kyoto 615-8510, Japan
| | - Taichi Kurita
- Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Kyoto Daigaku Katsura, Nishikyo-ku, Kyoto 615-8510, Japan
| | - Joan Gimenez-Dejoz
- Biomacromolecules Research Team, RIKEN Center for Sustainable Resource Science, 2-C1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Hiroyasu Masunaga
- Japan Synchrotron Radiation Research Institute, 1-1-1, Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198, Japan
| | - Kousuke Tsuchiya
- Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Kyoto Daigaku Katsura, Nishikyo-ku, Kyoto 615-8510, Japan
| | - Keiji Numata
- Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Kyoto Daigaku Katsura, Nishikyo-ku, Kyoto 615-8510, Japan
- Biomacromolecules Research Team, RIKEN Center for Sustainable Resource Science, 2-C1 Hirosawa, Wako, Saitama 351-0198, Japan
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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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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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Wang Y, Lau JKC, Lai CK, Hopkinson AC, Siu KWM. Doubly Charged Small Organic Fragments Derived from [Ce(tripeptide)(CH 3CN) m] 3+ Complexes: Observation of the Elusive [b n + H] 2+ Ions. J Phys Chem B 2019; 123:10192-10201. [PMID: 31693371 DOI: 10.1021/acs.jpcb.9b09090] [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
[a3 + H]2+ ions generated from Ln3+/tripeptide complexes, where Ln = La or Ce, have similar structures to the linear [an]+ ions but with protonation at both the terminal NH2 and N═CH2 groups. Ion stability is favored by having the basic secondary amine of the proline residue at the N-terminus and by an amino acid residue accommodating one of the protons on the side chain. Dissociation of [a3 + H]2+ ions derived from peptides containing only aliphatic residues is by cleavage of the second amide bond to give [b2]+ or [a2]+ ions along with internal [a1]+ ions. For [a3 + H]2+ ions containing a tryptophan residue in the central location, in addition to cleavage of the amide bond, losses of neutrals NH3, HN═CHR, (NH3 + CO), and HNCO were observed. Dissociations of some unsolvated Ln3+/tripeptide complexes gave [b3 + H]2+ ions in low abundance; formation of these [b3 + H]2+ ions was favored by the presence of a proline residue at the N-terminus and by either a histidine or tryptophan residue in the central position. Dissociation of these [b3 + H]2+ ions was by the loss of (H2O + CO) and not only CO, indicating that these ions did not have the same type of oxazolone structure as found for [bn]+ ions. Density functional theory calculations suggest that the observed [b3 + H]2+ ions of ProGlyGly were formed from [Ce(ProGlyGly)]3+ complexes in which the peptide was bound to the metal ion as an enolate. Dissociation of the slightly lower-energy complex, where the peptide is bound in the keto form, would produce an oxazolone but the high barrier required to create this isomer of the [b3 + H]2+ ion would be sufficient to result in further dissociation. Two isomers of the [b3 + H]2+ ion of ProHisGly have been created, one from the [Ce(ProHisGly)]3+ complex that characteristically dissociates by the combined loss of (H2O + CO) and the other by the loss of glycine from [ProHisGlyGly + 2H]2+. The [b3 + H]2+ ion derived from [ProHisGlyGly + 2H]2+ dissociated by the loss of only CO.
