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Pandeti S, Feketeová L, Reddy TJ, Abdoul-Carime H, Farizon B, Farizon M, Märk TD. Binding preference of nitroimidazolic radiosensitizers to nucleobases and nucleosides probed by electrospray ionization mass spectrometry and density functional theory. J Chem Phys 2019; 150:014302. [PMID: 30621427 DOI: 10.1063/1.5062604] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Nitroimidazolic radiosensitizers are used in radiation therapy to selectively sensitize cancer cells deprived of oxygen, and the actual mechanism of radiosensitization is still not understood. Selecting five radiosensitizers (1-methyl-5-nitroimidazole, ronidazole, ornidazole, metronidazole, and nimorazole) with a common 5-nitroimidazolic ring with different substitutions at N1 and C2 positions of the imidazole moiety, we investigate here their binding to nucleobases (A, T, G, and C) and nucleosides (As, Td, Gs, and Cd) via the positive electrospray ionization mass spectrometry experiments. In addition, quantum chemical calculations at the M062x/6-311+G(d,p) level of theory and basis set were used to determine binding energies of the proton bound dimers of a radiosensitizer and a nucleobase. The positive electrospray ionization leads to the formation of proton bound dimers of all radiosensitizers except 1-methyl-5-nitroimidazole in high abundance with C and smaller abundance with G. Ronidazole and metronidazole formed less abundant dimers also with A, while no dimers were observed to be formed at all with T. In contrast to the case of the nucleoside Td, the dimer intensity is as high as that with Cd, while the abundance of the dimer with Gs is smaller than that of the former. The experimental results are consistent with the calculations of binding energies suggesting proton bound dimers with C and G to be the strongest bound ones. Finally, a barrier-free proton transfer is observed when protonated G or C approaches the nitroimidazole ring.
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Affiliation(s)
- S Pandeti
- Université de Lyon, Université Claude Bernard Lyon1, Institut de Physique Nucléaire de Lyon, CNRS/IN2P3 UMR 5822, 69622 Villeurbanne Cedex, France
| | - L Feketeová
- Université de Lyon, Université Claude Bernard Lyon1, Institut de Physique Nucléaire de Lyon, CNRS/IN2P3 UMR 5822, 69622 Villeurbanne Cedex, France
| | - T J Reddy
- Analytical Chemistry and Mass Spectrometry Division, CSIR-Indian Institute of Chemical Technology, Hyderabad 500 007, India
| | - H Abdoul-Carime
- Université de Lyon, Université Claude Bernard Lyon1, Institut de Physique Nucléaire de Lyon, CNRS/IN2P3 UMR 5822, 69622 Villeurbanne Cedex, France
| | - B Farizon
- Université de Lyon, Université Claude Bernard Lyon1, Institut de Physique Nucléaire de Lyon, CNRS/IN2P3 UMR 5822, 69622 Villeurbanne Cedex, France
| | - M Farizon
- Université de Lyon, Université Claude Bernard Lyon1, Institut de Physique Nucléaire de Lyon, CNRS/IN2P3 UMR 5822, 69622 Villeurbanne Cedex, France
| | - T D Märk
- Institut für Ionenphysik und Angewandte Physik, Leopold Franzens Universität Innsbruck, Technikerstrasse 25, 6020 Innsbruck, Austria
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Khreis JM, Reitshammer J, Vizcaino V, Klawitter K, Feketeová L, Denifl S. High-energy collision-induced dissociation of histidine ions [His + H] + and [His - H] - and histidine dimer [His 2 + H] . RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2018; 32:113-120. [PMID: 29108138 DOI: 10.1002/rcm.8027] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Revised: 10/05/2017] [Accepted: 10/26/2017] [Indexed: 06/07/2023]
Abstract
RATIONALE Histidine (His) is an essential amino acid, whose side group consists of an aromatic imidazole moiety that can bind a proton or metal cation and act as a donor in intermolecular interactions in many biological processes. While the dissociation of His monomer ions is well known, information on the kinetic energy released in the dissociation is missing. METHODS Using a new home-built electrospray ionization (ESI) source adapted to a double-focusing mass spectrometer of BE geometry, we investigated the fragmentation reactions of protonated and deprotonated His, [His + H]+ and [His - H]- , and the protonated His dimer [His2 + H]+ , accelerated to 6 keV in a high-energy collision with helium gas. We evaluated the kinetic energy release (KER) for the observed dissociation channels. RESULTS ESI of His solution in positive mode led to the formation of His clusters [Hisn + H]+ , n = 1-6, with notably enhanced stability of the tetramer. [His + H]+ dissociates predominantly by loss of (H2 O + CO) with a KER of 278 meV, while the dominant dissociation channel of [His - H]- involves loss of NH3 with a high KER of 769 meV. Dissociation of [His2 + H]+ is dominated by loss of the monomer but smaller losses are also observed. CONCLUSIONS The KER for HCOOH loss from both [His + H]+ and [His - H]- is similar at 278 and 249 meV, respectively, which suggests that the collision-induced dissociation takes place via a similar mechanism. The loss of COOH and C2 H5 NO2 from the dimer suggests that the dimer of His binds through a shared proton between the imidazole moieties.
