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Zhang B, Burchill L, Altalhi WAO, Ma HZ, O'Hair RAJ. A fixed-charge model of the N-protomer of 4-aminobenzoic acid to facilitate the study of the unimolecular and bimolecular chemistry of its "neutral" carboxylic acid group. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2024; 38:e9681. [PMID: 38355884 DOI: 10.1002/rcm.9681] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2023] [Revised: 11/24/2023] [Accepted: 11/25/2023] [Indexed: 02/16/2024]
Abstract
RATIONALE There are a growing number of examples of protomers formed via electrospray ionization (ESI) that do not fragment under mobile proton conditions, giving rise to distinct tandem mass spectra. To model the N-protomer of 4-aminobenzoic acid, here we study the gas-phase unimolecular and bimolecular chemistry of the 4-(carboxyphenyl)trimethylammonium ion. METHODS 4-(Carboxyphenyl)trimethylammonium iodide was synthesized, purified via recrystallization and transferred to the gas phase via ESI. 4-(Carboxyphenyl)trimethylammonium ion, 7, was mass selected and subjected to collision-induced dissociation and ion-molecule reactions in a linear ion trap mass spectrometer. RESULTS The major fragmentation channel for the fixed-charge cation 7 is methyl radical loss, whereas loss of trimethylamine and CO2 represents minor pathways. The free carboxylic acid functional group of 7 is unreactive toward a number of neutral reagents (methanol, acetone, acetonitrile, and N,N'-diisopropylcarbodiimide). 7 reacts very slowly with trimethylborate via addition-elimination, consistent with density functional theory (DFT) calculations that show this reaction is slightly endothermic. The deuterated cation 7(D) undergoes slow D/H exchange with ethanol, and DFT calculations reveal that a flip-flop mechanism operates. CONCLUSIONS The free carboxylic group of 7 is not very reactive toward neutral reagents in the gas phase.
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Affiliation(s)
- Beiang Zhang
- School of Chemistry and Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria, Australia
| | - Laura Burchill
- School of Chemistry and Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria, Australia
| | - Weam A O Altalhi
- School of Chemistry and Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria, Australia
- Department of Chemistry, Prince Sattam Bin Abdulaziz University, Hotat Bani Tamim, Saudi Arabia
| | - Howard Z Ma
- School of Chemistry and Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria, Australia
| | - Richard A J O'Hair
- School of Chemistry and Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria, Australia
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2-Pyridine Carboxaldehyde for Semi-Automated Soft Spot Identification in Cyclic Peptides. Int J Mol Sci 2022; 23:ijms23084269. [PMID: 35457087 PMCID: PMC9028278 DOI: 10.3390/ijms23084269] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Revised: 04/07/2022] [Accepted: 04/10/2022] [Indexed: 11/17/2022] Open
Abstract
Cyclic peptides are an attractive option as therapeutics due to their ability to disrupt crucial protein-protein interactions and their flexibility in display type screening strategies, but they come with their own bioanalytical challenges in metabolite identification. Initial amide hydrolysis of a cyclic peptide results in a ring opening event in which the sequence is linearized. Unfortunately, the mass of the singly hydrolyzed sequence is the same (M + 18.0106 Da) irrespective of the initial site of hydrolysis, or soft spot. Soft spot identification at this point typically requires time-consuming manual interpretation of the tandem mass spectra, resulting in a substantial bottleneck in the hit to lead process. To overcome this, derivatization using 2-pyridine carboxaldehyde, which shows high selectivity for the alpha amine on the N-terminus, was employed. This strategy results in moderate- to high-efficiency derivatization with a unique mass tag and diagnostic ions that serve to highlight the first amino acid in the newly linearized peptide. The derivatization method and analytical strategy are demonstrated on a whole cell lysate digest, and the soft spot identification strategy is shown with two commercially available cyclic peptides: JB1 and somatostatin. Effective utilization of the automated sample preparation and interpretation of the resulting spectra shown here will serve to reduce the hit-to-lead time for generating promising proteolytically stable peptide candidates.
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Darii E, Gimbert Y, Alves S, Damont A, Perret A, Woods AS, Fenaille F, Tabet JC. First Direct Evidence of Interpartner Hydride/Deuteride Exchanges for Stored Sodiated Arginine/Fructose-6-phosphate Complex Anions within Salt-Solvated Structures. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2021; 32:1424-1440. [PMID: 33929837 DOI: 10.1021/jasms.1c00040] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Mass spectrometric investigations of noncovalent binding between low molecular weight compounds revealed the existence of gas-phase (GP) noncovalent complex (NCC) ions involving zwitterionic structures. ESI MS is used to prove the formation of stable sodiated NCC anions between fructose (F6P) and arginine (R) moieties. Theoretical calculations indicate a folded solvated salt (i.e., sodiated carboxylate interacting with phosphate) rather than a charge-solvated form. Under standard CID conditions, [(F6P+R-H+Na)-H]- competitively forms two major product ions (PIs) through partner splitting [(R-H+Na) loss] and charge-induced cross-ring cleavage while preserving the noncovalent interactions (noncovalent product ions (NCPIs)). MS/MS experiments combined with in-solution proton/deuteron exchanges (HDXs) demonstrated an unexpected labeling of PIs, i.e., a correlated D-enrichment/D-depletion. An increase in activation time up to 3000 ms favors such processes when limited to two H/D exchanges. These results are rationalized by interpartner hydride/deuteride exchanges (⟨HDX⟩) through stepwise isomerization/dissociation of sodiated NCC-d11 anions. In addition, the D-enrichment/D-depletion discrepancy is further explained by back HDX with residual water in LTQ (selective for the isotopologue NCPIs as shown by PI relaxation experiments). Each isotopologue leads to only one back HDX unlike multiple HDXs generally observed in GP. This behavior shows that NCPIs are zwitterions with charges solvated by a single water molecule, thus generating a back HDX through a relay mechanism, which quenches the charges and prevents further back HDX. By estimating back HDX impact on D-depletion, the interpartner ⟨HDX⟩ complementarity was thus illustrated. This is the first description of interpartner ⟨HDX⟩ and selective back HDX validating salt-solvated structures.
