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Ameixa J, Arthur-Baidoo E, Pereira-da-Silva J, Ončák M, Ruivo J, Varella MDN, Ferreira da Silva F, Denifl S. Parent anion radical formation in coenzyme Q 0: Breaking ubiquinone family rules. Comput Struct Biotechnol J 2022; 21:346-353. [PMID: 36582437 PMCID: PMC9792397 DOI: 10.1016/j.csbj.2022.12.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Revised: 12/06/2022] [Accepted: 12/06/2022] [Indexed: 12/13/2022] Open
Abstract
We report electron attachment (EA) measurements for the parent anion radical formation from coenzyme Q0 (CoQ0) at low electron energies (<2 eV) along with quantum chemical calculations. CoQ0 may be considered a prototype for the electron withdrawing properties of the larger CoQ n molecules, in particular ubiquinone (CoQ10), an electron carrier in aerobic cell respiration. Herein, we show that the mechanisms for the parent anion radical formation of CoQ0 and CoQ n (n = 1,2,4) are remarkably distinct. Reported EA data for CoQ1, CoQ2, CoQ4 and para-benzoquinone indicated stabilization of the parent anion radicals around 1.2-1.4 eV. In contrast, we observe for the yield of the parent anion radical of CoQ0 a sharp peak at ∼ 0 eV, a shoulder at 0.07 eV and a peak around 0.49 eV. Although the mechanisms for the latter feature remain unclear, our calculations suggest that a dipole bound state (DBS) would account for the lower energy signals. Additionally, the isoprenoid side chains in CoQ n (n = 1,2,4) molecules seem to influence the DBS formation for these compounds. In contrast, the side chains enhance the parent anion radical stabilization around 1.4 eV. The absence of parent anion radical formation around 1.4 eV for CoQ0 can be attributed to the short auto-ionization lifetimes. The present results shed light on the underappreciated role played by the side chains in the stabilization of the parent anion radical. The isoprenoid tails should be viewed as co-responsible for the electron-accepting properties of ubiquinone, not mere spectators of electron transfer reactions.
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Affiliation(s)
- J. Ameixa
- Institut für Ionenphysik und Angewandte Physik, Leopold-Franzens Universität Innsbruck, Technikerstraße 25/3, 6020 Innsbruck, Austria,CEFITEC, Department of Physics, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal,Center for Molecular Biosciences (CMBI), Leopold-Franzens Universität Innsbruck, Technikerstraße 25/3, 6020 Innsbruck, Austria
| | - E. Arthur-Baidoo
- Institut für Ionenphysik und Angewandte Physik, Leopold-Franzens Universität Innsbruck, Technikerstraße 25/3, 6020 Innsbruck, Austria,Center for Molecular Biosciences (CMBI), Leopold-Franzens Universität Innsbruck, Technikerstraße 25/3, 6020 Innsbruck, Austria
| | - J. Pereira-da-Silva
- CEFITEC, Department of Physics, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal
| | - M. Ončák
- Institut für Ionenphysik und Angewandte Physik, Leopold-Franzens Universität Innsbruck, Technikerstraße 25/3, 6020 Innsbruck, Austria
| | - J.C. Ruivo
- Institute of Physics, University of São Paulo, Rua do Matão 1731, 05508-090 São Paulo, Brazil
| | - M.T. do N. Varella
- Institute of Physics, University of São Paulo, Rua do Matão 1731, 05508-090 São Paulo, Brazil,Corresponding authors at: Institut für Ionenphysik und Angewandte Physik, Leopold-Franzens Universität Innsbruck, Technikerstraße 25/3, 6020 Innsbruck, Austria (S. Denifl).
| | - F. Ferreira da Silva
- CEFITEC, Department of Physics, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal,Corresponding authors at: Institut für Ionenphysik und Angewandte Physik, Leopold-Franzens Universität Innsbruck, Technikerstraße 25/3, 6020 Innsbruck, Austria (S. Denifl).
| | - S. Denifl
- Institut für Ionenphysik und Angewandte Physik, Leopold-Franzens Universität Innsbruck, Technikerstraße 25/3, 6020 Innsbruck, Austria,Center for Molecular Biosciences (CMBI), Leopold-Franzens Universität Innsbruck, Technikerstraße 25/3, 6020 Innsbruck, Austria,Corresponding authors at: Institut für Ionenphysik und Angewandte Physik, Leopold-Franzens Universität Innsbruck, Technikerstraße 25/3, 6020 Innsbruck, Austria (S. Denifl).
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Ameixa J, Arthur‐Baidoo E, Pereira‐da‐Silva J, Ruivo JC, T. do N. Varella M, Beyer MK, Ončák M, Ferreira da Silva F, Denifl S. Formation of Temporary Negative Ions and Their Subsequent Fragmentation upon Electron Attachment to CoQ 0 and CoQ 0 H 2. Chemphyschem 2022; 23:e202100834. [PMID: 35146888 PMCID: PMC9306667 DOI: 10.1002/cphc.202100834] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Revised: 01/05/2022] [Indexed: 11/06/2022]
Abstract
Ubiquinone molecules have a high biological relevance due to their action as electron carriers in the mitochondrial electron transport chain. Here, we studied the dissociative interaction of free electrons with CoQ0 , the smallest ubiquinone derivative with no isoprenyl units, and its fully reduced form, 2,3-dimethoxy-5-methylhydroquinone (CoQ0 H2 ), an ubiquinol derivative. The anionic products produced upon dissociative electron attachment (DEA) were detected by quadrupole mass spectrometry and studied theoretically through quantum chemical and electron scattering calculations. Despite the structural similarity of the two studied molecules, remarkably only a few DEA reactions are present for both compounds, such as abstraction of a neutral hydrogen atom or the release of a negatively charged methyl group. While the loss of a neutral methyl group represents the most abundant reaction observed in DEA to CoQ0 , this pathway is not observed for CoQ0 H2 . Instead, the loss of a neutral OH radical from the CoQ0 H2 temporary negative ion is observed as the most abundant reaction channel. Overall, this study gives insights into electron attachment properties of simple derivatives of more complex molecules found in biochemical pathways.
