1
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Deng L, Kumar J, Rose R, McIntyre W, Fabris D. Analyzing RNA posttranscriptional modifications to decipher the epitranscriptomic code. MASS SPECTROMETRY REVIEWS 2024; 43:5-38. [PMID: 36052666 DOI: 10.1002/mas.21798] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Revised: 05/23/2022] [Accepted: 05/27/2022] [Indexed: 06/15/2023]
Abstract
The discovery of RNA silencing has revealed that non-protein-coding sequences (ncRNAs) can cover essential roles in regulatory networks and their malfunction may result in severe consequences on human health. These findings have prompted a general reassessment of the significance of RNA as a key player in cellular processes. This reassessment, however, will not be complete without a greater understanding of the distribution and function of the over 170 variants of the canonical ribonucleotides, which contribute to the breathtaking structural diversity of natural RNA. This review surveys the analytical approaches employed for the identification, characterization, and detection of RNA posttranscriptional modifications (rPTMs). The merits of analyzing individual units after exhaustive hydrolysis of the initial biopolymer are outlined together with those of identifying their position in the sequence of parent strands. Approaches based on next generation sequencing and mass spectrometry technologies are covered in depth to provide a comprehensive view of their respective merits. Deciphering the epitranscriptomic code will require not only mapping the location of rPTMs in the various classes of RNAs, but also assessing the variations of expression levels under different experimental conditions. The fact that no individual platform is currently capable of meeting all such demands implies that it will be essential to capitalize on complementary approaches to obtain the desired information. For this reason, the review strived to cover the broadest possible range of techniques to provide readers with the fundamental elements necessary to make informed choices and design the most effective possible strategy to accomplish the task at hand.
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Affiliation(s)
- L Deng
- Department of Chemistry, University of Connecticut, Storrs, Connecticut, USA
| | - J Kumar
- Department of Chemistry, University of Connecticut, Storrs, Connecticut, USA
| | - R Rose
- Department of Advanced Research Technologies, New York University Langone Health Center, New York, USA
| | - W McIntyre
- Department of Chemistry, University of Connecticut, Storrs, Connecticut, USA
| | - Daniele Fabris
- Department of Chemistry, University of Connecticut, Storrs, Connecticut, USA
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2
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Raczyńska ED. On Prototropy and Bond Length Alternation in Neutral and Ionized Pyrimidine Bases and Their Model Azines in Vacuo. Molecules 2023; 28:7282. [PMID: 37959699 PMCID: PMC10648772 DOI: 10.3390/molecules28217282] [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: 09/25/2023] [Revised: 10/21/2023] [Accepted: 10/22/2023] [Indexed: 11/15/2023] Open
Abstract
In this review, the complete tautomeric equilibria are derived for disubstituted pyrimidine nucleic acid bases starting from phenol, aniline, and their model compounds-monosubstituted aromatic azines. The differences in tautomeric preferences for isolated (gaseous) neutral pyrimidine bases and their model compounds are discussed in light of different functional groups, their positions within the six-membered ring, electronic effects, and intramolecular interactions. For the discussion of tautomeric preferences and for the analysis of internal effects, recent quantum-chemical results are taken into account and compared to some experimental ones. For each possible tautomer-rotamer of the title compounds, the bond length alternation, measured by means of the harmonic oscillator model of electron delocalization (HOMED) index, is examined. Significant HOMED similarities exist for mono- and disubstituted derivatives. The lack of parallelism between the geometric (HOMED) and energetic (ΔG) parameters for all possible isomers clearly shows that aromaticity is not the main factor that dictates tautomeric preferences for pyrimidine bases, particularly for uracil and thymine. The effects of one-electron loss (positive ionization) and one-electron gain (negative ionization) on prototropy and bond length alternation are also reviewed for pyrimidine bases and their models.
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Affiliation(s)
- Ewa Daniela Raczyńska
- Department of Chemistry, Warsaw University of Life Sciences (SGGW), ul. Nowoursynowska 159c, 02-776 Warszawa, Poland
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3
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Hinz DJ, Zhang L, Lee JK. Mass spectrometry in organic and bio-organic catalysis: Using thermochemical properties to lend insight into mechanism. MASS SPECTROMETRY REVIEWS 2022. [PMID: 35899315 DOI: 10.1002/mas.21797] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
In this review, we discuss gas phase experimentation centered on the measurement of acidity and proton affinity of substrates that are useful for understanding catalytic mechanisms. The review is divided into two parts. The first covers examples of organocatalysis, while the second focuses on biological catalysis. The utility of gas phase acidity and basicity values for lending insight into mechanisms of catalysis is highlighted.
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Affiliation(s)
- Damon J Hinz
- Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, New Brunswick, New Jersey, USA
| | - Lanxin Zhang
- Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, New Brunswick, New Jersey, USA
| | - Jeehiun K Lee
- Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, New Brunswick, New Jersey, USA
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4
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Zhang L, Hinz DJ, Kiruba GSM, Ding X, Lee JK. Gas‐phase experimental and computational studies of human hypoxanthine‐guanine phosphoribosyltransferase substrates: Intrinsic properties and biological implications. J PHYS ORG CHEM 2022. [DOI: 10.1002/poc.4343] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Lanxin Zhang
- Department of Chemistry and Chemical Biology Rutgers, The State University of New Jersey New Brunswick NJ USA
| | - Damon J. Hinz
- Department of Chemistry and Chemical Biology Rutgers, The State University of New Jersey New Brunswick NJ USA
| | | | - Xiao Ding
- Department of Chemistry and Chemical Biology Rutgers, The State University of New Jersey New Brunswick NJ USA
| | - Jeehiun K. Lee
- Department of Chemistry and Chemical Biology Rutgers, The State University of New Jersey New Brunswick NJ USA
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5
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Krajewski AE, Lee JK. Gas-Phase Experimental and Computational Studies of 5-Halouracils: Intrinsic Properties and Biological Implications. J Org Chem 2021; 86:6361-6370. [PMID: 33891415 DOI: 10.1021/acs.joc.1c00183] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The gas-phase acidity and proton affinity (PA) of 5-halouracils (5-fluorouracil, 5-chlorouracil, 5-bromouracil, and 5-iodouracil) have been examined using both theoretical and experimental methods. This work represents a comprehensive study of the thermochemical properties of these nucleobases. Other than 5-fluorouracil acidity, the intrinsic acidity and PA of these halouracils have not been heretofore measured; these new experimental data provide a benchmark for the computational values. Furthermore, we examine these 5-halouracils in the context of the enzyme thymine DNA glycosylase (TDG), which is an enzyme that protects the genome by cleaving these substrates from DNA. Our gas-phase results are compared and contrasted to TDG excision rates to afford insights into the TDG mechanism.
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Affiliation(s)
- Allison E Krajewski
- Department of Chemistry and Chemical Biology Rutgers, The State University of New Jersey, New Brunswick, New Jersey 08901, USA
| | - Jeehiun K Lee
- Department of Chemistry and Chemical Biology Rutgers, The State University of New Jersey, New Brunswick, New Jersey 08901, USA
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6
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Islam SM, Ibnat Z. New Insights into the Structure and Reactivity of Uracil Derivatives in Different Solvents-A Computational Study. ACS OMEGA 2020; 5:22449-22458. [PMID: 32923803 PMCID: PMC7482307 DOI: 10.1021/acsomega.0c02943] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Accepted: 08/10/2020] [Indexed: 06/11/2023]
Abstract
Ab initio calculations were carried out to understand the reactivity and stability of some uracil derivatives, cytosine, 1-methyl cytosine, and cytidine in solvents, water, dimethyl sulfoxide (DMSO), n-octanol, and chloroform. Geometries were fully optimized at MP2 and B3LYP using the 6-31+G(d,p) basis set by applying the Solvation Model on Density (SMD) in solvent systems. The syn conformer of cytidine (cytidine II) is the most stable conformer in the gas phase, while the anticonformer (cytidine IV) is most stable in all of the solvents. Solvation free energy and polarizability values in different solvents decrease in the order water > DMSO > n-octanol > chloroform, while dipole moment, first-order hyperpolarizability, and HOMO-LUMO energy gap values follow the order of polar protic solvent (water and n-octanol) > polar aprotic solvent (DMSO) > nonpolar solvent (chloroform). The solvation free energy, dipole moment, polarizability, and first-order hyperpolarizability values also follow the order of cytosine > 1-methyl cytosine > cytidine. To illustrate that the molecular properties correlate well with the reactivity of the molecules, ab initio calculations were carried out for the reaction of uracil derivatives with Br2 in the gas phase, water, DMSO, n-octanol, and chloroform. All ground and transition state geometries were fully optimized at B3LYP/6-31+G(d,p), and energies were also calculated at G3MP2 for cytosine and 1-methyl cytosine. For cytosine and 1-methyl cytosine, Gibbs energies of activation decrease with the polarity of the solvent that is chloroform > n-octanol > DMSO > water, while the Gibbs energies of activation for the reaction with cytidine decrease in the order of water > DMSO > n-octanol > chloroform. These results suggest that solvent polarity is very important for the stability and reactivity of uracil derivatives. Hydrogen bonding may also play an important role mainly for cytidine. Free energies of activation decrease with the size of the molecule, i.e., cytosine > 1-methyl cytosine > cytidine.