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Affiliation(s)
- Yating Wang
- Department of Chemistry and Centre for Research in Mass Spectrometry , York University , 4700 Keele Street , Toronto , ON M3J 1P3 , Canada
| | - Justin Kai-Chi Lau
- Department of Chemistry and Centre for Research in Mass Spectrometry , York University , 4700 Keele Street , Toronto , ON M3J 1P3 , Canada.,Department of Chemistry and Biochemistry , University of Windsor , 401 Sunset Avenue , Windsor , ON N9B 3P4 , Canada
| | - Cheuk-Kuen Lai
- Department of Chemistry and Centre for Research in Mass Spectrometry , York University , 4700 Keele Street , Toronto , ON M3J 1P3 , Canada
| | - Alan C Hopkinson
- Department of Chemistry and Centre for Research in Mass Spectrometry , York University , 4700 Keele Street , Toronto , ON M3J 1P3 , Canada
| | - K W Michael Siu
- Department of Chemistry and Centre for Research in Mass Spectrometry , York University , 4700 Keele Street , Toronto , ON M3J 1P3 , Canada.,Department of Chemistry and Biochemistry , University of Windsor , 401 Sunset Avenue , Windsor , ON N9B 3P4 , Canada
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5
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Shen Y, Nemati R, Wang L, Yao X. Determining Linear Free Energy Relationships in Peptide Fragmentation Using Derivatization and Targeted Mass Spectrometry. Anal Chem 2018; 90:1587-1594. [DOI: 10.1021/acs.analchem.7b02191] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- Yuanyuan Shen
- Department
of Chemistry and ‡Institute for Systems Genomics, University of Connecticut, Storrs, Connecticut 06269, United States
| | - Reza Nemati
- Department
of Chemistry and ‡Institute for Systems Genomics, University of Connecticut, Storrs, Connecticut 06269, United States
| | - Lei Wang
- Department
of Chemistry and ‡Institute for Systems Genomics, University of Connecticut, Storrs, Connecticut 06269, United States
| | - Xudong Yao
- Department
of Chemistry and ‡Institute for Systems Genomics, University of Connecticut, Storrs, Connecticut 06269, United States
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6
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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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7
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Poutsma JC, Martens J, Oomens J, Maitre P, Steinmetz V, Bernier M, Jia M, Wysocki V. Infrared Multiple-Photon Dissociation Action Spectroscopy of the b 2+ Ion from PPG: Evidence of Third Residue Affecting b 2+ Fragment Structure. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2017; 28:1482-1488. [PMID: 28374317 PMCID: PMC5484043 DOI: 10.1007/s13361-017-1659-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Revised: 03/10/2017] [Accepted: 03/11/2017] [Indexed: 06/07/2023]
Abstract
Infrared multiple-photon dissociation (IRMPD) action spectroscopy was performed on the b2+ fragment ion from the protonated PPG tripeptide. Comparison of the experimental infrared spectrum with computed spectra for both oxazolone and diketopiperazine structures indicates that the majority of the fragment ion population has an oxazolone structure with the remainder having a diketopiperazine structure. This result is in contrast with a recent study of the IRMPD action spectrum of the PP b2+ fragment ion from PPP, which was found to be nearly 100% diketopiperazine (Martens et al. Int. J. Mass Spectrom. 2015, 377, 179). The diketopiperazine b2+ ion is thermodynamically more stable than the oxazolone but normally requires a trans/cis peptide bond isomerization in the dissociating peptide. Martens et al. showed through IRMPD action spectroscopy that the PPP precursor ion was in a conformation in which the first peptide bond is already in the cis conformation and thus it was energetically favorable to form the thermodynamically-favored diketopiperazine b2+ ion. In the present case, solution-phase NMR spectroscopy and gas-phase IRMPD action spectroscopy show that the PPG precursor ion has its first amide bond in a trans configuration suggesting that the third residue is playing an important role in both the structure of the peptide and the associated ring-closure barriers for oxazolone and diketopiperazine formation. Graphical Abstract ᅟ.
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Affiliation(s)
- John C Poutsma
- Department of Chemistry, College of William and Mary, Williamsburg, VA, 23187, USA.
| | - Jonathan Martens
- Radboud University, Institute for Molecules and Materials, FELIX Laboratory, Toernooiveld 7c, NL-6525ED, Nijmegen, The Netherlands
| | - Jos Oomens
- Radboud University, Institute for Molecules and Materials, FELIX Laboratory, Toernooiveld 7c, NL-6525ED, Nijmegen, The Netherlands
- Van't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 908, 1098XH, Amsterdam, The Netherlands
| | - Phillipe Maitre
- Laboratoire de Chimie Physique, CNRS UMR 8000, Université Paris Sud, Université Paris Saclay, CNRS, Orsay, France
| | - Vincent Steinmetz
- Laboratoire de Chimie Physique, CNRS UMR 8000, Université Paris Sud, Université Paris Saclay, CNRS, Orsay, France
| | - Matthew Bernier
- Department of Chemistry, Ohio State University, Columbus, OH, 43210, USA
| | - Mengxuan Jia
- Department of Chemistry, Ohio State University, Columbus, OH, 43210, USA
| | - Vicki Wysocki
- Department of Chemistry, Ohio State University, Columbus, OH, 43210, USA.
