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Development of an Fe II Complex Exhibiting Intermolecular Proton Shifting Coupled Spin Transition. Angew Chem Int Ed Engl 2024:e202404843. [PMID: 38622084 DOI: 10.1002/anie.202404843] [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: 03/11/2024] [Revised: 04/13/2024] [Accepted: 04/15/2024] [Indexed: 04/17/2024]
Abstract
In this study, we investigated reversible intermolecular proton shifting (IPS) coupled with spin transition (ST) in a novel FeII complex. The host FeII complex and the guest carboxylic acid anion were connected by intermolecular hydrogen bonds (IHBs). We extended the intramolecular proton transfer coupled ST phenomenon to the intermolecular system. The dynamic phenomenon was confirmed by variable-temperature single-crystal X-ray diffraction, neutron crystallography, and infrared spectroscopy. The mechanism of IPS was further validated using density functional theory calculations. The discovery of IPS-coupled ST in crystalline molecular materials provides good insights into fundamental processes and promotes the design of novel multifunctional materials with tunable properties for various applications, such as optoelectronics, information storage, and molecular devices.
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Tautomerisation Mechanisms in the Adenine-Thymine Nucleobase Pair during DNA Strand Separation. J Phys Chem B 2023; 127:4220-4228. [PMID: 36939840 DOI: 10.1021/acs.jpcb.2c08631] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/21/2023]
Abstract
The adenine-thymine tautomer (A*-T*) has previously been discounted as a spontaneous mutagenesis mechanism due to the energetic instability of the tautomeric configuration. We study the stability of A*-T* while the nucleobases undergo DNA strand separation. Our calculations indicate an increase in the stability of A*-T* as the DNA strands unzip and the hydrogen bonds between the bases stretch. Molecular Dynamics simulations reveal the time scales and dynamics of DNA strand separation and the statistical ensemble of opening angles present in a biological environment. Our results demonstrate that the unwinding of DNA, an inherently out-of-equilibrium process facilitated by helicase, will change the energy landscape of the adenine-thymine tautomerization reaction. We propose that DNA strand separation allows the stable tautomerization of adenine-thymine, providing a feasible pathway for genetic point mutations via proton transfer between the A-T bases.
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3
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Proton transfer during DNA strand separation as a source of mutagenic guanine-cytosine tautomers. Commun Chem 2022; 5:144. [PMID: 36697962 PMCID: PMC9814255 DOI: 10.1038/s42004-022-00760-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Accepted: 10/14/2022] [Indexed: 11/06/2022] Open
Abstract
Proton transfer between the DNA bases can lead to mutagenic Guanine-Cytosine tautomers. Over the past several decades, a heated debate has emerged over the biological impact of tautomeric forms. Here, we determine that the energy required for generating tautomers radically changes during the separation of double-stranded DNA. Density Functional Theory calculations indicate that the double proton transfer in Guanine-Cytosine follows a sequential, step-like mechanism where the reaction barrier increases quasi-linearly with strand separation. These results point to increased stability of the tautomer when the DNA strands unzip as they enter the helicase, effectively trapping the tautomer population. In addition, molecular dynamics simulations indicate that the relevant strand separation time is two orders of magnitude quicker than previously thought. Our results demonstrate that the unwinding of DNA by the helicase could simultaneously slow the formation but significantly enhance the stability of tautomeric base pairs and provide a feasible pathway for spontaneous DNA mutations.
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Mechanistic insight into the tautomerization of histidine initiated by water-catalyzed N-H and C-H cleavages. J Mol Model 2022; 28:325. [PMID: 36136156 DOI: 10.1007/s00894-022-05222-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Accepted: 07/12/2022] [Indexed: 10/14/2022]
Abstract
The N-H and C-H activation is of great significance in organic chemistry and chemical industry fields, especially, in the utilization of petroleum raw materials. High NδH (tautomer of natural histidine) content would increase Alzheimer's disease risk. To inhibit this and improve the activation of N-H and C-H bonds, the isomerization mechanism from NδH to NεH of histidine-containing dipeptide catalyzed by water cluster was explored. The results discovered that water cluster assists this reaction by reducing the activation energies from 68.20 to 9.60 kcal mol-1, and its size not only affects the reaction rate but also determines the reaction pathway in a degree. Moreover, water cluster, taken as a potential green catalyst, is more effective on the reactions involving N-H and C-H bond cleavages than reported common toxic organometallic compounds and has different catalytic mechanisms. This work also provides some theoretical guidance for the modulation of Alzheimer's disease induced by histidine isomerization.
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Time delay during intra-base proton tunneling in the guanine base of the single stranded DNA. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2022; 173:4-10. [PMID: 35659504 DOI: 10.1016/j.pbiomolbio.2022.05.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2021] [Revised: 05/17/2022] [Accepted: 05/29/2022] [Indexed: 06/15/2023]
Abstract
Spontaneous point mutations are one of the main actors in evolution, and the tautomerization of organic bases in the DNA is hypothesized to be the underlying mechanism of this crucial process. Tautomerization can be induced by proton tunneling, and if it occurs in single-stranded DNA (ssDNA) during the replication process, tautomerized bases might give rise to a mismatch, which will eventually defect the genetic code. In the present work, we report on the tautomerization time in the guanine base of the ssDNA. The model we use includes an intra-base tunneling mechanism such that time tunneling (delay time) is estimated to be around a few pico-seconds. The time delay is found to be biologically relevant which indicates that it is long enough to induce point mutations. Our results close a gap in the literature and sheds light on the importance of point mutations originating from quantum effects in the ssDNA.
