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Jiang Y, Hu Z, Yang Y, Peng P, Zhong C, Sun H, Sun Z, Wang XB. Beyond Duality: Rationalizing Repulsive Coulomb Barriers in Host-Guest Cyclodextrin-Dodecaborate Complexes. J Phys Chem Lett 2023:6736-6742. [PMID: 37470699 DOI: 10.1021/acs.jpclett.3c01345] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/21/2023]
Abstract
The repulsive Coulomb barrier (RCB), an intrinsic potential energy barrier along electron detachment or charge-separation coordinates in multiply charged anions (MCAs), provides dynamic stability to MCAs whose electronic and thermodynamic stabilities are largely dictated by strong internal Coulomb repulsions. Spectroscopic and theoretical characterizations of the RCB have been focused on isolated MCAs. In this work, we extend the RCB investigation beyond the previous scope by including noncovalent host-guest cyclodextrin-closo-dodecaborate dianionic complexes χCD·B12X122- (χ = α, β, γ; X = H, F-I). Photodechment photoelectron spectroscopy reveals the existence of two distinctly different RCBs, derived from detaching electrons from the guest dianions (RCB1) or ionizing the host neutrals (RCB2), respectively, with the latter being substantially smaller than the former. Theoretical calculations support the duality of RCBs in these complexes and further exhibit highly anisotropic nature of the RCBs.
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Affiliation(s)
- Yanrong Jiang
- State Key Laboratory of Precision Spectroscopy, School of Physics and Electronic Science, East China Normal University, Shanghai 200241, China
- Center for Transformative Science, ShanghaiTech University, Shanghai 201210, China
| | - Zhubin Hu
- State Key Laboratory of Precision Spectroscopy, School of Physics and Electronic Science, East China Normal University, Shanghai 200241, China
| | - Yan Yang
- State Key Laboratory of Precision Spectroscopy, School of Physics and Electronic Science, East China Normal University, Shanghai 200241, China
| | - Peng Peng
- Center for Transformative Science, ShanghaiTech University, Shanghai 201210, China
| | - Cheng Zhong
- College of Chemistry & Molecular Sciences, Wuhan University, Wuhan, Hubei 430072, China
| | - Haitao Sun
- State Key Laboratory of Precision Spectroscopy, School of Physics and Electronic Science, East China Normal University, Shanghai 200241, China
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi 030006, China
- NYU-ECNU Center for Computational Chemistry at NYU Shanghai, Shanghai 200062, China
| | - Zhenrong Sun
- State Key Laboratory of Precision Spectroscopy, School of Physics and Electronic Science, East China Normal University, Shanghai 200241, China
| | - Xue-Bin Wang
- Physical Sciences Division, Pacific Northwest National Laboratory, 902 Battelle Boulevard, P.O. Box 999, Richland, Washington 99352, United States
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2
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Yuan Q, Chomicz-Mańka L, Makurat S, Cao W, Rak J, Wang XB. Photoelectron Spectroscopy and Theoretical Investigations of Gaseous Doubly Deprotonated 2'-Deoxynucleoside 5'-Monophosphate Dianions. J Phys Chem Lett 2021; 12:9463-9469. [PMID: 34558897 DOI: 10.1021/acs.jpclett.1c02678] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
A better understanding of the mechanism of oxidative DNA damage requires obtaining a molecular level description of nucleotides in various charge states. Herein, we report a systematic photoelectron spectroscopy and theoretical investigation of the electronic and geometric structures of four doubly deprotonated 2'-deoxynucleoside 5'-monophosphate dianions, the smallest quintessential DNA building block. These dianions are intrinsically stable with their adiabatic/vertical detachment energies (ADE/VDE) ranging from 0.85/1.07 (A) and 1.05/1.30 (G) to 1.20/1.50 (C) and 1.80/2.10 eV (T). The repulsive Coulomb barrier against electron detachment is 2.0 eV for purines and 2.5 eV for pyrimidines. Dianions are deprotonated at the phosphate group and the amino group of a nucleobase. The π-type HOMO orbital resides on the nucleobase moiety for each dianion. This spatial distribution of HOMO suggests that the most loosely bound electron is detached along the direction perpendicular to the nucleobase. When combined with the previous results, this work makes complete the depiction of basic building blocks of DNA at the molecular level.