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Affiliation(s)
- Shahidul M. Islam
- Department of Chemistry, University of Illinois at Chicago, Chicago, Illinois 60607, United States
| | - Zahin Ibnat
- Department of Chemistry, University of Illinois at Chicago, Chicago, Illinois 60607, United States
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7
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Crystallographic evidence of Watson-Crick connectivity in the base pair of anionic adenine with thymine. Proc Natl Acad Sci U S A 2020; 117:18224-18230. [PMID: 32680959 PMCID: PMC7414232 DOI: 10.1073/pnas.2008379117] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Utilizing an ionic liquid strategy, we report crystal structures of salts of free anionic nucleobases and base pairs previously studied only computationally and in the gas phase. Reaction of tetrabutylammonium ([N4444]+) or tetrabutylphosphonium ([P4444]+) hydroxide with adenine (HAd) and thymine (HThy) led to hydrated salts of deprotonated adenine, [N4444][Ad]·2H2O, and thymine, [P4444][Thy]·2H2O, as well as the double salt cocrystal, [P4444]2[Ad][Thy]·3H2O·2HThy. The cocrystal includes the anionic [Ad-(HThy)] base pair which is a stable formation in the solid state that has previously not even been suggested. It exhibits Watson-Crick connectivity as found in DNA but which is unusual for the free neutral base pairs. The stability of the observed anionic bases and their supramolecular formations and hydrates has also been examined by electronic structure calculations, contributing to more insight into how base pairs can bind when a proton is removed and highlighting mechanisms of stabilization or chemical transformation in the DNA chains.
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8
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Wang N, Lee JK. Gas-Phase and Ionic Liquid Experimental and Computational Studies of Imidazole Acidity and Carbon Dioxide Capture. J Org Chem 2019; 84:14593-14601. [PMID: 31647232 DOI: 10.1021/acs.joc.9b02193] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The capture and storage of carbon dioxide are pressing environmental concerns. Nucleophilic capture by anions in ionic liquids, such as imidazolates, is a promising strategy. Herein, the gas-phase acidity of a series of imidazoles is examined both experimentally and computationally. The intrinsic acidity of these imidazoles has not heretofore been measured; these experimental data provide a benchmark for the computational values. The relationship between imidazole acidity and carbon dioxide capture is explored computationally, both in the gas phase and in ionic liquid. The improved understanding of imidazolate properties provided herein is important for the design and development of improved systems for carbon dioxide capture.
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Affiliation(s)
- Ning Wang
- Department of Chemistry and Chemical Biology , Rutgers, The State University of New Jersey , New Brunswick , New Jersey 08901 United States
| | - Jeehiun K Lee
- Department of Chemistry and Chemical Biology , Rutgers, The State University of New Jersey , New Brunswick , New Jersey 08901 United States
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9
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Xu J, Krajewski AE, Niu Y, Kiruba GSM, Lee JK. Kinetic hydricity of silane hydrides in the gas phase. Chem Sci 2019; 10:8002-8008. [PMID: 31853355 PMCID: PMC6837013 DOI: 10.1039/c9sc02118c] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Accepted: 07/09/2019] [Indexed: 12/01/2022] Open
Abstract
Herein, gas phase studies of the kinetic hydricity of a series of silane hydrides are described. An understanding of hydricity is important as hydride reactions figure largely in many processes, including organic synthesis, photoelectrocatalysis, and hydrogen activation. We find that hydricity trends in the gas phase differ from those in solution, revealing the effect of solvent. Calculations and further experiments, including H/D studies, were used to delve into the reactivity and structure of the reactants. These studies also represent a first step toward systematically understanding nucleophilicity and electrophilicity in the absence of solvent.
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Affiliation(s)
- Jiahui Xu
- Department of Chemistry and Chemical Biology , Rutgers The State University of New Jersey , New Brunswick , NJ 08901 , USA .
| | - Allison E Krajewski
- Department of Chemistry and Chemical Biology , Rutgers The State University of New Jersey , New Brunswick , NJ 08901 , USA .
| | - Yijie Niu
- Department of Chemistry and Chemical Biology , Rutgers The State University of New Jersey , New Brunswick , NJ 08901 , USA .
| | - G S M Kiruba
- Department of Chemistry and Chemical Biology , Rutgers The State University of New Jersey , New Brunswick , NJ 08901 , USA .
| | - Jeehiun K Lee
- Department of Chemistry and Chemical Biology , Rutgers The State University of New Jersey , New Brunswick , NJ 08901 , USA .
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10
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Xu J, Mieres-Perez J, Sanchez-Garcia E, Lee JK. Gas-Phase Deprotonation of Benzhydryl Cations: Carbene Basicity, Multiplicity, and Rearrangements. J Org Chem 2019; 84:7685-7693. [PMID: 31008604 DOI: 10.1021/acs.joc.9b00496] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Many fundamental properties of carbenes, particularly basicity, remain poorly understood. Herein, an experimental and computational examination of the deprotonation of a series of benzhydryl cations has been undertaken. These studies represent the first attempt at providing experimental values for diarylcarbene basicities. Pathways to deprotonation, including whether the singlet or triplet carbene is formed, are probed. Because diarylcarbenes are expected to be among the strongest organic bases known, assessing the energetics of protonation of these species is of fundamental importance for a wide range of chemical processes.
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Affiliation(s)
- Jiahui Xu
- Department of Chemistry and Chemical Biology , Rutgers, The State University of New Jersey , New Brunswick , New Jersey 08901 , United States
| | - Joel Mieres-Perez
- Computational Biochemistry, Center of Medical Biotechnology , University of Duisburg-Essen , D-45141 Essen , Germany
| | - Elsa Sanchez-Garcia
- Computational Biochemistry, Center of Medical Biotechnology , University of Duisburg-Essen , D-45141 Essen , Germany
| | - Jeehiun K Lee
- Department of Chemistry and Chemical Biology , Rutgers, The State University of New Jersey , New Brunswick , New Jersey 08901 , United States
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11
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Cheng R, Loire E, Fridgen TD. Hydrogen bonding in alkali metal cation-bound i-motif-like dimers of 1-methyl cytosine: an IRMPD spectroscopic and computational study. Phys Chem Chem Phys 2019; 21:11103-11110. [PMID: 31094375 DOI: 10.1039/c9cp01223k] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The structures of alkali metal cation bound 1-methylcytosine (1-mCyt) dimers were explored using vibrational spectroscopy in the form of infrared multiple photon dissociation (IRMPD) spectroscopy and by computational methods. For the smaller alkali metal cations, Li+ and Na+, only non-hydrogen bonded symmetric anti-parallel structures were observed in agreement with the lowest energy computed structures. For K+, Rb+, and Cs+ the vibrational spectra in the N-H stretch region showed strong evidence for hydrogen bonding in agreement with the lowest energy structures which contained hydrogen bonding interactions between the amine group of one cytosine and the carbonyl oxygen of the other cytosine. The lowest energy structures for these complexes were compared to previously studied cytosine complexes [(Cyt)2M]+ where M = Li, Na, and K. The calculations are in agreement that only the non-hydrogen bonded structures would be observed for these cytosine complexes.