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8
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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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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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10
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Webb IK, Chen TC, Danielson WF, Ibrahim YM, Tang K, Anderson GA, Smith RD. Implementation of dipolar resonant excitation for collision induced dissociation with ion mobility/time-of-flight MS. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2014; 25:563-71. [PMID: 24470195 PMCID: PMC4113219 DOI: 10.1007/s13361-013-0815-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Revised: 12/19/2013] [Accepted: 12/19/2013] [Indexed: 05/26/2023]
Abstract
An ion mobility/time-of-flight mass spectrometer (IMS/TOF MS) platform that allows for resonant excitation collision induced dissociation (CID) is presented. Highly efficient, mass-resolved fragmentation without additional excitation of product ions was accomplished and over-fragmentation common in beam-type CID experiments was alleviated. A quadrupole ion guide was modified to apply a dipolar AC signal across a pair of rods for resonant excitation. The method was characterized with singly protonated methionine enkephalin and triply protonated peptide angiotensin I, yielding maximum CID efficiencies of 44% and 84%, respectively. The Mathieu q(x,y) parameter was set at 0.707 for these experiments to maximize pseudopotential well depths and CID efficiencies. Resonant excitation CID was compared with beam-type CID for the peptide mixture. The ability to apply resonant waveforms in mobility-resolved windows is demonstrated with a peptide mixture yielding fragmentation over a range of mass-to-charge (m/z) ratios within a single IMS-MS analysis.
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11
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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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12
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Pechan T, Gwaltney SR. Calculations of relative intensities of fragment ions in the MSMS spectra of a doubly charged penta-peptide. BMC Bioinformatics 2012; 13 Suppl 15:S13. [PMID: 23046347 PMCID: PMC3439735 DOI: 10.1186/1471-2105-13-s15-s13] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Currently, the tandem mass spectrometry (MSMS) of peptides is a dominant technique used to identify peptides and consequently proteins. The peptide fragmentation inside the mass analyzer typically offers a spectrum containing several different groups of ions. The mass to charge (m/z) values of these ions can be exactly calculated following simple rules based on the possible peptide fragmentation reactions. But the (relative) intensities of the particular ions cannot be simply predicted from the amino-acid sequence of the peptide. This study presents initial work towards developing a theoretical fundamental approach to ion intensity elucidation by utilizing quantum mechanical computations. METHODS MSMS spectra of the doubly charged GAVLK peptide were collected on electrospray ion trap mass spectrometers using low energy modes of fragmentation. Density functional theory (DFT) calculations were performed on the population of ion precursors to determine the fragment ion intensities corresponding to a Boltzmann distribution of the protonation of nitrogens in the peptide backbone amide bonds. RESULTS We were able to a) predict the y and b ions intensities order in concert with the experimental observation; b) predict relative intensities of y ions with errors not exceeding the experimental variation. CONCLUSIONS These results suggest that the GAVLK peptide fragmentation process in the ion trap mass spectrometer is predominantly driven by the thermodynamic stability of the precursor ions formed upon ionization of the sample. The computational approach presented in this manuscript successfully calculated ion intensities in the mass spectra of this doubly charged tryptic peptide, based solely on its amino acid sequence. As such, this work indicates a potential of incorporating quantum mechanical calculations into mass spectrometry based algorithms for molecular identification.
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Affiliation(s)
- Tibor Pechan
- Institute for Genomics, Biocomputing and Biotechnology, Mississippi Agricultural and Forestry Experiment Station, High Performance Computing Collaboratory, Mississippi State University, Mississippi State, MS 39762, USA.