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Affiliation(s)
- Ekaterina Darii
- Génomique Métabolique, Genoscope, Institut François Jacob, CEA, CNRS, Univ Evry, Université Paris-Saclay, 91057 Evry, France
| | - Yves Gimbert
- Département de Chimie Moléculaire, UMR CNRS 5250, Université Grenoble Alpes, 38058 Grenoble, France
- Sorbonne Université, Faculté des Sciences et de l'Ingénierie, Institut Parisien de Chimie Moléculaire (IPCM), F-75005 Paris, France
| | - Sandra Alves
- Sorbonne Université, Faculté des Sciences et de l'Ingénierie, Institut Parisien de Chimie Moléculaire (IPCM), F-75005 Paris, France
| | - Annelaure Damont
- Université Paris-Saclay, CEA, INRAE, Département Médicaments et Technologies pour la Santé (DMTS), MetaboHUB, F-91191 Gif sur Yvette, France
| | - Alain Perret
- Génomique Métabolique, Genoscope, Institut François Jacob, CEA, CNRS, Univ Evry, Université Paris-Saclay, 91057 Evry, France
| | - Amina S Woods
- NIDA IRP, NIH Structural Biology Unit Cellular Neurobiology Branch, 333 Cassell Drive, Baltimore, Maryland 21224, United States
- The Johns Hopkins University School of Medicine, Pharmacology and Molecular Sciences, Baltimore, Maryland 21205, United States
| | - François Fenaille
- Université Paris-Saclay, CEA, INRAE, Département Médicaments et Technologies pour la Santé (DMTS), MetaboHUB, F-91191 Gif sur Yvette, France
| | - Jean-Claude Tabet
- Sorbonne Université, Faculté des Sciences et de l'Ingénierie, Institut Parisien de Chimie Moléculaire (IPCM), F-75005 Paris, France
- Université Paris-Saclay, CEA, INRAE, Département Médicaments et Technologies pour la Santé (DMTS), MetaboHUB, F-91191 Gif sur Yvette, France
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Dos Santos NA, de Almeida CM, Gonçalves FF, Ortiz RS, Kuster RM, Saquetto D, Romão W. Analysis of Erythroxylum coca Leaves by Imaging Mass Spectrometry (MALDI-FT-ICR IMS). JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2021; 32:946-955. [PMID: 33715356 DOI: 10.1021/jasms.0c00449] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Matrix-assisted laser desorption/ionization imaging mass spectrometry (MALDI IMS) can determine the chemical identity and spatial distribution of several molecules in a single analysis, conserving its natural histology. However, there are no specific studies on the spatial distribution of alkaloids in Erythroxylum coca leaves by MALDI IMS, preserving the histology of the monitored compounds. Therefore, in this work, positive-ion mode MALDI Fourier-transform ion cyclotron resonance imaging mass spectrometry (MALDI(+)FT-ICR IMS) was applied to identify and analyze the distribution of alkaloids on the surface of coca leaves, evaluating the ionization efficiency of three matrices (α-cyano-4-hydroxycinnamic acid (CHCA), 2-mercaptobenzothiazole (MBT), and 2,5-dihydroxybenzoic acid (DHB)). The last was chosen as the best matrix in this study, and it was studied in five concentrations (0.5, 1.0, 2.0, 4.0, and 8.0 mg·mL-1), where 2 mg·mL-1 was the most efficient. The washing of coca leaves with the organic solvents (acetonitrile, methanol, toluene, and dichloromethane) tested did not improve the performance of the ionization process. Finally, a tissue section, 50 μm thick, was used to study the inner part of the leaf tissue, where alkaloids and flavonoid molecules were detected.
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Affiliation(s)
- Nayara Araujo Dos Santos
- Laboratório de Petroleômica e Forense, Universidade Federal do Espírito Santo (UFES), Avenida Fernando Ferrari, 514, Goiabeiras, Vitória, ES 29075-910, Brazil
- Instituto Nacional de Ciência e Tecnologia Forense (INCT Forense), Av. Ministro Salgado Filho, Soteco, Vila Velha, Espírito Santo 29106-010, Brazil
| | - Camila Medeiros de Almeida
- Laboratório de Petroleômica e Forense, Universidade Federal do Espírito Santo (UFES), Avenida Fernando Ferrari, 514, Goiabeiras, Vitória, ES 29075-910, Brazil
- Instituto Nacional de Ciência e Tecnologia Forense (INCT Forense), Av. Ministro Salgado Filho, Soteco, Vila Velha, Espírito Santo 29106-010, Brazil
| | - Fernanda Fachim Gonçalves
- Laboratório de Petroleômica e Forense, Universidade Federal do Espírito Santo (UFES), Avenida Fernando Ferrari, 514, Goiabeiras, Vitória, ES 29075-910, Brazil
| | - Rafael Scorsatto Ortiz
- Instituto Nacional de Ciência e Tecnologia Forense (INCT Forense), Av. Ministro Salgado Filho, Soteco, Vila Velha, Espírito Santo 29106-010, Brazil
- Superintendência da Polícia Federal no Rio Grande Sul, Porto Alegre, RS 90040-410, Brazil
| | - Ricardo Machado Kuster
- Laboratório de Petroleômica e Forense, Universidade Federal do Espírito Santo (UFES), Avenida Fernando Ferrari, 514, Goiabeiras, Vitória, ES 29075-910, Brazil
| | - Diemerson Saquetto
- Instituto Federal de Educação, Ciência e Tecnologia do Espírito Santo (IFES), Av. Ministro Salgado Filho, Soteco, Vila Velha, Espírito Santo 29106-010, Brazil
| | - Wanderson Romão
- Laboratório de Petroleômica e Forense, Universidade Federal do Espírito Santo (UFES), Avenida Fernando Ferrari, 514, Goiabeiras, Vitória, ES 29075-910, Brazil
- Instituto Nacional de Ciência e Tecnologia Forense (INCT Forense), Av. Ministro Salgado Filho, Soteco, Vila Velha, Espírito Santo 29106-010, Brazil
- Instituto Federal de Educação, Ciência e Tecnologia do Espírito Santo (IFES), Av. Ministro Salgado Filho, Soteco, Vila Velha, Espírito Santo 29106-010, Brazil
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Dias HJ, Crevelin EJ, Palaretti V, Vessecchi R, Crotti AEM. Electrospray ionization tandem mass spectrometry of deprotonated dihydrobenzofuran neolignans. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2021; 35:e8990. [PMID: 33119941 DOI: 10.1002/rcm.8990] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Revised: 10/21/2020] [Accepted: 10/24/2020] [Indexed: 06/11/2023]
Abstract
RATIONALE Although dihydrobenzofuran neolignans (DBNs) display a wide diversity of biological activities, the identification of their in vivo metabolites using liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) remains a challenge to be overcome. Recently, ESI-MS/MS data of protonated DBNs have been reported, but they were shown to be limited due to the scarcity of diagnostic ions. METHODS The gas-phase fragmentation pathways of a series of biologically active synthetic benzofuran neolignans (BNs) and DBNs were elucidated by means of negative ESI accurate-mass tandem and sequential mass spectrometry, and thermochemical data estimated using computational chemistry and the B3LYP/6-31+G(d,p) model. RESULTS Deprotonated DBNs produced more diagnostic product ions than the corresponding protonated molecules. Moreover, a series of odd-electron product ions (radical anions) were detected, which has not been reported for protonated DBNs. Direct C2 H3 O2 • elimination from the precursor ion (deprotonated molecule) only occurred for the BNs and can help to distinguish these compounds from the DBNs. The mechanism through which the [M - H - CH3 OH]- ion is formed is strongly dependent on specific structural features. CONCLUSIONS The negative ion mode provides much more information than the positive ion mode (at least one diagnostic product ion was detected for all the analyzed compounds) and does not require the use of additives to produce the precursor ions (deprotonated molecules).