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Electromagnetic bioeffects: a multiscale molecular simulation perspective. Phys Chem Chem Phys 2022; 24:6327-6348. [PMID: 35245928 DOI: 10.1039/d1cp05510k] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Electromagnetic bioeffects remain an enigma from both the experimental and theoretical perspectives despite the ubiquitous presence of related technologies in contemporary life. Multiscale computational modelling can provide valuable insights into biochemical systems and predict how they will be perturbed by external stimuli. At a microscopic level, it can be used to determine what (sub)molecular scale reactions various stimuli might induce; at a macroscopic level, it can be used to examine how these changes affect dynamic behaviour of essential molecules within the crowded biomolecular milieu in living tissues. In this review, we summarise and evaluate recent computational studies that examined the impact of externally applied electric and electromagnetic fields on biologically relevant molecular systems. First, we briefly outline the various methodological approaches that have been employed to study static and oscillating field effects across different time and length scales. The practical value of such modelling is then illustrated through representative case-studies that showcase the diverse effects of electric and electromagnetic field on the main physiological solvent - water, and the essential biomolecules - DNA, proteins, lipids, as well as some novel biomedically relevant nanomaterials. The implications and relevance of the theoretical multiscale modelling to practical applications in therapeutic medicine are also discussed. Finally, we summarise ongoing challenges and potential opportunities for theoretical modelling to advance the current understanding of electromagnetic bioeffects for their modulation and/or beneficial exploitation in biomedicine and industry.
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7
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Computational Insights in DNA Methylation: Catalytic and Mechanistic Elucidations for Forming 3-Methyl Cytosine. J CHEM-NY 2022. [DOI: 10.1155/2022/2673396] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Methylation at C5 position of cytosine (5 mC) is the most abundantly occurring methylation process at CpG island, which has been well known as an epigenetic modification linked to many human diseases. Recently, another methylation approach has been discovered to show that DNA methyltransferases (DNMTs) promote the addition of the methyl group at position 3 to yield 3 mC. The existence of 3 mC can cause severe damages to the DNA strand, such as blocking its replication, repair, and transcription, affecting its stability, and initiating a double-strand DNA break. To gain a deeper insight into the formation of 3 mC, we have performed density functional theory (DFT) modeling studies at different levels of theory to clearly map out the mechanistic details for this new methylation approach. Our computed results are in harmony with pertinent experimental observations and shed light on a crucial off-target activity of DNMTs.
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Atomistic mechanisms of the tautomerization of the G·C base pairs through the proton transfer: quantum-chemical survey. J Mol Model 2021; 27:367. [PMID: 34855024 DOI: 10.1007/s00894-021-04988-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2021] [Accepted: 11/23/2021] [Indexed: 10/19/2022]
Abstract
This study is devoted to the investigation of the G·C*tO2(WC)↔G*NH3·C*t(WC), G·C*O2(WC)↔G*NH3·C*(WC) and G*·C*O2(WC)↔G*NH3·C(wWC)↓ tautomerization reactions occurring through the proton transfer, obtained at the MP2/6-311++G(2df,pd)//B3LYP/6-311++G(d,p) level of theory in gas phase under normal conditions ('WC' means base pair in Watson-Crick configuration, T=298.15 K). These reactions lead to the formation of the G*NH3·C*t(WC), G*NH3·C*(WC) and G*NH3·C(wWC)↓ base pairs by the participation of the G*NH3 base with NH3 group. Gibbs free energies of activation for these reactions are 6.43, 11.00 and 1.63 kcal·mol-1, respectively. All of these tautomerization reactions are dipole active. Finally, we believe that these non-dissociative processes, which are tightly connected with the tautomeric transformations of the G·C base pairs, play an outstanding role in supporting of the spatial structure of the DNA and RNA molecules with various functional purposes.
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Quantum and classical effects in DNA point mutations: Watson-Crick tautomerism in AT and GC base pairs. Phys Chem Chem Phys 2021; 23:4141-4150. [PMID: 33533770 DOI: 10.1039/d0cp05781a] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Proton transfer along the hydrogen bonds of DNA can lead to the creation of short-lived, but biologically relevant point mutations that can further lead to gene mutation and, potentially, cancer. In this work, the energy landscape of the canonical A-T and G-C base pairs (standard, amino-keto) to tautomeric A*-T* and G*-C* (non-standard, imino-enol) Watson-Crick DNA base pairs is modelled with density functional theory and machine-learning nudge-elastic band methods. We calculate the energy barriers and tunnelling rates of hydrogen transfer between and within each base monomer (A, T, G and C). We show that the role of tunnelling in A-T tautomerisation is statistically unlikely due to the presence of a small reverse reaction barrier. On the contrary, the thermal populations of the G*-C* point mutation could be non-trivial and propagate through the replisome. For the direct intramolecular transfer, the reaction is hindered by a substantial energy barrier. However, our calculations indicate that tautomeric bases in their monomeric form have remarkably long lifetimes.