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Affiliation(s)
- Jusuf M Khreis
- Institut für Ionenphysik und Angewandte Physik and Center for Molecular Biosciences Innsbruck (CMBI), Leopold Franzens Universität Innsbruck, Technikerstrasse 25, 6020, Innsbruck, Austria
| | - Julia Reitshammer
- Institut für Ionenphysik und Angewandte Physik and Center for Molecular Biosciences Innsbruck (CMBI), Leopold Franzens Universität Innsbruck, Technikerstrasse 25, 6020, Innsbruck, Austria
| | | | - Kevin Klawitter
- Institut für Ionenphysik und Angewandte Physik and Center for Molecular Biosciences Innsbruck (CMBI), Leopold Franzens Universität Innsbruck, Technikerstrasse 25, 6020, Innsbruck, Austria
| | - Linda Feketeová
- Institut für Ionenphysik und Angewandte Physik and Center for Molecular Biosciences Innsbruck (CMBI), Leopold Franzens Universität Innsbruck, Technikerstrasse 25, 6020, Innsbruck, Austria
- Université de Lyon, Université Claude Bernard Lyon1, CNRS/IN2P3, UMR5822, Institut de Physique Nucléaire de Lyon, 43 Bd du 11 novembre 1918, 69622, Villeurbanne, France
| | - Stephan Denifl
- Institut für Ionenphysik und Angewandte Physik and Center for Molecular Biosciences Innsbruck (CMBI), Leopold Franzens Universität Innsbruck, Technikerstrasse 25, 6020, Innsbruck, Austria
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Feketeová L, Khairallah GN, O'Hair RAJ, Nielsen SB. Gas-phase fragmentation of deprotonated tryptophan and its clusters [Trpn -H]- induced by different activation methods. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2015; 29:1395-1402. [PMID: 26147479 DOI: 10.1002/rcm.7233] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2015] [Revised: 05/19/2015] [Accepted: 05/19/2015] [Indexed: 06/04/2023]
Abstract
RATIONALE Non-covalent amino acid clusters are the subject of intense research in diverse areas including peptide bond formation studies or the determination of proton affinities or methylating abilities of amino acids. However, most of the research has focused on positive ions and little is known about anionic clusters. METHODS Fragmentation reactions of deprotonated tryptophan (Trp), [Trp-H](-) and Trp singly deprotonated non-covalently bound clusters [Trp(n) -H](-), n = 2, 3, 4, were investigated using low-energy collision-induced dissociation (CID) with He atoms, high-energy CID with Na atoms, and electron-induced dissociation (EID) with 20-35 eV electrons. Fragmentation of the monomeric Trp anion, where all labile hydrogens were exchanged for deuterium [d(4) -Trp-D](-), was investigated using low-energy CID and EID, in order to shed light on the dissociation mechanisms. RESULTS The main fragmentation channel for Trp cluster anions, [Trp(n) -H](-), n >1, is the loss of the neutral monomer. The fragmentation of the deprotonated Trp monomer induced by electrons resembles the fragmentation induced by high-energy collisions through electronic excitation of the parent. However, the excitation must precede in a different way, shown through only monomer loss from larger clusters, n >1, in case of EID, but intracluster chemistry in the case of high-energy CID. CONCLUSIONS The anion of the indole ring C(8)H(6) N(-) has been identified in the product ion spectra of [Trp(n) -H](-) using all activation methods, thus providing a diagnostic marker ion. No evidence was found for formation of peptide bonds as a route to prebiotic peptides in the fragmentation reactions of these singly deprotonated Trp cluster ions.