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Affiliation(s)
- Herbert J Dias
- Departamento de Química, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brazil
| | - Eduardo J Crevelin
- Departamento de Química, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brazil
| | - Vinicius Palaretti
- Departamento de Química, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brazil
| | - Ricardo Vessecchi
- Departamento de Química, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brazil
| | - Antônio E M Crotti
- Departamento de Química, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brazil
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Andersson Å, Poline M, Kodambattil M, Rebrov O, Loire E, Maître P, Zhaunerchyk V. Structure of Proton-Bound Methionine and Tryptophan Dimers in the Gas Phase Investigated with IRMPD Spectroscopy and Quantum Chemical Calculations. J Phys Chem A 2020; 124:2408-2415. [PMID: 32106670 PMCID: PMC7307929 DOI: 10.1021/acs.jpca.9b11811] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
![]()
The
structures of three proton-bound dimers (Met2H+, MetTrpH+, and Trp2H+) are
investigated in the gas phase with infrared multiple photon disassociation
(IRMPD) spectroscopy in combination with quantum chemical calculations.
Their IRMPD spectra in the range of 600–1850 cm–1 are obtained experimentally using an FT-ICR mass spectrometer and
the CLIO free electron laser as an IR light source. The most abundant
conformers are elucidated by comparing the IRMPD spectra with harmonic
frequencies obtained at the B3LYP-GD3BJ/6-311++G** level of theory.
Discrepancies between the experimental and theoretical data in the
region of 1500–1700 cm–1 are attributed to
the anharmonicity of the amino bending modes. We confirm the result
of a previous IRMPD study that the structure of gas-phase Trp2H+ is charge-solvated but find that there are more
stable structures than originally reported (Feng, R.; Yin, H.; Kong,
X. Rapid Commun. Mass Spectrom.2016, 30, 24–28). In addition, gas-phase Met2H+ and MetTrpH+ have been revealed to
have charge-solvated structures. For all three dimers, the most stable
conformer is found to be of type A. The spectrum of Met2H+, however, cannot be explained without some abundance
of type B charge-solvated conformers as well as salt-bridged structures.
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Affiliation(s)
- Åke Andersson
- Chalmers University of Technology, 412 96 Gothenburg, Sweden
| | - Mathias Poline
- Department of Physics, Stockholm University, 114 19 Stockholm, Sweden
| | - Meena Kodambattil
- Department of Physics, University of Gothenburg, 405 30 Gothenburg, Sweden.,International School of Photonics, Cochin University of Science and Technology, Kochi, Kerala 682022, India
| | - Oleksii Rebrov
- Department of Physics, Stockholm University, 114 19 Stockholm, Sweden
| | - Estelle Loire
- Laboratoire de Chimie Physique (UMR8000), Université Paris-Sud, CNRS, Université Paris Saclay, Orsay 91405, France
| | - Philippe Maître
- Laboratoire de Chimie Physique (UMR8000), Université Paris-Sud, CNRS, Université Paris Saclay, Orsay 91405, France
| | - Vitali Zhaunerchyk
- Department of Physics, University of Gothenburg, 405 30 Gothenburg, Sweden
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Bouchoux G. Gas phase basicities of polyfunctional molecules. Part 6: Cyanides and isocyanides. MASS SPECTROMETRY REVIEWS 2018; 37:533-564. [PMID: 28621817 DOI: 10.1002/mas.21538] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Accepted: 05/15/2017] [Indexed: 05/26/2023]
Abstract
This paper gathers structural and thermochemical informations related to the gas-phase basicity of molecules containing cyanides (nitriles) and isocyanides (isonitriles) functional groups. It constitutes the sixth part of a general review devoted to gas-phase basicities of polyfunctional compounds. A large corpus of cyanides and isocyanides molecules is examined under seven major chapters. In the first one, a rapid overview of the definitions and methods leading to gas-phase basicity, GB, proton affinity, PA, and protonation entropy, Δp S°, is given. In the same chapter, several aspects of the gas phase chemistry of protonated cyanides and isocyanides are also presented. Chapters II-VI detail the protonation energetics of aliphatic, unsaturated, and heteroatom substituted (halogens, O, S, N, P) cyanides. A seventh chapter is devoted to isocyanides. Experimental data available in the literature (120 references) were reevaluated according to the presently adopted basicity scale that is the NIST database anchored to PA(NH3 ) = 853.6 kJ/mol and GB (NH3 ) = 819 kJ/mol. In this latter source, however, several erroneous values have been identified which were corrected in the present review. Structural and energetic information given by G4MP2 quantum chemistry computations on ca. 60 typical systems are presented. The present review includes the GB, PA, and Δp S° values of ca. 110 cyanides and isocyanides, and, for selected examples, is completed by a set of computed heats of formation (Δf H°) at 0 and 298 K.