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Long living excited state of protonated adenosine unveiled by ultrafast fluorescence spectroscopy and density functional theoretical study. Phys Chem Chem Phys 2021; 23:6472-6480. [PMID: 33729247 DOI: 10.1039/d0cp06439d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Adenosine (Ado) possesses ultrafast nonradiative dynamics accounting for its remarkably high photostability. The deactivation dynamics of Ado after protonation in an aqueous solution remains an elusive issue. Herein we report an investigation of the excited state dynamics of protonated Ado (AdoH+) performed using ultrafast time-resolved fluorescence spectroscopy combined with density functional theoretical calculation. The result obtained from comparison of conformers with protonation at different sites revealed that the syn-conformer with protonation occurring at the N3 position (syn-N3) is the predominant form of AdoH+ in the ground state, similar to that of Ado. In contrast, the fluorescence of AdoH+ with maximum intensity at 385 nm, significantly red-shifted from that of Ado, displaying decay dynamics composed of an ultrafast component with the lifetime of ∼0.5 ps and a slower one of ∼2.9 ns. The former is because of the decay of the syn-N3 conformer, similar to that reported for AdoH+ under the gas phase condition. The latter is due to the syn-N1 conformer formed via ultrafast proton transfer of the syn-N3. The excited state of syn-N1 has a peculiar nonplanar conformation over the purine molecule, which is responsible for the substantial Stokes shift showed in the fluorescence spectrum and correlates with a large energy barrier for nonradiative decay likely involving a reversed proton transfer. This study demonstrates the importance of protonation and solvent environment in altering dramatically the excited states of Ado, providing insight for better understanding nonradiative dynamics of both the monomeric bases and the oligomeric or polymeric DNAs.
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The influence of base pair tautomerism on single point mutations in aqueous DNA. Interface Focus 2020; 10:20190120. [PMID: 33178413 PMCID: PMC7653342 DOI: 10.1098/rsfs.2019.0120] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/24/2020] [Indexed: 12/11/2022] Open
Abstract
The relationship between base pair hydrogen bond proton transfer and the rate of spontaneous single point mutations at ambient temperatures and pressures in aqueous DNA is investigated. By using an ensemble-based multiscale computational modelling method, statistically robust rates of proton transfer for the A:T and G:C base pairs within a solvated DNA dodecamer are calculated. Several different proton transfer pathways are observed within the same base pair. It is shown that, in G:C, the double proton transfer tautomer is preferred, while the single proton transfer process is favoured in A:T. The reported range of rate coefficients for double proton transfer is consistent with recent experimental data. Notwithstanding the approximately 1000 times more common presence of single proton transfer products from A:T, observationally there is bias towards G:C to A:T mutations in a wide range of living organisms. We infer that the double proton transfer reactions between G:C base pairs have a negligible contribution towards this bias for the following reasons: (i) the maximum half-life of the G*:C* tautomer is in the range of picoseconds, which is significantly smaller than the milliseconds it takes for DNA to unwind during replication, (ii) statistically, the majority of G*:C* tautomers revert back to their canonical forms through a barrierless process, and (iii) the thermodynamic instability of the tautomers with respect to the canonical base pairs. Through similar reasoning, we also deduce that proton transfer in the A:T base pair does not contribute to single point mutations in DNA.
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A procedure to understanding the C-G to A-T transversion. SMD simulations from guanine oxidation pathways assisted by one H2O2 molecule in the C-G basis pair. J Mol Liq 2020. [DOI: 10.1016/j.molliq.2020.114123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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13
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Density functional theory studies on cytosine analogues for inducing double-proton transfer with guanine. Sci Rep 2020; 10:9671. [PMID: 32541653 PMCID: PMC7295794 DOI: 10.1038/s41598-020-66530-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Accepted: 05/14/2020] [Indexed: 01/29/2023] Open
Abstract
To induce double-proton transfer (DPT) with guanine in a biological environment, 12 cytosine analogues (Ca) were formed by atomic substitution. The DPT reactions in the Watson-Crick cytosine-guanine model complex (Ca0G) and 12 modified cytosine-guanine complexes (Ca1-12G) were investigated using density functional theory methods at the M06-2X/def2svp level. The intramolecular proton transfers within the analogues are not facile due to high energy barriers. The hydrogen bond lengths of the Ca1-12G complexes are shorter than those in the Ca0G complex, which are conducive to DPT reactions. The DPT energy barriers of Ca1-12G complexes are also lower than that of the Ca0G complex, in particular, the barriers in the Ca7G and Ca11G complexes were reduced to -1.33 and -2.02 kcal/mol, respectively, indicating they are significantly more prone to DPT reactions. The DPT equilibrium constants of Ca1-12G complexes range from 1.60 × 100 to 1.28 × 107, among which the equilibrium constants of Ca7G and Ca11G are over 1.0 × 105, so their DPT reactions may be adequate. The results demonstrate that those cytosine analogues, especially Ca7 and Ca11, are capable of inducing DPT with guanine, and then the guanine tautomer will form mismatches with thymine during DNA replication, which may provide new strategies for gene therapy.