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Affiliation(s)
- Ruodi Cheng
- Department of Chemistry, Memorial University, St. John's, NL A1B 3 × 7, Canada.
| | - Estelle Loire
- Laboratoire Chimie Physique - CLIO, Batiment 201, Porte 2, Campus Universite d'Orsay, 91405, France
| | - Travis D Fridgen
- Department of Chemistry, Memorial University, St. John's, NL A1B 3 × 7, Canada.
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12
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Halder A, Data D, Seelam PP, Bhattacharyya D, Mitra A. Estimating Strengths of Individual Hydrogen Bonds in RNA Base Pairs: Toward a Consensus between Different Computational Approaches. ACS OMEGA 2019; 4:7354-7368. [PMID: 31459834 PMCID: PMC6648064 DOI: 10.1021/acsomega.8b03689] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/31/2018] [Accepted: 04/12/2019] [Indexed: 06/10/2023]
Abstract
Noncoding RNA molecules are composed of a large variety of noncanonical base pairs that shape up their functionally competent folded structures. Each base pair is composed of at least two interbase hydrogen bonds (H-bonds). It is expected that the characteristic geometry and stability of different noncanonical base pairs are determined collectively by the properties of these interbase H-bonds. We have studied the ground-state electronic properties [using density functional theory (DFT) and DFT-D3-based methods] of all the 118 normal base pairs and 36 modified base pairs, belonging to 12 different geometric families (cis and trans of WW, WH, HH, WS, HS, and SS) that occur in a nonredundant set of high-resolution RNA crystal structures. Having addressed some of the limitations of the earlier approaches, we provide here a comprehensive compilation of the average energies of different types of interbase H-bonds (E HB). We have also characterized each interbase H-bond using 13 different parameters that describe its geometry, charge distribution at its bond critical point (BCP), and n → σ*-type charge transfer from filled π orbitals of the H-bond acceptor to the empty antibonding orbital of the H-bond donor. On the basis of the extent of their linear correlation with the H-bonding energy, we have shortlisted five parameters to model linear equations for predicting E HB values. They are (i) electron density at the BCP: ρ, (ii) its Laplacian: ∇2ρ, (iii) stabilization energy due to n → σ*-type charge transfer: E(2), (iv) donor-hydrogen distance, and (v) hydrogen-acceptor distance. We have performed single variable and multivariable linear regression analysis over the normal base pairs and have modeled sets of linear relationships between these five parameters and E HB. Performance testing of our model over the set of modified base pairs shows promising results, at least for the moderately strong H-bonds.
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Affiliation(s)
- Antarip Halder
- Center
for Computational Natural Sciences and Bioinformatics (CCNSB), International Institute of Information Technology
(IIIT-H), Gachibowli, Hyderabad 500032, India
| | - Dhruv Data
- Center
for Computational Natural Sciences and Bioinformatics (CCNSB), International Institute of Information Technology
(IIIT-H), Gachibowli, Hyderabad 500032, India
| | - Preethi P. Seelam
- Center
for Computational Natural Sciences and Bioinformatics (CCNSB), International Institute of Information Technology
(IIIT-H), Gachibowli, Hyderabad 500032, India
| | - Dhananjay Bhattacharyya
- Computational
Science Division, Saha Institute of Nuclear
Physics(SINP), 1/AF,
Bidhannagar, Kolkata 700064, India
| | - Abhijit Mitra
- Center
for Computational Natural Sciences and Bioinformatics (CCNSB), International Institute of Information Technology
(IIIT-H), Gachibowli, Hyderabad 500032, India
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13
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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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14
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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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15
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Kobetić R, Ključarić V, Saftić D, Matić J, Ban Ž, Kazazić S, Žinić B. The transformation from 2°-amine to 3°-amine of cyclam ring alters the fragmentation patterns of 1-tosylcytosine-cyclam conjugates. JOURNAL OF MASS SPECTROMETRY : JMS 2018; 53:655-664. [PMID: 29739033 DOI: 10.1002/jms.4197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Revised: 04/06/2018] [Accepted: 04/23/2018] [Indexed: 06/08/2023]
Abstract
The novel N-1-sulfonylcytosine-cyclam conjugates 1 and 2 conjugates are ionized by electrospray ionization mass spectrometry (ESI MS) in positive and negative modes (ES+ and ES- ) as singly protonated/deprotonated species or as singly or doubly charged metal complexes. Their structure and fragmentation behavior is examined by collision induced experiments. It was observed that the structure of the conjugate dictated the mode of the ionization: 1 was analyzed in ES- mode while 2 in positive mode. Complexation with metal ions did not have the influence on the ionization mode. Zn2+ and Cu2+ complexes with ligand 1 followed the similar fragmentation pattern in negative ionization mode. The transformation from 2°-amine in 1 to 3°-amine of cyclam ring in 2 leads to the different fragmentation patterns due to the modification of the protonation priority which changed the fragmentation channels within the conjugate itself. Cu2+ ions formed complexes practically immediately, and the priority had the cyclam portion of the ligand 2. The structure of the formed Zn2+ complexes with ligand 2 depended on the number of 3° amines within the cyclam portion of the conjugate and the ratio of the metal:ligand used. The cleavage of the cyclam ring of metal complexes is driven by the formation of the fragment that suited the coordinating demand of the metal ions and the collision energy applied. Finally, it was shown that the structure of the cyclam conjugate dictates the fragmentation reactions and not the metal ions.
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Affiliation(s)
- Renata Kobetić
- Laboratory for Biomolecular Interactions and Spectroscopy, Division of Organic Chemistry and Biochemistry, Ruđer Bošković Institute, Bijenička cesta 54, 10 000, Zagreb, Croatia
| | - Valentina Ključarić
- Ministry of Defense of the Republic of Croatia, Dr. Franjo Tuđman Croatian Defense Academy, Ilica 256 b, Zagreb, Croatia
| | - Dijana Saftić
- Laboratory for Biomolecular Interactions and Spectroscopy, Division of Organic Chemistry and Biochemistry, Ruđer Bošković Institute, Bijenička cesta 54, 10 000, Zagreb, Croatia
| | - Josipa Matić
- Laboratory for Biomolecular Interactions and Spectroscopy, Division of Organic Chemistry and Biochemistry, Ruđer Bošković Institute, Bijenička cesta 54, 10 000, Zagreb, Croatia
| | - Željka Ban
- Laboratory for Biomolecular Interactions and Spectroscopy, Division of Organic Chemistry and Biochemistry, Ruđer Bošković Institute, Bijenička cesta 54, 10 000, Zagreb, Croatia
| | - Snježana Kazazić
- Laboratory for Mass Spectrometry, Division of Physical Chemistry, Ruđer Bošković Institute, Bijenička cesta 54, 10 000, Zagreb, Croatia
| | - Biserka Žinić
- Laboratory for Biomolecular Interactions and Spectroscopy, Division of Organic Chemistry and Biochemistry, Ruđer Bošković Institute, Bijenička cesta 54, 10 000, Zagreb, Croatia
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16
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Lu W, Liu J. Deprotonated guanine·cytosine and 9-methylguanine·cytosine base pairs and their "non-statistical" kinetics: a combined guided-ion beam and computational study. Phys Chem Chem Phys 2018; 18:32222-32237. [PMID: 27849082 DOI: 10.1039/c6cp06670d] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We report a guided-ion beam mass spectrometric study on collision-induced dissociation (CID) of deprotonated guanine(G)·cytosine(C) base pairs and their 9-methylguanine (9MG) analogue with Xe, including measurements of product cross sections as a function of collision energy and determination of dissociation thresholds. DFT, RI-MP2 and DLPNO-CCSD(T) calculations and Rice-Ramsperger-Kassel-Marcus (RRKM) modeling were performed to elucidate structures and kinetics. The experiment and theoretical study have provided considerable insight into tautomerization, intra-base-pair proton transfer and dissociation of deprotonated G·C and 9MG·C. In contrast to the previously reported lowest-energy deprotonated base pair structure G·[C-H1]- that consists of H-bonded neutral guanine and N1-deprotonated cytosine, we found that proton transfer from guanine N1 to cytosine N3 within G·[C-H1]- (or 9MG·[C-H1]-) leads to another slightly more stable conformer denoted as G·[C-H1]-_PT1 (or 9MG·[C-H1]-_PT1). The conventional (non-proton-transferred) and the proton-transferred conformers are close in energy and interconvert quickly, but they can be distinguished by dissociation products. The conventional structure dissociates into deprotonated cytosine and neutral guanine, while the other dissociates into deprotonated guanine and neutral cytosine. The two dissociation asymptotes have similar threshold energies, but surprisingly the CID product mass spectra of deprotonated G·C and 9MG·C are both overwhelmingly dominated by deprotonated G or 9MG, with their branching ratios greater than RRKM predictions by one to two orders of magnitude. The proton-transferred structures of deprotonated base pairs and the "unexpected" non-statistical kinetics provide new leads for understanding purine-pyrimidine interactions, forming rare nucleobase tautomers, and base pair opening.
