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Wang X, Norgate E, Dai J, Benoit F, Bristow T, England RM, Kalapothakis JMD, Barran PE. Conformational landscapes of rigid and flexible molecules explored with variable temperature ion mobility-mass spectrometry. Nat Commun 2025; 16:4183. [PMID: 40324998 PMCID: PMC12052783 DOI: 10.1038/s41467-025-59065-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2024] [Accepted: 04/10/2025] [Indexed: 05/07/2025] Open
Abstract
Understanding the effect of temperature to the structural integrity of proteins is relevant to diverse areas such as biotechnology and climate change. Variable temperature ion mobility-mass spectrometry (VT-IM-MS) can measure the effect of temperature on conformational landscapes. To delineate collision effects from structural change we report measurements using molecules with different degrees of rigidity namely: poly (L-lysine) (PLL) dendrimer, ubiquitin, β-casein and α-synuclein from 190-350 K. The CCS of PLL dendrimer varies with temperature consistent with collision theory, by contrast, the structure of each protein alters with notable restructuring at 350 K and 250 K, following predicted in vitro stability curves. At 210 K and 190 K we kinetically trap unfolding intermediates. For alpha-synuclein, the 13+ ions present two distinct conformers and VT-IM-MS measurements allow us to calculate the transition rate and activation energies of their conversion. These data exemplify the capacity of VT-IM-MS to provide insights on the thermodynamics of conformational restructuring.
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Affiliation(s)
- Xudong Wang
- Michael Barber Centre for Collaborative Mass Spectrometry, Manchester Institute of Biotechnology, Department of Chemistry, The University of Manchester, 131 Princess Street, Manchester, M1 7DN, UK
| | - Emma Norgate
- Michael Barber Centre for Collaborative Mass Spectrometry, Manchester Institute of Biotechnology, Department of Chemistry, The University of Manchester, 131 Princess Street, Manchester, M1 7DN, UK
| | - Junxiao Dai
- Michael Barber Centre for Collaborative Mass Spectrometry, Manchester Institute of Biotechnology, Department of Chemistry, The University of Manchester, 131 Princess Street, Manchester, M1 7DN, UK
| | - Florian Benoit
- Michael Barber Centre for Collaborative Mass Spectrometry, Manchester Institute of Biotechnology, Department of Chemistry, The University of Manchester, 131 Princess Street, Manchester, M1 7DN, UK
| | - Tony Bristow
- Chemical Development, Pharmaceutical Technology and Development, Operations, AstraZeneca, Charter Way, Macclesfield, SK102NA, UK
| | - Richard M England
- Advanced Drug Delivery, Pharmaceutical Sciences, R&D, AstraZeneca, Macclesfield, SK10 2NA, UK
| | - Jason M D Kalapothakis
- Michael Barber Centre for Collaborative Mass Spectrometry, Manchester Institute of Biotechnology, Department of Chemistry, The University of Manchester, 131 Princess Street, Manchester, M1 7DN, UK
| | - Perdita E Barran
- Michael Barber Centre for Collaborative Mass Spectrometry, Manchester Institute of Biotechnology, Department of Chemistry, The University of Manchester, 131 Princess Street, Manchester, M1 7DN, UK.
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2
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Ucur B, Shiels OJ, Maccarone AT, Blanksby SJ, Trevitt AJ. What Drives the Vehicle Mechanism? Protonation Isomer Interconversion of Arylamine Derivatives Probed with Solvent-Mediated Kinetics. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2025; 36:601-612. [PMID: 39937067 DOI: 10.1021/jasms.4c00470] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/13/2025]
Abstract
Reactions with mobile protons occur under electrospray ionization (ESI) in many applications of mass spectrometry. Understanding how protonation isomers (protomers) form and how molecular structure influences protomer interconversion provides fundamental insight into ESI mechanisms, which can then be exploited to rationalize ion mobility and ion activation processes for robust analyte detection. Using ten arylamine protomer systems, this paper establishes the key substrate properties that influence protomer isomerism. Protomers from ten arylamines are separated by differential ion mobility spectrometry (DMS) mass spectrometry and identified by characteristic collision-induced dissociation mass spectra. These assignments are further rationalized using quantum chemical calculations (M06-2X/6-31G(2df,p)). Based on these assignments, mobility-selected protomers are then allowed to react with methanol vapor under atmospheric and reduced pressure conditions (2.5 mTorr, 300 K). The latter enabled measurements of the second-order rate coefficients for methanol-catalyzed protomer isomerization, which span 3.9 × 10-11-2 × 10-13 cm3 molecule-1 s-1. Double-hybrid quantum chemical calculations (DSD-PBEP86-D3(BJ)/aug-cc-pVDZ) show that the direction of proton transfer is controlled by protomer relative stability, whereas reaction rates are controlled by a key transition state that separates the protonation sites. Computational exploration of a larger substituted-arylamine test-set shows that the protomer proton affinity generally correlates with energy of the key transition state. Applying the Bell-Evans-Polanyi principle to this reaction set highlights that outliers in the predictive model correspond to transition states with significant displacements along the reaction coordinate. This archetype system of derivatized arylamines provides a foundation to understand how substrate functionalization influences protomer isomerism for ions during ESI and predicts protonation isomer distributions.
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Affiliation(s)
- Boris Ucur
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, New South Wales 2522, Australia
| | - Oisin J Shiels
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, New South Wales 2522, Australia
| | - Alan T Maccarone
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, New South Wales 2522, Australia
| | - Stephen J Blanksby
- Central Analytical Research Facility and the School of Chemistry and Physics, Queensland University of Technology, Brisbane 4001, Australia
| | - Adam J Trevitt
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, New South Wales 2522, Australia
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3
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Arndt T, Schäfer M, Kuck D, Breugst M. A Unique Intramolecular Redox Reaction by Unidirectional Migration of Three Hydrogen Atoms: Theoretical Elucidation of the 3H-Transfer Sequence. Chemistry 2025; 31:e202404638. [PMID: 39840655 DOI: 10.1002/chem.202404638] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2024] [Revised: 01/20/2025] [Accepted: 01/21/2025] [Indexed: 01/23/2025]
Abstract
The intramolecular migration of three hydrogen atoms from one moiety of a gaseous radical cation to the other prior to fragmentation is an extremely rare type of redox reaction. Within the scope of this investigation, this scenario requires an ionized but electron-rich arene acceptor bearing a para-(3-hydroxyalkyl) residue. The precise mechanism of such unidirectional 3H transfer processes, including the order of the individual H transfer steps, has remained unclear in spite of previous isotope labelling and recent infrared ion spectroscopy (IRIS) studies. Herein, the details of this peculiar process have been investigated for ionized 4-(N,N-dimethylaminophenyl)-2-butanol, 2, by state-of-the-art density functional theory (DFT) calculations. The energetically most favorable pathway consists of a sequence of successive 1,4-, 1,6- and 1,5-H steps. During these steps the secondary alcohol functionality is oxidized to a carbonyl group and the radical-cationic aniline ring is reduced to an ionized 2,3-dihydroaniline unit. Several alternative sequences, such as three successive 1,5-H shifts, could be excluded. A concomitant unidirectional 2H migration reaction of ion 2 was also investigated and the intermediacy of ion-neutral complexes (INCs) enabling sequential hydride and proton transfer was confirmed by the calculations.
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Affiliation(s)
- Thiemo Arndt
- Institut für Chemie, Technische Universität Chemnitz, Straße der Nationen 62, 09111, Chemnitz, Germany
| | - Mathias Schäfer
- Department of Chemistry, University of Cologne, Greinstraße 4, 50939, Köln, Germany
| | - Dietmar Kuck
- Department of Chemistry, Bielefeld University, Universitätsstraße 25, 33615, Bielefeld, Germany
| | - Martin Breugst
- Institut für Chemie, Technische Universität Chemnitz, Straße der Nationen 62, 09111, Chemnitz, Germany
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4
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Lee J, Tantillo DJ, Wang LP, Fiehn O. Impact of Protonation Sites on Collision-Induced Dissociation-MS/MS Using CIDMD Quantum Chemistry Modeling. J Chem Inf Model 2024; 64:7457-7469. [PMID: 39329341 PMCID: PMC11492807 DOI: 10.1021/acs.jcim.4c00761] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/28/2024]
Abstract
Protonation is the most frequent adduct found in positive electrospray ionization collision-induced mass spectra (CID-MS/MS). In a parallel report Lee, J. J. Chem. Inf. Model. 2024, 10.1021/acs.jcim.4c00760, we developed a quantum chemistry framework to predict mass spectra by collision-induced dissociation molecular dynamics (CIDMD). As different protonation sites affect fragmentation pathways of a given molecule, the accuracy of predicting tandem mass spectra by CIDMD ultimately depends on the choice of its protomers. To investigate the impact of molecular protonation sites on MS/MS spectra, we compared CIDMD-predicted spectra to all available experimental MS/MS spectra by similarity matching. We probed 10 molecules with a total of 43 protomers, the largest study to date, including organic acids (sorbic acid, citramalic acid, itaconic acid, mesaconic acid, citraconic acid, and taurine) as well as aromatic amines including uracil, aniline, bufotenine, and psilocin. We demonstrated how different protomers can converge different fragmentation pathways to the same fragment ions but also may explain the presence of different fragment ions in experimental MS/MS spectra. For the first time, we used in silico MS/MS predictions to test the impact of solvents on proton affinities, comparing the gas phase and a mixture of acetonitrile/water (1:1). We also extended applications of in silico MS/MS predictions to investigate the impact of protonation sites on the energy barriers of isomerization between protomers via proton transfer. Despite our initial hypothesis that the thermodynamically most stable protomer should give the best match to the experiment, we found only weak inverse relationships between the calculated proton affinities and corresponding entropy similarities of experimental and CIDMD-predicted MS/MS spectra. CIDMD-predicted mechanistic details of fragmentation reaction pathways revealed a clear preference for specific protomer forms for several molecules. Overall, however, proton affinity was not a good predictor corresponding to the predicted CIDMD spectra. For example, for uracil, only one protomer predicted all experimental MS/MS fragment ions, but this protomer had neither the highest proton affinity nor the best MS/MS match score. Instead of proton affinity, the transfer of protons during the electrospray process from the initial protonation site (i.e., mobile proton model) better explains the differences between the thermodynamic rationale and experimental data. Protomers that undergo fragmentation with lower energy barriers have greater contributions to experimental MS/MS spectra than their thermodynamic Boltzmann populations would suggest. Hence, in silico predictions still need to calculate MS/MS spectra for multiple protomers, as the extent of distributions cannot be readily predicted.