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Mechanisms of the T-A to C-G transition studied by SMD simulations: Deamination vs tautomerisation. J Mol Liq 2020. [DOI: 10.1016/j.molliq.2020.113036] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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15
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Non-poissonian Distribution of Point Mutations in DNA. Front Chem 2020; 8:38. [PMID: 32083056 PMCID: PMC7005246 DOI: 10.3389/fchem.2020.00038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Accepted: 01/13/2020] [Indexed: 12/01/2022] Open
Abstract
In general, for chemical reactions occurring in systems, where fluctuations are not negligibly small, it is necessary to introduce a master equation for distribution of probability of fluctuations. It has been established that the monomolecular reactions of a type as A ↔ X are described by the master equation, which leads to a Poisson distribution with the variance equal to the average value N 0. However, the consideration of the Löwdin mechanism as autocatalytic non-linear chemical reactions such as A + X ↔ 2X and the corresponding master equation lead to a non-Poissonian probability distribution of fluctuations. In the presented work, first-order autocatalysis has been applied to the Löwdin's mechanism of spontaneous mutations in DNA. Describing double proton transfers between complimentary nucleotide bases along the chain by first-order autocatalytic reactions, the corresponding master equation for protons in tautomeric states becomes non-linear, and at non-equilibrium conditions this leads to the non-Poissonian distribution of spontaneous mutations in DNA. It is also suggested that the accumulation of large fluctuations of successive cooperative concerted protons along the chain may produce higher non-linearities which could have a significant impact on some biochemical processes, occurring in DNA.
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Abstract
Hydrogen bonds play a critical role in nucleobase studies as they encode genes, map protein structures, provide stability to the base pairs, and are involved in spontaneous and induced mutations. Proton transfer mechanism is a critical phenomenon that is related to the acid-base characteristics of the nucleobases in Watson-Crick base pairs. The energetic and dynamical behavior of the proton can be depicted from these characteristics and their adjustment to the water molecules or the surrounding ions. Further, new pathways open up in which protonated nucleobases are generated by proton transfer from the ionized water molecules and elimination of a hydroxyl radical in this review, the analysis will be focused on understanding the mechanism of untargeted mutations in canonical, wobble, Hoogsteen pairs, and mutagenic tautomers through the non-covalent interactions. Further, rare tautomer formation through the single proton transfer (SPT) and the double proton transfer (DPT), quantum tunneling in nucleobases, radiation-induced bystander effects, role of water in proton transfer (PT) reactions, PT in anticancer drugs-DNA interaction, displacement and oriental polarization, possible models for mutations in DNA, genome instability, and role of proton transfer using kinetic parameters for RNA will be discussed.
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Theoretical Study of Adenine to Guanine Transition Assisted by Water and Formic Acid Using Steered Molecular Dynamic Simulations. Front Chem 2019; 7:414. [PMID: 31249828 PMCID: PMC6582222 DOI: 10.3389/fchem.2019.00414] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Accepted: 05/20/2019] [Indexed: 01/22/2023] Open
Abstract
The free energy profile of the adenine to guanine transition in the gas and aqueous phases was obtained by applying steered molecular dynamic (SMD) simulations. Three processes were considered to explain the mechanism assisted by water and formic acid molecules. The first process is hydrolytic deamination of adenine, then oxidation of the hypoxanthine previously formed, and finally, the animation from xanthine to guanine. In the gas phase these processes indicate a slow and not spontaneous conversion (ΔG g = 4.07 kcal·mol-1, k = 5.59·10-40 s-1), and a lifetime for guanine of τ = 7.75·10+22 s. The presence of solvent makes the transition more difficult by increasing the reaction energy to 26.90 kcal·mol-1 and decreasing the speed of the process to 1.63·10-55 s-1. However, it decreases the energy of the deamination process to -9.63 kcal·mol-1 and the lifetime of guanine base to τ = 6.85·10+17 s when the surrounding medium used in the transition process is aqueous. The results show that the guanine could participate in genetic mutations based on the lifetimes obtained. Transition states and intermediates structures were analyzed at the molecular dynamic level. This allows to follow the mechanism over time and to calculate thermodynamic and kinetic properties.
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Structural and thermodynamic studies of cytosine to thymine conversion in gas and solution phases using steered molecular dynamic simulations. J Mol Liq 2019. [DOI: 10.1016/j.molliq.2018.12.152] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Extended Efficacy of Low-Dose Valganciclovir for Prevention of Cytomegalovirus Disease in Intermediate-Risk Kidney Transplant Recipients: Two-Year Follow-Up. EXP CLIN TRANSPLANT 2019; 17:339-343. [PMID: 30674240 DOI: 10.6002/ect.2018.0020] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
OBJECTIVES In a previous study, we evaluated 1-year outcomes of using low-dose valganciclovir prophylaxis for cytomegalovirus infection in intermediate-risk kidney transplant recipients. Whether this effect persists in the long term is unknown. We aimed to evaluate the 2-year follow up of such adopted prophylaxis. MATERIALS AND METHODS We randomized 2 matched groups of kidney transplant recipients (1:1) to receive valganciclovir as 450 mg daily (group 1) or 900 mg daily (group 2) for the first 6 months after kidney transplant. The final analysis included 196 patients as intermediate-risk patients (98 in each treatment group) after exclusion of 5 high-risk patients. Serologically, all patients were at moderate risk for cytomegalovirus infection. Long-term outcomes including cytomegalovirus disease, acute rejection, new-onset diabetes after transplant, graft loss, and patient survival were assessed. RESULTS Through year 2 of follow-up, cytomegalovirus infection was reported in only 1 patient in group 1 (at month 13) and 1 patient in group 2 (at month 19) (not significant). Biopsy-proven acute rejection episodes were not statistically different between the groups (2 episodes in group 1 and 6 in group 2; P = .431). New-onset diabetes posttransplant was reported in 8.1% in group 1 and 13.2% in group 2 (P = .535). Graft failure was equal in both groups (1 in each group) at 2 years of follow up (not significant). Patient survival was comparable in both groups (100% in group 1 versus 97.9% in group 2; P = .661). The total number of cytomegalovirus infections at 2 years was numerically less in group 1 (P = .128). CONCLUSIONS Low-dose valganciclovir prophylaxis for 6 months was associated with sustained reduction of cytomegalovirus infection up to 2 years after kidney transplant without significant impact on the acute rejection, new-onset diabetes posttransplant, or patient and graft outcomes.