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Affiliation(s)
- Qinqin Yuan
- Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Lidia Chomicz-Mańka
- Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, Gdańsk 80-308, Poland
| | - Samanta Makurat
- Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, Gdańsk 80-308, Poland
| | - Wenjin Cao
- Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Janusz Rak
- Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, Gdańsk 80-308, Poland
| | - Xue-Bin Wang
- Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
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3
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Castellani ME, Avagliano D, Verlet JRR. Ultrafast Dynamics of the Isolated Adenosine-5'-triphosphate Dianion Probed by Time-Resolved Photoelectron Imaging. J Phys Chem A 2021; 125:3646-3652. [PMID: 33882670 DOI: 10.1021/acs.jpca.1c01646] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The excited state dynamics of the doubly deprotonated dianion of adenosine-5'-triphosphate, [ATP-H2]2-, has been spectroscopically explored by time-resolved photoelectron spectroscopy following excitation at 4.66 eV. Time-resolved photoelectron spectra show that two competing processes occur for the initially populated 1ππ* state. The first is rapid electron emission by tunneling through a repulsive Coulomb barrier as the 1ππ* state is a resonance. The second is nuclear motion on the 1ππ* state surface leading to an intermediate that no longer tunnels and subsequently decays by internal conversion to the ground electronic state. The spectral signatures of the features are similar to those observed for other adenine-derivatives, suggesting that this nucleobase is quite insensitive to the nearby negative charges localized on the phosphates, except of course for the appearance of the additional electron tunneling channel, which is open in the dianion.
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Affiliation(s)
| | - Davide Avagliano
- Institute of Theoretical Chemistry, Faculty of Chemistry, University of Vienna, Währinger Strasse 17 1090 Vienna, Austria
| | - Jan R R Verlet
- Department of Chemistry, Durham University, DH1 3LE Durham, U.K
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4
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EKİNCİOĞLU Y, KILIÇ HŞ, DERELİ Ö. A DFT/TD-DFT study on the Molecular Structure Absorption and Fluorescence Spectra of Gas/Solution Phases Adenosine 5’–triphosphate Molecule. GAZI UNIVERSITY JOURNAL OF SCIENCE 2021. [DOI: 10.35378/gujs.834249] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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5
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Castellani ME, Avagliano D, González L, Verlet JRR. Site-Specific Photo-oxidation of the Isolated Adenosine-5'-triphosphate Dianion Determined by Photoelectron Imaging. J Phys Chem Lett 2020; 11:8195-8201. [PMID: 32886886 DOI: 10.1021/acs.jpclett.0c02089] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Photoelectron imaging of the isolated adenosine-5'-triphosphate dianion excited to the 1ππ* states reveals that electron emission is predominantly parallel to the polarization axis of the light and arises from subpicosecond electron tunneling through the repulsive Coulomb barrier (RCB). The computed RCB shows that the most probable electron emission site is on the amino group of adenine. This is consistent with the photoelectron imaging: excitation to the 1ππ* states leads to an aligned ensemble distributed predominantly parallel to the long axis of adenine; the subsequent electron tunneling site is along this axis; and the negatively charged phosphate groups guide the outgoing electron mostly along this axis at long range. Imaging of electron tunneling from polyanions combined with computational chemistry may offer a general route for probing the intrinsic photo-oxidation site and dynamics as well as the overall structure of complex isolated species.
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Affiliation(s)
| | - Davide Avagliano
- Institute of Theoretical Chemistry, Faculty of Chemistry, University of Vienna, Währinger Str. 17, 1090 Vienna, Austria
| | - Leticia González
- Institute of Theoretical Chemistry, Faculty of Chemistry, University of Vienna, Währinger Str. 17, 1090 Vienna, Austria
| | - Jan R R Verlet
- Department of Chemistry, Durham University, Durham DH1 3LE, United Kingdom
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6
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van Outersterp RE, Martens J, Berden G, Steill JD, Oomens J, Rijs AM. Structural characterization of nucleotide 5'-triphosphates by infrared ion spectroscopy and theoretical studies. Phys Chem Chem Phys 2018; 20:28319-28330. [PMID: 30398499 DOI: 10.1039/c8cp03314e] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The molecular family of nucleotide triphosphates (NTPs), with adenosine 5'-triphosphate (ATP) as its best-known member, is of high biochemical importance as their phosphodiester bonds form Nature's main means to store and transport energy. Here, gas-phase IR spectroscopic studies and supporting theoretical studies have been performed on adenosine 5'-triphosphate, cytosine 5'-triphosphate and guanosine 5'-triphosphate to elucidate the intrinsic structural properties of NTPs, focusing on the influence of the nucleobase and the extent of deprotonation. Mass spectrometric studies involving collision induced dissociation showed similar fragmentation channels for the three studied NTPs within a selected charge state. The doubly charged anions exhibit fragmentation similar to the energy-releasing hydrolysis reaction in nature, while the singly charged anions show different dominant fragmentation channels, suggesting that the charge state plays a significant role in the favorability of the hydrolysis reaction. A combination of infrared ion spectroscopy and quantum-chemical computations indicates that the singly charged anions of all NTPs are preferentially deprotonated at their β-phosphates, while the doubly-charged anions are dominantly αβ-deprotonated. The assigned three-dimensional structure differs for ATP and CTP on the one hand and GTP on the other, in the sense that ATP and CTP show no interaction between nucleobase and phosphate tail, while in GTP they are hydrogen bonded. This can be rationalized by considering the structure and geometry of the NTPs where the final three dimensional structure depends on a subtle balance between hydrogen bond strength, flexibility and steric hindrance.