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13
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Bokatzian-Johnson SS, Stover ML, Dixon DA, Cassady CJ. A comparison of the effects of amide and acid groups at the C-terminus on the collision-induced dissociation of deprotonated peptides. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2012; 23:1544-1557. [PMID: 22833234 DOI: 10.1007/s13361-012-0431-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2011] [Revised: 05/10/2012] [Accepted: 06/12/2012] [Indexed: 06/01/2023]
Abstract
The dissociative behavior of peptide amides and free acids was explored using low-energy collision-induced dissociation and high level computational theory. Both positive and negative ion modes were utilized, but the most profound differences were observed for the deprotonated species. Deprotonated peptide amides produce a characteristic c(m-2)(-) product ion (where m is the number of residues in the peptide) that is either absent or in low abundance in the analogous peptide acid spectrum. Peptide acids show an enhanced formation of c(m-3)(-); however, this is not generally as pronounced as c(m-2)(-) production from amides. The most notable occurrence of an amide-specific product ion is for laminin amide (YIGSR-NH(2)) and this case was investigated using several modified peptides. Mechanisms involving 6- and 9-membered ring formation were proposed, and their energetic properties were investigated using G3(MP2) molecular orbital theory calculations. For example, with C-terminal deprotonation of pentaglycine amide, formation of c(m-2)(-) and a 6-membered ring diketopiperazine neutral requires >31.6 kcal/mol, which is 26.1 kcal/mol less than the analogous process involving the peptide acid. The end group specific fragmentation of peptide amides in the negative ion mode may be useful for identifying such groups in proteomic applications.
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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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15
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Paizs B, Bythell BJ, Maître P. Rearrangement pathways of the a (4) ion of protonated YGGFL characterized by IR spectroscopy and modeling. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2012; 23:664-675. [PMID: 22270874 DOI: 10.1007/s13361-011-0322-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2011] [Revised: 12/07/2011] [Accepted: 12/13/2011] [Indexed: 05/31/2023]
Abstract
The structure of the a (4) ion from protonated YGGFL was studied in a quadrupole ion trap mass spectrometer by 'action' infrared spectroscopy in the 1000-2000 cm(-1) ('fingerprint') range using the CLIO Free Electron Laser. The potential energy surface (PES) of this ion was characterized by detailed molecular dynamics scans and density functional theory calculations exploring a large number of isomers and protonation sites. IR and theory indicate the a (4) ion population is primarily populated by the rearranged, linear structure proposed recently (Bythell et al., J. Am. Chem. Soc. 2010, 132, 14766). This structure contains an imine group at the N- terminus and an amide group -CO-NH(2) at the C-terminus. Our data also indicate that the originally proposed N-terminally protonated linear structure and macrocyclic structures (Polfer et al., J. Am. Chem. Soc. 2007, 129, 5887) are also present as minor populations. The clear differences between the present and previous IR spectra are discussed in detail. This mixture of gas-phase structures is also in agreement with the ion mobility spectrum published by Clemmer and co-workers recently (J. Phys. Chem. A 2008, 112, 1286). Additionally, the calculated cross-sections for the rearranged structures indicate these correspond to the most abundant (and previously unassigned) feature in Clemmer's work.
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Affiliation(s)
- Béla Paizs
- Computational Proteomics Group, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 580, 69120, Heidelberg, Germany.
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Kilpatrick LE, Neta P, Yang X, Simón-Manso Y, Liang Y, Stein SE. Formation of y + 10 and y + 11 ions in the collision-induced dissociation of peptide ions. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2012; 23:655-663. [PMID: 22161574 DOI: 10.1007/s13361-011-0277-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2011] [Revised: 10/07/2011] [Accepted: 10/12/2011] [Indexed: 05/31/2023]
Abstract
Tandem mass spectra of peptide ions, acquired in shotgun proteomic studies of selected proteins, tissues, and organisms, commonly include prominent peaks that cannot be assigned to the known fragmentation product ions (y, b, a, neutral losses). In many cases these persist even when creating consensus spectra for inclusion in spectral libraries, where it is important to determine whether these peaks represent new fragmentation paths or arise from impurities. Using spectra from libraries and synthesized peptides, we investigate a class of fragment ions corresponding to y(n-1) + 10 and y(n-1) + 11, where n is the number of amino acid residues in the peptide. These 10 and 11 Da differences in mass of the y ion were ascribed before to the masses of [+ CO - H(2)O] and [+ CO - NH(3)], respectively. The mechanism is suggested to involve dissociation of the N-terminal residue at the CH-CO bond following loss of H(2)O or NH(3). MS(3) spectra of these ions show that the location of the additional 10 or 11 Da is at the N-terminal residue. The y(n-1) + 10 ion is most often found in peptides with N-terminal proline, asparagine, and histidine, and also with serine and threonine in the adjacent position. The y(n-1) + 11 ion is observed predominantly with histidine and asparagine at the N-terminus, but also occurs with asparagine in positions two through four. The intensities of the y(n-1) + 10 ions decrease with increasing peptide length. These data for y(n-1) + 10 and y(n-1) + 11 ion formation may be used to improve peptide identification from tandem mass spectra.