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The prediction of intermolecular proton-transfer of guanine-cytosine base pair under the influence of fragments from decomposed MOFs. J Mol Model 2019; 25:40. [PMID: 30666421 DOI: 10.1007/s00894-019-3926-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2018] [Accepted: 01/03/2019] [Indexed: 10/27/2022]
Abstract
Metal-organic frameworks (MOFs) can be decomposed into various fragments, including negative/positive charges, Zn+ or Cu2+ when used as drug delivery materials. To evaluate the safety of MOFs, different mechanisms of intermolecular proton-transfer in guanine-cytosine (GC) base pair under the influence of such fragments were investigated by density functional theory methods. In a vacuum, calculation results show that an excess electron assists proton transfer in the anionic GC radical, and a hole assists proton transfer in the cationic GC radical with small energy barriers. The mechanism for Zn+-GC transfer is that the located hole assists proton transfer from G to C. All proton-transfers of Cu2+-GC become spontaneous with stable proton-transferred structures, and the driving force is the Cu2+ due to its electrostatic and oxidative effects. However, in a micro-water environment, the average energy barrier of all proton-transfer processes increases by 2.8 kcal mol-1 because of the redistribution of charges. Water molecules play a very important role in buffering, and the influence of fragments on intermolecular proton-transfer processes of GC is reduced.
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Effects of Intense Electric Fields on the Double Proton Transfer in the Watson–Crick Guanine–Cytosine Base Pair. J Phys Chem B 2018; 122:8631-8641. [DOI: 10.1021/acs.jpcb.8b05053] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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23
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Theoretical study of mechanisms for double proton transfer in adenine–uracil base pair via steered molecular dynamic simulations. J Mol Liq 2018. [DOI: 10.1016/j.molliq.2018.06.018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Solvent effect on the intermolecular proton transfer of the Watson and Crick guanine-cytosine and adenine-thymine base pairs: a polarizable continuum model study. Phys Chem Chem Phys 2018; 20:1198-1209. [PMID: 29242886 DOI: 10.1039/c7cp05356h] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Herein we present our results on the study of the double proton transfer (DPT) mechanism in the adenine-thymine (AT) and guanine-cytosine (GC) base pairs, both in gas phase and in solution. The latter was modeled using the polarizable continuum method (PCM) in different solvents. According to our DFT calculations, the DPT may occur for both complexes in a stepwise mechanism in condensate phase. In gas phase only the GC base pair exhibits a concerted DPT mechanism. Using the Wigner's tunneling corrections to the transition state theory we demonstrate that such corrections are important for the prediction of the rate constants of both systems in gas and in condensate phase. We also show that (i) as the polarity of the medium decreases the equilibrium constant of the DPT reaction increases in both complexes, and (ii) that the equilibrium constant in the GC complex is four orders of magnitude larger than in AT. This observation suggests that the spontaneous mutations in DNA base pairs are more probable in GC than in AT.
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25
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Mechanisms for guanine–cytosine tautomeric equilibrium in solution via steered molecular dynamic simulations. J Mol Liq 2018. [DOI: 10.1016/j.molliq.2017.12.091] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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26
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Adenine–thymine tautomerization under the influence of strong homogeneous electric fields. Phys Chem Chem Phys 2018; 20:12406-12412. [DOI: 10.1039/c8cp01122b] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
This paper reveals the key energy correction terms contributing to the low probability of AT tautomerization under electric fields.