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Affiliation(s)
- Linda Feketeová
- ARC Centre of Excellence for Free Radical Chemistry and Biotechnology, School of Chemistry and Bio21 Institute of Molecular Science and Biotechnology, The University of Melbourne, 30 Flemington Road, Parkville, Victoria, 3010, Australia
- Université de Lyon, 69003 Lyon, France; Université Claude Bernard Lyon1; Institut de Physique Nucléaire de Lyon, CNRS/IN2P3, UMR5822, 69622 Villeurbanne, France
| | - George N Khairallah
- ARC Centre of Excellence for Free Radical Chemistry and Biotechnology, School of Chemistry and Bio21 Institute of Molecular Science and Biotechnology, The University of Melbourne, 30 Flemington Road, Parkville, Victoria, 3010, Australia
| | - Richard A J O'Hair
- ARC Centre of Excellence for Free Radical Chemistry and Biotechnology, School of Chemistry and Bio21 Institute of Molecular Science and Biotechnology, The University of Melbourne, 30 Flemington Road, Parkville, Victoria, 3010, Australia
| | - Steen Brøndsted Nielsen
- Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, Aarhus C, 8000, Denmark
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Gilbert JD, Prentice BM, McLuckey SA. Ion/ion reactions with "onium" reagents: an approach for the gas-phase transfer of organic cations to multiply-charged anions. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2015; 26:818-25. [PMID: 25652935 PMCID: PMC4654941 DOI: 10.1007/s13361-015-1077-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Revised: 12/27/2014] [Accepted: 01/08/2015] [Indexed: 05/13/2023]
Abstract
The use of ion/ion reactions to effect gas-phase alkylation is demonstrated. Commonly used fixed-charge "onium" cations are well-suited for ion/ion reactions with multiply deprotonated analytes because of their tendency to form long-lived electrostatic complexes. Activation of these complexes results in an SN2 reaction that yields an alkylated anion with the loss of a neutral remnant of the reagent. This alkylation process forms the basis of a general method for alkylation of deprotonated analytes generated via electrospray, and is demonstrated on a variety of anionic sites. SN2 reactions of this nature are demonstrated empirically and characterized using density functional theory (DFT). This method for modification in the gas phase is extended to the transfer of larger and more complex R groups that can be used in later gas-phase synthesis steps. For example, N-cyclohexyl-N'-(2-morpholinoethyl)carbodiimide (CMC) is used to transfer a carbodiimide functionality to a peptide anion containing a carboxylic acid. Subsequent activation yields a selective reaction between the transferred carbodiimide group and a carboxylic acid, suggesting the carbodiimide functionality is retained through the transfer process. Many different R groups are transferable using this method, allowing for new possibilities for charge manipulation and derivatization in the gas phase.
