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Raczyńska ED, Makowski M. Effects of Positive and Negative Ionization on Prototropy in Pyrimidine Bases: An Unusual Case of Isocytosine. J Phys Chem A 2018; 122:7863-7879. [PMID: 30192141 DOI: 10.1021/acs.jpca.8b07539] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Intramolecular proton-transfers (prototropic conversions) have been studied for the guanine building block isocytosine (iC), and effects of positive ionization, called one-electron oxidation (iC - e → iC+•), and negative ionization, called one-electron reduction (iC + e → iC-•), on tautomeric conversions when proceeding from neutral to ionized isocytosine have been discussed. Although radical cations and radical anions are very short-lived species, the ionization effects could be investigated by quantum-chemical methods. Such kind of studies gives some information about the labile protons and the most basic positions in the neutral and radical forms of the tautomeric system. For investigations, the complete isomeric mixture of isocytosine has been considered and calculations performed in two extreme environments, apolar {DFT(B3LYP)/6-311+G(d,p)} and polar {PCM(water)//DFT(B3LYP)/6-311+G(d,p)}. For selected isomers, the G4 theory has also been applied. There are no good relations for energetic parameters of neutral and ionized forms. Ionization energies depend on localization of labile protons. Tautomeric equilibria for neutral and ionized isocytosine, favored sites of protonation and deprotonation, and favored structures of protonated and deprotonated forms strongly depend on environment. Acidity of iC+• is close to that of the iC conjugate acid, and basicity of iC-• is close to that of the iC conjugate base. This increase of acid-base properties of charged radicals explains the proton-transfer in ionized pairs of nucleobases. When compared to other pyrimidine bases such as uracil (U) and cytosine (C), which exhibit analogous tautomeric equilibria between nine prototropic tautomers as isocytosine, the tautomeric preferences for iC, iC+•, iC-•, U, U+•, U-•, C, C+•, and C-• are completely different. The differences suggest that acid-base properties of functional groups, their stabilities, and ionization energies play a principal role in proton-transfers for pyrimidine bases and influence compositions of tautomeric mixtures.
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Affiliation(s)
- Ewa D Raczyńska
- Department of Chemistry , Warsaw University of Life Sciences (SGGW) , ul. Nowoursynowska 159c , 02-776 Warszawa , Poland
| | - Mariusz Makowski
- Faculty of Chemistry , University of Gdańsk , ul. Wita Stwosza 63 , 80-308 Gdańsk , Poland
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2
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Wasserman A, Nafziger J, Jiang K, Kim MC, Sim E, Burke K. The Importance of Being Inconsistent. Annu Rev Phys Chem 2017; 68:555-581. [PMID: 28463652 DOI: 10.1146/annurev-physchem-052516-044957] [Citation(s) in RCA: 74] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Adam Wasserman
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907
- Department of Physics and Astronomy, Purdue University, West Lafayette, Indiana 47907
| | - Jonathan Nafziger
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907
| | - Kaili Jiang
- Department of Physics and Astronomy, Purdue University, West Lafayette, Indiana 47907
| | - Min-Cheol Kim
- Department of Chemistry, Yonsei University, Seoul 03722, South Korea
| | - Eunji Sim
- Department of Chemistry, Yonsei University, Seoul 03722, South Korea
| | - Kieron Burke
- Department of Chemistry, University of California, Irvine, California 92697
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Zeng Z, Bernstein ER. Anionic fructose-related conformational and positional isomers assigned through PES experiments and DFT calculations. Phys Chem Chem Phys 2017; 19:23325-23344. [DOI: 10.1039/c7cp03492j] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Fructose− exists as an open chain structure with substrate dependent specific conformational isomers. (Fructose-H2O)− evidences two types of positional isomers.