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Affiliation(s)
- Jesi Lee
- Department of Chemistry, University of California, Davis, California 95616, United States
- West Coast Metabolomics Center, University of California, Davis, California 95616, United States
| | - Dean Joseph Tantillo
- Department of Chemistry, University of California, Davis, California 95616, United States
| | - Lee-Ping Wang
- Department of Chemistry, University of California, Davis, California 95616, United States
| | - Oliver Fiehn
- West Coast Metabolomics Center, University of California, Davis, California 95616, United States
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5
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Kumar M, Attygalle AB. Manipulating Non-Dissociative Transformations of Gaseous Ion Ensembles Prior to Ion-Mobility Separation. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2024; 35:1197-1207. [PMID: 38718179 DOI: 10.1021/jasms.4c00032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2024]
Abstract
Molecules with multiple sites capable of accepting protons form ensembles of protomers. The manifested protomer ratios in such ensembles are influenced by many experimental conditions. In a Synapt G2 ion mobility (IM)-enabled mass spectrometry system, there are several physical locations where ion population changes can be manifested. Using APCI-generated protomers of aminonaphthalenes, we investigated its intramolecular proton transfers from the N-protomer to the C-protomer. This lossless transformation of the N-protomer to the thermodynamically favored C-protomer can take place in the ion source itself. Initially, we learned that the cone gas slows down the transformation to the C-protomer. Gaseous ions are then accelerated in the first vacuum region, where ions undergo collisional activation (heating), which facilitates the transformation to the C-protomer. Afterward, the ions are mass selected and transferred to the pre-IM (Trap)-collision cell, where ions can also be transformed to the thermodynamically favored protomers. Trap accumulated ions are then released to the IM separator via a helium-filled entry cell. The role of helium is to minimize ion activation and scattering taking place upon entry to the high-pressure T-Wave IM separator (TWIMS). The helium cell is known to increase the IM peak resolution. However, we found that significant changes occur depending on the presence or absence of helium. Without helium, source-generated protomers rapidly changed to a predominantly thermodynamically favorable ensemble protomers. Apparently, the introduction of helium into the precell induced a dramatic decrease in collisional "heating" effect, which effectively slowed down the conversion rate of the amino-protomer into the more favorable ring-protomer. The final message is that mobilograms should not be considered as direct real-time, or intrinsic, representations of the protomer ratios in the ion source.
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Affiliation(s)
- Meenu Kumar
- Center for Mass Spectrometry, Department of Chemistry and Chemical Biology, Stevens Institute of Technology, Hoboken, New Jersey 07030, United States
| | - Athula B Attygalle
- Center for Mass Spectrometry, Department of Chemistry and Chemical Biology, Stevens Institute of Technology, Hoboken, New Jersey 07030, United States
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6
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Habeck T, Maciel EVS, Kretschmer K, Lermyte F. Charge site manipulation to enhance top-down fragmentation efficiency. Proteomics 2024; 24:e2300082. [PMID: 37043727 DOI: 10.1002/pmic.202300082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Revised: 04/05/2023] [Accepted: 04/06/2023] [Indexed: 04/14/2023]
Abstract
In recent years, top-down mass spectrometry has become a widely used approach to study proteoforms; however, improving sequence coverage remains an important goal. Here, two different proteins, α-synuclein and bovine carbonic anhydrase, were subjected to top-down collision-induced dissociation (CID) after electrospray ionisation. Two high-boiling solvents, DMSO and propylene carbonate, were added to the protein solution in low concentration (2%) and the effects on the top-down fragmentation patterns of the proteins were systematically investigated. Each sample was measured in triplicate, which revealed highly reproducible differences in the top-down CID fragmentation patterns in the presence of a solution additive, even if the same precursor charge state was isolated in the quadrupole of the instrument. Further investigation supports the solution condition-dependent selective formation of different protonation site isomers as the underlying cause of these differences. Higher sequence coverage was often observed in the presence of additives, and the benefits of this approach became even more evident when datasets from different solution conditions were combined, as increases up to 35% in cleavage coverage were obtained. Overall, this approach therefore represents a promising opportunity to increase top-down fragmentation efficiency.
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Affiliation(s)
- Tanja Habeck
- Department of Chemistry, Clemens-Schöpf-Institute of Chemistry and Biochemistry, Technical University of Darmstadt, Darmstadt, Hessen, Germany
| | - Edvaldo Vasconcelos Soares Maciel
- Department of Chemistry, Clemens-Schöpf-Institute of Chemistry and Biochemistry, Technical University of Darmstadt, Darmstadt, Hessen, Germany
| | - Kevin Kretschmer
- Department of Chemistry, Clemens-Schöpf-Institute of Chemistry and Biochemistry, Technical University of Darmstadt, Darmstadt, Hessen, Germany
| | - Frederik Lermyte
- Department of Chemistry, Clemens-Schöpf-Institute of Chemistry and Biochemistry, Technical University of Darmstadt, Darmstadt, Hessen, Germany
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7
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Lee J, Kim H, Lee H, Boraste DR, Kim K, Seo J. Protomer of Imipramine Captured in Cucurbit[7]uril. J Phys Chem A 2023; 127:10758-10765. [PMID: 38091518 DOI: 10.1021/acs.jpca.3c04556] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2023]
Abstract
Small molecules possessing multiple proton-accessible sites are important not only to many biological systems but also to host-guest chemistry; their protonation states are causal to boosting or hindering specific host-guest interactions. However, determining the protonation site is not trivial. Herein, we conduct electrospray ionization ion mobility spectrometry-mass spectrometry to imipramine, a known molecule with two protonation sites, based on the introduction of cucurbit[7]uril as a host molecule. For protonated imipramine, the proposed strategy allows clear distinction of the two protomers as host-guest complex ions and can be leveraged to capture the energetically less preferable protomer of the protonated imipramine.
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Affiliation(s)
- Jiyeon Lee
- Department of Chemistry, Pohang University of Science and Technology (POSTECH), Pohang 37673, Republic of Korea
| | - Hyerim Kim
- Department of Chemistry, Pohang University of Science and Technology (POSTECH), Pohang 37673, Republic of Korea
| | - Hochan Lee
- Department of Chemistry, Pohang University of Science and Technology (POSTECH), Pohang 37673, Republic of Korea
- Center for Self-assembly and Complexity, Institute for Basic Science, Pohang University of Science and Technology (POSTECH), Pohang 37673, Republic of Korea
| | - Deepak R Boraste
- Center for Self-assembly and Complexity, Institute for Basic Science, Pohang University of Science and Technology (POSTECH), Pohang 37673, Republic of Korea
| | - Kimoon Kim
- Department of Chemistry, Pohang University of Science and Technology (POSTECH), Pohang 37673, Republic of Korea
- Center for Self-assembly and Complexity, Institute for Basic Science, Pohang University of Science and Technology (POSTECH), Pohang 37673, Republic of Korea
| | - Jongcheol Seo
- Department of Chemistry, Pohang University of Science and Technology (POSTECH), Pohang 37673, Republic of Korea
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8
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Limbach MN, Do TD. Solvent-Free Nuclear Magnetic Resonance Spectroscopy of Charged Molecules. J Phys Chem A 2023; 127:9149-9157. [PMID: 37861438 DOI: 10.1021/acs.jpca.3c05241] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2023]
Abstract
Nuclear magnetic resonance (NMR) spectroscopy of small molecules protonated in a solvent-free environment was successfully demonstrated. The method is referred to as solvent-free protonation NMR (SoF-NMR). Leveraging matrix-assisted ionization (MAI), we generated protonated species of aniline, 4-chloroaniline, 4-aminobiphenyl, and benzocaine for NMR analysis under mild pressure and temperature conditions. The SoF-NMR spectra were compared to traditional solution NMR spectra, and the shift changes in nuclear spin resonance frequencies verify that these small molecules are protonated by 3-nitrobenzonitrile (3-NBN). As the sample pressure decreased, new spectral features appeared, indicating the presence of differently charged species. Several advantages of SoF-NMR are highlighted, such as the elimination of H/D exchange in labile protons, resulting in the precise observation of protons that are otherwise transient in solution. Notably, the data on benzocaine show evidence of neutral, N-protonated, and O-protonated species all in the same spectrum. SoF-NMR eliminates the solvent effects and interactions that can hinder important spectral features. Optimizing SoF-NMR will result in more cost-effective and efficient NMR experimentation to monitor high-temperature, solvent-free reactions. SoF-NMR has a viable future application for studying exchangeable protons, intermediates, and products in gas-phase chemistry.
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Affiliation(s)
- Miranda N Limbach
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Thanh D Do
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, United States
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9
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Valadbeigi Y, Causon T. Mechanism of formation and ion mobility separation of protomers and deprotomers of diaminobenzoic acids and aminophthalic acids. Phys Chem Chem Phys 2023. [PMID: 37490344 DOI: 10.1039/d3cp01968c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/27/2023]
Abstract
Aminobenzoic acids are well-established candidates for understanding the formation of isomeric ions in positive mode electrospray ionization as they yield both N- and O-protomers (prototropic isomers) at the amine and carbonyl sites, respectively. In the present work, a combination of ion mobility-mass spectrometry and density functional theory calculations to determine the protonation and deprotonation behaviour of four diamino benzoic acid and four aminophthalic acid isomers is presented. The additional COOH group on the ring of aminophthalic acids provides experimental evidence regarding the mechanism of intramolecular NH3+ → O proton transfer, which has been the subject of debate in recent years. To determine the proton acceptor O atom, ion mobility spectra of the fragments of protomers were used as a new method for the confidential assignment of the O-protomer structure, confirming only short-distance intramolecular NH3+ → O proton transfer. Additionally, the substitution pattern both influences the basicity of the protonation sites and enables these molecules to form internal hydrogen bonds with the protonated or deprotonated sites. The formation of the hydrogen bonds in the deprotonated aminophthalic acids changed the charge distribution and subsequently their ion mobility-derived collision cross sections in nitrogen (CCSN2) leading to separation of the four isomers studied. Finally, an interesting effect of the substitution pattern was observed as a synergistic electron-donating effect of the amine groups of 3,5-diaminobenzoic acid on enhancing the basicity of the carbon atom C2 of the ring and previously unreported formation of a C-protomer within aminobenzoic acid systems.