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Affiliation(s)
- Lisa E Kilpatrick
- Chemical and Biochemical Reference Data Division, National Institute of Standards and Technology, 100 Bureau Drive, MS8320, Gaithersburg, MD 20899, USA.
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Bleiholder C, Suhai S, Harrison AG, Paizs B. Towards understanding the tandem mass spectra of protonated oligopeptides. 2: The proline effect in collision-induced dissociation of protonated Ala-Ala-Xxx-Pro-Ala (Xxx = Ala, Ser, Leu, Val, Phe, and Trp). JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2011; 22:1032-9. [PMID: 21953044 DOI: 10.1007/s13361-011-0092-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2010] [Revised: 01/29/2011] [Accepted: 01/30/2011] [Indexed: 05/21/2023]
Abstract
The product ion spectra of proline-containing peptides are commonly dominated by y(n) ions generated by cleavage at the N-terminal side of proline residues. This proline effect is investigated in the current work by collision-induced dissociation (CID) of protonated Ala-Ala-Xxx-Pro-Ala (Xxx includes Ala, Ser, Leu, Val, Phe, and Trp) in an electrospray/quadrupole/time-of-flight (QqTOF) mass spectrometer and by quantum chemical calculations on protonated Ala-Ala-Ala-Pro-Ala. The CID spectra of all investigated peptides show a dominant y(2) ion (Pro-Ala sequence). Our computational results show that the proline effect mainly arises from the particularly low threshold energy for the amide bond cleavage N-terminal to the proline residue, and from the high proton affinity of the proline-containing C-terminal fragment produced by this cleavage. These theoretical results are qualitatively supported by the experimentally observed y(2)/b(3) abundance ratios for protonated Ala-Ala-Xxx-Pro-Ala (Xxx = Ala, Ser, Leu, Val, Phe, and Trp). In the post-cleavage phase of fragmentation the N-terminal oxazolone fragment with the Ala-Ala-Xxx sequence and Pro-Ala compete for the ionizing proton for these peptides. As the proton affinity of the oxazolone fragment increases, the y(2)/b(3) abundance ratio decreases.
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Affiliation(s)
- Christian Bleiholder
- Department of Molecular Biophysics, German Cancer Research Center (DKFZ), Heidelberg, Germany
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Neta P, Stein SE. Charge states of y ions in the collision-induced dissociation of doubly charged tryptic peptide ions. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2011; 22:898-905. [PMID: 21472524 DOI: 10.1007/s13361-011-0089-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2010] [Revised: 01/20/2011] [Accepted: 01/22/2011] [Indexed: 05/30/2023]
Abstract
Bonds that break in collision-induced dissociation (CID) are often weakened by a nearby proton, which can, in principle, be carried away by either of the product fragments. Since peptide backbone dissociation is commonly charge-directed, relative intensities of charge states of product y- and b-ions depend on the final location of that proton. This study examines y-ion charge distributions for dissociation of doubly charged peptide ions, using a large reference library of peptide ion fragmentation generated from ion-trap CID of peptide ions from tryptic digests. Trends in relative intensities of y(2+) and y(1+) ions are examined as a function of bond cleavage position, peptide length (n), residues on either side of the bond and effects of residues remote from the bond. It is found that y(n-2)/b(2) dissociation is the most sensitive to adjacent amino acids, that y(2+)/y(1+) steadily increase with increasing peptide length, that the N-terminal amino acid can have a major influence in all dissociations, and in some cases other residues remote from the bond cleavage exert significant effects. Good correlation is found between the values of y(2+)/y(1+) for the peptide and the proton affinities of the amino acids present at the dissociating peptide bond. A few deviations from this correlation are rationalized by specific effects of the amino acid residues. These correlations can be used to estimate trends in y(2+)/y(1+) ratios for peptide ions from amino acid proton affinities.