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Theoretical study of mechanisms for the hydrolytic deamination of cytosine via steered molecular dynamic simulations. RSC Adv 2018; 8:34867-34876. [PMID: 35547048 PMCID: PMC9087476 DOI: 10.1039/c8ra07390b] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Accepted: 10/04/2018] [Indexed: 12/31/2022] Open
Abstract
Gibbs free energy profiles of the cytosine deamination assisted by a water molecule in a discrete aqueous medium were obtained by the application of Steered Molecular Dynamic (SMD) simulations. Two pathways were considered to explain the mechanism of this process, where the water molecule attacks the C–N bond to give an intermediate (an amino–hydroxy–oxo structure in the A-path, and a hydroxy–oxo in the B-path) as the determinant step of reaction. Stationary structures along both energy profiles were analyzed at molecular dynamics level, obtaining states with higher free energies than those from electronic calculations in the gas phase and in solution described as a continuous medium. From the results obtained, the more complex A-pathway, with five steps, was kinetically the most favorable (with an endergonic reaction energy of 7.41 kcal mol−1, a high barrier of 67.53 kcal mol−1, and a small velocity constant k2 = 1.80 × 10−37 s−1), concluding that the uracil base can participate in a spontaneous genetic mutation since the uracil–ammonia complex has a long lifetime of 6.10 × 1027 s. This process turns out exergonic and faster when carried out in gas phase simulation or electronic calculation with a continuous medium, due to the disappearance of explicit water molecules that can compete with the assistant molecule. Gibbs free energy profiles of the cytosine deamination assisted by a water molecule in a discrete aqueous medium were obtained by the application of Steered Molecular Dynamic (SMD) simulations.![]()
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Proton transfer in guanine-cytosine base pair analogues studied by NMR spectroscopy and PIMD simulations. Faraday Discuss 2018; 212:331-344. [PMID: 30234207 DOI: 10.1039/c8fd00070k] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
It has been hypothesised that proton tunnelling between paired nucleobases significantly enhances the formation of rare tautomeric forms and hence leads to errors in DNA replication. Here, we study nuclear quantum effects (NQEs) using deuterium isotope-induced changes of nitrogen NMR chemical shifts in a model base pair consisting of two tautomers of isocytosine, which form hydrogen-bonded dimers in the same way as the guanine-cytosine base pair. Isotope effects in NMR are consequences of NQEs, because ro-vibrational averaging of different isotopologues gives rise to different magnetic shielding of the nuclei. The experimental deuterium-induced chemical shift changes are compared with those calculated by a combination of path integral molecular dynamics (PIMD) simulations with DFT calculations of nuclear shielding. These calculations can directly link the observable isotope-induced shifts with NQEs. A comparison of the deuterium-induced changes of 15N chemical shifts with those predicted by PIMD simulations shows that inter-base proton transfer reactions do not take place in this system. We demonstrate, however, that NMR isotope shifts provide a unique possibility to study NQEs and to evaluate the accuracy of the computational methods used for modelling quantum effects in molecules. Calculations based on the PBE functional from the general-gradient-approximation family provided significantly worse predictions of deuterium isotope shifts than those with the hybrid B3LYP functional.
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Influence of Coupling and Embedding Schemes on QM Size Convergence in QM/MM Approaches for the Example of a Proton Transfer in DNA. J Chem Theory Comput 2017; 13:1102-1107. [PMID: 28195707 DOI: 10.1021/acs.jctc.6b00727] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The influence of embedding and coupling schemes on the convergence of the QM size in the QM/MM approach is investigated for the transfer of a proton in a DNA base pair. We find that the embedding scheme (mechanical or electrostatic) has a much greater impact on the convergence behavior than the coupling scheme (additive QM/MM or subtractive ONIOM). To achieve size convergence, QM regions with up to 6000 atoms are necessary for pure QM or mechanical embedding. In contrast, electrostatic embedding converges faster: for the example of the transfer of a proton between DNA base pairs, we recommend including at least five base pairs and 5 Å of solvent (including counterions) into the QM region, i.e., a total of 1150 atoms.
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Exposing the G-quadruplex to electric fields: the role played by telomeres in the propagation of DNA errors. Phys Chem Chem Phys 2017; 19:9358-9365. [DOI: 10.1039/c7cp01034f] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
We use quantum calculations to assess the impact of external electric fields on the stability of G-quadruplex, a key structure in telomere functionality.
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DNA spontaneous mutation and its role in the evolution of GC-content: assessing the impact of the genetic sequence. Phys Chem Chem Phys 2015; 17:7754-60. [DOI: 10.1039/c4cp05806b] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
We use theoretical tools to investigate the possible role played by a DNA sequence in the base pair tautomerization phenomena.
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Abstract
Environment-assisted quantum tunnelling is unlikely to play a significant role in adenine–thymine tautomerisation.
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Abstract
Although engineered by millions of years of evolution, the cellular machinery is not flawless, and errors regularly appear during DNA replication. The subsequent alteration of the stored genetic message results in a mutation and might be the starting point of important health disorders. The question therefore is what causes DNA mutations? All living organisms are constantly exposed to a number of external agents such as free radicals and to radiation, which may lead to induced mutations. There are also mutations happening without invoking the action of any exogenous element, the so-called spontaneous mutations. The former can be partially controlled by avoiding exposure to high-risk environments, while the latter are more intriguing because their origin is unclear and difficult to determine. As noted by Watson and Crick when they first discovered the DNA structure, the correct replication of DNA rests on the assumption that the base pairs remain in their most stable, canonical form. However, protons along the interbase hydrogen-bond network are not static entities. They can in fact interchange their positions in DNA bases through proton transfer (PT) reactions before strands unwind, giving rise to noncanonical structures defined as rare tautomers. The importance of these rare tautomers was also cleverly anticipated by Watson and Crick and some years later claimed by Löwdin to be a source of spontaneous mutations. In Watson and Crick's words: "It would be of interest to know the precise difference in free energy between the various tautomeric forms under physiological conditions." Unfortunately, rare tautomeric forms are very difficult to detect, so no direct and accurate free energy measure has been discerned. In contrast, theoretical chemistry is making good progress toward the quantification of PT reactions in DNA and their biological consequences. This Account touches upon the theoretical studies devoted to appraising the importance of rare tautomers as promoters of spontaneous mutations. We focus in particular on the crucial role played by the biological environment on DNA stability. It has now been demonstrated that valuable macroscopic predictions require not only highly accurate theories but also refined chemical models. Hybrid quantum mechanics/molecular mechanics (QM/MM) simulations performed on short but complete DNA sequence fragments emerge in this context as the most adequate tools. In addition, these methods can be used to quantify the effect of different external agents on the PT tautomeric equilibria and, eventually, to conveniently handle them. This is the case for the possible alteration of the naturally observed mutation rate by exposure to intense electric fields. Theoretical predictions envision in this respect promising applications of ultrashort electric pulses in medicine to selectively modify the mutated/canonical ratio in DNA.