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Affiliation(s)
- Zhen Zeng
- Department of Chemistry
- NSF ERC for Extreme Ultraviolet Science and Technology
- Colorado State University
- Fort Collins
- USA
| | - Elliot R. Bernstein
- Department of Chemistry
- NSF ERC for Extreme Ultraviolet Science and Technology
- Colorado State University
- Fort Collins
- USA
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Effects of ionization on stability of 1-methylcytosine - DFT and PCM studies. J Mol Model 2016; 22:146. [PMID: 27259531 PMCID: PMC4893064 DOI: 10.1007/s00894-016-3020-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Accepted: 05/26/2016] [Indexed: 01/01/2023]
Abstract
Consequences of ionization were studied by quantum-chemical methods (DFT and PCM) for 1-methylcytosine (MC)—a model of the nucleobase cytosine (C) connected with sugar in DNA. For calculations, three prototropic tautomers (one amino and two imino forms) and two imino zwitterions were considered, including conformational or configurational isomerism of exo heterogroups. Ionization and interactions between neighboring groups affect intramolecular proton-transfers, geometric and thermodynamic parameters, and electron delocalization for individual isomers. We discovered that an imino isomer is present in the isomeric mixture in the highest amount for positively ionized MC. Its contribution in neutral and negatively ionized MC is considerably smaller. Acid-base parameters for selected radical ions were estimated in the gas phase and compared to those of neutral MC. Gas-phase acidity of radical cations is close to that of the conjugate acid of MC, and gas-phase basicity of radical anions is close to that of the conjugate base of MC. Various routes of amino-imino conversion between neutral and ionized isomers were considered. Energetic-barrier for intramolecular proton-transfer in MC is close to that in the parent system—formamidine.
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Shao P, Ding LP, Cai JT, Lu C, Liu B, Sun CB. Microhydration effects on the structures and electrophilic properties of cytidine. RSC Adv 2016. [DOI: 10.1039/c6ra11720a] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Adiabatic electron affinities (AEAs) for cytidine hydrates with up to four water molecules.
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Affiliation(s)
- Peng Shao
- Department of Physics
- Shaanxi University of Science & Technology
- Xi'an 710021
- China
| | - Li-Ping Ding
- Department of Optoelectronic Science & Technology
- College of Electrical & Information Engineering
- Shaanxi University of Science & Technology
- Xi'an 710021
- China
| | - Jiang-Tao Cai
- Department of Physics
- Shaanxi University of Science & Technology
- Xi'an 710021
- China
| | - Cheng Lu
- Beijing Computational Science Research Center
- Beijing 100084
- China
| | - Bo Liu
- Department of Physics
- Shaanxi University of Science & Technology
- Xi'an 710021
- China
| | - Chang-Bo Sun
- Department of Physics
- Shaanxi University of Science & Technology
- Xi'an 710021
- China
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Shao P, Kuang XY, Ding LP, Zhao YR. Structures, electrophilic properties, and hydrogen bonds of cytidine, uridine, and their radical anions: Microhydration effects. J Chem Phys 2013; 139:024305. [PMID: 23862941 DOI: 10.1063/1.4812500] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Structures, electrophilic properties, and hydrogen bonds of the neutral and anionic monohydrated nucleoside, (cytidine)H2O, and (uridine)H2O have been systematically investigated using density functional theory. Various water-binding sites were predicted by explicitly considering the optimized monohydrated structures. Meanwhile, predictions of electron affinities and vertical detachment energies were also carried out to investigate their electrophilic properties. By examining the singly occupied molecular orbital and natural population analysis, we found the excess negative charge is localized on the cytidine and uridine moiety in anionic monohydrates. This may be the reason why the strength of hydrogen bonding undergoes an obvious change upon the extra electron attachment. Based on the electron density (ρ) and reduced density gradient (RDG), we present an approach to map and analyze the weak interaction (especially hydrogen bond) in monohydrated cytidine and uridine. The scatter plots of RDG versus ρ allow us to identify the different type interactions. Meanwhile, the maps of the gradient isosurfaces show a rich visualization of hydrogen bond, van der Waals interaction, and steric effect.
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Affiliation(s)
- Peng Shao
- Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065, China
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Gu J, Leszczynski J, Schaefer HF. Interactions of electrons with bare and hydrated biomolecules: from nucleic acid bases to DNA segments. Chem Rev 2012; 112:5603-40. [PMID: 22694487 DOI: 10.1021/cr3000219] [Citation(s) in RCA: 158] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Jiande Gu
- Drug Design & Discovery Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, CAS, PR China.
