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Moscato D, Mandelli G, Bondanza M, Lipparini F, Conte R, Mennucci B, Ceotto M. Unraveling Water Solvation Effects with Quantum Mechanics/Molecular Mechanics Semiclassical Vibrational Spectroscopy: The Case of Thymidine. J Am Chem Soc 2024; 146:8179-8188. [PMID: 38470354 DOI: 10.1021/jacs.3c12700] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/13/2024]
Abstract
We introduce a quantum mechanics/molecular mechanics semiclassical method for studying the solvation process of molecules in water at the nuclear quantum mechanical level with atomistic detail. We employ it in vibrational spectroscopy calculations because this is a tool that is very sensitive to the molecular environment. Specifically, we look at the vibrational spectroscopy of thymidine in liquid water. We find that the C═O frequency red shift and the C═C frequency blue shift, experienced by thymidyne upon solvation, are mainly due to reciprocal polarization effects, that the molecule and the water solvent exert on each other, and nuclear zero-point energy effects. In general, this work provides an accurate and practical tool to study quantum vibrational spectroscopy in solution and condensed phase, incorporating high-level and computationally affordable descriptions of both electronic and nuclear problems.
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Affiliation(s)
- Davide Moscato
- Dipartimento di Chimica, Università degli Studi di Milano, Via Golgi, 19, 20133 Milano, Italy
| | - Giacomo Mandelli
- Dipartimento di Chimica, Università degli Studi di Milano, Via Golgi, 19, 20133 Milano, Italy
| | - Mattia Bondanza
- Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Via Giuseppe Moruzzi, 13, 56124 Pisa, Italy
| | - Filippo Lipparini
- Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Via Giuseppe Moruzzi, 13, 56124 Pisa, Italy
| | - Riccardo Conte
- Dipartimento di Chimica, Università degli Studi di Milano, Via Golgi, 19, 20133 Milano, Italy
| | - Benedetta Mennucci
- Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Via Giuseppe Moruzzi, 13, 56124 Pisa, Italy
| | - Michele Ceotto
- Dipartimento di Chimica, Università degli Studi di Milano, Via Golgi, 19, 20133 Milano, Italy
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2
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Moscato D, Gabas F, Conte R, Ceotto M. Vibrational spectroscopy simulation of solvation effects on a G-quadruplex. J Biomol Struct Dyn 2023; 41:14248-14258. [PMID: 36856120 DOI: 10.1080/07391102.2023.2180435] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Accepted: 02/07/2023] [Indexed: 03/02/2023]
Abstract
It is commonly believed that solvation effects on the vibrational properties of a solute are easily accounted for by simple rules of thumbs, that is, solvating a polar molecule in a polar medium has the only effect of red shifting all its spectroscopical features and, similarly, solvating a polar molecule in a nonpolar medium has the opposite effect. In this work, we use theoretical vibrational spectroscopy at quasi-classical and quantum approximate semiclassical level to gain atomistic insights about solvent-solute interactions for 2'-deoxyguanosine and the G-quadruplex. We employ the quasi-classical trajectory method to include full anharmonicity into our calculated spectra, and then introduce quantum nuclear effects by means of divide-and-conquer semiclassical spectroscopy calculations. Solvation is treated explicitly leading to a good reproducibility of the available experimental data and reliable predictions when an experimental reference is missing.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Davide Moscato
- Dipartimento di Chimica, Università degli Studi di Milano, Milano, Italy
| | - Fabio Gabas
- Dipartimento di Chimica, Università degli Studi di Milano, Milano, Italy
| | - Riccardo Conte
- Dipartimento di Chimica, Università degli Studi di Milano, Milano, Italy
| | - Michele Ceotto
- Dipartimento di Chimica, Università degli Studi di Milano, Milano, Italy
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3
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Zhou M, Jiao L, Xu S, Xu Y, Du M, Zhang X, Kong X. A novel method for photon unfolding spectroscopy of protein ions in the gas phase. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2022; 93:043003. [PMID: 35489914 DOI: 10.1063/5.0080040] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2021] [Accepted: 03/18/2022] [Indexed: 06/14/2023]
Abstract
In this study, a new experimental method for photon unfolding spectroscopy of protein ions based on a Fourier transform ion cyclotron resonance (FT ICR) mass spectrometer was developed. The method of short-time Fourier transform has been applied here to obtain decay curves of target ions trapped in the cell of the FT ICR mass spectrometer. Based on the decay constants, the collision cross sections (CCSs) of target ions were calculated using the energetic hard-sphere model. By combining a tunable laser to the FT ICR mass spectrometer, the changes of CCSs of the target ions were recorded as a function of the wavelengths; thus, the photon isomerization spectrum was obtained. As one example, the photon isomerization spectrum of [Cyt c + 13H]13+ was recorded as the decay constants relative to the applied wavelengths of the laser in the 410-480 nm range. The spectrum shows a maximum at 426 nm, where an unfolded structure induced by a 4 s irradiation can be deduced. The strong peak at 426 nm was also observed for another ion of [Cyt c + 15H]15+, although some difference at 410 nm between the two spectra was found at the same time. This novel method can be expanded to ultraviolet or infrared region, making the experimental study of wavelength-dependent photon-induced structural variation of a variety of organic or biological molecules possible.