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Affiliation(s)
- Rianne E van Outersterp
- Radboud University, Institute for Molecules and Materials, FELIX Laboratory, Toernooiveld 7, 6525ED, Nijmegen, The Netherlands.
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7
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Cercola R, Matthews E, Dessent CEH. Photoexcitation of Adenosine 5'-Triphosphate Anions in Vacuo: Probing the Influence of Charge State on the UV Photophysics of Adenine. J Phys Chem B 2017; 121:5553-5561. [PMID: 28521097 DOI: 10.1021/acs.jpcb.7b03435] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We report the first UV laser photodissociation spectra (4.0-5.8 eV) of gas-phase deprotonated adenosine 5'-triphosphate, diphosphate and monophosphate anions. The photodepletion spectra of these anions display strong absorption bands across the region of 4.6-5.2 eV, consistent with excitation of a primarily adenine-centered π-π* transition. The spectra appear insensitive to the charge of the species (i.e., the spectrum of [ATP-2H]2- closely resembles that of [ATP-H]-), while the spectral profile is affected to a greater extent by the variation of the molecular structure, i.e. the [AMP-H]- and [ADP-H]- photodepletion spectra display similar profiles while the [ATP-H]- spectrum is distinctive. The photodepletion cross-section also decreases for the ATP anions compared to both the AMP and ADP anions, reflecting a high intrinsic photostability of ATP versus both AMP and ADP. A range of photofragments are produced across the 4.0-5.8 eV spectral range for all of the ATP analogues studied. These fragments are primarily associated with fragmentation on the ground-state electronic surface, indicative of a statistical decay process where ultrafast decay is followed by ergodic dissociation. However, while the photofragments observed following photoexcitation of the monoanionic species, [AMP-H]- to [ADP-H]- to [ATP-H]- are entirely consistent with statistical decay, an additional group of photofragments are observed for the dianionic species, [ADP-2H]2- and [ATP-2H]2-, that we associate with electron detachment, and subsequent fragmentation of the resulting electron-detached photofragment. TDDFT calculations are presented to support the interpretation of the experimental data, and confirm that the electronic structure of the adenine moiety is relatively unperturbed by varying the overall charge.