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Gupta A, Jaeger HM, Compaan KR, Schaefer HF. Electron attachment to the guanine-cytosine nucleic acid base pair and the effects of monohydration and proton transfer. J Phys Chem B 2012; 116:5579-87. [PMID: 22530702 DOI: 10.1021/jp211608b] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The guanine-cytosine (GC) radical anion and its interaction with a single water molecule is studied using ab initio and density functional methods. Z-averaged second-order perturbation theory (ZAPT2) was applied to GC radical anion for the first time. Predicted spin densities show that the radical character is localized on cytosine. The Watson-Crick monohydrated GC anion is compared to neutral GC·H2O, as well as to the proton-transferred analogue on the basis of structural and energetic properties. In all three systems, local minima are identified that correspond to water positioned in the major and minor grooves of macromolecular DNA. On the anionic surface, two novel structures have water positioned above or below the GC plane. On the neutral and anionic surfaces, the global minimum can be described as water interacting with the minor groove. These structures are predicted to have hydration energies of 9.7 and 11.8 kcal mol(-1), respectively. Upon interbase proton-transfer (PT), the anionic global minimum has water positioned in the major groove, and the hydration energy increases to 13.4 kcal mol(-1). PT GC·H2O(•-) has distonic character; the radical character resides on cytosine, while the negative charge is localized on guanine. The effects of proton transfer are further investigated through the computed adiabatic electron affinities (AEA) of GC and monohydrated GC, and the vertical detachment energies (VDE) of the corresponding anions. Monohydration increases the AEAs and VDEs by only 0.1 eV, while proton-transfer increases the VDEs substantially (0.8 eV). The molecular charge distribution of monohydrated guanine-cytosine radical anion depends heavily on interbase proton transfer.
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Melicherčík M, Pašteka LF, Neogrády P, Urban M. Electron Affinities of Uracil: Microsolvation Effects and Polarizable Continuum Model. J Phys Chem A 2012; 116:2343-51. [DOI: 10.1021/jp211994k] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Miroslav Melicherčík
- Department of Physical and Theoretical
Chemistry, Faculty of Natural Sciences, Comenius University, Mlynská dolina, SK-842 15 Bratislava, Slovakia
| | - Lukáš F. Pašteka
- Department of Physical and Theoretical
Chemistry, Faculty of Natural Sciences, Comenius University, Mlynská dolina, SK-842 15 Bratislava, Slovakia
| | - Pavel Neogrády
- Department of Physical and Theoretical
Chemistry, Faculty of Natural Sciences, Comenius University, Mlynská dolina, SK-842 15 Bratislava, Slovakia
| | - Miroslav Urban
- Department of Physical and Theoretical
Chemistry, Faculty of Natural Sciences, Comenius University, Mlynská dolina, SK-842 15 Bratislava, Slovakia
- Slovak University of Technology
in Bratislava, Faculty of Materials Science and Technology in Trnava, Institute of Materials Science, Bottova 25, SK-917
24 Trnava, Slovakia
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10
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Kim MC, Sim E, Burke K. Communication: Avoiding unbound anions in density functional calculations. J Chem Phys 2011; 134:171103. [DOI: 10.1063/1.3590364] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Min-Cheol Kim
- Department of Chemistry and Institute of Nano-Bio Molecular Assemblies, Yonsei University, 50 Yonsei-ro Seodaemun-gu, Seoul 120-749, South Korea
| | - Eunji Sim
- Department of Chemistry and Institute of Nano-Bio Molecular Assemblies, Yonsei University, 50 Yonsei-ro Seodaemun-gu, Seoul 120-749, South Korea
| | - Kieron Burke
- Department of Chemistry, University of California, Irvine, California, 92697, USA
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Dedíková P, Neogrády P, Urban M. Electron Affinities of Small Uracil−Water Complexes: A Comparison of Benchmark CCSD(T) Calculations with DFT. J Phys Chem A 2011; 115:2350-8. [DOI: 10.1021/jp111104j] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Pavlína Dedíková
- Department of Physical and Theoretical Chemistry, Faculty of Natural Sciences, Comenius University, Mlynská dolina, SK-842 15 Bratislava, Slovakia
| | - Pavel Neogrády
- Department of Physical and Theoretical Chemistry, Faculty of Natural Sciences, Comenius University, Mlynská dolina, SK-842 15 Bratislava, Slovakia
| | - Miroslav Urban
- Department of Physical and Theoretical Chemistry, Faculty of Natural Sciences, Comenius University, Mlynská dolina, SK-842 15 Bratislava, Slovakia
- Faculty of Materials Science and Technology in Trnava, Institute of Materials Science, Slovak University of Technology in Bratislava, Bottova 25, SK-917 24 Trnava, Slovakia
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