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Affiliation(s)
- Wenchao Lu
- Department of Chemistry and Biochemistry, Queens College of the City University of New York, 65-30 Kissena Blvd., Queens, NY 11367, USA. and Ph.D. Program in Chemistry, The Graduate Center of the City University of New York, 365 5th Ave., New York, NY 10016, USA
| | - Jianbo Liu
- Department of Chemistry and Biochemistry, Queens College of the City University of New York, 65-30 Kissena Blvd., Queens, NY 11367, USA. and Ph.D. Program in Chemistry, The Graduate Center of the City University of New York, 365 5th Ave., New York, NY 10016, USA
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17
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Jawiczuk M. A theoretical study on the hydrogen bond and stability of cytosine and thymine dimers. COMPUT THEOR CHEM 2018. [DOI: 10.1016/j.comptc.2017.11.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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18
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19
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Niu Y, Wang N, Muñoz A, Xu J, Zeng H, Rovis T, Lee JK. Experimental and Computational Gas Phase Acidities of Conjugate Acids of Triazolylidene Carbenes: Rationalizing Subtle Electronic Effects. J Am Chem Soc 2017; 139:14917-14930. [PMID: 29039669 DOI: 10.1021/jacs.7b05229] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In recent years, triazolylidene carbenes have come to the forefront as important organocatalysts for a wide range of reactions. The fundamental properties of these species, however, remain largely unknown. Herein, the gas phase acidities have been measured and calculated for a series of triazolium cations (the conjugate acids of the triazolylidene carbenes) that have not been heretofore examined in vacuo. The results are discussed in the context of these species as catalysts. We find correlations between the gas phase acidity and selectivity in two Umpolung reactions catalyzed by these species; such correlations are the first of their kind. We are able to use these linear correlations to improve reaction enantioselectivity. These results establish the possibility of using these thermochemical properties to predict reactivity in related transformations.
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Affiliation(s)
- Yijie Niu
- Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey , New Brunswick, New Jersey 08901, United States
| | - Ning Wang
- Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey , New Brunswick, New Jersey 08901, United States
| | - Alberto Muñoz
- Department of Chemistry, Columbia University , New York, New York 10027, United States
| | - Jiahui Xu
- Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey , New Brunswick, New Jersey 08901, United States
| | - Hao Zeng
- Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey , New Brunswick, New Jersey 08901, United States
| | - Tomislav Rovis
- Department of Chemistry, Columbia University , New York, New York 10027, United States
| | - Jeehiun K Lee
- Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey , New Brunswick, New Jersey 08901, United States
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20
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Raczyńska ED, Gal JF, Maria PC. Enhanced Basicity of Push-Pull Nitrogen Bases in the Gas Phase. Chem Rev 2016; 116:13454-13511. [PMID: 27739663 DOI: 10.1021/acs.chemrev.6b00224] [Citation(s) in RCA: 73] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Nitrogen bases containing one or more pushing amino-group(s) directly linked to a pulling cyano, imino, or phosphoimino group, as well as those in which the pushing and pulling moieties are separated by a conjugated spacer (C═X)n, where X is CH or N, display an exceptionally strong basicity. The n-π conjugation between the pushing and pulling groups in such systems lowers the basicity of the pushing amino-group(s) and increases the basicity of the pulling cyano, imino, or phosphoimino group. In the gas phase, most of the so-called push-pull nitrogen bases exhibit a very high basicity. This paper presents an analysis of the exceptional gas-phase basicity, mostly in terms of experimental data, in relation with structure and conjugation of various subfamilies of push-pull nitrogen bases: nitriles, azoles, azines, amidines, guanidines, vinamidines, biguanides, and phosphazenes. The strong basicity of biomolecules containing a push-pull nitrogen substructure, such as bioamines, amino acids, and peptides containing push-pull side chains, nucleobases, and their nucleosides and nucleotides, is also analyzed. Progress and perspectives of experimental determinations of GBs and PAs of highly basic compounds, termed as "superbases", are presented and benchmarked on the basis of theoretical calculations on existing or hypothetical molecules.
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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
| | - Jean-François Gal
- Institut de Chimie de Nice (ICN) - UMR CNRS 7272, University Nice Sophia Antipolis , Parc Valrose, 06108 Nice Cedex 2, France
| | - Pierre-Charles Maria
- Institut de Chimie de Nice (ICN) - UMR CNRS 7272, University Nice Sophia Antipolis , Parc Valrose, 06108 Nice Cedex 2, France
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21
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Trachsel MA, Wiedmer T, Blaser S, Frey HM, Li Q, Ruiz-Barragan S, Blancafort L, Leutwyler S. The excited-state structure, vibrations, lifetimes, and nonradiative dynamics of jet-cooled 1-methylcytosine. J Chem Phys 2016; 145:134307. [DOI: 10.1063/1.4964091] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Affiliation(s)
- Maria A. Trachsel
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
| | - Timo Wiedmer
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
| | - Susan Blaser
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
| | - Hans-Martin Frey
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
| | - Quansong Li
- Key Laboratory of Cluster Science of Ministry of Education, School of Chemistry, Beijing Institute of Technology, 100081 Beijing, China
| | - Sergi Ruiz-Barragan
- Lehrstuhl für Theoretische Chemie, Ruhr-Universitat Bochum, 44780 Bochum, Germany
| | - Lluís Blancafort
- Institut de Química Computacional i Catàlisi and Departament de Química, Universitat de Girona, Facultat de Ciències, C/ M. Aurèlia Campmany 69, 17003 Girona, Spain
| | - Samuel Leutwyler
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
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22
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Wincel H. Microhydration of Deprotonated Nucleobases. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2016; 27:1383-92. [PMID: 27178262 PMCID: PMC4942500 DOI: 10.1007/s13361-016-1411-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Revised: 04/17/2016] [Accepted: 04/19/2016] [Indexed: 06/05/2023]
Abstract
Hydration reactions of deprotonated nucleobases (uracil, thymine, 5-fluorouracil,2-thiouracil, cytosine, adenine, and hypoxanthine) produced by electrospray have been experimentally studied in the gas phase at 10 mbar using a pulsed ion-beam high-pressure mass spectrometer. The thermochemical data, ΔH (o) , ΔS (o) , and ΔG (o) , for the monohydrated systems were determined. The hydration enthalpies were found to be similar for all studied systems and varied between 39.4 and 44.8 kJ/mol. A linear correlation was found between water binding energies in the hydrated complexes and the corresponding acidities of the most acidic site of nucleobases. The structural and energetic aspects of the precursors for the hydrated complexes are discussed in conjunction with available literature data. Graphical Abstract ᅟ.
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Affiliation(s)
- Henryk Wincel
- Institute of Physical Chemistry, Polish Academy of Sciences, 01-224, Warsaw, Poland.