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Affiliation(s)
- Younes Valadbeigi
- Department of Chemistry, Faculty of Science, Imam Khomeini International University, Qazvin, Iran.
| | - Tim Causon
- University of Natural Resources and Life Sciences, Vienna, Department of Chemistry, Institute of Analytical Chemistry, Muthgasse 18, 1190 Vienna, Austria.
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10
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Ashworth EK, Dezalay J, Ryan CRM, Ieritano C, Hopkins WS, Chambrier I, Cammidge AN, Stockett MH, Noble JA, Bull JN. Protomers of the green and cyan fluorescent protein chromophores investigated using action spectroscopy. Phys Chem Chem Phys 2023. [PMID: 37465988 DOI: 10.1039/d3cp02661b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/20/2023]
Abstract
The photophysics of biochromophore ions often depends on the isomeric or protomeric distribution, yet this distribution, and the individual isomer contributions to an action spectrum, can be difficult to quantify. Here, we use two separate photodissociation action spectroscopy instruments to record electronic spectra for protonated forms of the green (pHBDI+) and cyan (Cyan+) fluorescent protein chromophores. One instrument allows for cryogenic (T = 40 ± 10 K) cooling of the ions, while the other offers the ability to perform protomer-selective photodissociation spectroscopy. We show that both chromophores are generated as two protomers when using electrospray ionisation, and that the protomers have partially overlapping absorption profiles associated with the S1 ← S0 transition. The action spectra for both species span the 340-460 nm range, although the spectral onset for the pHBDI+ protomer with the proton residing on the carbonyl oxygen is red-shifted by ≈40 nm relative to the lower-energy imine protomer. Similarly, the imine and carbonyl protomers are the lowest energy forms of Cyan+, with the main band for the carbonyl protomer red-shifted by ≈60 nm relative to the lower-energy imine protomer. The present strategy for investigating protomers can be applied to a wide range of other biochromophore ions.
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Affiliation(s)
- Eleanor K Ashworth
- School of Chemistry, Norwich Research Park, University of East Anglia, Norwich NR4 7TJ, UK.
| | - Jordan Dezalay
- Department of Physics, Stockholm University, SE-10691 Stockholm, Sweden
| | | | - Christian Ieritano
- Department of Chemistry, University of Waterloo, Waterloo N2L 3G1, Canada
| | - W Scott Hopkins
- Department of Chemistry, University of Waterloo, Waterloo N2L 3G1, Canada
| | - Isabelle Chambrier
- School of Chemistry, Norwich Research Park, University of East Anglia, Norwich NR4 7TJ, UK.
| | - Andrew N Cammidge
- School of Chemistry, Norwich Research Park, University of East Anglia, Norwich NR4 7TJ, UK.
| | - Mark H Stockett
- Department of Physics, Stockholm University, SE-10691 Stockholm, Sweden
| | | | - James N Bull
- School of Chemistry, Norwich Research Park, University of East Anglia, Norwich NR4 7TJ, UK.
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11
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Finazzi L, Martens J, Berden G, Oomens J. Probing radical versus proton migration in the aniline cation with IRMPD spectroscopy. Mol Phys 2023. [DOI: 10.1080/00268976.2023.2192307] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/30/2023]
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12
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Valadbeigi Y, Causon T. Monitoring intramolecular proton transfer with ion mobility-mass spectrometry and in-source ion activation. Chem Commun (Camb) 2023; 59:1673-1676. [PMID: 36689277 DOI: 10.1039/d2cc05237g] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Here, we show how intramolecular proton transfer can be induced and monitored with the example of polycyclic aromatic amines using in-source ion-activation and ion mobility-mass spectrometry. Experiment and DFT calculations reveal that the protonation rate of C-atoms in aromatic rings is controlled by the energy barrier of intramolecular NH3+ → C proton transfer.
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Affiliation(s)
- Younes Valadbeigi
- University of Natural Resources and Life Sciences, Vienna, Department of Chemistry, Institute of Analytical Chemistry, Muthgasse 18, 1190 Vienna, Austria.
| | - Tim Causon
- University of Natural Resources and Life Sciences, Vienna, Department of Chemistry, Institute of Analytical Chemistry, Muthgasse 18, 1190 Vienna, Austria.
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13
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Fu D, Habtegabir SG, Wang H, Feng S, Han Y. Understanding of protomers/deprotomers by combining mass spectrometry and computation. Anal Bioanal Chem 2023:10.1007/s00216-023-04574-1. [PMID: 36737499 DOI: 10.1007/s00216-023-04574-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Revised: 01/19/2023] [Accepted: 01/27/2023] [Indexed: 02/05/2023]
Abstract
Multifunctional compounds may form different prototropic isomers under different conditions, which are known as protomers/deprotomers. In biological systems, these protomer/deprotomer isomers affect the interaction modes and conformational landscape between compounds and enzymes and thus present different biological activities. Study on protomers/deprotomers is essentially the study on the acidity/basicity of each intramolecular functional group and its effect on molecular structure. In recent years, the combination of mass spectrometry (MS) and computational chemistry has been proven to be a powerful and effective means to study prototropic isomers. MS-based technologies are developed to discriminate and characterize protomers/deprotomers to provide structural information and monitor transformations, showing great superiority than other experimental methods. Computational chemistry is used to predict the thermodynamic stability of protomers/deprotomers, provide the simulated MS/MS spectra, infrared spectra, and calculate collision cross-section values. By comparing the theoretical data with the corresponding experimental results, the researchers can not only determine the protomer/deprotomer structure, but also investigate the structure-activity relationship in a given system. This review covers various MS methods and theoretical calculations and their devotion to isomer discrimination, structure identification, conformational transformation, and phase transition investigation of protomers/deprotomers.
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Affiliation(s)
- Dali Fu
- State Key Laboratory of Heavy Oil Processing, College of Chemical Engineering and Environment, China University of Petroleum-Beijing, Beijing, 102249, People's Republic of China
| | - Sara Girmay Habtegabir
- State Key Laboratory of Heavy Oil Processing, College of Chemical Engineering and Environment, China University of Petroleum-Beijing, Beijing, 102249, People's Republic of China
| | - Haodong Wang
- State Key Laboratory of Heavy Oil Processing, College of Chemical Engineering and Environment, China University of Petroleum-Beijing, Beijing, 102249, People's Republic of China
| | - Shijie Feng
- State Key Laboratory of Heavy Oil Processing, College of Chemical Engineering and Environment, China University of Petroleum-Beijing, Beijing, 102249, People's Republic of China
| | - Yehua Han
- State Key Laboratory of Heavy Oil Processing, College of Chemical Engineering and Environment, China University of Petroleum-Beijing, Beijing, 102249, People's Republic of China.
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14
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Samarasinghe I, Attygalle AB. Impact of Ambient Vapors on Spectra of 4-Nitroaniline Recorded under Atmospheric Solids Analysis Probe (ASAP) Mass Spectrometric Conditions. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2023; 34:205-217. [PMID: 36689202 DOI: 10.1021/jasms.2c00259] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Thermally desorbed 4-nitroaniline (4-NA), upon atmospheric pressure chemical ionization (APCI), generates gaseous ions for its protonated species. The APCI mass spectrum recorded under mild in-source ion-activating conditions from 4-NA showed a peak at m/z 139, whereas that acquired under high ion-activating conditions showed two additional peaks at m/z 122 (•OH loss) and 92 (•NO loss). The spectrum changed instantaneously when acetonitrile vapor was introduced to the source. In the new spectrum, both m/z 122 and 92 peaks were absent, while a new peak appeared at m/z 93. Ion-mobility separation carried out with the m/z 139 ion revealed that the initial ion represented the thermodynamically favored nitro-protonated tautomer. The ion population changed to an ensemble dominated by the less-favored amino-protomer when acetonitrile vapor was introduced to the ion source. The amino-protomer, upon collisional activation, loses •NO2 to generate an m/z 93 ion, which was confirmed to be the 4-dehydroanilinium ion. Ion mobility provided a practical way to monitor the changes secured by acetonitrile vapor because the two protomers showed different arrival times. Under spray-ionization conditions, the formation of the thermodynamically less favored protomer has been attributed to kinetic trapping. Our study demonstrated that the less favored amino-protomer could be generated by introducing acetonitrile vapor under nonspray conditions. Apparently, under APCI conditions, protonated water vapor attaches to the nitro group to generate a proton-bound heterodimer, which upon activation dissociates to yield the nitro-protomer. In contrast, protonated acetonitrile makes a tighter complex preferentially with the amino group, which upon activation breaks to the amino-protomer.