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Affiliation(s)
- Guy Bouchoux
- Département de Chimie, Laboratoire de Chimie Moléculaire, UMR CNRS 9168, Ecole Polytechnique, Palaiseau, France
- Université Paris-Sud XI, ICMO, Orsay, France
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Dias HJ, Bento MVB, da Silva ÉH, Saturnino-Júnior A, de Oliveira MF, Vessecchi R, Parreira RLT, Crotti AEM. Gas-phase fragmentation reactions of protonated cocaine: New details to an old story. JOURNAL OF MASS SPECTROMETRY : JMS 2018; 53:203-213. [PMID: 29247586 DOI: 10.1002/jms.4053] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Revised: 11/22/2017] [Accepted: 12/05/2017] [Indexed: 06/07/2023]
Affiliation(s)
- Herbert J Dias
- Departamento de Química, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brazil
- Núcleo de Pesquisas em Ciências Exatas e Tecnológicas, Universidade de Franca, Franca, SP, Brazil
| | - Mariana V B Bento
- Núcleo de Pesquisas em Ciências Exatas e Tecnológicas, Universidade de Franca, Franca, SP, Brazil
| | | | - Andrade Saturnino-Júnior
- Núcleo de Pesquisas em Ciências Exatas e Tecnológicas, Universidade de Franca, Franca, SP, Brazil
| | - Marcelo F de Oliveira
- Departamento de Química, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brazil
| | - Ricardo Vessecchi
- Departamento de Química, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brazil
| | - Renato L T Parreira
- Núcleo de Pesquisas em Ciências Exatas e Tecnológicas, Universidade de Franca, Franca, SP, Brazil
| | - Antônio E M Crotti
- Departamento de Química, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brazil
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Nikolić D, Macias C, Lankin DC, van Breemen RB. Collision-induced dissociation of phenethylamides: role of ion-neutral complexes. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2017; 31:1385-1395. [PMID: 28558170 PMCID: PMC5555735 DOI: 10.1002/rcm.7915] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Revised: 04/21/2017] [Accepted: 05/25/2017] [Indexed: 06/07/2023]
Abstract
RATIONALE Phenethylamides are a large group of naturally occurring molecules found both in the plant and animal kingdoms. In addition, they are used as intermediates for the synthesis of pharmaceutically important dihydro- and tetrahydroisoquinolines. To enable efficient characterization of this class of molecules, a detailed mass spectrometric fragmentation study of a broad series of analogs was carried out. METHODS The test compounds were synthesized using standard methods for amide bond formation. Low-energy high-resolution tandem mass spectra were acquired on a hybrid quadrupole/time-of-flight mass spectrometer using positive ion electrospray ionization. RESULTS A total of 26 analogs were investigated in the study. Fragmentation of phenethylamides was found to proceed via intermediate ion-neutral complexes. The complexes can break down via multiple pathways including dissociation, proton transfer, Friedel-Crafts acylation, and single electron transfer. The relative contribution of each of these pathways strongly depends on the structure of the coupling amine and acid. CONCLUSIONS A general scheme for the fragmentation of phenethylamides was developed. This study further extends the knowledge base of the ion-neutral complex by discovering Friedel-Crafts acylation as a novel reaction. The strong influence of minor structural modifications on the fragmentation patterns highlights the importance of testing many analogs in order to fully predict a fragmentation pattern of a particular class of molecules.
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Affiliation(s)
- Dejan Nikolić
- Corresponding Author: Dejan Nikolić, Department of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago, 833 S. Wood St., Chicago, IL 60612-7231, Telephone (312) 413-5867, FAX (312) 996-7107,
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10
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da Silva-Junior EA, Paludo CR, Gouvea DR, Kato MJ, Furtado NAJC, Lopes NP, Vessecchi R, Pupo MT. Gas-phase fragmentation of protonated piplartine and its fungal metabolites using tandem mass spectrometry and computational chemistry. JOURNAL OF MASS SPECTROMETRY : JMS 2017; 52:517-525. [PMID: 28581151 DOI: 10.1002/jms.3955] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Revised: 05/29/2017] [Accepted: 05/31/2017] [Indexed: 06/07/2023]
Abstract
Piplartine, an alkaloid produced by plants in the genus Piper, displays promising anticancer activity. Understanding the gas-phase fragmentation of piplartine by electrospray ionization tandem mass spectrometry can be a useful tool to characterize biotransformed compounds produced by in vitro and in vivo metabolism studies. As part of our efforts to understand natural product fragmentation in electrospray ionization tandem mass spectrometry, the gas-phase fragmentation of piplartine and its two metabolites 3,4-dihydropiplartine and 8,9-dihydropiplartine, produced by the endophytic fungus Penicillium crustosum VR4 biotransformation, were systematically investigated. Proposed fragmentation reactions were supported by ESI-MS/MS data and computational thermochemistry. Cleavage of the C-7 and N-amide bond, followed by the formation of an acylium ion, were characteristic fragmentation reactions of piplartine and its analogs. The production of the acylium ion was followed by three consecutive and competitive reactions that involved methyl and methoxyl radical eliminations and neutral CO elimination, followed by the formation of a four-member ring with a stabilized tertiary carbocation. The absence of a double bond between carbons C-8 and C-9 in 8,9-dihydropiplartine destabilized the acylium ion and resulted in a fragmentation pathway not observed for piplartine and 3,4-dihydropiplartine. These results contribute to the further understanding of alkaloid gas-phase fragmentation and the future identification of piplartine metabolites and analogs using tandem mass spectrometry techniques. Copyright © 2017 John Wiley & Sons, Ltd.