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Coupling between hydrogen atoms transfer and stacking interaction in adenine-thymine/guanine-cytosine complexes: a theoretical study. J Phys Chem B 2014; 118:5439-52. [PMID: 24813562 DOI: 10.1021/jp502792r] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Four different complexes of two base pairs, an adenine-thymine and a guanine-cytosine one, have been studied in order to understand the modifications induced by the staking interaction between the two base pairs on the hydrogen atoms transfers between the bases in either base pair. The inclusion of these two kinds of interactions allows us to clarify if some properties, as the mechanism of hydrogen transfer, is exclusively a local effect of a base pair or can be modified by a more long-range interaction between the base pairs. The results on these four complexes are compared with those of the monomeric systems, the A-T and G-C base pair, and with those of the A-T and G-C dimers. The specificity of each complex and of each hydrogen bond has been analyzed.
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DPT tautomerisation of the wobble guanine·thymine DNA base mispair is not mutagenic: QM and QTAIM arguments. J Biomol Struct Dyn 2014; 33:674-89. [PMID: 24650179 DOI: 10.1080/07391102.2014.897259] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
We have shown for the first time, connecting QM methods with QTAIM analysis and using the methodology of the sweeps of the energetical, electron-topological and geometrical parameters, that the tautomerisation of the wobble guanine·thymine (wG·T) DNA base mispair into the wG(*)·T(*) base mispair induced by the double proton transfer (DPT), which undergoes a concerted asynchronous pathway, is not mutagenic. The wG·T → wG(*)·T(*) DPT tautomerisation does not result in the transition of the G base into its mutagenic tautomeric form G(*) able to mispair with the T base within the Watson-Crick base pairing scheme. This observation is explained by the so-called quantum protection of the wG·T DNA base mispair from its mutagenic tautomerisation - the dynamical non-stability of the tautomerised wG(*)·T(*) base mispair and significantly negative value of the Gibbs free energy of activation for the reverse reaction of the wG·T → wG(*)·T(*) DPT tautomerisation.
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(DNS)C: a fluorescent, environmentally sensitive cytidine derivative for the direct detection of GGG triad sequences. Org Biomol Chem 2014; 11:5605-14. [PMID: 23846401 DOI: 10.1039/c3ob41222a] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
With the goal of developing a fluorescent nucleoside sensitive to its environment, in this study we synthesized (DNS)C, a novel modified 2'-deoxycytidine bearing a 5-(dimethylamino)naphthalene-1-sulfonyl (dansyl) moiety at the N4 position, and tested its properties in monomeric and oligomeric states. (DNS)C undergoes intramolecular photoinduced electron transfer between its dansyl and cytosine units, resulting in remarkable changes in fluorescence that depend on the choice of solvent. In addition, the fluorescence behavior and thermal stability of oligonucleotides containing (DNS)C are dependent on the nature of the flanking and neighboring bases. Notably, (DNS)C exhibits fluorescence enhancement only in fully matched duplex DNA containing a GGG triad sequence. The environmental sensitivity of (DNS)C can be exploited as a fluorescence tool for monitoring the interactions of DNA with other biomolecules, including DNA, RNA, and proteins.
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Substrate dependent reaction channels of the Wolff-Kishner reduction reaction: A theoretical study. Beilstein J Org Chem 2014; 10:259-70. [PMID: 24605145 PMCID: PMC3943666 DOI: 10.3762/bjoc.10.21] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2013] [Accepted: 12/18/2013] [Indexed: 11/23/2022] Open
Abstract
Wolff–Kishner reduction reactions were investigated by DFT calculations for the first time. B3LYP/6-311+G(d,p) SCRF=(PCM, solvent = 1,2-ethanediol) optimizations were carried out. To investigate the role of the base catalyst, the base-free reaction was examined by the use of acetone, hydrazine (H2N–NH2) and (H2O)8. A ready reaction channel of acetone → acetone hydrazine (Me2C=N–NH2) was obtained. The channel involves two likely proton-transfer routes. However, it was found that the base-free reaction was unlikely at the N2 extrusion step from the isopropyl diimine intermediate (Me2C(H)–N=N–H). Two base-catalyzed reactions were investigated by models of the ketone, H2N–NH2 and OH−(H2O)7. Here, ketones are acetone and acetophenone. While routes of the ketone → hydrazone → diimine are similar, those from the diimines are different. From the isopropyl diimine, the N2 extrusion and the C–H bond formation takes place concomitantly. The concomitance leads to the propane product concertedly. From the (1-phenyl)ethyl substituted diimine, a carbanion intermediate is formed. The para carbon of the phenyl ring of the anion is subject to the protonation, which leads to a 3-ethylidene-1,4-cyclohexadiene intermediate. Its [1,5]-hydrogen migration gives the ethylbenzene product. For both ketone substrates, the diimines undergoing E2 reactions were found to be key intermediates.