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23
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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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24
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Kiruba GSM, Xu J, Zelikson V, Lee JK. Gas-Phase Studies of Formamidopyrimidine Glycosylase (Fpg) Substrates. Chemistry 2016; 22:3881-90. [DOI: 10.1002/chem.201505003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Indexed: 11/08/2022]
Affiliation(s)
- G. S. M. Kiruba
- Department of Chemistry and Chemical Biology; Rutgers; The State University of New Jersey; New Brunswick NJ 08901 USA
| | - Jiahui Xu
- Department of Chemistry and Chemical Biology; Rutgers; The State University of New Jersey; New Brunswick NJ 08901 USA
| | - Victoria Zelikson
- Department of Chemistry and Chemical Biology; Rutgers; The State University of New Jersey; New Brunswick NJ 08901 USA
| | - Jeehiun K. Lee
- Department of Chemistry and Chemical Biology; Rutgers; The State University of New Jersey; New Brunswick NJ 08901 USA
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25
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Yang B, Wu RR, Rodgers MT. Base-Pairing Energies of Proton-Bound Dimers and Proton Affinities of 1-Methyl-5-Halocytosines: Implications for the Effects of Halogenation on the Stability of the DNA i-Motif. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2015; 26:1469-1482. [PMID: 26148525 DOI: 10.1007/s13361-015-1174-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2014] [Revised: 04/22/2015] [Accepted: 04/24/2015] [Indexed: 06/04/2023]
Abstract
(CCG)(n)•(CGG)(n) trinucleotide repeats have been found to be associated with fragile X syndrome, the most widespread inherited cause of mental retardation in humans. The (CCG)(n)•(CGG)(n) repeats adopt i-motif conformations that are preferentially stabilized by base-pairing interactions of noncanonical proton-bound dimers of cytosine (C(+)•C). Halogenated cytosine residues are one form of DNA damage that may be important in altering the structure and stability of DNA or DNA-protein interactions and, hence, regulate gene expression. Previously, we investigated the effects of 5-halogenation and 1-methylation of cytosine on the base-pairing energies (BPEs) using threshold collision-induced dissociation (TCID) techniques. In the present study, we extend our work to include proton-bound homo- and heterodimers of cytosine, 1-methyl-5-fluorocytosine, and 1-methyl-5-bromocytosine. All modifications examined here are found to produce a decrease in the BPEs. However, the BPEs of all of the proton-bound dimers examined significantly exceed those of Watson-Crick G•C, neutral C•C base pairs, and various methylated variants such that DNA i-motif conformations should still be preserved in the presence of these modifications. The proton affinities (PAs) of the halogenated cytosines are also obtained from the experimental data by competitive analysis of the primary dissociation pathways that occur in parallel for the proton-bound heterodimers. 5-Halogenation leads to a decrease in the N3 PA of cytosine, whereas 1-methylation leads to an increase in the N3 PA. Thus, the 1-methyl-5-halocytosines exhibit PAs that are intermediate.
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Affiliation(s)
- Bo Yang
- Department of Chemistry, Wayne State University, Detroit, MI, 48202, USA
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26
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Yang B, Rodgers MT. Base-Pairing Energies of Protonated Nucleoside Base Pairs of dCyd and m(5)dCyd: Implications for the Stability of DNA i-Motif Conformations. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2015; 26:1394-1403. [PMID: 26002790 DOI: 10.1007/s13361-015-1144-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2015] [Revised: 03/10/2015] [Accepted: 03/17/2015] [Indexed: 06/04/2023]
Abstract
Hypermethylation of cytosine in expanded (CCG)n•(CGG)n trinucleotide repeats results in Fragile X syndrome, the most common cause of inherited mental retardation. The (CCG)n•(CGG)n repeats adopt i-motif conformations that are preferentially stabilized by base-pairing interactions of protonated base pairs of cytosine. Here we investigate the effects of 5-methylation and the sugar moiety on the base-pairing energies (BPEs) of protonated cytosine base pairs by examining protonated nucleoside base pairs of 2'-deoxycytidine (dCyd) and 5-methyl-2'-deoxycytidine (m(5)dCyd) using threshold collision-induced dissociation techniques. 5-Methylation of a single or both cytosine residues leads to very small change in the BPE. However, the accumulated effect may be dramatic in diseased state trinucleotide repeats where many methylated base pairs may be present. The BPEs of the protonated nucleoside base pairs examined here significantly exceed those of Watson-Crick dGuo•dCyd and neutral dCyd•dCyd base pairs, such that these base-pairing interactions provide the major forces responsible for stabilization of DNA i-motif conformations. Compared with isolated protonated nucleobase pairs of cytosine and 1-methylcytosine, the 2'-deoxyribose sugar produces an effect similar to the 1-methyl substituent, and leads to a slight decrease in the BPE. These results suggest that the base-pairing interactions may be slightly weaker in nucleic acids, but that the extended backbone is likely to exert a relatively small effect on the total BPE. The proton affinity (PA) of m(5)dCyd is also determined by competitive analysis of the primary dissociation pathways that occur in parallel for the protonated (m(5)dCyd)H(+)(dCyd) nucleoside base pair and the absolute PA of dCyd previously reported.
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Affiliation(s)
- Bo Yang
- Department of Chemistry, Wayne State University, Detroit, MI, 48202, USA
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27
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Halder A, Halder S, Bhattacharyya D, Mitra A. Feasibility of occurrence of different types of protonated base pairs in RNA: a quantum chemical study. Phys Chem Chem Phys 2015; 16:18383-96. [PMID: 25070186 DOI: 10.1039/c4cp02541e] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Protonated nucleobases have significant roles in facilitating catalytic functions of RNA, and in stabilizing different structural motifs. Reported pKa values of nucleobase protonation suggest that the population of neutral nucleobases is 10(3)-10(4) times higher than that of protonated nucleobases under physiological conditions (pH ∼ 7.4). Therefore, a molecular level understanding of various putative roles of protonated nucleobases cannot be achieved without addressing the question of how their occurrence propensities and stabilities are related to the free energy costs associated with the process of protonation under physiological conditions. With water as the proton donor, we use advanced QM methods to evaluate the site specific protonation propensities of nucleobases in terms of their associated free energy changes (ΔGprot). Quantitative follow up on the energetics of base pair formation and database search for evaluating their occurrence frequencies, reveal a lack of correlation between base pair stability and occurrence propensities on the one hand, and ease of protonation on the other. For example, although N7 protonated adenine (ΔGprot = 40.0 kcal mol(-1)) is found to participate in stable base pairing, base pairs involving N7 protonated guanine (ΔGprot = 36.8 kcal mol(-1)), on geometry optimization, converge to a minima where guanine transfers its extra proton to its partner base. Such observations, along with examples of weak base pairs involving N3 protonation of cytosine (ΔGprot = 37.0 kcal mol(-1)) are rationalized by analysing the protonation induced charge redistributions which are found to significantly influence, both positively and negatively, the hydrogen bonding potentials of different functional sites of individual nucleobases. Protonation induced charge redistribution is also found to strongly influence (i) the aromatic character of the rings of the participating bases and (ii) hydrogen bonding potential of the free edges of the protonated base pair. Comprehensive analysis of a non-redundant RNA crystal structure dataset further reveals that, while availability of stabilization possibilities determine the feasibility of occurrence of protonated bases, their occurrence context and specific functional roles are important factors determining their occurrence propensities.
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Affiliation(s)
- Antarip Halder
- Center for Computational Natural Sciences and Bioinformatics (CCNSB), International Institute of Information Technology (IIIT-H), Gachibowli, Hyderabad 500032, India.