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Affiliation(s)
- Min Zhou
- State Key Laboratory of Elemento-organic Chemistry, Collage of Chemistry, Nankai University, Tianjin 300071, China
| | - Luyang Jiao
- State Key Laboratory of Elemento-organic Chemistry, Collage of Chemistry, Nankai University, Tianjin 300071, China
| | - Shiyin Xu
- State Key Laboratory of Elemento-organic Chemistry, Collage of Chemistry, Nankai University, Tianjin 300071, China
| | - Yicheng Xu
- State Key Laboratory of Elemento-organic Chemistry, Collage of Chemistry, Nankai University, Tianjin 300071, China
| | - Mengying Du
- State Key Laboratory of Elemento-organic Chemistry, Collage of Chemistry, Nankai University, Tianjin 300071, China
| | - Xianyi Zhang
- School of Physics and Electronic Information, Anhui Normal University, Wuhu 241000, China
| | - Xianglei Kong
- State Key Laboratory of Elemento-organic Chemistry, Collage of Chemistry, Nankai University, Tianjin 300071, China
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4
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Niedner‐Schatteburg G, Kappes MM. Advancing Inorganic Coordination Chemistry by Spectroscopy of Isolated Molecules: Methods and Applications. Chemistry 2021; 27:15027-15042. [PMID: 34636096 PMCID: PMC8596414 DOI: 10.1002/chem.202102815] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Indexed: 12/14/2022]
Abstract
A unique feature of the work carried out in the Collaborative Research Center 3MET continues to be its emphasis on innovative, advanced experimental methods which hyphenate mass-selection with further analytical tools such as laser spectroscopy for the study of isolated molecular ions. This allows to probe the intrinsic properties of the species of interest free of perturbing solvent or matrix effects. This review explains these methods and uses examples from past and ongoing 3MET studies of specific classes of multicenter metal complexes to illustrate how coordination chemistry can be advanced by applying them. As a corollary, we will show how the challenges involved in providing well-defined, for example monoisomeric, samples of the molecular ions have helped to further improve the methods themselves thus also making them applicable to many other areas of chemistry.
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Affiliation(s)
| | - Manfred M. Kappes
- Institute of Physical Chemistry and Institute of NanotechnologyKarlsruhe Institute of Technology (KIT)76128KarlsruheGermany
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5
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Donor MT, Wilson JW, Shepherd SO, Prell JS. Lipid Head Group Adduction to Soluble Proteins Follows Gas-Phase Basicity Predictions: Dissociation Barriers and Charge Abstraction. INTERNATIONAL JOURNAL OF MASS SPECTROMETRY 2021; 469:116670. [PMID: 34421332 PMCID: PMC8372978 DOI: 10.1016/j.ijms.2021.116670] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Native mass spectrometry analysis of membrane proteins has yielded many useful insights in recent years with respect to membrane protein-lipid interactions, including identifying specific interactions and even measuring binding affinities based on observed abundances of lipid-bound ions after collision-induced dissociation (CID). However, the behavior of non-covalent complexes subjected to extensive CID can in principle be affected by numerous factors related to gas-phase chemistry, including gas-phase basicity (GB) and acidity, shared-proton bonds, and other factors. A recent report from our group showed that common lipids span a wide range of GB values. Notably, phosphatidylcholine (PC) and sphingomyelin lipids are more basic than arginine, suggesting they may strip charge upon dissociation in positive ion mode, while phosphoserine lipids are slightly less basic than arginine and may form especially strong shared-proton bonds. Here, we use CID to probe the strength of non-specific gas-phase interactions between lipid head groups and several soluble proteins, used to deliberately avoid possible physiological protein-lipid interactions. The strengths of the protein-head group interactions follow the trend predicted based solely on lipid and amino acid GBs: phosphoserine (PS) head group forms the strongest bonds with these proteins and out-competes the other head groups studied, while glycerophosphocholine (GPC) head groups form the weakest interactions and dissociate carrying away a positive charge. These results indicate that gas-phase thermochemistry can play an important role in determining which head groups remain bound to protein ions with native-like structures and charge states in positive ion mode upon extensive collisional activation.