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Affiliation(s)
- João Ameixa
- Institut für Ionenphysik und Angewandte PhysikLeopold-Franzens Universität InnsbruckTechnikerstraße 256020InnsbruckAustria
- Center for Biomolecular Sciences Innsbruck (CMBI)Leopold-Franzens Universität InnsbruckTechnikerstraße 256020InnsbruckAustria
- Centre of Physics and Technological ResearchDepartamento de FísicaFaculdade de Ciências e TecnologiaUniversidade NOVA de Lisboa2829-516CaparicaPortugal
| | - Eugene Arthur‐Baidoo
- Institut für Ionenphysik und Angewandte PhysikLeopold-Franzens Universität InnsbruckTechnikerstraße 256020InnsbruckAustria
- Center for Biomolecular Sciences Innsbruck (CMBI)Leopold-Franzens Universität InnsbruckTechnikerstraße 256020InnsbruckAustria
| | - João Pereira‐da‐Silva
- Centre of Physics and Technological ResearchDepartamento de FísicaFaculdade de Ciências e TecnologiaUniversidade NOVA de Lisboa2829-516CaparicaPortugal
| | - Júlio C. Ruivo
- Instituto de FísicaUniversidade de São PauloRua do Matão 173105508-090São PauloBrazil
| | | | - Martin K. Beyer
- Institut für Ionenphysik und Angewandte PhysikLeopold-Franzens Universität InnsbruckTechnikerstraße 256020InnsbruckAustria
| | - Milan Ončák
- Institut für Ionenphysik und Angewandte PhysikLeopold-Franzens Universität InnsbruckTechnikerstraße 256020InnsbruckAustria
| | - Filipe Ferreira da Silva
- Centre of Physics and Technological ResearchDepartamento de FísicaFaculdade de Ciências e TecnologiaUniversidade NOVA de Lisboa2829-516CaparicaPortugal
| | - Stephan Denifl
- Institut für Ionenphysik und Angewandte PhysikLeopold-Franzens Universität InnsbruckTechnikerstraße 256020InnsbruckAustria
- Center for Biomolecular Sciences Innsbruck (CMBI)Leopold-Franzens Universität InnsbruckTechnikerstraße 256020InnsbruckAustria
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Ziegler P, Pelc A, Arthur-Baidoo E, Ameixa J, Ončák M, Denifl S. Negative ion formation and fragmentation upon dissociative electron attachment to the nicotinamide molecule. RSC Adv 2021; 11:32425-32434. [PMID: 35495526 PMCID: PMC9041917 DOI: 10.1039/d1ra06083j] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Accepted: 09/13/2021] [Indexed: 12/20/2022] Open
Abstract
Nicotinamide (C6H6N2O) is a biologically relevant molecule. This compound has several important roles related to the anabolic and metabolic processes that take place in living organisms. It is also used as a radiosensitizer in tumor therapy. As a result of the interaction of high-energy radiation with matter, low-energy electrons are also released, which can also interact with other molecules, forming several types of ions. In the present investigation, dissociative electron attachment to C6H6N2O has been studied in a crossed electron-molecular beams experiment in the electron energy range of about 0-15 eV. In the experiment, six anionic species were detected: C6H5N2O-, C5H4N-, NCO-, O-/NH2 -, and CN-, with NCO- being the most prominent anion. We also provide detailed computational results regarding the energetic thresholds and pathways of the respective dissociative electron attachment (DEA) channels. The experimental results are compared with the theoretical ones and on this basis, the possible DEA reactions for the formation of anions at a given resonance energy were assigned as well as the generation of neutrals fragments such as pyridine and its several derivatives and radicals are predicted. The pyridine ring seems to stay intact during the DEA process.
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Affiliation(s)
- Patrick Ziegler
- Institute for Ion Physics and Applied Physics, University of Innsbruck Technikerstrasse 25 6020 Innsbruck Austria
| | - Andrzej Pelc
- Maria Curie-Skłodowska University, Department of Biophysics, Mass Spectrometry Laboratory Pl. M. C.-Skłodowskiej 1 20-031 Lublin Poland
| | - Eugene Arthur-Baidoo
- Institute for Ion Physics and Applied Physics, University of Innsbruck Technikerstrasse 25 6020 Innsbruck Austria
| | - Joao Ameixa
- Institute for Ion Physics and Applied Physics, University of Innsbruck Technikerstrasse 25 6020 Innsbruck Austria
- Centre of Physics and Technological Research, Departamento de Física, Faculdade de Ciências e Tecnologia, Universidade NOVA de Lisboa 2829-516 Caparica Portugal
| | - Milan Ončák
- Institute for Ion Physics and Applied Physics, University of Innsbruck Technikerstrasse 25 6020 Innsbruck Austria
| | - Stephan Denifl
- Institute for Ion Physics and Applied Physics, University of Innsbruck Technikerstrasse 25 6020 Innsbruck Austria
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