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28
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Wu RR, Yang B, Frieler CE, Berden G, Oomens J, Rodgers MT. N3 and O2 protonated tautomeric conformations of 2'-deoxycytidine and cytidine coexist in the gas phase. J Phys Chem B 2015; 119:5773-84. [PMID: 25874502 DOI: 10.1021/jp5130316] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Infrared multiple photon dissociation action spectra of the protonated forms of the cytidyl nucleosides, 2'-deoxycytidine, [dCyd+H](+), and cytidine, [Cyd+H](+), are acquired over the IR fingerprint and hydrogen-stretching regions. Electronic structure calculations are performed at the B3LYP/6-311+G(d,p) level to determine the stable low-energy tautomeric conformations of these species generated upon electrospray ionization (ESI) and to generate the linear IR absorption spectra of these protonated nucleosides. Comparison between the experimental and theoretical spectra allows the tautomeric conformations of [dCyd+H](+) and [Cyd+H](+) populated by ESI to be determined. B3LYP predicts N3 as the preferred protonation site for both [dCyd+H](+) and [Cyd+H](+), whereas MP2 suggests that protonation at O2 is more favorable. The 2'-hydroxyl substituent does not significantly alter the structures of the B3LYP N3 and MP2 O2 protonated ground tautomeric conformations of [dCyd+H](+) vs [Cyd+H](+). [dCyd+H](+) and [Cyd+H](+) exhibit very similar spectral signatures in both regions. Nonetheless, the 2'-hydroxyl does affect the relative intensities of the IRMPD bands of [dCyd+H](+) vs [Cyd+H](+). The spectral features observed in the hydrogen-stretching region complement those of the fingerprint region and allow the N3 and O2 protonated tautomeric conformations to be readily distinguished. Comparison between the measured and computed spectra indicates that both N3 and O2 protonated tautomeric conformations coexist in the experiments, and the populations are dominated by the most stable N3 and O2 protonated tautomeric conformations. Least-squares fitting of the IRMPD spectra to the IR spectra for these most stable conformers suggests relative populations of ∼55% N3 vs 45% O2 protonated conformers of [dCyd+H](+), whereas ∼47% N3 vs 53% O2 protonated conformers of [Cyd+H](+). This change in the preferred site of protonation indicates that the 2'-hydroxyl substituent plays an important role in controlling the reactivity of the cytidyl nucleosides.
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Affiliation(s)
- R R Wu
- †Department of Chemistry, Wayne State University, Detroit, Michigan 48202, United States
| | - Bo Yang
- †Department of Chemistry, Wayne State University, Detroit, Michigan 48202, United States
| | - C E Frieler
- †Department of Chemistry, Wayne State University, Detroit, Michigan 48202, United States
| | - G Berden
- ‡Institute for Molecules and Materials, FELIX Facility, Radboud University Nijmegen, Toernooiveld 7, 6525 ED, Nijmegen, The Netherlands
| | - J Oomens
- ‡Institute for Molecules and Materials, FELIX Facility, Radboud University Nijmegen, Toernooiveld 7, 6525 ED, Nijmegen, The Netherlands.,§van't Hoff Institute for Molecular Sciences, University of Amsterdam, Amsterdam, The Netherlands
| | - M T Rodgers
- †Department of Chemistry, Wayne State University, Detroit, Michigan 48202, United States
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29
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Riml C, Glasner H, Rodgers MT, Micura R, Breuker K. On the mechanism of RNA phosphodiester backbone cleavage in the absence of solvent. Nucleic Acids Res 2015; 43:5171-81. [PMID: 25904631 PMCID: PMC4446422 DOI: 10.1093/nar/gkv288] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Accepted: 03/24/2015] [Indexed: 12/18/2022] Open
Abstract
Ribonucleic acid (RNA) modifications play an important role in the regulation of gene expression and the development of RNA-based therapeutics, but their identification, localization and relative quantitation by conventional biochemical methods can be quite challenging. As a promising alternative, mass spectrometry (MS) based approaches that involve RNA dissociation in ‘top-down’ strategies are currently being developed. For this purpose, it is essential to understand the dissociation mechanisms of unmodified and posttranscriptionally or synthetically modified RNA. Here, we have studied the effect of select nucleobase, ribose and backbone modifications on phosphodiester bond cleavage in collisionally activated dissociation (CAD) of positively and negatively charged RNA. We found that CAD of RNA is a stepwise reaction that is facilitated by, but does not require, the presence of positive charge. Preferred backbone cleavage next to adenosine and guanosine in CAD of (M+nH)n+ and (M−nH)n− ions, respectively, is based on hydrogen bonding between nucleobase and phosphodiester moieties. Moreover, CAD of RNA involves an intermediate that is sufficiently stable to survive extension of the RNA structure and intramolecular proton redistribution according to simple Coulombic repulsion prior to backbone cleavage into c and y ions from phosphodiester bond cleavage.
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Affiliation(s)
- Christian Riml
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innrain 80-82, 6020 Innsbruck, Austria
| | - Heidelinde Glasner
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innrain 80-82, 6020 Innsbruck, Austria
| | - M T Rodgers
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, MI 48202-3489, United States
| | - Ronald Micura
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innrain 80-82, 6020 Innsbruck, Austria
| | - Kathrin Breuker
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innrain 80-82, 6020 Innsbruck, Austria
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30
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Hokmabady L, Raissi H, Khanmohammadi A. Interactions of the 5-fluorouracil anticancer drug with DNA pyrimidine bases: a detailed computational approach. Struct Chem 2015. [DOI: 10.1007/s11224-015-0578-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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31
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Yang B, Moehlig AR, Frieler CE, Rodgers MT. Base-pairing energies of protonated nucleobase pairs and proton affinities of 1-methylated cytosines: model systems for the effects of the sugar moiety on the stability of DNA i-motif conformations. J Phys Chem B 2015; 119:1857-68. [PMID: 25565341 DOI: 10.1021/acs.jpcb.5b00035] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Expansion of (CCG)n·(CGG)n trinucleotide repeats leads to hypermethylation of cytosine residues and results in Fragile X syndrome, the most common cause of inherited intellectual disability in humans. The (CCG)n·(CGG)n repeats adopt i-motif conformations that are preferentially stabilized by base-pairing interactions of noncanonical protonated nucleobase pairs of cytosine (C(+)·C). Previously, we investigated the effects of 5-methylation of cytosine on the base-pairing energies (BPEs) using threshold collision-induced dissociation (TCID) techniques. In the present work, we extend our investigations to include protonated homo- and heteronucleobase pairs of cytosine, 1-methylcytosine, 5-methylcytosine, and 1,5-dimethylcytosine. The 1-methyl substituent prevents most tautomerization processes of cytosine and serves as a mimic for the sugar moiety of DNA nucleotides. In contrast to permethylation of cytosine at the 5-position, 1-methylation is found to exert very little influence on the BPE. All modifications to both nucleobases lead to a small increase in the BPEs, with 5-methylation producing a larger enhancement than either 1-methyl or 1,5-dimethylation. In contrast, modifications to a single nucleobase are found to produce a small decrease in the BPEs, again with 5-methylation producing a larger effect than 1-methylation. However, the BPEs of all of the protonated nucleobase pairs examined here significantly exceed those of canonical G·C and neutral C·C base pairs, and thus should still provide the driving force stabilizing DNA i-motif conformations even in the presence of such modifications. The proton affinities of the methylated cytosines are also obtained from the TCID experiments by competitive analyses of the primary dissociation pathways that occur in parallel for the protonated heteronucleobase pairs.
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Affiliation(s)
- Bo Yang
- Department of Chemistry, Wayne State University , Detroit, Michigan 48202, United States
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32
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Chen M, Lee JK. Computational Studies of the Gas-Phase Thermochemical Properties of Modified Nucleobases. J Org Chem 2014; 79:11295-300. [DOI: 10.1021/jo502058w] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Mu Chen
- Department of Chemistry and
Chemical Biology Rutgers, The State University of New Jersey, New Brunswick, New Jersey 08901, United States
| | - Jeehiun K. Lee
- Department of Chemistry and
Chemical Biology Rutgers, The State University of New Jersey, New Brunswick, New Jersey 08901, United States
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33
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Maiti A, Michelson AZ, Armwood CJ, Lee JK, Drohat AC. Divergent mechanisms for enzymatic excision of 5-formylcytosine and 5-carboxylcytosine from DNA. J Am Chem Soc 2013; 135:15813-22. [PMID: 24063363 DOI: 10.1021/ja406444x] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
5-Methylcytosine (mC) is an epigenetic mark that impacts transcription, development, and genome stability, and aberrant DNA methylation contributes to aging and cancer. Active DNA demethylation involves stepwise oxidation of mC to 5-hydroxymethylcytosine, 5-formylcytosine (fC), and potentially 5-carboxylcytosine (caC), excision of fC or caC by thymine DNA glycosylase (TDG), and restoration of cytosine via follow-on base excision repair. Here, we investigate the mechanism for TDG excision of fC and caC. We find that 5-carboxyl-2'-deoxycytidine ionizes with pK(a) values of 4.28 (N3) and 2.45 (carboxyl), confirming that caC exists as a monoanion at physiological pH. Calculations do not support the proposal that G·fC and G·caC base pairs adopt a wobble structure that is recognized by TDG. Previous studies show that N-glycosidic bond hydrolysis follows a stepwise (S(N)1) mechanism, and that TDG activity increases with pyrimidine N1 acidity, that is, leaving group quality of the target base. Calculations here show that fC and the neutral tautomers of caC are acidic relative to other TDG substrates, but the caC monoanion exhibits poor acidity and likely resists TDG excision. While fC activity is independent of pH, caC excision is acid-catalyzed, and the pH profile indicates that caC ionizes in the enzyme-substrate complex with an apparent pKa of 5.8, likely at N3. Mutational analysis reveals that Asn191 is essential for excision of caC but dispensable for fC activity, indicating that N191 may stabilize N3-protonated forms of caC to facilitate acid catalysis and suggesting that N191A-TDG could potentially be useful for studying DNA demethylation in cells.