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Affiliation(s)
- Joshua D Gilbert
- Department of Chemistry, Purdue University, West Lafayette, IN, 4907-2084, USA
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Li J, Khairallah GN, O’Hair RAJ. Dimethylcuprate-Mediated Transformation of Acetate to Dithioacetate. Organometallics 2015. [DOI: 10.1021/om501117p] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Jiawei Li
- School
of Chemistry, Bio21
Institute of Molecular Science and Biotechnology, and ARC Centre of Excellence for Free Radical Chemistry
and Biotechnology, The University of Melbourne, Melbourne, Victoria 3010, Australia
| | - George N. Khairallah
- School
of Chemistry, Bio21
Institute of Molecular Science and Biotechnology, and ARC Centre of Excellence for Free Radical Chemistry
and Biotechnology, The University of Melbourne, Melbourne, Victoria 3010, Australia
| | - Richard A. J. O’Hair
- School
of Chemistry, Bio21
Institute of Molecular Science and Biotechnology, and ARC Centre of Excellence for Free Radical Chemistry
and Biotechnology, The University of Melbourne, Melbourne, Victoria 3010, Australia
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Peng Z, McGee WM, Bu J, Barefoot NZ, McLuckey SA. Gas phase reactivity of carboxylates with N-hydroxysuccinimide esters. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2015; 26:174-80. [PMID: 25338221 PMCID: PMC4654944 DOI: 10.1007/s13361-014-1002-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2014] [Revised: 09/06/2014] [Accepted: 09/08/2014] [Indexed: 05/13/2023]
Abstract
N-hydroxysuccinimide (NHS) esters have been used for gas-phase conjugation reactions with peptides at nucleophilic sites, such as primary amines (N-terminus, ε-amine of lysine) or guanidines, by forming amide bonds through a nucleophilic attack on the carbonyl carbon. The carboxylate has recently been found to also be a reactive nucleophile capable of initiating a similar nucleophilic attack to form a labile anhydride bond. The fragile bond is easily cleaved, resulting in an oxygen transfer from the carboxylate-containing species to the reagent, nominally observed as a water transfer. This reactivity is shown for both peptides and non-peptidic species. Reagents isotopically labeled with O(18) were used to confirm reactivity. This constitutes an example of distinct differences in reactivity of carboxylates between the gas phase, where they are shown to be reactive, and the solution phase, where they are not regarded as reactive with NHS esters.
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Affiliation(s)
- Zhou Peng
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana USA 47907-2084
| | - William M. McGee
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana USA 47907-2084
| | - Jiexun Bu
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana USA 47907-2084
| | - Nathan Z. Barefoot
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana USA 47907-2084
| | - Scott A. McLuckey
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana USA 47907-2084
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Woolley M, Khairallah GN, da Silva G, Donnelly PS, O’Hair RAJ. Direct versus Water-Mediated Protodecarboxylation of Acetic Acid Catalyzed by Group 10 Carboxylates, [(phen)M(O2CCH3)]+. Organometallics 2014. [DOI: 10.1021/om500493w] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Matthew Woolley
- School of Chemistry, ‡Bio21 Institute of Molecular Science
and Biotechnology, §ARC Centre of Excellence
for Free Radical Chemistry and Biotechnology, and ∥Department of Chemical and Biomolecular
Engineering, The University of Melbourne, Melbourne, Victoria 3010, Australia
| | - George N. Khairallah
- School of Chemistry, ‡Bio21 Institute of Molecular Science
and Biotechnology, §ARC Centre of Excellence
for Free Radical Chemistry and Biotechnology, and ∥Department of Chemical and Biomolecular
Engineering, The University of Melbourne, Melbourne, Victoria 3010, Australia
| | - Gabriel da Silva
- School of Chemistry, ‡Bio21 Institute of Molecular Science
and Biotechnology, §ARC Centre of Excellence
for Free Radical Chemistry and Biotechnology, and ∥Department of Chemical and Biomolecular
Engineering, The University of Melbourne, Melbourne, Victoria 3010, Australia
| | - Paul S. Donnelly
- School of Chemistry, ‡Bio21 Institute of Molecular Science
and Biotechnology, §ARC Centre of Excellence
for Free Radical Chemistry and Biotechnology, and ∥Department of Chemical and Biomolecular
Engineering, The University of Melbourne, Melbourne, Victoria 3010, Australia
| | - Richard A. J. O’Hair
- School of Chemistry, ‡Bio21 Institute of Molecular Science
and Biotechnology, §ARC Centre of Excellence
for Free Radical Chemistry and Biotechnology, and ∥Department of Chemical and Biomolecular
Engineering, The University of Melbourne, Melbourne, Victoria 3010, Australia
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