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Affiliation(s)
- Ishira Samarasinghe
- Department of Chemistry and Chemical Biology, Stevens Institute of Technology, Hoboken, New Jersey07030, United States
| | - Athula B Attygalle
- Department of Chemistry and Chemical Biology, Stevens Institute of Technology, Hoboken, New Jersey07030, United States
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15
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Naylor CN, Schaefer C, Kirk AT, Zimmermann S. The origin of isomerization of aniline revealed by high kinetic energy ion mobility spectrometry (HiKE-IMS). Phys Chem Chem Phys 2023; 25:1139-1152. [PMID: 36515135 DOI: 10.1039/d2cp01994a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Although aniline is a relatively simple small molecule, the origin of its two peaks observed in ion mobility spectrometry (IMS) has remained under debate for at least 30 years. First hypothesized as a difference in protonation site (amine vs. benzene ring), each ion mobility peak differs by one Dalton when coupled with mass spectrometry where the faster mobility peak is the molecular ion peak, and the slower mobility peak is protonated. To complicate the deconvolution of structures, some previous literature shows the peaks as unresolved and thus proposes these species exist in equilibrium. In this work, we show that when measured with high kinetic energy ion mobility spectrometry (HiKE-IMS), the two peaks observed in spectra of both aniline and all n-fluoroanilines are fully separated (chromatographic resolution from 2-7, Rp > 110) and therefore not in equilibrium. The HiKE-IMS is capable of changing ionization conditions independently of drift region conditions, and our results agree with previous literature showing that ionization source settings (including possible fragmentation at this stage) are the only influence determining the speciation of the two aniline peaks. Finally, when the drift and reactant gas are changed to nitrogen, a third peak appears at high E/N for 2-fluoroaniline and 4-fluoroaniline for the first time in reported literature. As observed by HiKE-IMS-MS, the new third peak is also protonated showing that the para-protonated aniline and resulting fragment ion, molecular ion aniline, can be fully separated in the mobility domain for the first time. The appearance of the third peak is only possible due to the increased separation of the other two peaks within the HiKE-IMS.
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Affiliation(s)
- Cameron N Naylor
- Leibniz University Hannover, Institute of Electrical Engineering and Measurement Technology, Department of Sensors and Measurement Technology, 30167 Hannover, Germany.
| | - Christoph Schaefer
- Leibniz University Hannover, Institute of Electrical Engineering and Measurement Technology, Department of Sensors and Measurement Technology, 30167 Hannover, Germany.
| | - Ansgar T Kirk
- Leibniz University Hannover, Institute of Electrical Engineering and Measurement Technology, Department of Sensors and Measurement Technology, 30167 Hannover, Germany.
| | - Stefan Zimmermann
- Leibniz University Hannover, Institute of Electrical Engineering and Measurement Technology, Department of Sensors and Measurement Technology, 30167 Hannover, Germany.
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16
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Strong KA, Stokes P, Parker D, Buckley AK, Mosely JA, Brodie CN, Dyer PW. Versatile, Cheap, Readily Modifiable Sample Delivery Method for Analysis of Air-/Moisture-Sensitive Samples Using Atmospheric Pressure Solids Analysis Probe Mass Spectrometry. Anal Chem 2022; 94:11315-11320. [PMID: 35930735 PMCID: PMC9386681 DOI: 10.1021/acs.analchem.2c02039] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A cheap, versatile, readily modified, and reusable glass probe system enabling delivery of solid air-/moisture-sensitive samples for mass spectrometric (MS) analysis using an Atmospheric pressure Solids Analysis Probe (ASAP) is described. The simplicity of the design allows quick and easy ASAP MS analyses of sensitive solid and liquid samples without the need for any modifications to commercially available vertically loaded ASAP mass spectrometers. A comparison of ASAP mass spectra obtained for metal complexes under air and an inert atmosphere is given.
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Affiliation(s)
- Kerry A Strong
- Department of Chemistry, Durham University, Durham DH1 3LE, United Kingdom
| | - Peter Stokes
- Department of Chemistry, Durham University, Durham DH1 3LE, United Kingdom
| | - David Parker
- Department of Chemistry, Durham University, Durham DH1 3LE, United Kingdom
| | - Amy K Buckley
- Department of Chemistry, Durham University, Durham DH1 3LE, United Kingdom
| | - Jackie A Mosely
- Department of Chemistry, Durham University, Durham DH1 3LE, United Kingdom
| | - Claire N Brodie
- Department of Chemistry, Durham University, Durham DH1 3LE, United Kingdom
| | - Philip W Dyer
- Department of Chemistry, Durham University, Durham DH1 3LE, United Kingdom
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17
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Oluwatoba DS, Islam MF, Som B, Sindt AJ, Smith MD, Shimizu LS, Do TD. Evaluating the Effects of Metal Adduction and Charge Isomerism on Ion-Mobility Measurements using m-Xylene Macrocycles as Models. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2022; 33:840-850. [PMID: 35471025 DOI: 10.1021/jasms.2c00033] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Gas-phase ion-mobility spectrometry provides a unique platform to study the effect of mobile charge(s) or charge location on collisional cross section and ion separation. Here, we evaluate the effects of cation/anion adduction in a series of xylene and pyridyl macrocycles that contain ureas and thioureas. We explore how zinc binding led to unexpected deprotonation of the thiourea macrocyclic host in positive polarity ionization and subsequently how charge isomerism due to cation (zinc metal) and anion (chloride counterion) adduction or proton competition among acceptors can affect the measured collisional cross sections in helium and nitrogen buffer gases. Our approach uses synthetic chemistry to design macrocycle targets and a combination of ion-mobility spectrometry mass spectrometry experiments and quantum mechanics calculations to characterize their structural properties. We demonstrate that charge isomerism significantly improves ion-mobility resolution and allows for determination of the metal binding mechanism in metal-inclusion macrocyclic complexes. Additionally, charge isomers can be populated in molecules where individual protons are shared between acceptors. In these cases, interactions via drift gas collisions magnify the conformational differences. Finally, for the macrocyclic systems we report here, charge isomers are observed in both helium and nitrogen drift gases with similar resolution. The separation factor does not simply increase with increasing drift gas polarizability. Our study sheds light on important properties of charge isomerism and offers strategies to take advantage of this phenomenon in analytical separations.
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Affiliation(s)
- Damilola S Oluwatoba
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Md Faizul Islam
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States
| | - Bozumeh Som
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States
- Department of Chemistry, University of Ghana, P.O. Box LG 56, Legon, Accra, Ghana
| | - Ammon J Sindt
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States
| | - Mark D Smith
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States
| | - Linda S Shimizu
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States
| | - Thanh D Do
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, United States
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18
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McCann A, Kune C, Massonnet P, Far J, Ongena M, Eppe G, Quinton L, De Pauw E. Cyclic Peptide Protomer Detection in the Gas Phase: Impact on CCS Measurement and Fragmentation Patterns. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2022; 33:851-858. [PMID: 35467879 DOI: 10.1021/jasms.2c00035] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
With the recent improvements in ion mobility resolution, it is now possible to separate small protomeric tautomers, called protomers. In larger molecules above 1000 Da such as peptides, a few studies suggest that protomers do exist as well and may contribute to their gas-phase conformational heterogeneity. In this work, we observed a CCS distribution that can be explained by the presence of protomers of surfactin, a small lipopeptide with no basic site. Following preliminary density functional theoretical calculations, several protonation sites in the gas phase were energetically favorable in positive ionization mode. Experimentally, at least three near-resolved IM peaks were observed in positive ionization mode, while only one was detected in negative ionization mode. These results were in good agreement with the DFT predictions. CID breakdown curve analysis after IM separation showed different inflection points (CE50) suggesting that different intramolecular interactions were implied in the stabilization of the structures of surfactin. The fragment ratio observed after collision-induced fragmentation was also different, suggesting different ring-opening localizations. All these observations support the presence of protomers on the cyclic peptide moieties of the surfactin. These data strongly suggest that protomeric tautomerism can still be observed on molecules above 1000 Da if the IM resolving power is sufficient. It also supports that the proton localization involves a change in the 3D structure that can affect the experimental CCS and the fragmentation channels of such peptides.
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Affiliation(s)
- Andréa McCann
- Mass Spectrometry Laboratory, MolSys Research Unit, University of Liège, 4000 Liège, Belgium
| | - Christopher Kune
- Mass Spectrometry Laboratory, MolSys Research Unit, University of Liège, 4000 Liège, Belgium
| | - Philippe Massonnet
- Mass Spectrometry Laboratory, MolSys Research Unit, University of Liège, 4000 Liège, Belgium
- Maastricht Multimodal Molecular Imaging (M4I) Institute, Division of Imaging Mass Spectrometry, 6229ER Maastricht, Limburg, The Netherlands
| | - Johann Far
- Mass Spectrometry Laboratory, MolSys Research Unit, University of Liège, 4000 Liège, Belgium
| | - Marc Ongena
- Gembloux Agro-Bio Tech, University of Liege, 5030 Gembloux, Belgium
| | - Gauthier Eppe
- Mass Spectrometry Laboratory, MolSys Research Unit, University of Liège, 4000 Liège, Belgium
| | - Loïc Quinton
- Mass Spectrometry Laboratory, MolSys Research Unit, University of Liège, 4000 Liège, Belgium
| | - Edwin De Pauw
- Mass Spectrometry Laboratory, MolSys Research Unit, University of Liège, 4000 Liège, Belgium
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19
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Mashmoushi N, Juhász DR, Coughlan NJA, Schneider BB, Le Blanc JCY, Guna M, Ziegler BE, Campbell JL, Hopkins WS. UVPD Spectroscopy of Differential Mobility-Selected Prototropic Isomers of Rivaroxaban. J Phys Chem A 2021; 125:8187-8195. [PMID: 34432451 DOI: 10.1021/acs.jpca.1c05564] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Two ion populations of protonated Rivaroxaban, [C19H18ClN3O5S + H]+, are separated under pure N2 conditions using differential mobility spectrometry prior to characterization in a hybrid triple quadrupole linear ion trap mass spectrometer. These populations are attributed to bare protonated Rivaroxaban and to a proton-bound Rivaroxaban-ammonia complex, which dissociates prior to mass-selecting the parent ion. Ultraviolet photodissociation (UVPD) and collision-induced dissociation (CID) studies indicate that both protonated Rivaroxaban ion populations are comprised of the computed global minimum prototropic isomer. Two ion populations are also observed when the collision environment is modified with 1.5% (v/v) acetonitrile. In this case, the protonated Rivaroxaban ion populations are produced by the dissociation of the ammonium complex and by the dissociation of a proton-bound Rivaroxaban-acetonitrile complex prior to mass selection. Again, both populations exhibit a similar CID behavior; however, UVPD spectra indicate that the two ion populations are associated with different prototropic isomers. The experimentally acquired spectra are compared with computed spectra and are assigned to two prototropic isomers that exhibit proton sharing between distal oxygen centers.