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Affiliation(s)
- Pedatsur Neta
- Chemical and Biochemical Reference Data Division, National Institute of Standards and Technology, Gaithersburg, Maryland, USA
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Harrison AG. Effect of the identity of Xaa on the fragmentation modes of doubly-protonated Ala-Ala-Xaa-Ala-Ala-Ala-Arg. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2011; 22:906-911. [PMID: 21472525 DOI: 10.1007/s13361-011-0091-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2010] [Revised: 01/20/2011] [Accepted: 01/22/2011] [Indexed: 05/30/2023]
Abstract
The product ion mass spectra resulting from collisional activation of doubly-protonated tryptic-type peptides Ala-Ala-Xaa-Ala-Ala-Ala-Arg have been determined for Xaa = Ala(A), Ser(S), Val(V), Thr(T), Ile(I), Phe(F), Tyr(Y), Sar, Met(M), Trp(W), Pro(P), and Gln(Q). The major fragmentation reaction involves cleavage of the second amide bond (counting from the N-terminus) except for Xaa = Ser and Thr where elimination of H(2)O from the [M + 2H](+2) ion forms the base peak. In general, the extent of cleavage of the second amide bond shows little dependence on the identity of Xaa and little dependence on whether the bond cleavage involves symmetrical bond cleavage to form a y(5)/b(2) ion pair or asymmetrically to form y (5) (+2) and a neutral b(2) species. Notable exceptions to this generalization occur for Xaa equal to Pro or Sar. For Xaa = Pro only cleavage of the second amide bond is observed, consistent with a pronounced proline effect, i.e., cleavage N-terminal to Pro. When Xaa = Sar considerably enhanced cleavage of the second amide bond also is observed, suggesting that at least part of the proline effect relates to the tertiary nature of the amide nitrogen. In the competition between symmetric and asymmetric bond cleavage an attempt to establish a linear free energy correlation in relating ln(y(5)(+2)/y(5)) to PA(H-Xaa-OH) did not lead to a reasonable correlation although the trend of increasing y(5)(+2)/y(5) ratio with increasing proton affinity of H-Xaa-OH was clear. Proline showed a unique behavior in giving a much higher y(5)(+2)/y(5) ratio than any of the other residues studied.
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Affiliation(s)
- Alex G Harrison
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, ON, M5S 3H6, Canada.
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Bythell BJ, Knapp-Mohammady M, Paizs B, Harrison AG. Effect of the His residue on the cyclization of b ions. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2010; 21:1352-1363. [PMID: 20541953 DOI: 10.1016/j.jasms.2010.05.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2010] [Revised: 05/07/2010] [Accepted: 05/07/2010] [Indexed: 05/29/2023]
Abstract
The MS(n) spectra of the [M + H](+) and b(5) peaks derived from the peptides HAAAAA, AHAAAA, AAHAAA, AAAHAA, and AAAAHA have been measured, as have the spectra of the b(4) ions derived from the first four peptides. The MS(2) spectra of the [M + H](+) ions show a substantial series of b(n) ions with enhanced cleavage at the amide bond C-terminal to His and substantial cleavage at the amide bond N-terminal to His (when there are at least two residues N-terminal to the His residue). There is compelling experimental and theoretical evidence for formation of nondirect sequence ions via cyclization/reopening chemistry in the CID spectra of the b ions when the His residue is near the C-terminus. The experimental evidence is less clear for ions when the His residue is near the N-terminus, although this may be due to the use of multiple alanine residues in the peptide making identifying scrambled peaks more difficult. The product ion mass spectra of the b(4) and b(5) ions from these isomeric peptides with cyclically permuted amino acid sequences are similar, but also show clear differences. This indicates less active cyclization/reopening followed by fragmentation of common structures for b(n) ions containing His than for sequences of solely aliphatic residues. Despite more energetically favorable cyclization barriers for the b(5) structures, the b(4) ions experimental data show more clear evidence of cyclization and sequence scrambling before fragmentation. For both b(4) and b(5) the energetically most favored structure is a macrocyclic isomer protonated at the His side chain.
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Affiliation(s)
- Benjamin J Bythell
- Computational Proteomics Group, German Cancer Research Center (DKFZ), Heidelberg, Germany
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