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Affiliation(s)
- Rosaria Cercola
- Department of Chemistry, University of York , Heslington, York, YO10 5DD, U.K
| | - Edward Matthews
- Department of Chemistry, University of York , Heslington, York, YO10 5DD, U.K
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8
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Frański R, Gierczyk B, Jaroszyńska N, Michalak A, Rosik M. Gas phase conversion of triphosphate to trimetaphosphate. JOURNAL OF MASS SPECTROMETRY : JMS 2016; 51:165-168. [PMID: 26889933 DOI: 10.1002/jms.3742] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2015] [Revised: 12/03/2015] [Accepted: 12/04/2015] [Indexed: 06/05/2023]
Affiliation(s)
- Rafał Frański
- Faculty of Chemistry, Adam Mickiewicz University, Umultowska 89B, 61-614, Poznań, Poland
| | - Błażej Gierczyk
- Faculty of Chemistry, Adam Mickiewicz University, Umultowska 89B, 61-614, Poznań, Poland
| | - Natalia Jaroszyńska
- Faculty of Chemistry, Adam Mickiewicz University, Umultowska 89B, 61-614, Poznań, Poland
| | - Agnieszka Michalak
- Faculty of Chemistry, Adam Mickiewicz University, Umultowska 89B, 61-614, Poznań, Poland
| | - Marta Rosik
- Faculty of Chemistry, Adam Mickiewicz University, Umultowska 89B, 61-614, Poznań, Poland
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9
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Ligare MR, Rijs AM, Berden G, Kabeláč M, Nachtigallova D, Oomens J, de Vries MS. Resonant Infrared Multiple Photon Dissociation Spectroscopy of Anionic Nucleotide Monophosphate Clusters. J Phys Chem B 2015; 119:7894-901. [PMID: 26004928 DOI: 10.1021/acs.jpcb.5b02222] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We report mid-infrared spectra and potential energy surfaces of four anionic, 2'-deoxynucleotide-5'-monophosphates (dNMPs) and the ionic DNA pairs [dGMP-dCMP-H](1-), [dAMP-dTMP-H](1-) with a total charge of the complex equal to -1. We recorded IR action spectra by resonant IR multiple-photon dissociation (IRMPD) using the FELIX free electron laser. The potential energy surface study employed an on-the-fly molecular dynamics quenching method (MD/Q), using a semiempirical AM1 method, followed by an optimization of the most stable structures using density functional theory. By employing infrared multiple-photon dissociation (IRMPD) spectroscopy in combination with high-level computational methods, we aim at a better understanding of the hydrogen bonding competition between the phosphate moieties and the nucleobases. We find that, unlike in multimer double stranded DNA structures, the hydrogen bonds in these isolated nucleotide pairs are predominantly formed between the phosphate groups. This intermolecular interaction appears to exceed the stabilization energy resulting from base pairing and directs the overall cluster structure and alignment.
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Affiliation(s)
- Marshall R Ligare
- †Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, California 93106, United States
| | - Anouk M Rijs
- ‡FELIX Facility, Institute for Molecules and Materials, Radboud University Nijmegen, Toernooiveld 7c, 6525 ED Nijmegen, The Netherlands
| | - Giel Berden
- ‡FELIX Facility, Institute for Molecules and Materials, Radboud University Nijmegen, Toernooiveld 7c, 6525 ED Nijmegen, The Netherlands
| | - Martin Kabeláč
- §Faculty of Science, University of South Bohemia, Branišovská 31, 370 05 České Budějovice, Czech Republic
| | - Dana Nachtigallova
- ∥Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, 166 10 Prague 6, Czech Republic
| | - Jos Oomens
- ‡FELIX Facility, Institute for Molecules and Materials, Radboud University Nijmegen, Toernooiveld 7c, 6525 ED Nijmegen, The Netherlands.,∥Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, 166 10 Prague 6, Czech Republic.,⊥van 't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, 1098XH Amsterdam, The Netherlands
| | - Mattanjah S de Vries
- †Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, California 93106, United States
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10
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Gu H, Rapakousiou A, Castel P, Guidolin N, Pinaud N, Ruiz J, Astruc D. Living Ring-Opening Metathesis–Polymerization Synthesis and Redox-Sensing Properties of Norbornene Polymers and Copolymers Containing Ferrocenyl and Tetraethylene Glycol Groups. Organometallics 2014. [DOI: 10.1021/om5006897] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Haibin Gu
- ISM,
UMR CNRS No. 5255, University of Bordeaux, 33405 Talence Cedex, France
| | - Amalia Rapakousiou
- ISM,
UMR CNRS No. 5255, University of Bordeaux, 33405 Talence Cedex, France
| | - Patricia Castel
- ISM,
UMR CNRS No. 5255, University of Bordeaux, 33405 Talence Cedex, France
| | - Nicolas Guidolin
- LCPO,
UMR CNRS No. 5629, University of Bordeaux, 33607 Pessac Cedex, France
| | - Nöel Pinaud
- ISM,
UMR CNRS No. 5255, University of Bordeaux, 33405 Talence Cedex, France
| | - Jaime Ruiz
- ISM,
UMR CNRS No. 5255, University of Bordeaux, 33405 Talence Cedex, France
| | - Didier Astruc
- ISM,
UMR CNRS No. 5255, University of Bordeaux, 33405 Talence Cedex, France
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11
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Panek PT, Jacob CR. Efficient calculation of anharmonic vibrational spectra of large molecules with localized modes. Chemphyschem 2014; 15:3365-77. [PMID: 25080397 DOI: 10.1002/cphc.201402251] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2014] [Indexed: 11/11/2022]
Abstract
The analysis and interpretation of the vibrational spectra of complex (bio)molecular systems, such as polypeptides and proteins, requires support from quantum-chemical calculations. Such calculations are currently restricted to the harmonic approximation. Here, we show how one of the main bottlenecks in such calculations, the evaluation of the potential energy surface, can be overcome by using localized modes instead of the commonly employed normal modes. We apply such local vibrational self-consistent field (L-VSCF) and vibrational configuration interaction (L-VCI) calculations to a cyclic water tetramer and a helical hexa-alanine peptide. The results show that the use of localized modes is equivalent to the commonly used normal modes, but offers several advantages. First, a faster convergence with respect to the excitation level is observed in L-VCI calculations. Second, the localized modes provide a reduced representation of the couplings between modes that show a regular coupling pattern. This can be used to disregard a significant number of small two-mode potentials a priori. Several such reduced coupling approximations are explored, and we show that the number of single-point calculations required to evaluate the potential energy surface can be significantly reduced without introducing noticeable errors in the resulting vibrational spectra.
