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Chakraborty D, Eckermann L, Carmichael I, Ptasińska S. Dissociative electron attachment to amide bond containing molecules: N-ethylformamide and N-ethylacetamide. J Chem Phys 2020; 153:224306. [PMID: 33317314 DOI: 10.1063/5.0029614] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
To advance our quest to understand the role of low energy electrons in biomolecular systems, we performed investigations on dissociative electron attachment (DEA) to gas-phase N-ethylformamide (NEF) and N-ethylacetamide (NEA) molecules. Both molecules contain the amide bond, which is the linkage between two consecutive amino acid residues in proteins. Thus, their electron-induced dissociation can imitate the resonant behavior of the DEA process in more complex biostructures. Our experimental results indicate that in these two molecules, the dissociation of the amide bond results in a double resonant structure with peaks at ∼5 eV and 9 eV. We also determined the energy position of resonant states for several negative ions, i.e., the other dissociation products from NEF and NEA. Our predictions of dissociation channels were supported by density functional theory calculations of the corresponding threshold energies. Our results and those previously reported for small amides and peptides imply the fundamental nature for breakage of the amide bond through the DEA process.
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Affiliation(s)
- Dipayan Chakraborty
- Radiation Laboratory, University of Notre Dame, Notre Dame, Indiana 46556, USA
| | - Lauren Eckermann
- Radiation Laboratory, University of Notre Dame, Notre Dame, Indiana 46556, USA
| | - Ian Carmichael
- Radiation Laboratory, University of Notre Dame, Notre Dame, Indiana 46556, USA
| | - Sylwia Ptasińska
- Radiation Laboratory, University of Notre Dame, Notre Dame, Indiana 46556, USA
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Kossoski F, Varella MTDN. How does methylation suppress the electron-induced decomposition of 1-methyl-nitroimidazoles? J Chem Phys 2018; 147:164310. [PMID: 29096502 DOI: 10.1063/1.5005604] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The efficient decomposition of nitroimidazoles (NIs) by low energy electrons is believed to underlie their radiosensitizing properties. Recent dissociative electron attachment (DEA) measurements showed that methylation at the N1 site unexpectedly suppresses the electron-induced reactions in 4(5)-NI. We report theoretical results that provide a clear interpretation of that astounding finding. Around 1.5 eV, DEA reactions into several fragments are initiated by a π* resonance, not considered in previous studies. The autoionization lifetime of this anion state, which limits the predissociation dynamics, is considerably shorter in the methylated species, thereby suppressing the DEA signals. On the other hand, the lifetime of the π* resonance located around 3 eV is less affected by methylation, which explains why DEA is still observed at these energies. Our results demonstrate how even a simple methylation can significantly modify the probabilities for DEA reactions, which may be significant for NI-based cancer therapy.
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Affiliation(s)
- F Kossoski
- Instituto de Física "Gleb Wataghin", Universidade Estadual de Campinas, 13083-859 Campinas, São Paulo, Brazil
| | - M T do N Varella
- Instituto de Física, Universidade de São Paulo, Rua do Matão 1731, 05508-090 São Paulo, São Paulo, Brazil
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Kocisek J, Piekarski DG, Delaunay R, Huber BA, Adoui L, Martín F, Alcamí M, Rousseau P, Domaracka A, Kopyra J, Díaz-Tendero S. N-Acetylglycine Cation Tautomerization Enabled by the Peptide Bond. J Phys Chem A 2015; 119:9581-9. [PMID: 26243533 DOI: 10.1021/acs.jpca.5b06009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We present a combined experimental and theoretical study of the ionization of N-acetylglycine molecules by 48 keV O(6+) ions. We focus on the single ionization channel of this interaction. In addition to the prompt fragmentation of the N-acetylglycine cation, we also observe the formation of metastable parent ions with lifetimes in the microsecond range. On the basis of density functional theory calculations, we assign these metastable ions to the diol tautomer of N-acetylglycine. In comparison with the simple amino acids, the tautomerization rate is higher because of the presence of the peptide bond. The study of a simple biologically relevant molecule containing a peptide bond allows us to demonstrate how increasing the complexity of the structure influences the behavior of the ionized molecule.
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Affiliation(s)
- Jaroslav Kocisek
- CIMAP, UMR 6252 (CEA/CNRS/ENSICAEN/UCBN), Bd. Henri Becquerel, BP 5133, 14070 Caen Cedex 5, France
| | | | - Rudy Delaunay
- CIMAP, UMR 6252 (CEA/CNRS/ENSICAEN/UCBN), Bd. Henri Becquerel, BP 5133, 14070 Caen Cedex 5, France.,Université de Caen Basse-Normandie , Esplanade de la Paix, CS 14032, 14032 Caen Cedex 5, France
| | - Bernd A Huber
- CIMAP, UMR 6252 (CEA/CNRS/ENSICAEN/UCBN), Bd. Henri Becquerel, BP 5133, 14070 Caen Cedex 5, France
| | - Lamri Adoui
- CIMAP, UMR 6252 (CEA/CNRS/ENSICAEN/UCBN), Bd. Henri Becquerel, BP 5133, 14070 Caen Cedex 5, France.,Université de Caen Basse-Normandie , Esplanade de la Paix, CS 14032, 14032 Caen Cedex 5, France
| | - Fernando Martín
- Departamento de Química, Módulo 13, Universidad Autónoma de Madrid , 28049 Madrid, Spain.,Instituto Madrileño de Estudios Avanzados en Nanociencias (IMDEA-Nanociencia), Cantoblanco, 28049 Madrid, Spain.,Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid , 28049 Madrid, Spain
| | - Manuel Alcamí
- Departamento de Química, Módulo 13, Universidad Autónoma de Madrid , 28049 Madrid, Spain.,Instituto Madrileño de Estudios Avanzados en Nanociencias (IMDEA-Nanociencia), Cantoblanco, 28049 Madrid, Spain
| | - Patrick Rousseau
- CIMAP, UMR 6252 (CEA/CNRS/ENSICAEN/UCBN), Bd. Henri Becquerel, BP 5133, 14070 Caen Cedex 5, France.,Université de Caen Basse-Normandie , Esplanade de la Paix, CS 14032, 14032 Caen Cedex 5, France
| | - Alicja Domaracka
- CIMAP, UMR 6252 (CEA/CNRS/ENSICAEN/UCBN), Bd. Henri Becquerel, BP 5133, 14070 Caen Cedex 5, France
| | - Janina Kopyra
- Faculty of Science, Siedlce University , 3 Maja 54, 08-110 Siedlce, Poland
| | - Sergio Díaz-Tendero
- Departamento de Química, Módulo 13, Universidad Autónoma de Madrid , 28049 Madrid, Spain
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Feng WL, Tian SX. Ab Initio Molecular Dynamics Simulation Study of Dissociative Electron Attachment to Dialanine Conformers. J Phys Chem A 2015; 119:1838-45. [DOI: 10.1021/jp512173z] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Wen-Ling Feng
- Hefei
National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Shan Xi Tian
- Hefei
National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026, China
- Department
of Chemical Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
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Dawley MM, Tanzer K, Cantrell WA, Plattner P, Brinkmann NR, Scheier P, Denifl S, Ptasińska S. Electron ionization of the nucleobases adenine and hypoxanthine near the threshold: a combined experimental and theoretical study. Phys Chem Chem Phys 2014; 16:25039-53. [DOI: 10.1039/c4cp03452j] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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