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Affiliation(s)
- Nour Mashmoushi
- Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada.,Waterloo Institute for Nanotechnology, University of 200 University Avenue West, Waterloo, Ontario N2L 3G1, Canada
| | - Daniel R Juhász
- Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
| | - Neville J A Coughlan
- Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada.,Waterloo Institute for Nanotechnology, University of 200 University Avenue West, Waterloo, Ontario N2L 3G1, Canada
| | | | | | - Mircea Guna
- SCIEX, 71 Four Valley Drive, Concord, Ontario L4K 4V8, Canada
| | - Blake E Ziegler
- Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada.,Watermine Innovation, Waterloo, Ontario N0B 2T0, Canada
| | - J Larry Campbell
- Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada.,Watermine Innovation, Waterloo, Ontario N0B 2T0, Canada.,Bedrock Scientific, Milton, Ontario L6T 6J9, Canada
| | - W Scott Hopkins
- Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada.,Waterloo Institute for Nanotechnology, University of 200 University Avenue West, Waterloo, Ontario N2L 3G1, Canada.,Watermine Innovation, Waterloo, Ontario N0B 2T0, Canada.,Centre for Eye and Vision Research, New Territories 999077, Hong Kong
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20
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Borges R, Colby SM, Das S, Edison AS, Fiehn O, Kind T, Lee J, Merrill AT, Merz KM, Metz TO, Nunez JR, Tantillo DJ, Wang LP, Wang S, Renslow RS. Quantum Chemistry Calculations for Metabolomics. Chem Rev 2021; 121:5633-5670. [PMID: 33979149 PMCID: PMC8161423 DOI: 10.1021/acs.chemrev.0c00901] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Indexed: 02/07/2023]
Abstract
A primary goal of metabolomics studies is to fully characterize the small-molecule composition of complex biological and environmental samples. However, despite advances in analytical technologies over the past two decades, the majority of small molecules in complex samples are not readily identifiable due to the immense structural and chemical diversity present within the metabolome. Current gold-standard identification methods rely on reference libraries built using authentic chemical materials ("standards"), which are not available for most molecules. Computational quantum chemistry methods, which can be used to calculate chemical properties that are then measured by analytical platforms, offer an alternative route for building reference libraries, i.e., in silico libraries for "standards-free" identification. In this review, we cover the major roadblocks currently facing metabolomics and discuss applications where quantum chemistry calculations offer a solution. Several successful examples for nuclear magnetic resonance spectroscopy, ion mobility spectrometry, infrared spectroscopy, and mass spectrometry methods are reviewed. Finally, we consider current best practices, sources of error, and provide an outlook for quantum chemistry calculations in metabolomics studies. We expect this review will inspire researchers in the field of small-molecule identification to accelerate adoption of in silico methods for generation of reference libraries and to add quantum chemistry calculations as another tool at their disposal to characterize complex samples.
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Affiliation(s)
- Ricardo
M. Borges
- Walter
Mors Institute of Research on Natural Products, Federal University of Rio de Janeiro, Rio de Janeiro 21941-901, Brazil
| | - Sean M. Colby
- Biological
Science Division, Pacific Northwest National
Laboratory, Richland, Washington 99352, United States
| | - Susanta Das
- Department
of Chemistry, Michigan State University, East Lansing, Michigan 48824, United States
| | - Arthur S. Edison
- Departments
of Genetics and Biochemistry and Molecular Biology, Complex Carbohydrate
Research Center and Institute of Bioinformatics, University of Georgia, Athens, Georgia 30602, United States
| | - Oliver Fiehn
- West
Coast Metabolomics Center for Compound Identification, UC Davis Genome
Center, University of California, Davis, California 95616, United States
| | - Tobias Kind
- West
Coast Metabolomics Center for Compound Identification, UC Davis Genome
Center, University of California, Davis, California 95616, United States
| | - Jesi Lee
- West
Coast Metabolomics Center for Compound Identification, UC Davis Genome
Center, University of California, Davis, California 95616, United States
- Department
of Chemistry, University of California, Davis, California 95616, United States
| | - Amy T. Merrill
- Department
of Chemistry, University of California, Davis, California 95616, United States
| | - Kenneth M. Merz
- Department
of Chemistry, Michigan State University, East Lansing, Michigan 48824, United States
| | - Thomas O. Metz
- Biological
Science Division, Pacific Northwest National
Laboratory, Richland, Washington 99352, United States
| | - Jamie R. Nunez
- Biological
Science Division, Pacific Northwest National
Laboratory, Richland, Washington 99352, United States
| | - Dean J. Tantillo
- Department
of Chemistry, University of California, Davis, California 95616, United States
| | - Lee-Ping Wang
- Department
of Chemistry, University of California, Davis, California 95616, United States
| | - Shunyang Wang
- West
Coast Metabolomics Center for Compound Identification, UC Davis Genome
Center, University of California, Davis, California 95616, United States
- Department
of Chemistry, University of California, Davis, California 95616, United States
| | - Ryan S. Renslow
- Biological
Science Division, Pacific Northwest National
Laboratory, Richland, Washington 99352, United States
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21
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Demireva M, Armentrout PB. Relative Energetics of the Gas Phase Protomers of p-Aminobenzoic Acid and the Effect of Protonation Site on Fragmentation. J Phys Chem A 2021; 125:2849-2865. [DOI: 10.1021/acs.jpca.0c11540] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Maria Demireva
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, United States
| | - P. B. Armentrout
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, United States
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22
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Zheng Z, Attygalle AB. Impact of Ambient Vapors Present in an Electrospray Ionization Source on Gas-Phase Ion Structures. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2021; 32:725-735. [PMID: 33606934 DOI: 10.1021/jasms.0c00430] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
According to current consensus, structures of protomeric (or deprotomeric) tautomers of gaseous ions generated by electrospray ionization depend primarily on the nature of the spray solvent. To probe the effect of the spray solvent on protonation, 4-aminobenzoic acid (PABA) has often been selected as the model compound. It is widely accepted that the protonation in the gas phase takes place primarily on the carbonyl oxygen atom when the sample is sprayed in methanol and on the nitrogen atom when acetonitrile is used as the spray solvent. Although this observation is valid, our current results indicate that the determination of the predominant protomer in the gas phase by the spray solvent is an indirect effect moderated by the solvent vapor molecules present in the ambient ion source. To investigate real-time changes in protomer distributions due to solvents, we used ion-mobility mass spectrometry (IM-MS). Initially, when a PABA solution in methanol was electrosprayed, the ion-mobility arrival-time profile recorded showed essentially one peak for the O-protomer. However, when acetonitrile or acetone vapors were introduced to the ambient-pressure ion source via the flowing desolvation gas, the intensity of the O-protomer peak diminished rapidly, and the N-protomer signal became dominant. The moment the acetonitrile (or acetone) vapors were removed from the ion source, the protomer-distribution signals began gradually reverting back to their original intensities. Furthermore, when PABA samples in methanol and acetonitrile were electrosprayed separately via a dual-sprayer setup, which allowed for the selective blocking of the gaseous ion-generation cascade of charged droplets from either sprayer, the predominant signal corresponded only to the N-protomer, irrespective of the position of the mechanical barrier. Because the mechanical barrier prevents only the gaseous ion formation, but not the physical access of solvent vapors to the ion source, it is evident that the solvent vapor that engulfs the ion source is the governing factor that decides the protomer distribution, not the nature of the spray solvent. Noticeably, acetonitrile wields a stronger effect on the manifested protomer distribution than many other solvents, including methanol, water, hexanes, and toluene. Apparently, the so-called "memory" of the solution-phase structures and the phenomenon described as "kinetic trapping" are both due to indirect effects caused by the solvent vapor engulfing the atmospheric-pressure ion source. Moreover, the so-called "memory" effect can either be "saved" or "erased" by exposing the initially formed gaseous ions to different solvent vapors from an alternative source.
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Affiliation(s)
- Zhaoyu Zheng
- Center for Mass Spectrometry, Department of Chemistry and Chemical Biology, Stevens Institute of Technology, Hoboken, New Jersey 07030, United States
| | - Athula B Attygalle
- Center for Mass Spectrometry, Department of Chemistry and Chemical Biology, Stevens Institute of Technology, Hoboken, New Jersey 07030, United States
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23
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Marlton SJP, McKinnon BI, Hill NS, Coote ML, Trevitt AJ. Electrostatically Tuning the Photodissociation of the Irgacure 2959 Photoinitiator in the Gas Phase by Cation Binding. J Am Chem Soc 2021; 143:2331-2339. [PMID: 33427467 DOI: 10.1021/jacs.0c11978] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The low-lying electronic states of Irgacure 2959, a Norrish-type I photoinitiator, complexed with a single metal cation are investigated in the gas phase by photodissociation action spectroscopy. Analysis of the band shifts using quantum chemical calculations (TD-DFT and SCS-CC2) reveals the underlying influence of the charge on the key electronic energy levels. Since the cations (H+, Li+, Na+, K+, Zn2+, Ca2+, and Mg2+) bind at varying distances, the magnitude of the electric field at the center of the chromophore due to the cation is altered, and this shifts the electronic states by different amounts. Photodissociation action spectra of cation-Irg complexes show that absorption transitions to the first 1ππ* state are red-shifted with a magnitude proportional to the electric field strength (with red shifts >1 eV), and in most cases, the cation is essentially acting as a point charge. Calculations show that a neighboring 3nπ* state, a key state for the α-cleavage pathway, is destabilized (blue-shifted) by the orientated electric field. As such, if the 1ππ*-3nπ* energy gap is reduced, increased intersystem crossing rates are expected, resulting in higher yields of the desired radical photoproducts, and this is controlled by the orientated electric field arising from the cation.