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Affiliation(s)
- E A da Silva-Junior
- Departamento de Ciências Farmacêuticas, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Av. do Café, S/N, Ribeirão Preto, SP, 14040-903, Brazil
| | - C R Paludo
- Departamento de Ciências Farmacêuticas, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Av. do Café, S/N, Ribeirão Preto, SP, 14040-903, Brazil
| | - D R Gouvea
- Núcleo de Pesquisa em Produtos Naturais e Sintéticos (NPPNS), Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Av. do Café, S/N, Ribeirão Preto, SP, 14040-903, Brazil
| | - M J Kato
- Instituto de Química, Universidade de São Paulo, Av. Professor Lineu Prestes, São Paulo, SP, 05508-000, Brazil
| | - N A J C Furtado
- Departamento de Ciências Farmacêuticas, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Av. do Café, S/N, Ribeirão Preto, SP, 14040-903, Brazil
| | - N P Lopes
- Núcleo de Pesquisa em Produtos Naturais e Sintéticos (NPPNS), Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Av. do Café, S/N, Ribeirão Preto, SP, 14040-903, Brazil
| | - R Vessecchi
- Departamento de Química, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Av. Bandeirantes, 3900, Ribeirão Preto, SP, 14040-901, Brazil
| | - M T Pupo
- Departamento de Ciências Farmacêuticas, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Av. do Café, S/N, Ribeirão Preto, SP, 14040-903, Brazil
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11
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Ma G, Liu G, Shen S, Chai Y, Yue L, Zhao S, Pan Y. Competitive benzyl cation transfer and proton transfer: collision-induced mass spectrometric fragmentation of protonated N,N-dibenzylaniline. JOURNAL OF MASS SPECTROMETRY : JMS 2017; 52:197-203. [PMID: 28109035 DOI: 10.1002/jms.3914] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Revised: 01/14/2017] [Accepted: 01/17/2017] [Indexed: 06/06/2023]
Abstract
Collision-induced dissociation of protonated N,N-dibenzylaniline was investigated by electrospray tandem mass spectrometry. Various fragmentation pathways were dominated by benzyl cation and proton transfer. Benzyl cation transfers from the initial site (nitrogen) to benzylic phenyl or aniline phenyl ring. The benzyl cations transfer to the two different sites, and both result in the benzene loss combined with 1,3-H shift. In addition, after the benzyl cation transfers to the benzylic phenyl ring, 1,2-H shift and 1,4-H shift proceed competitively to trigger the diphenylmethane loss and aniline loss, respectively. Deuterium labeling experiments, substituent labeling experiments and density functional theory calculations were performed to support the proposed benzyl cation and proton transfer mechanism. Overall, this study enriches the knowledge of fragmentation mechanisms of protonated N-benzyl compounds. Copyright © 2017 John Wiley & Sons, Ltd.
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Affiliation(s)
- G Ma
- Deparment of Chemistry, Zhejiang University, 38 Zheda Road, Hangzhou, 310027, Zhejiang, China
| | - G Liu
- Radiation Monitoring Technical Center, Ministry of Environmental Protection of China, 306 Wen Yi Road, Hangzhou, 310012, China
| | - S Shen
- Deparment of Chemistry, Zhejiang University, 38 Zheda Road, Hangzhou, 310027, Zhejiang, China
| | - Y Chai
- College of Pharmaceutical Sciences, Zhejiang University, 866 Yuhangtang Road, Hangzhou, 310058, China
| | - L Yue
- Deparment of Chemistry, Zhejiang University, 38 Zheda Road, Hangzhou, 310027, Zhejiang, China
| | - S Zhao
- Radiation Monitoring Technical Center, Ministry of Environmental Protection of China, 306 Wen Yi Road, Hangzhou, 310012, China
| | - Y Pan
- Deparment of Chemistry, Zhejiang University, 38 Zheda Road, Hangzhou, 310027, Zhejiang, China
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12
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Le Pogam P, Le Lamer AC, Legouin B, Boustie J, Rondeau D. In situ DART-MS as a Versatile and Rapid Dereplication Tool in Lichenology: Chemical Fingerprinting of Ophioparma ventosa. PHYTOCHEMICAL ANALYSIS : PCA 2016; 27:354-363. [PMID: 27687704 DOI: 10.1002/pca.2635] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Revised: 05/25/2016] [Accepted: 05/27/2016] [Indexed: 06/06/2023]
Abstract
INTRODUCTION Lichens widely occur all over the world and are known to produce unique secondary metabolites with various biological activities. OBJECTIVE To develop high-throughput screening approaches requiring little to no sample preparation to alleviate the dereplication holdup and accelerate the discovery workflow of new structures from lichens. METHODOLOGY The extracellular distribution of lichen metabolites is incentive for in situ chemical profiling of lichens using the ambient mass spectrometry DART-MS. For this purpose, the chlorolichen Ophioparma ventosa, producing an array of lichen polyphenolics that encompass the main structural classes associated to lichen chemodiversity, represented a relevant model to assess the versatility of this platform. The feasibility of this approach was first established by analysing the pure compounds known from this species prior to being extended to different solid organs of the lichen. RESULTS All tested compounds could be detected in positive and negative ion modes, most often with prevalent protonated or deprotonated molecules. Only depsides underwent a significant in-source fragmentation in both ionisation modes, which should be regarded as an added value for their structural elucidation. In situ DART-MS analyses of Ophioparma ventosa provided an extensive chemical profile and noteworthy pinpointed miriquidic acid, an unusual lichen depside so far unknown within this species. At last, in situ DART-MS granted a first insight into the distribution of the metabolites within the lichen. CONCLUSION DART-MS represents a versatile tool to the wide field of lichenology, facilitating accelerated and sharp analyses of lichens and bypassing costly and tedious procedures of solvent extraction. Copyright © 2016 John Wiley & Sons, Ltd.
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Affiliation(s)
- Pierre Le Pogam
- Laboratoire de Pharmacognosie, Equipe PNSCM (ISCR UMR CNRS 6226), Faculté des Sciences Pharmaceutiques et Biologiques, 2 av. du Pr Léon-Bernard, 35042, Rennes Cedex, France
| | - Anne-Cécile Le Lamer
- Laboratoire de Pharmacognosie, Equipe PNSCM (ISCR UMR CNRS 6226), Faculté des Sciences Pharmaceutiques et Biologiques, 2 av. du Pr Léon-Bernard, 35042, Rennes Cedex, France.