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Affiliation(s)
- Paweł T Panek
- Karlsruhe Institute of Technology (KIT), Center for Functional Nanostructures and Institute of Physical Chemistry, Wolfgang-Gaede-Str. 1a, 76131 Karlsruhe (Germany) http://www.christophjacob.eu
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12
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Schinle F, Jacob CR, Wolk AB, Greisch JF, Vonderach M, Weis P, Hampe O, Johnson MA, Kappes MM. Ion mobility spectrometry, infrared dissociation spectroscopy, and ab initio computations toward structural characterization of the deprotonated leucine-enkephalin peptide anion in the gas phase. J Phys Chem A 2014; 118:8453-63. [PMID: 24884600 DOI: 10.1021/jp501772d] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Although the sequencing of protonated proteins and peptides with tandem mass spectrometry has blossomed into a powerful means of characterizing the proteome, much less effort has been directed at their deprotonated analogues, which can offer complementary sequence information. We present a unified approach to characterize the structure and intermolecular interactions present in the gas-phase pentapeptide leucine-enkephalin anion by several vibrational spectroscopy schemes as well as by ion-mobility spectrometry, all of which are analyzed with the help of quantum-chemical computations. The picture emerging from this study is that deprotonation takes place at the C terminus. In this configuration, the excess charge is stabilized by strong intramolecular hydrogen bonds to two backbone amide groups and thus provides a detailed picture of a potentially common charge accommodation motif in peptide anions.
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Affiliation(s)
- Florian Schinle
- Institute of Nanotechnology, Karlsruhe Institute of Technology (KIT) , 76021 Karlsruhe, Germany
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13
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Walker M, Harvey AJA, Sen A, Dessent CEH. Performance of M06, M06-2X, and M06-HF density functionals for conformationally flexible anionic clusters: M06 functionals perform better than B3LYP for a model system with dispersion and ionic hydrogen-bonding interactions. J Phys Chem A 2013; 117:12590-600. [PMID: 24147965 DOI: 10.1021/jp408166m] [Citation(s) in RCA: 442] [Impact Index Per Article: 40.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We present a comparative assessment of the performance of the M06 suite of density functionals (M06, M06-2X, and M06-HF) against an MP2 benchmark for calculating the relative energies and geometric structures of the Cl(-)·arginine and Br(-)·arginine halide ion-amino acid clusters. Additional results are presented for the popular B3LYP density functional. The Cl(-)·arginine and Br(-)·arginine complexes are important prototypes for the phenomenon of anion-induced zwitterion formation. Results are presented for the canonical (noncharge separated) and zwitterionic (charge separated) tautomers of the clusters, as well as the numerous conformational isomers of the clusters. We find that all of the M06 functions perform well in terms of predicting the general trends in the conformer relative energies and identifying the global minimum conformer. This is in contrast to the B3LYP functional, which performed significantly less well for the canonical tautomers of the clusters where dispersion interactions contribute more significantly to the conformer energetics. We find that the M06 functional gave the lowest mean unsigned error for the relative energies of the canonical conformers (2.10 and 2.36 kJ/mol for Br(-)·arginine and Cl(-)·arginine), while M06-2X gave the lowest mean unsigned error for the zwitterionic conformers (0.85 and 1.23 kJ/mol for Br(-)·arginine and Cl(-)·arginine), thus providing insight into the types of physical systems where each of these functionals should perform best.
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Affiliation(s)
- Martin Walker
- Department of Chemistry, University of York , Heslington, York YO10 5DD, U.K
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