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Affiliation(s)
- Samuel J P Marlton
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW 2522, Australia
| | - Benjamin I McKinnon
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW 2522, Australia
| | - Nicholas S Hill
- ARC Centre of Excellence for Electromaterials Science, Research School of Chemistry, Australian National University, Canberra, ACT 2601, Australia
| | - Michelle L Coote
- ARC Centre of Excellence for Electromaterials Science, Research School of Chemistry, Australian National University, Canberra, ACT 2601, Australia
| | - Adam J Trevitt
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW 2522, Australia
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24
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Shiels OJ, Kelly PD, Bright CC, Poad BLJ, Blanksby SJ, da Silva G, Trevitt AJ. Reactivity Trends in the Gas-Phase Addition of Acetylene to the N-Protonated Aryl Radical Cations of Pyridine, Aniline, and Benzonitrile. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2021; 32:537-547. [PMID: 33444019 DOI: 10.1021/jasms.0c00386] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
A key step in gas-phase polycyclic aromatic hydrocarbon (PAH) formation involves the addition of acetylene (or other alkyne) to σ-type aromatic radicals, with successive additions yielding more complex PAHs. A similar process can happen for N-containing aromatics. In cold diffuse environments, such as the interstellar medium, rates of radical addition may be enhanced when the σ-type radical is charged. This paper investigates the gas-phase ion-molecule reactions of acetylene with nine aromatic distonic σ-type radical cations derived from pyridinium (Pyr), anilinium (Anl), and benzonitrilium (Bzn) ions. Three isomers are studied in each case (radical sites at the ortho, meta, and para positions). Using a room temperature ion trap, second-order rate coefficients, product branching ratios, and reaction efficiencies are measured. The rate coefficients increase from para to ortho positions. The second-order rate coefficients can be sorted into three groups: low, between 1 and 3 × 10-12 cm3 molecule-1 s-1 (3Anl and 4Anl); intermediate, between 5 and 15 × 10-12 cm3 molecule-1 s-1 (2Bzn, 3Bzn, and 4Bzn); and high, between 8 and 31 × 10-11 cm3 molecule-1 s-1 (2Anl, 2Pyr, 3Pyr, and 4Pyr); and 2Anl is the only radical cation with a rate coefficient distinctly different from its isomers. Quantum chemical calculations, using M06-2X-D3(0)/6-31++G(2df,p) geometries and DSD-PBEP86-NL/aug-cc-pVQZ energies, are deployed to rationalize reactivity trends based on the stability of prereactive complexes. The G3X-K method guides the assignment of product ions following adduct formation. The rate coefficient trend can be rationalized by a simple model based on the prereactive complex forward barrier height.
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Affiliation(s)
- Oisin J Shiels
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, New South Wales 2522, Australia
| | - P D Kelly
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, New South Wales 2522, Australia
| | - Cameron C Bright
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, New South Wales 2522, Australia
| | - Berwyck L J Poad
- Central Analytical Research Facility, Institute for Future Environments, Queensland University of Technology, Brisbane, Queensland 4001, Australia
| | - Stephen J Blanksby
- Central Analytical Research Facility, Institute for Future Environments, Queensland University of Technology, Brisbane, Queensland 4001, Australia
| | - Gabriel da Silva
- Department of Chemical Engineering, The University of Melbourne, Melbourne, Victoria 3010, Australia
| | - Adam J Trevitt
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, New South Wales 2522, Australia
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25
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Lermyte F, Theisen A, O'Connor PB. Solution Condition-Dependent Formation of Gas-Phase Protomers of Alpha-Synuclein in Electrospray Ionization. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2021; 32:364-372. [PMID: 33237779 DOI: 10.1021/jasms.0c00373] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
One of the main characteristics of biomolecular ions in mass spectrometry is their net charge, and a range of approaches exist to either increase or decrease this quantity in the gas phase. In the context of small molecules, it is well known that, in addition to the charge state, the charge site also has a profound effect on an ion's gas-phase behavior; however, this effect has been far less explored for peptides and intact proteins. Methods exist to determine charge sites of protein ions, and others have observed that the interplay of electrostatic repulsion and inherent basicity leads to different sites gaining or losing a charge depending on the total net charge. Here, we report two distinct protonation site isomers ("protomers") of α-synuclein occurring at the same charge state. The protomers showed important differences in their gas-phase fragmentation behavior and were furthermore distinguishable by ion mobility spectrometry. One protomer was produced under standard electrospray conditions, while the other was observed after addition of 10% dimethyl sulfoxide to the protein solution. Charge sites for both protomers were determined using ultraviolet photodissociation.
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Affiliation(s)
- Frederik Lermyte
- Department of Chemistry, Technical University of Darmstadt, 64287 Darmstadt, Germany
- School of Engineering, University of Warwick, Coventry CV4 7AL, U.K
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, U.K
| | - Alina Theisen
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, U.K
| | - Peter B O'Connor
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, U.K
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26
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Kumar R, Kenttämaa HI. Effects of Analyte Concentration on the Protonation Sites of 4-Aminobenzoic Acid upon Atmospheric Pressure Chemical Ionization As Revealed by Gas-Phase Ion-Molecule Reactions. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2020; 31:2210-2217. [PMID: 32852952 DOI: 10.1021/jasms.0c00285] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The most basic site of 4-aminobenzoic acid in aqueous solution is the amino nitrogen, while the carbonyl oxygen is calculated to be the most basic site in the gas phase. However, the preferred protonation site of 4-aminobenzoic acid upon electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI) depends upon the ionization solvent and ion source parameters. The influence of the concentration of the analyte on the manifested protonation sites upon APCI has not been investigated and is reported here. Gas-phase ion-molecule reactions of trimethoxymethylsilane were used to identify the protonation sites of 4-aminobenzoic acid ionized using APCI with methanol or acetonitrile-water as the solvent. The nitrogen-protomer was found to be about twice as abundant as the oxygen-protomer at low analyte concentrations (10-9-10-6 M) in methanol solvent. This finding was rationalized on the basis of a previous finding that when the O-protomer is surrounded by more than eight methanol molecules in the gas phase it starts behaving as if it were in an aqueous solution and converts to the N-protomer. At greater analyte concentrations (≥10-4 M), the amino group was predominantly protonated, which was rationalized based on the formation of a particularly stable proton-bound dimer of 4-aminobenzoic acid that preferentially dissociates to form the N-protomer. The above findings suggest that solution processes are much more important in APCI than commonly assumed, in agreement with recent literature. Indeed, when 1:1 (v/v) acetonitrile-water was used as the solvent system for 4-aminobenzoic acid, the N-protomer was predominantly generated at all analyte concentrations.
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Affiliation(s)
- Rashmi Kumar
- Chemistry Department, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907, United States
| | - Hilkka I Kenttämaa
- Chemistry Department, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907, United States
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27
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Errabelli R, Zheng Z, Attygalle AB. Formation of Protonated ortho-Quinonimide from ortho-Iodoaniline in the Gas Phase by a Molecular-Oxygen-Mediated, ortho-Isomer-Specific Fragmentation Mechanism. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2020; 31:864-872. [PMID: 32233379 DOI: 10.1021/jasms.9b00108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Upon collisional activation under mass spectrometric conditions, protonated 2-, 3-, and 4-iodoanilines lose an iodine radical to generate primarily dehydroanilinium radical cations (m/z 93), which are the distonic counterparts of the conventional molecular ion of aniline. When briefly accumulated in the Trap region of a Triwave cell in a SYNAPT G2 instrument, before being released for ion-mobility separation, these dehydroanilinium cations react readily with traces of oxygen present in the mobility gas to form peroxyl radical cations. Although all three isomeric dehydroanilinium ions showed avid affinity for O2, their reactivities were distinctly different. For example, the product-ion spectra recorded from mass-selected m/z 93 ion from 3- and 4-iodoanilines showed a peak at m/z 125 for the respective peroxylbenzenaminium ion. In contrast, an analogous peak at m/z 125 was absent in the spectrum of the 2-dehydroanilinium ion generated from 2-iodoaniline. Evidently, the 2-peroxylbenzenaminium ion generated from the 2-dehydroanilinium ion immediately loses a •OH to form protonated ortho-quinonimide (m/z 108).
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Affiliation(s)
- Ramu Errabelli
- Center for Mass Spectrometry, Department of Chemistry, and Chemical Biology, Stevens Institute of Technology, Hoboken, New Jersey 07030, United States
| | - Zhaoyu Zheng
- Center for Mass Spectrometry, Department of Chemistry, and Chemical Biology, Stevens Institute of Technology, Hoboken, New Jersey 07030, United States
| | - Athula B Attygalle
- Center for Mass Spectrometry, Department of Chemistry, and Chemical Biology, Stevens Institute of Technology, Hoboken, New Jersey 07030, United States
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28
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Tsuge M, Chen YH, Lee YP. Infrared Spectra of Isomers of Protonated Aniline in Solid para-Hydrogen. J Phys Chem A 2020; 124:2253-2263. [DOI: 10.1021/acs.jpca.0c00241] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Masashi Tsuge
- Department of Applied Chemistry and Institute of Molecular Science, National Chiao Tung University, Hsinchu 30010, Taiwan
- Institute of Low Temperature Sciences, Hokkaido University, Sapporo 060-0819, Japan
| | - Yu-Hsuan Chen
- Department of Applied Chemistry and Institute of Molecular Science, National Chiao Tung University, Hsinchu 30010, Taiwan
| | - Yuan-Pern Lee
- Department of Applied Chemistry and Institute of Molecular Science, National Chiao Tung University, Hsinchu 30010, Taiwan
- Center for Emergent Functional Matter Science, National Chiao Tung University, Hsinchu 30010, Taiwan
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan
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29
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Kumar R, Yerabolu R, Kenttämaa HI. Effects of Residual Water in a Linear Quadrupole Ion Trap on the Protonation Sites of 4-Aminobenzoic Acid. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2020; 31:124-131. [PMID: 32881520 DOI: 10.1021/jasms.9b00001] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
In solution, the most basic site in 4-aminobenzoic acid is the amino nitrogen, while the carboxylic acid oxygen is the most basic site in the gas phase. However, the protonation site in the gas phase has been demonstrated to depend on the ionization solvents when ionized using positive ion mode electrospray ionization (ESI). In many of these studies, collision-activated dissociation (CAD) was used to differentiate the protomers. To explore the influence of different CAD conditions on the manifested protonation site, 4-aminobenzoic acid dissolved either in 1:1 acetonitrile-water or 3:1 methanol-water was ionized by ESI and subjected to three different CAD experiments in a linear quadrupole ion trap/orbitrap mass spectrometer. Based on in-source CAD (ISCAD) and beam-type medium-energy CAD (MCAD), the proton resided on the nitrogen atom (N-protomer) when acetonitrile-water was used as the solvent system but on the oxygen atom (O-protomer) when methanol-water was used. Interestingly, a predominant N-protomer was observed when CAD was performed in the linear quadrupole ion trap (ITCAD), irrespective of the solvents used, in disagreement with literature. This unexpected result is rationalized based on the formation of long-lived water clusters of varying sizes for the protomers in the quadrupole ion trap due to residual water, low ion kinetic energies, long ion storage times, and relatively high pressure. Further, addition of extra water into the quadrupole ion trap resulted in nearly identical protomer distributions for both protomers. Therefore, this distribution must be near the equilibrium distribution caused by the presence of water clusters of varying sizes, some favoring the N-protomer and others the O-protomer.