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Is the DPT tautomerization of the long A·G Watson-Crick DNA base mispair a source of the adenine and guanine mutagenic tautomers? A QM and QTAIM response to the biologically important question. J Comput Chem 2013; 35:451-66. [PMID: 24382756 DOI: 10.1002/jcc.23515] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2013] [Revised: 11/12/2013] [Accepted: 11/30/2013] [Indexed: 02/04/2023]
Abstract
Herein, we first address the question posed in the title by establishing the tautomerization trajectory via the double proton transfer of the adenine·guanine (A·G) DNA base mispair formed by the canonical tautomers of the A and G bases into the A*·G* DNA base mispair, involving mutagenic tautomers, with the use of the quantum-mechanical calculations and quantum theory of atoms in molecules (QTAIM). It was detected that the A·G ↔ A*·G* tautomerization proceeds through the asynchronous concerted mechanism. It was revealed that the A·G base mispair is stabilized by the N6H···O6 (5.68) and N1H···N1 (6.51) hydrogen bonds (H-bonds) and the N2H···HC2 dihydrogen bond (DH-bond) (0.68 kcal·mol(-1) ), whereas the A*·G* base mispair-by the O6H···N6 (10.88), N1H···N1 (7.01) and C2H···N2 H-bonds (0.42 kcal·mol(-1) ). The N2H···HC2 DH-bond smoothly and without bifurcation transforms into the C2H···N2 H-bond at the IRC = -10.07 Bohr in the course of the A·G ↔ A*·G* tautomerization. Using the sweeps of the energies of the intermolecular H-bonds, it was observed that the N6H···O6 H-bond is anticooperative to the two others-N1H···N1 and N2H···HC2 in the A·G base mispair, while the latters are significantly cooperative, mutually strengthening each other. In opposite, all three O6H···N6, N1H···N1, and C2H···N2 H-bonds are cooperative in the A*·G* base mispair. All in all, we established the dynamical instability of the А*·G* base mispair with a short lifetime (4.83·10(-14) s), enabling it not to be deemed feasible source of the A* and G* mutagenic tautomers of the DNA bases. The small lifetime of the А*·G* base mispair is predetermined by the negative value of the Gibbs free energy for the A*·G* → A·G transition. Moreover, all of the six low-frequency intermolecular vibrations cannot develop during this lifetime that additionally confirms the aforementioned results. Thus, the A*·G* base mispair cannot be considered as a source of the mutagenic tautomers of the DNA bases, as the A·G base mispair dissociates during DNA replication exceptionally into the A and G monomers in the canonical tautomeric form.
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Abstract
The proton transfer processes of microhydrated adenine–thymine anions are studied using density functional theory with the B3LYP method and DZP++ basis set. The microhydration effects on the geometrical structures, adsorption site, and the proton transfer reaction of the adenine–thymine anion are investigated. The site N10 atom of the adenine moiety has a larger proton affinity than the site O24 atom of thymine, which facilitates the proton H26 transfers from the N25 site of thymine to the N10 site of adenine. Therefore, the first single-proton transfer pathway (SPT1) is found for the all of the monohydrated adenine–thymine anions (AN4T)−·H2O, (AN13T)−·H2O, (ATO24)−·H2O, and (ATO28)−·H2O and tetrahydrated adenine–thymine anions (AT)−·4H2O. The proton H9 at the N7 site of adenine is also found to transfer to the O24 site of thymine for (AN4T)−·H2O and (AN13T)−·H2O in the gas phase. The double-proton transferred pathway is found when one water molecule interacts with the O28 atom of thymine. The reactant structures before the proton transfer are more stable than the product structures, and the structural changes mainly occur in thymine. The reaction energies of the microhydrated adenine–thymine anion in the gas phase and in the aqueous environment predict that the proton transfer process of the microhydrated adenine–thymine anion are more favorable in the gas phase than in aqueous solution.
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Nuclear quantum effect and temperature dependency on the hydrogen-bonded structure of base pairs. J Comput Chem 2013; 34:2403-11. [DOI: 10.1002/jcc.23399] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2013] [Revised: 06/28/2013] [Accepted: 07/05/2013] [Indexed: 11/12/2022]
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Why the tautomerization of the G·C Watson–Crick base pairviathe DPT does not cause point mutations during DNA replication? QM and QTAIM comprehensive analysis. J Biomol Struct Dyn 2013; 32:1474-99. [DOI: 10.1080/07391102.2013.822829] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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47
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Theoretical investigation of the coupling between hydrogen atoms transfer and stacking interaction in guanine–cytosine dimers. Phys Chem Chem Phys 2013; 15:19242-52. [DOI: 10.1039/c3cp52855c] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Electric-field induced mutation of DNA: a theoretical investigation of the GC base pair. Phys Chem Chem Phys 2013; 15:4548-53. [DOI: 10.1039/c2cp44066k] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Theoretical investigation of the proton transfer mechanism in guanine-cytosine and adenine-thymine base pairs. J Chem Phys 2012. [DOI: 10.1063/1.4766319] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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