- Université Paul Sabatier Toulouse 3, 118 Route de Narbonne, 31062, Toulouse Cedex 09, France.
| | - Béatrice Legouin
- Laboratoire de Pharmacognosie, Equipe PNSCM (ISCR UMR CNRS 6226), Faculté des Sciences Pharmaceutiques et Biologiques, 2 av. du Pr Léon-Bernard, 35042, Rennes Cedex, France
| | - Joël Boustie
- Laboratoire de Pharmacognosie, Equipe PNSCM (ISCR UMR CNRS 6226), Faculté des Sciences Pharmaceutiques et Biologiques, 2 av. du Pr Léon-Bernard, 35042, Rennes Cedex, France
| | - David Rondeau
- Institut d'Electronique et de Télécommunication de Rennes (IETR UMR CNRS 6164), Université de Rennes 1, Campus de Beaulieu, 263 Avenue du General Leclerc, 35042, Rennes Cedex, France.
- Département de Chimie, Université de Bretagne Occidentale, 6 avenue le Gorgeu, 29238, Brest Cedex 03, France.
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13
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Wright P, Alex A, Pullen F. Predicting collision-induced dissociation mass spectra: understanding the role of the mobile proton in small molecule fragmentation. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2016; 30:1163-1175. [PMID: 27525343 DOI: 10.1002/rcm.7521] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
RATIONALE Intramolecular proton migration has been reported to be required for fragmentation by collision-induced dissociation (CID). If the collision energy is required to provide energy for proton movement to a ‘dissociative’ site, it may be possible to predict the optimal collision energy for fragmentation using quantum computational chemistry software. A greater understanding of the mechanism(s) of proton migration is necessary. METHODS The product ion spectra of seven compounds were obtained at collision energies stepped in the range from 5 to 50 eV, with precursor ions being generated in positive ion mode by both atmospheric pressure chemical ionization (APCI) and electrospray ionisation (ESI) (using an ESCi ionisation source with or without corona discharge, respectively). The products ions observed at each collision energy were assessed in terms of structure to ascertain if they were formed as a result of protonation at the initial ionisation site or if the proton had migrated to a dissociative site. RESULTS Proton migration was shown to be independent of collision energy, stability of the protonated molecule and the distance that the proton moved. Therefore, proton migration is not a barrier to fragmentation as the proton appears to be fully mobile at 5 eV. As proton migration is independent of collision energy for these compounds, whereas fragmentation is energy dependent, protonation at the dissociative site alone is not sufficient to cause bond cleavage. CONCLUSIONS The role of collision energy in bond cleavage may be to increase the vibrational energy of the bond and/or increase the rate of bond cleavage such that it occurs within the residence time of the ion within the collision cell rather than to supply the energy for proton migration. Therefore, quantum chemistry alone cannot predict the collision energies appropriate for fragmentation on the basis of modelling proton movements.
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14
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Xia H, Zhang Y, Pavlov J, Jariwala FB, Attygalle AB. Competitive homolytic and heterolytic decomposition pathways of gas-phase negative ions generated from aminobenzoate esters. JOURNAL OF MASS SPECTROMETRY : JMS 2016; 51:245-253. [PMID: 26956391 DOI: 10.1002/jms.3740] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2015] [Revised: 11/11/2015] [Accepted: 11/24/2015] [Indexed: 06/05/2023]
Abstract
An alkyl-radical loss and an alkene loss are two competitive fragmentation pathways that deprotonated aminobenzoate esters undergo upon activation under mass spectrometric conditions. For the meta and para isomers, the alkyl-radical loss by a homolytic cleavage of the alkyl-oxygen bond of the ester moiety is the predominant fragmentation pathway, while the contribution from the alkene elimination by a heterolytic pathway is less significant. In contrast, owing to a pronounced charge-mediated ortho effect, the alkene loss becomes the predominant pathway for the ortho isomers of ethyl and higher esters. Results from isotope-labeled compounds confirmed that the alkene loss proceeds by a specific γ-hydrogen transfer mechanism that resembles the McLafferty rearrangement for radical cations. Even for the para compounds, if the alkoxide moiety bears structural motifs required for the elimination of a more stable alkene molecule, the heterolytic pathway becomes the predominant pathway. For example, in the spectrum of deprotonated 2-phenylethyl 4-aminobenzoate, m/z 136 peak is the base peak because the alkene eliminated is styrene. Owing to the fact that all deprotonated aminobenzoate esters, irrespective of the size of the alkoxy group, upon activation fragment to form an m/z 135 ion, aminobenzoate esters in mixtures can be quantified by precursor ion discovery mass spectrometric experiments.
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Affiliation(s)
- Hanxue Xia
- Center for Mass Spectrometry, Department of Chemistry, Chemical Biology, and Biomedical Engineering, Stevens Institute of Technology, Hoboken, NJ, 07030, USA
| | | | - Julius Pavlov
- Center for Mass Spectrometry, Department of Chemistry, Chemical Biology, and Biomedical Engineering, Stevens Institute of Technology, Hoboken, NJ, 07030, USA
| | - Freneil B Jariwala
- Center for Mass Spectrometry, Department of Chemistry, Chemical Biology, and Biomedical Engineering, Stevens Institute of Technology, Hoboken, NJ, 07030, USA
| | - Athula B Attygalle
- Center for Mass Spectrometry, Department of Chemistry, Chemical Biology, and Biomedical Engineering, Stevens Institute of Technology, Hoboken, NJ, 07030, USA
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15
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Fusetto R, White JM, Hutton CA, O'Hair RAJ. Structure of olefin–imidacloprid and gas-phase fragmentation chemistry of its protonated form. Org Biomol Chem 2016; 14:1715-26. [DOI: 10.1039/c5ob02371h] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Gas-phase fragmentation reactions of protonated olefin–imidacloprid.