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Affiliation(s)
- Atanu Maiti
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine , Baltimore, Maryland 21201, United States
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34
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Wang K, Chen M, Wang Q, Shi X, Lee JK. 1,2,3-Triazoles: Gas Phase Properties. J Org Chem 2013; 78:7249-58. [PMID: 23805820 DOI: 10.1021/jo4012738] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Kai Wang
- Department of Chemistry and
Chemical Biology, Rutgers, The State University of New Jersey, New Brunswick, New Jersey 08901, United States
| | - Mu Chen
- Department of Chemistry and
Chemical Biology, Rutgers, The State University of New Jersey, New Brunswick, New Jersey 08901, United States
| | - Qiaoyi Wang
- C. Eugene Bennett Department
of Chemistry, West Virginia University,
Morgantown, West Virginia 26506, United States
| | - Xiaodong Shi
- C. Eugene Bennett Department
of Chemistry, West Virginia University,
Morgantown, West Virginia 26506, United States
| | - Jeehiun K. Lee
- Department of Chemistry and
Chemical Biology, Rutgers, The State University of New Jersey, New Brunswick, New Jersey 08901, United States
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35
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Comparison of gas phase intrinsic properties of cytosine and thymine nucleobases with their O-alkyl adducts: different hydrogen bonding preferences for thymine versus O-alkyl thymine. J Mol Model 2013; 19:2993-3005. [DOI: 10.1007/s00894-013-1813-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2012] [Accepted: 03/03/2013] [Indexed: 12/11/2022]
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36
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Palamarchuk GV, Shishkin OV, Gorb L, Leszczynski J. Nucleic acid bases in anionic 2'-deoxyribonucleotides: a DFT/B3LYP study of structures, relative stability, and proton affinities. J Phys Chem B 2013; 117:2841-9. [PMID: 23425497 DOI: 10.1021/jp311363c] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Protonation of nucleobases in anions of canonical 2'-deoxyribonucleotides has been investigated by the DFT computational study at the B3LYP/aug-cc-pvdz level of theory. It is demonstrated that the protonation leads to a significant decrease of conformational space of purine nucleotides while almost all conformers found for non-protonated molecules correspond to minima of the potential energy surface for protonated mdTMP and mdCMP. However, in all nucleotides, only one conformer is populated. This applies to all tautomers of protonated molecules except the mdTMP and mdCMP with the proton attached to the carbonyl group where a minor population of second conformer is observed. Protonation of nucleobase leads to significant elongation of the N-glycosidic bond. These findings agree well with suggestions that protonation of nucleobase is a first step in cleavage of the glycosidic bond. The oxygen atoms of both carbonyl groups of thymine and the N3 atom of the pyrimidine ring of cytosine, guanine, and adenine represent the most preferable sites for protonation of anions of 2'-deoxyrobonucleotides. The highest proton affinity is observed for the base in mdGMP and the lowest for the thymine moiety in mdTMP. It should be noted that calculated values of the proton affinities in anionic nucleotides are significantly higher (by 2-3 eV) than for nucleosides and neutral nucleotides. This allows assuming that the proton affinity of the base in DNA macromolecule may be tuned by changing the extent of shielding or neutralization of negative charge of the phosphate group.
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Affiliation(s)
- Gennady V Palamarchuk
- STC Institute for Single Crystals, National Academy of Sciences of Ukraine, 60 Lenina ave., Kharkiv 61001, Ukraine
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37
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Feketeová L, Khairallah GN, Chan B, Steinmetz V, Maître P, Radom L, O'Hair RAJ. Gas-phase infrared spectrum and acidity of the radical cation of 9-methylguanine. Chem Commun (Camb) 2013; 49:7343-5. [DOI: 10.1039/c3cc43244k] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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38
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Michelson AZ, Rozenberg A, Tian Y, Sun X, Davis J, Francis AW, O'Shea VL, Halasyam M, Manlove AH, David SS, Lee JK. Gas-phase studies of substrates for the DNA mismatch repair enzyme MutY. J Am Chem Soc 2012; 134:19839-50. [PMID: 23106240 PMCID: PMC4204490 DOI: 10.1021/ja309082k] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The gas-phase thermochemical properties (tautomeric energies, acidity, and proton affinity) have been measured and calculated for adenine and six adenine analogues that were designed to test features of the catalytic mechanism used by the adenine glycosylase MutY. The gas-phase intrinsic properties are correlated to possible excision mechanisms and MutY excision rates to gain insight into the MutY mechanism. The data support a mechanism involving protonation at N7 and hydrogen bonding to N3 of adenine. We also explored the acid-catalyzed (non-enzymatic) depurination of these substrates, which appears to follow a different mechanism than that employed by MutY, which we elucidate using calculations.
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Affiliation(s)
- Anna Zhachkina Michelson
- Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, New Brunswick, New Jersey 08901, United States
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39
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Aliakbar Tehrani Z, Shakourian-Fard M, Fattahi A. Computational investigation of thermochemical properties of non-natural C-nucloebases: different hydrogen-bonding preferences for non-natural Watson–Crick base pairs. Struct Chem 2012. [DOI: 10.1007/s11224-012-0115-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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40
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Psciuk BT, Lord RL, Munk BH, Schlegel HB. Theoretical Determination of One-Electron Oxidation Potentials for Nucleic Acid Bases. J Chem Theory Comput 2012; 8:5107-23. [PMID: 26593200 DOI: 10.1021/ct300550x] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The oxidation potentials for N-methyl substituted nucleic acid bases guanine, adenine, cytosine, thymine, uracil, xanthine, and 8-oxoguanine were computed using B3LYP and CBS-QB3 with the SMD solvation model. Acid-base and tautomeric equilibria present in aqueous solution were accounted for by combining standard redox potentials with calculated pKa and tautomerization energies to produce an ensemble averaged pH dependent potential. Gas phase free energies were computed using B3LYP/aug-cc-pVTZ//B3LYP/6-31+G(d,p) and CBS-QB3. Solvation free energies were computed at the SMD/B3LYP/6-31+G(d,p) level of theory. Compared to experimental results, calculations with the CBS-QB3 level of theory have a mean absolute error (MAE) of ca. 1 kcal/mol for the gas phase proton affinity/gas phase basicity and an MAE of ca. 0.04 eV for the adiabatic/vertical ionization potentials. The B3LYP calculations have a MAE of ∼2 kcal/mol for the proton affinity/gas phase basicity data but systematically underestimated ionization potentials by 0.14-0.21 eV. Solvent cavities for charged solute species were rescaled uniformly by fitting computed pKa data to experimentally measured pKa values. After solvent cavity scaling, the MAEs for computed pKa's compared to experimental results are 0.7 for B3LYP and 0.9 for CBS-QB3. In acetonitrile, the computed E°(XH(+•)/XH) redox potentials are systematically lower than experimentally measured potentials by 0.21 V for CBS-QB3 and 0.33 V for B3LYP. However, the redox potentials relative to adenine are in very good agreement with experimental results, with MAEs of 0.10 V for CBS-QB3 and 0.07 V for B3LYP. In aqueous solution, B3LYP and CBS-QB3 have MAEs of 0.21 and 0.19 V for E7(X(•),H(+)/XH). Replacing the methyl substituent with ribose changes the calculated E7 potentials by 0.1-0.2 V. The calculated difference between the guanine and adenine oxidation potentials is too large compared to experimental results, but the calculated difference between guanine and 8-oxoguanine is in good agreement with the measured values.