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Affiliation(s)
- Rashmi Kumar
- Chemistry Department, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907, United States
| | - Ravikiran Yerabolu
- Chemistry Department, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907, United States
| | - Hilkka I Kenttämaa
- Chemistry Department, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907, United States
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30
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Chandran J, Zheng Z, Thomas VI, Rajalakshmi C, Attygalle AB. LC-MS analysis of p-aminosalicylic acid under electrospray ionization conditions manifests a profound solvent effect. Analyst 2020; 145:5333-5344. [DOI: 10.1039/d0an00680g] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Under identical mass spectrometric conditions, chromatographic peak intensities of p-aminosalicylic acid recorded by LC-MS, using methanol as the mobile phase are drastically different from those acquired using is it acetonitrile as the eluent.
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Affiliation(s)
- Jisha Chandran
- Inter University Instrumentation Centre (IUIC)
- School of Environmental Sciences
- Mahatma Gandhi University
- Kottayam
- 686560 India
| | - Zhaoyu Zheng
- Center for Mass Spectrometry
- Department of Chemistry and Chemical Biology
- Stevens Institute of Technology
- Hoboken
- USA
| | | | | | - Athula B. Attygalle
- Center for Mass Spectrometry
- Department of Chemistry and Chemical Biology
- Stevens Institute of Technology
- Hoboken
- USA
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31
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Kune C, Delvaux C, Haler JRN, Quinton L, Eppe G, De Pauw E, Far J. A Mechanistic Study of Protonated Aniline to Protonated Phenol Substitution Considering Tautomerization by Ion Mobility Mass Spectrometry and Tandem Mass Spectrometry. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2019; 30:2238-2249. [PMID: 31520338 DOI: 10.1007/s13361-019-02321-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Revised: 08/01/2019] [Accepted: 08/11/2019] [Indexed: 06/10/2023]
Abstract
We report the use of ion mobility mass spectrometry (IMMS) and energy-resolved collisional activation to investigate gas-phase reactions of protonated aniline and protonated phenol. Protonated aniline prototropic tautomerization and nucleophilic substitution (SN1) to produce phenol with traces of water in the IMMS cell are reported. Tautomerization of protonated phenol and its ability to form protonated aniline in presence of ammonia in the gas phase are also observed. These results are supported by energy landscapes obtained from computational chemistry. These structure modifications in the IMMS cell affected the measured collision cross section (CCS). A thorough understanding of the gas-phase reactions occurring in IMMS appears mandatory before using the experimental CCS as a robust descriptor which is stated by the recent literature.
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Affiliation(s)
- Christopher Kune
- MOLSYS, Mass Spectrometry Laboratory, University of Liège, Quartier Agora, Allée du Six Aout 11, B-4000, Liège, Belgium.
| | - Cédric Delvaux
- MOLSYS, Mass Spectrometry Laboratory, University of Liège, Quartier Agora, Allée du Six Aout 11, B-4000, Liège, Belgium
| | - Jean R N Haler
- MOLSYS, Mass Spectrometry Laboratory, University of Liège, Quartier Agora, Allée du Six Aout 11, B-4000, Liège, Belgium
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL, 33199, USA
| | - Loïc Quinton
- MOLSYS, Mass Spectrometry Laboratory, University of Liège, Quartier Agora, Allée du Six Aout 11, B-4000, Liège, Belgium
| | - Gauthier Eppe
- MOLSYS, Mass Spectrometry Laboratory, University of Liège, Quartier Agora, Allée du Six Aout 11, B-4000, Liège, Belgium
| | - Edwin De Pauw
- MOLSYS, Mass Spectrometry Laboratory, University of Liège, Quartier Agora, Allée du Six Aout 11, B-4000, Liège, Belgium
| | - Johann Far
- MOLSYS, Mass Spectrometry Laboratory, University of Liège, Quartier Agora, Allée du Six Aout 11, B-4000, Liège, Belgium
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32
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Kruve A. Semi-quantitative non-target analysis of water with liquid chromatography/high-resolution mass spectrometry: How far are we? RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2019; 33 Suppl 3:54-63. [PMID: 29943466 DOI: 10.1002/rcm.8208] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2018] [Accepted: 06/10/2018] [Indexed: 06/08/2023]
Abstract
Combining high-resolution mass spectrometry (HRMS) with liquid chromatography (LC) has considerably increased the capability of analytical chemistry. Among others, it has stimulated the growth of the non-target analysis, which aims at identifying compounds without their preceding selection. This approach is already widely applied in various fields, such as metabolomics, proteomics, etc. The applicability of LC/HRMS-based non-target analysis in environmental analyses, such as water studies, would be beneficial for understanding the environmental fate of polar pollutants and evaluating the health risks exposed by the new emerging contaminants. During the last five to seven years the use of LC/HRMS-based non-target analysis has grown rapidly. However, routine non-target analysis is still uncommon for most environmental monitoring agencies and environmental scientists. The main reasons are the complicated data processing and the inability to provide quantitative information about identified compounds. The latter shortcoming follows from the lack of standard substances, considered so far as the soul of each quantitative analysis for the newly discovered pollutants. To overcome this, non-target analyses could be combined with semi-quantitation. This Perspective aims at describing the current methods for non-target analysis, the possibilities and challenges of standard substance-free semi-quantitative analysis, and proposes tools to join these two fields together.
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Affiliation(s)
- Anneli Kruve
- Institut für Chemie und Biochemie, Freie Universität Berlin, Takustr. 3, 14195, Berlin, Germany
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33
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Gabelica V, Shvartsburg AA, Afonso C, Barran P, Benesch JL, Bleiholder C, Bowers MT, Bilbao A, Bush MF, Campbell JL, Campuzano ID, Causon T, Clowers BH, Creaser CS, De Pauw E, Far J, Fernandez‐Lima F, Fjeldsted JC, Giles K, Groessl M, Hogan CJ, Hann S, Kim HI, Kurulugama RT, May JC, McLean JA, Pagel K, Richardson K, Ridgeway ME, Rosu F, Sobott F, Thalassinos K, Valentine SJ, Wyttenbach T. Recommendations for reporting ion mobility Mass Spectrometry measurements. MASS SPECTROMETRY REVIEWS 2019; 38:291-320. [PMID: 30707468 PMCID: PMC6618043 DOI: 10.1002/mas.21585] [Citation(s) in RCA: 328] [Impact Index Per Article: 54.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Revised: 11/01/2018] [Accepted: 11/02/2018] [Indexed: 05/02/2023]
Abstract
Here we present a guide to ion mobility mass spectrometry experiments, which covers both linear and nonlinear methods: what is measured, how the measurements are done, and how to report the results, including the uncertainties of mobility and collision cross section values. The guide aims to clarify some possibly confusing concepts, and the reporting recommendations should help researchers, authors and reviewers to contribute comprehensive reports, so that the ion mobility data can be reused more confidently. Starting from the concept of the definition of the measurand, we emphasize that (i) mobility values (K0 ) depend intrinsically on ion structure, the nature of the bath gas, temperature, and E/N; (ii) ion mobility does not measure molecular surfaces directly, but collision cross section (CCS) values are derived from mobility values using a physical model; (iii) methods relying on calibration are empirical (and thus may provide method-dependent results) only if the gas nature, temperature or E/N cannot match those of the primary method. Our analysis highlights the urgency of a community effort toward establishing primary standards and reference materials for ion mobility, and provides recommendations to do so. © 2019 The Authors. Mass Spectrometry Reviews Published by Wiley Periodicals, Inc.