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Affiliation(s)
- Roberto Fusetto
- School of Chemistry
- Bio21 Institute of Molecular Science and Biotechnology
- and ARC Centre of Excellence for Free Radical Chemistry and Biotechnology
- University of Melbourne
- Melbourne
| | - Jonathan M. White
- School of Chemistry
- Bio21 Institute of Molecular Science and Biotechnology
- and ARC Centre of Excellence for Free Radical Chemistry and Biotechnology
- University of Melbourne
- Melbourne
| | - Craig A. Hutton
- School of Chemistry
- Bio21 Institute of Molecular Science and Biotechnology
- and ARC Centre of Excellence for Free Radical Chemistry and Biotechnology
- University of Melbourne
- Melbourne
| | - Richard A. J. O'Hair
- School of Chemistry
- Bio21 Institute of Molecular Science and Biotechnology
- and ARC Centre of Excellence for Free Radical Chemistry and Biotechnology
- University of Melbourne
- Melbourne
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16
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Xu S, Zhang Y, Errabelli R, Attygalle AB. Ambulation of Incipient Proton during Gas-Phase Dissociation of Protonated Alkyl Dihydrocinnamates. J Org Chem 2015; 80:9468-79. [DOI: 10.1021/acs.joc.5b01390] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Sihang Xu
- Center for Mass Spectrometry,
Department of Chemistry, Chemical Biology, and Biomedical Engineering, Stevens Institute of Technology, Hoboken, New Jersey 07030, United States
| | - Yong Zhang
- Center for Mass Spectrometry,
Department of Chemistry, Chemical Biology, and Biomedical Engineering, Stevens Institute of Technology, Hoboken, New Jersey 07030, United States
| | - Ramu Errabelli
- Center for Mass Spectrometry,
Department of Chemistry, Chemical Biology, and Biomedical Engineering, Stevens Institute of Technology, Hoboken, New Jersey 07030, United States
| | - Athula B. Attygalle
- Center for Mass Spectrometry,
Department of Chemistry, Chemical Biology, and Biomedical Engineering, Stevens Institute of Technology, Hoboken, New Jersey 07030, United States
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17
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Bouchoux G. Gas-phase basicities of polyfunctional molecules. Part 4: Carbonyl groups as basic sites. MASS SPECTROMETRY REVIEWS 2015; 34:493-534. [PMID: 24399766 DOI: 10.1002/mas.21416] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2013] [Revised: 09/30/2013] [Accepted: 09/30/2013] [Indexed: 06/03/2023]
Abstract
This article constitutes the fourth part of a general review of the gas-phase protonation thermochemistry of polyfunctional molecules (Part 1: Theory and methods, Mass Spectrom Rev 2007, 26:775-835, Part 2: Saturated basic sites, Mass Spectrom Rev 2012, 31:353-390, Part 3: Amino acids, Mass Spectrom Rev 2012, 31:391-435). This fourth part is devoted to carbonyl containing polyfunctional molecules. After a short reminder of the methods of determination of gas-phase basicity and the underlying physicochemical concepts, specific examples are examined under two major chapters. In the first one, aliphatic and unsaturated (conjugated and cyclic) ketones, diketones, ketoalcohols, and ketoethers are considered. A second chapter describes the protonation energetic of gaseous acids and derivatives including diacids, diesters, diamides, anhydrides, imides, ureas, carbamates, amino acid derivatives, and peptides. Experimental data were re-evaluated according to the presently adopted basicity scale. Structural and energetic information given by G3 and G4 quantum chemistry computations on typical systems are presented.
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Affiliation(s)
- Guy Bouchoux
- Département de Chimie, Laboratoire des Mécanismes Réactionnels, Ecole Polytechnique, 91120, Palaiseau, France
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18
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Chen J, Green KB, Nichols KK. Characterization of Wax Esters by Electrospray Ionization Tandem Mass Spectrometry: Double Bond Effect and Unusual Product Ions. Lipids 2015; 50:821-36. [PMID: 26178197 DOI: 10.1007/s11745-015-4044-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2014] [Accepted: 06/22/2015] [Indexed: 11/26/2022]
Abstract
A series of different types of wax esters (represented by RCOOR') were systematically studied by using electrospray ionization (ESI) collision-induced dissociation tandem mass spectrometry (MS/MS) along with pseudo MS(3) (in-source dissociation combined with MS/MS) on a quadrupole time-of-flight (Q-TOF) mass spectrometer. The tandem mass spectra patterns resulting from dissociation of ammonium/proton adducts of these wax esters were influenced by the wax ester type and the collision energy applied. The product ions [RCOOH2](+), [RCO](+) and [RCO-H2O](+) that have been reported previously were detected; however, different primary product ions were demonstrated for the three wax ester types including: (1) [RCOOH2](+) for saturated wax esters, (2) [RCOOH2](+), [RCO](+) and [RCO-H2O](+) for unsaturated wax esters containing only one double bond in the fatty acid moiety or with one additional double bond in the fatty alcohol moiety, and (3) [RCOOH2](+) and [RCO](+) for unsaturated wax esters containing a double bond in the fatty alcohol moiety alone. Other fragments included [R'](+) and several series of product ions for all types of wax esters. Interestingly, unusual product ions were detected, such as neutral molecule (including water, methanol and ammonia) adducts of [RCOOH2](+) ions for all types of wax esters and [R'-2H](+) ions for unsaturated fatty acyl-containing wax esters. The patterns of tandem mass spectra for different types of wax esters will inform future identification and quantification approaches of wax esters in biological samples as supported by a preliminary study of quantification of isomeric wax esters in human meibomian gland secretions.
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Affiliation(s)
- Jianzhong Chen
- Applied Biotechnology Branch, Air Force Research Laboratory, Dayton, OH, 45433, USA,
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19
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Lyczko J, Beach DG, Gabryelski W. Commercial formaldehyde standard for mass calibration in mass spectrometry. JOURNAL OF MASS SPECTROMETRY : JMS 2015; 50:463-469. [PMID: 25800182 DOI: 10.1002/jms.3550] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2014] [Revised: 11/19/2014] [Accepted: 11/19/2014] [Indexed: 06/04/2023]
Abstract
Common calibration standards for mass spectrometry can be a source of many problems including instrument contamination, ionization suppression and formation of unidentified ions during subsequent analysis. In this article, we present a new approach for the calibration of mass analyzers such as a quadrupole-time-of-flight mass spectrometry using a diluted solution of commercial formaldehyde. Formaldehyde is an inexpensive and commonly used solvent, and its intrinsic polymerization leads to the formation of polyoxymethylene (POM) oligomers, which are excellent multiple calibration standards for a low-mass spectral region (up to m/z 400) in the positive and negative mode of electrospray ionization. We explore the nature and origin of these polymeric species and attributed them to chemical reactions of formaldehyde and stabilizing agents in commercial formaldehyde solutions and during electrospray ionization. In contrast to other calibrants, POM oligomers do not contaminate the instrument and can easily be removed from the sample delivery system. Using tandem mass spectrometry, we elucidate the structures of the detected POM oligomers and report their reference masses, which are tightly spaced by 30 mass units. In our calibration method, mass errors of <5 ppm can be obtained from m/z 20-400 using external calibration with a simple one-point zero-order correction of spectral data and without the need for operation of a dual spray or internal calibrants. Our approach will be particularly useful for those interested in the analysis of fragile ions with low m/z values and can function at instrumental conditions required for analysis of the most labile metabolites and environmental contaminants.