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Affiliation(s)
- Brian T Psciuk
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202, United States
| | - Richard L Lord
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202, United States
| | - Barbara H Munk
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202, United States
| | - H Bernhard Schlegel
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202, United States
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41
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Michelson AZ, Chen M, Wang K, Lee JK. Gas-Phase Studies of Purine 3-Methyladenine DNA Glycosylase II (AlkA) Substrates. J Am Chem Soc 2012; 134:9622-33. [DOI: 10.1021/ja211960r] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Anna Zhachkina Michelson
- Department
of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, New Brunswick,
New Jersey 08901, United States
| | - Mu Chen
- Department
of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, New Brunswick,
New Jersey 08901, United States
| | - Kai Wang
- Department
of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, New Brunswick,
New Jersey 08901, United States
| | - Jeehiun K. Lee
- Department
of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, New Brunswick,
New Jersey 08901, United States
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42
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Thermochemical properties of some vinyl chloride-induced DNA lesions: detailed view from NBO & AIM analysis. Struct Chem 2012. [DOI: 10.1007/s11224-012-0026-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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43
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Michelson AZ, Petronico A, Lee JK. 2-Pyridone and Derivatives: Gas-Phase Acidity, Proton Affinity, Tautomer Preference, and Leaving Group Ability. J Org Chem 2011; 77:1623-31. [DOI: 10.1021/jo201991y] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2022]
Affiliation(s)
- Anna Zhachkina Michelson
- Department of Chemistry and Chemical
Biology, Rutgers, The State University of New Jersey, New Brunswick, New Jersey
08901, United States
| | - Aaron Petronico
- Department of Chemistry and Chemical
Biology, Rutgers, The State University of New Jersey, New Brunswick, New Jersey
08901, United States
| | - Jeehiun K. Lee
- Department of Chemistry and Chemical
Biology, Rutgers, The State University of New Jersey, New Brunswick, New Jersey
08901, United States
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44
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Liu M, Tran NT, Franz AK, Lee JK. Gas-Phase Acidity Studies of Dual Hydrogen-Bonding Organic Silanols and Organocatalysts. J Org Chem 2011; 76:7186-94. [DOI: 10.1021/jo201214x] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- Min Liu
- Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, New Brunswick, New Jersey 08901, United States
| | - Ngon T. Tran
- Department of Chemistry, University of California, One Shields Avenue, Davis, California 95616, United States
| | - Annaliese K. Franz
- Department of Chemistry, University of California, One Shields Avenue, Davis, California 95616, United States
| | - Jeehiun K. Lee
- Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, New Brunswick, New Jersey 08901, United States
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45
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Shakourian-Fard M, Fattahi A. Theoretical investigation on the structural and electronic properties of complexes formed by thymine and 2′-deoxythymidine with different anions. Struct Chem 2011. [DOI: 10.1007/s11224-011-9837-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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46
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Shakourian-Fard M, Fattahi A, Jamshidi Z. Interaction of cations with 2′-deoxythymidine nucleoside and analysis of the nature and strength of cation bonds. J PHYS ORG CHEM 2011. [DOI: 10.1002/poc.1888] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Mehdi Shakourian-Fard
- Department of Chemistry; Sharif University of Technology; Tehran Iran
- Chemistry and Chemical Engineering Research Center of Iran; Tehran Iran
| | - Alireza Fattahi
- Department of Chemistry; Sharif University of Technology; Tehran Iran
| | - Zahra Jamshidi
- Chemistry and Chemical Engineering Research Center of Iran; Tehran Iran
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47
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Gardner MW, Li N, Ellington AD, Brodbelt JS. Infrared multiphoton dissociation of small-interfering RNA anions and cations. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2010; 21:580-91. [PMID: 20129797 PMCID: PMC2847665 DOI: 10.1016/j.jasms.2009.12.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2009] [Revised: 12/21/2009] [Accepted: 12/22/2009] [Indexed: 05/13/2023]
Abstract
Infrared multiphoton dissociation (IRMPD) on a linear ion trap mass spectrometer is applied for the sequencing of small interfering RNA (siRNA). Both single-strand siRNAs and duplex siRNA were characterized by IRMPD, and the results were compared with that obtained by traditional ion trap-based collision induced dissociation (CID). The single-strand siRNA anions were observed to dissociate via cleavage of the 5' P-O bonds yielding c- and y-type product ions as well as undergo neutral base loss. Full sequence coverage of the siRNA anions was obtained by both IRMPD and CID. While the CID mass spectra were dominated by base loss ions, accounting for approximately 25% to 40% of the product ion current, these ions were eliminated through secondary dissociation by increasing the irradiation time in the IRMPD mass spectra to produce higher abundances of informative sequence ions. With longer irradiation times, however, internal ions corresponding to cleavage of two 5' P-O bonds began to populate the product ion mass spectra as well as higher abundances of [a - Base] and w-type ions. IRMPD of siRNA cations predominantly produced c- and y-type ions with minimal contributions of [a - Base] and w-type ions to the product ion current; the presence of only two complementary series of product ions in the IRMPD mass spectra simplified spectral interpretation. In addition, IRMPD produced high abundances of protonated nucleobases, [G + H](+), [A + H](+), and [C + H](+), which were not detected in the CID mass spectra due to the low-mass cut-off associated with conventional CID in ion traps. CID and IRMPD using short irradiation times of duplex siRNA resulted in strand separation, similar to the dissociation trends observed for duplex DNA. With longer irradiation times, however, the individual single-strands underwent secondary dissociation to yield informative sequence ions not obtained by CID.
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Affiliation(s)
- Myles W Gardner
- Department of Chemistry and Biochemistry, The University of Texas at Austin, Austin, Texas 78712-0165, USA
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48
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Zhachkina A, Lee JK. Uracil and thymine reactivity in the gas phase: the S(N)2 reaction and implications for electron delocalization in leaving groups. J Am Chem Soc 2010; 131:18376-85. [PMID: 19928991 DOI: 10.1021/ja906814d] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
The gas-phase substitution reactions of methyl chloride and 1,3-dimethyluracil (at the N1-CH(3)) are examined computationally and experimentally. It is found that, although hydrochloric acid and 3-methyluracil are similar in acidity, the leaving group abilities of chloride and N1-deprotonated 3-methyluracil are not: chloride is a slightly better leaving group. The reason for this difference is most likely related to the electron delocalization in the N1-deprotonated 3-methyluracil anion, which we explore further herein. The leaving group ability of the N1-deprotonated 3-methyluracil anion relative to the N1-deprotonated 3-methylthymine anion is also examined in the context of an enzymatic reaction that cleaves uracil but not thymine from DNA.
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Affiliation(s)
- Anna Zhachkina
- Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, New Brunswick, New Jersey 08901, USA
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49
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Sun X, Lee JK. Stability of DNA Duplexes Containing Hypoxanthine (Inosine): Gas versus Solution Phase and Biological Implications. J Org Chem 2010; 75:1848-54. [DOI: 10.1021/jo9023683] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Xuejun Sun
- Department of Chemistry and Chemical Biology Rutgers, The State University of New Jersey, New Brunswick, New Jersey 08901
| | - Jeehiun K. Lee
- Department of Chemistry and Chemical Biology Rutgers, The State University of New Jersey, New Brunswick, New Jersey 08901
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50
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Anion interactions of cytosine nucleobase and its nucleosides: Detailed view from DFT study. ACTA ACUST UNITED AC 2009. [DOI: 10.1016/j.theochem.2009.08.008] [Citation(s) in RCA: 7] [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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