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Affiliation(s)
- Valérie Gabelica
- University of Bordeaux, INSERM and CNRS, ARNA Laboratory, IECB site2 rue Robert Escarpit, 33600PessacFrance
| | | | | | - Perdita Barran
- Michael Barber Centre for Collaborative Mass SpectrometryManchester Institute for Biotechnology, University of ManchesterManchesterUK
| | - Justin L.P. Benesch
- Department of Chemistry, Chemistry Research LaboratoryUniversity of Oxford, Mansfield Road, OX1 3TAOxfordUK
| | - Christian Bleiholder
- Department of Chemistry and BiochemistryFlorida State UniversityTallahasseeFlorida32311
| | | | - Aivett Bilbao
- Biological Sciences DivisionPacific Northwest National LaboratoryRichlandWashington
| | - Matthew F. Bush
- Department of ChemistryUniversity of WashingtonSeattleWashington
| | | | | | - Tim Causon
- University of Natural Resources and Life Sciences (BOKU)Department of Chemistry, Division of Analytical ChemistryViennaAustria
| | - Brian H. Clowers
- Department of ChemistryWashington State UniversityPullmanWashington
| | - Colin S. Creaser
- Centre for Analytical ScienceDepartment of Chemistry, Loughborough UniversityLoughboroughUK
| | - Edwin De Pauw
- Laboratoire de spectrométrie de masse (L.S.M.) − Molecular SystemsUniversité de LiègeLiègeBelgium
| | - Johann Far
- Laboratoire de spectrométrie de masse (L.S.M.) − Molecular SystemsUniversité de LiègeLiègeBelgium
| | | | | | | | - Michael Groessl
- Department of Nephrology and Hypertension and Department of BioMedical ResearchInselspital, Bern University Hospital, University of Bern, Switzerland and TofwerkThunSwitzerland
| | | | - Stephan Hann
- University of Natural Resources and Life Sciences (BOKU)Department of Chemistry, Division of Analytical ChemistryViennaAustria
| | - Hugh I. Kim
- Department of ChemistryKorea UniversitySeoulKorea
| | | | - Jody C. May
- Department of ChemistryCenter for Innovative Technology, Vanderbilt UniversityNashvilleTennessee
| | - John A. McLean
- Department of ChemistryCenter for Innovative Technology, Vanderbilt UniversityNashvilleTennessee
| | - Kevin Pagel
- Freie Universitaet BerlinInstitute for Chemistry and BiochemistryBerlinGermany
| | | | | | - Frédéric Rosu
- CNRS, INSERM and University of BordeauxInstitut Européen de Chimie et BiologiePessacFrance
| | - Frank Sobott
- Antwerp UniversityBiomolecular & Analytical Mass SpectrometryAntwerpBelgium
- Astbury Centre for Structural Molecular BiologyUniversity of LeedsLeedsUK
- School of Molecular and Cellular BiologyUniversity of LeedsLeedsUK
| | - Konstantinos Thalassinos
- Institute of Structural and Molecular Biology, Division of BiosciencesUniversity College LondonLondonWC1E 6BTUK
- United Kingdom and Institute of Structural and Molecular BiologyDepartment of Biological Sciences, Birkbeck College, University of LondonLondonWC1E 7HXUK
| | - Stephen J. Valentine
- C. Eugene Bennett Department of ChemistryWest Virginia UniversityMorgantownWest Virginia
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34
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Marlton SJP, McKinnon BI, Ucur B, Maccarone AT, Donald WA, Blanksby SJ, Trevitt AJ. Selecting and identifying gas-phase protonation isomers of nicotineH+ using combined laser, ion mobility and mass spectrometry techniques. Faraday Discuss 2019; 217:453-475. [DOI: 10.1039/c8fd00212f] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Protonation isomers of gas-phase nicotineH+ are separated and assigned using a combination of FAIMS and UV photodissociation action spectroscopy.
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Affiliation(s)
| | | | - Boris Ucur
- School of Chemistry
- University of Wollongong
- Wollongong
- Australia
| | | | | | - Stephen J. Blanksby
- Central Analytical Research Facility
- Institute for Future Environments
- Queensland University of Technology
- Brisbane
- Australia
| | - Adam J. Trevitt
- School of Chemistry
- University of Wollongong
- Wollongong
- Australia
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35
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Kune C, Haler JRN, Far J, De Pauw E. Effectiveness and Limitations of Computational Chemistry and Mass Spectrometry in the Rational Design of Target-specific Shift Reagents for Ion Mobility Spectrometry. Chemphyschem 2018; 19:2921-2930. [DOI: 10.1002/cphc.201800555] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Indexed: 01/14/2023]
Affiliation(s)
- Christopher Kune
- Mass Spectrometry Laboratory; University of Liège; Quartier Agora; Allée du Six Aout 11, B- 4000 Liège Belgium
| | - Jean R. N. Haler
- Mass Spectrometry Laboratory; University of Liège; Quartier Agora; Allée du Six Aout 11, B- 4000 Liège Belgium
| | - Johann Far
- Mass Spectrometry Laboratory; University of Liège; Quartier Agora; Allée du Six Aout 11, B- 4000 Liège Belgium
| | - Edwin De Pauw
- Mass Spectrometry Laboratory; University of Liège; Quartier Agora; Allée du Six Aout 11, B- 4000 Liège Belgium
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36
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Bell MR, Cruzeiro VWD, Cismesia AP, Tesler LF, Roitberg AE, Polfer NC. Probing the Structures of Solvent-Complexed Ions Formed in Electrospray Ionization Using Cryogenic Infrared Photodissociation Spectroscopy. J Phys Chem A 2018; 122:7427-7436. [DOI: 10.1021/acs.jpca.8b05896] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- Matthew R. Bell
- Department of Chemistry, University of Florida, P.O. Box 117200, Gainesville, Florida 32611-7200, United States
| | - Vinícius Wilian D. Cruzeiro
- Department of Chemistry, University of Florida, P.O. Box 117200, Gainesville, Florida 32611-7200, United States
| | - Adam P. Cismesia
- Department of Chemistry, University of Florida, P.O. Box 117200, Gainesville, Florida 32611-7200, United States
| | - Larry F. Tesler
- Department of Chemistry, University of Florida, P.O. Box 117200, Gainesville, Florida 32611-7200, United States
| | - Adrian E. Roitberg
- Department of Chemistry, University of Florida, P.O. Box 117200, Gainesville, Florida 32611-7200, United States
| | - Nicolas C. Polfer
- Department of Chemistry, University of Florida, P.O. Box 117200, Gainesville, Florida 32611-7200, United States
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37
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Xia H, Attygalle AB. Transformation of the gas-phase favored O-protomer of p-aminobenzoic acid to its unfavored N-protomer by ion activation in the presence of water vapor: An ion-mobility mass spectrometry study. JOURNAL OF MASS SPECTROMETRY : JMS 2018; 53:353-360. [PMID: 29377420 DOI: 10.1002/jms.4066] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Revised: 01/12/2018] [Accepted: 01/18/2018] [Indexed: 05/26/2023]
Abstract
An ion-mobility mass spectrometry study showed that the preferred O-protonated form of p-aminobenzoic in the gas phase can be converted to the thermodynamically less favored N-protomer by in-source collision-induced ion activation during the ion transfer process from the atmospheric region to the first vacuum region if the humidity is high in the ion source. Upon the addition of water vapor to the nitrogen gas used to promote the solid analyte to the gas phase under helium-plasma ionization conditions, the intensity of the ion-mobility arrival-time peak for the N-protomer increased dramatically. Evidently, the ion-activation process in the first vacuum region is able to provide the energy required to surmount the barrier to isomerize the O-protomer to the more energetic N-protomer. The transfer of the proton attached to the carbonyl oxygen atom of the O-protomer to the amino group takes place by a water-bridge mechanism. Apparently, the postionization transformations that take place during the transmission of ions from the atmospheric-pressure ion source to the detector, via different physical compartments of low to high vacuum, play an eminent role in determining the population ratios eventually manifested at the detector.
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Affiliation(s)
- Hanxue Xia
- Center for Mass Spectrometry, Department of Chemistry and Chemical Biology, Stevens Institute of Technology, Hoboken, New Jersey, 07030, USA
| | - Athula B Attygalle
- Center for Mass Spectrometry, Department of Chemistry and Chemical Biology, Stevens Institute of Technology, Hoboken, New Jersey, 07030, USA
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38
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Walker SWC, Mark A, Verbuyst B, Bogdanov B, Campbell JL, Hopkins WS. Characterizing the Tautomers of Protonated Aniline Using Differential Mobility Spectrometry and Mass Spectrometry. J Phys Chem A 2017; 122:3858-3865. [DOI: 10.1021/acs.jpca.7b10872] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Stephen W. C. Walker
- Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
| | - Alison Mark
- Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
| | - Brent Verbuyst
- Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
| | - Bogdan Bogdanov
- Department of Chemistry, University of the Pacific, Stockton, California 95211, United States
- Shimadzu Scientific Instruments, Pleasanton, California 94566, United States
| | - J. Larry Campbell
- Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
- SCIEX, 71 Four Valley Drive, Concord, Ontario L4K 4 V8, Canada
| | - W. Scott Hopkins
- Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
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39
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Xia H, Attygalle AB. Untrapping Kinetically Trapped Ions: The Role of Water Vapor and Ion-Source Activation Conditions on the Gas-Phase Protomer Ratio of Benzocaine Revealed by Ion-Mobility Mass Spectrometry. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2017; 28:2580-2587. [PMID: 28936768 DOI: 10.1007/s13361-017-1806-9] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Revised: 08/25/2017] [Accepted: 08/30/2017] [Indexed: 06/07/2023]
Abstract
The role of water vapor in transforming the thermodynamically preferred species of protonated benzocaine to the less favored protomer was investigated using helium-plasma ionization (HePI) in conjunction with ion-mobility mass spectrometry (IM-MS). The IM arrival-time distribution (ATD) recorded from a neat benzocaine sample desorbed to the gas phase by a stream of dry nitrogen and ionized by HePI showed essentially one peak for the O-protonated species. However, when water vapor was introduced to the enclosed ion source, within a span of about 150 ms the ATD profile changed completely to one dominated by the N-protonated species. Under spray-based ionization conditions, the nature and composition of the solvents have been postulated to play a decisive role in defining the manifested protomer ratios. In reality, the solvent vapors present in the ion source (particularly the ambient humidity) indirectly dictate the gas-phase ratio of the protomers. Evidently, the gas-phase protomer ratio established at the confinement of the ions is readjusted by the ion-activation that takes place during the transmission of ions to the vacuum. Although it has been repeatedly stated that ions can retain a "memory" of their solution structures because they can be kinetically trapped, and thereby represent their solution-based stabilities, we show that the initial airborne ions can undergo significant transformations in the transit through the intermediate vacuum zones between the ion source and the mass detector. In this context, we demonstrate that the kinetically trapped N-protomer of benzocaine can be untrapped by reducing the humidity of the enclosed ion source. Graphical Abstract ᅟ.
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Affiliation(s)
- Hanxue Xia
- Center for Mass Spectrometry, Department of Biomedical Engineering, Chemistry, and Biological Sciences, Stevens Institute of Technology, Hoboken, NJ, 07030, USA
| | - Athula B Attygalle
- Center for Mass Spectrometry, Department of Biomedical Engineering, Chemistry, and Biological Sciences, Stevens Institute of Technology, Hoboken, NJ, 07030, USA.
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