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Affiliation(s)
- Jadwiga Lyczko
- Department of Chemistry, University of Guelph, Guelph, ON, Canada
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20
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Rajabi K. Microsecond pulsed hydrogen/deuterium exchange of electrosprayed ubiquitin ions stored in a linear ion trap. Phys Chem Chem Phys 2015; 17:3607-16. [DOI: 10.1039/c4cp04716h] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The pulsed HDX MS method is sampling a population of ubiquitin ions with a similar backbone fold as solution.
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Affiliation(s)
- Khadijeh Rajabi
- Department of Chemistry
- University of British Columbia (UBC)
- Vancouver
- Canada
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21
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Grossert JS, Cubero Herrera L, Ramaley L, Melanson JE. Studying the chemistry of cationized triacylglycerols using electrospray ionization mass spectrometry and density functional theory computations. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2014; 25:1421-1440. [PMID: 24867430 DOI: 10.1007/s13361-014-0917-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2014] [Revised: 04/01/2014] [Accepted: 04/02/2014] [Indexed: 06/03/2023]
Abstract
Analysis of triacylglycerols (TAGs), found as complex mixtures in living organisms, is typically accomplished using liquid chromatography, often coupled to mass spectrometry. TAGs, weak bases not protonated using electrospray ionization, are usually ionized by adduct formation with a cation, including those present in the solvent (e.g., Na(+)). There are relatively few reports on the binding of TAGs with cations or on the mechanisms by which cationized TAGs fragment. This work examines binding efficiencies, determined by mass spectrometry and computations, for the complexation of TAGs to a range of cations (Na(+), Li(+), K(+), Ag(+), NH4(+)). While most cations bind to oxygen, Ag(+) binding to unsaturation in the acid side chains is significant. The importance of dimer formation, [2TAG + M](+) was demonstrated using several different types of mass spectrometers. From breakdown curves, it became apparent that two or three acid side chains must be attached to glycerol for strong cationization. Possible mechanisms for fragmentation of lithiated TAGs were modeled by computations on tripropionylglycerol. Viable pathways were found for losses of neutral acids and lithium salts of acids from different positions on the glycerol moiety. Novel lactone structures were proposed for the loss of a neutral acid from one position of the glycerol moiety. These were studied further using triple-stage mass spectrometry (MS(3)). These lactones can account for all the major product ions in the MS(3) spectra in both this work and the literature, which should allow for new insights into the challenging analytical methods needed for naturally occurring TAGs.
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Affiliation(s)
- J Stuart Grossert
- National Research Council Canada, Halifax, Nova Scotia, B3H 3Z1, Canada,
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22
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Sartori LR, Vessecchi R, Humpf HU, Da Costa FB, Lopes NP. A systematic investigation of the fragmentation pattern of two furanoheliangolide C-8 stereoisomers using electrospray ionization mass spectrometry. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2014; 28:723-730. [PMID: 24573803 DOI: 10.1002/rcm.6839] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2013] [Revised: 01/08/2014] [Accepted: 01/12/2014] [Indexed: 06/03/2023]
Abstract
RATIONALE Budlein A is a sesquiterpene lactone (STL) with some reported biological activities. Pre-clinical studies to identify in vivo metabolites often employ hyphenated techniques such as liquid chromatography/tandem mass spectrometry (LC/MS/MS). It is also possible to use the fragmentation pattern obtained by Collision-Induced Dissociation (CID) and Higher Energy Collision-Induced Dissociation (HCD) to distinguish between the stereoisomers budlein A and centratherin. METHODS The experiments were carried out in the positive mode using four different spectrometers with an electrospray ionization (ESI) source: (a) Waters ACQUITY(®) TQD triple quadrupole mass spectrometer (QqQ), (b) AB Sciex API 4000 QTrap(®) (QqQ), (c) Bruker Daltonics micrOTOF™-Q II (time-of-flight, QTOF), and (d) Thermo Scientific LTQ Orbitrap XL hybrid FTMS (Fourier transform mass spectrometer). Computational chemistry studies helped to identify the protonation sites. The B3LYP/6-31G(d) model furnished the equilibrium geometries and energies. RESULTS The stereochemistry (α- or β-orientation) of the centratherin and budlein A side-chain esters influences the fragmentation pattern recorded on QqQ, QTOF, and Orbitrap-HCD. On QqQ, centratherin releases the side chain, to generate the m/z 275 fragment ion, whereas budlein A gives the m/z 83 fragment ion. On QTOF and Orbitrap-HCD, only budlein A affords the m/z 293 and 83 fragment ions, respectively. CONCLUSIONS The data suggest that proton migration governs the fragmentation pathways under α- or β-orientation. The difference in the QqQ, QTOF, and Orbitrap-HCD spectral profiles of each isomer can help to distinguish between centratherin and budlein A using MS/MS, which becomes an alternative to nuclear magnetic resonance (NMR) analysis.
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Affiliation(s)
- Lucas Rossi Sartori
- Núcleo de Pesquisa em Produtos Naturais e Sintéticos (NPPNS) - Departamento de Física e Química, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Avenida do Café s/n, 14040-903, Ribeirão Preto, SP, Brazil; Institute of Food Chemistry, Westfälische Wilhelms-Universität Münster, Corrensstrasse 45, 48149, Münster, Germany
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