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Affiliation(s)
- Micah T. Donor
- Department of Chemistry and Biochemistry, 1253 University of Oregon, Eugene OR 97403-1253
| | - Jesse W. Wilson
- Department of Chemistry and Biochemistry, 1253 University of Oregon, Eugene OR 97403-1253
| | - Samantha O. Shepherd
- Department of Chemistry and Biochemistry, 1253 University of Oregon, Eugene OR 97403-1253
| | - James S. Prell
- Department of Chemistry and Biochemistry, 1253 University of Oregon, Eugene OR 97403-1253
- Materials Science Institute, University of Oregon, 1252 University of Oregon, Eugene, OR 97403-1252
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Gloaguen E, Mons M, Schwing K, Gerhards M. Neutral Peptides in the Gas Phase: Conformation and Aggregation Issues. Chem Rev 2020; 120:12490-12562. [PMID: 33152238 DOI: 10.1021/acs.chemrev.0c00168] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Combined IR and UV laser spectroscopic techniques in molecular beams merged with theoretical approaches have proven to be an ideal tool to elucidate intrinsic structural properties on a molecular level. It offers the possibility to analyze structural changes, in a controlled molecular environment, when successively adding aggregation partners. By this, it further makes these techniques a valuable starting point for a bottom-up approach in understanding the forces shaping larger molecular systems. This bottom-up approach was successfully applied to neutral amino acids starting around the 1990s. Ever since, experimental and theoretical methods developed further, and investigations could be extended to larger peptide systems. Against this background, the review gives an introduction to secondary structures and experimental methods as well as a summary on theoretical approaches. Vibrational frequencies being characteristic probes of molecular structure and interactions are especially addressed. Archetypal biologically relevant secondary structures investigated by molecular beam spectroscopy are described, and the influences of specific peptide residues on conformational preferences as well as the competition between secondary structures are discussed. Important influences like microsolvation or aggregation behavior are presented. Beyond the linear α-peptides, the main results of structural analysis on cyclic systems as well as on β- and γ-peptides are summarized. Overall, this contribution addresses current aspects of molecular beam spectroscopy on peptides and related species and provides molecular level insights into manifold issues of chemical and biochemical relevance.
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Affiliation(s)
- Eric Gloaguen
- CEA, CNRS, Université Paris-Saclay, CEA Paris-Saclay, Bât 522, 91191 Gif-sur-Yvette, France
| | - Michel Mons
- CEA, CNRS, Université Paris-Saclay, CEA Paris-Saclay, Bât 522, 91191 Gif-sur-Yvette, France
| | - Kirsten Schwing
- TU Kaiserslautern & Research Center Optimas, Erwin-Schrödinger-Straße 52, D-67663 Kaiserslautern, Germany
| | - Markus Gerhards
- TU Kaiserslautern & Research Center Optimas, Erwin-Schrödinger-Straße 52, D-67663 Kaiserslautern, Germany
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Application of Infrared Multiple Photon Dissociation (IRMPD) Spectroscopy in Chiral Analysis. Molecules 2020; 25:molecules25215152. [PMID: 33167464 PMCID: PMC7663940 DOI: 10.3390/molecules25215152] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2020] [Revised: 11/03/2020] [Accepted: 11/04/2020] [Indexed: 12/24/2022] Open
Abstract
In recent years, methods based on photodissociation in the gas phase have become powerful means in the field of chiral analysis. Among them, infrared multiple photon dissociation (IRMPD) spectroscopy is a very attractive one, since it can provide valuable spectral and structural information of chiral complexes in addition to chiral discrimination. Experimentally, the method can be fulfilled by the isolation of target diastereomeric ions in an ion trap followed by the irradiation of a tunable IR laser. Chiral analysis is performed by comparing the difference existing in the spectra of enantiomers. Combined with theoretical calculations, their structures can be further understood on the molecular scale. By now, lots of chiral molecules, including amino acids and peptides, have been studied with the method combined with theoretical calculations. This review summarizes the relative experimental results obtained, and discusses the limitation and prospects of the method.
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Ren J, Zhang XY, Kong XL. Structure of protonated heterodimer of proline and phenylalanine: Revealed by infrared multiphoton dissociation spectroscopy and theoretical calculations. CHINESE J CHEM PHYS 2020. [DOI: 10.1063/1674-0068/cjcp2006089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Affiliation(s)
- Juan Ren
- State Key Laboratory of Elemento-organic Chemistry, College of Chemistry, Nankai University, Tianjin 300071, China
| | - Xian-yi Zhang
- School of Physics and Electronic Information, Anhui Normal University, Anhui Normal University, Wuhu 241000, China
| | - Xiang-lei Kong
- State Key Laboratory of Elemento-organic Chemistry, College of Chemistry, Nankai University, Tianjin 300071, China
- Collaborative Innovation Center of Chemical Science and Engineering, Nankai University, Tianjin 300071, China
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9
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Andersson Å, Poline M, Kodambattil M, Rebrov O, Loire E, Maître P, Zhaunerchyk V. Structure of Proton-Bound Methionine and Tryptophan Dimers in the Gas Phase Investigated with IRMPD Spectroscopy and Quantum Chemical Calculations. J Phys Chem A 2020; 124:2408-2415. [PMID: 32106670 PMCID: PMC7307929 DOI: 10.1021/acs.jpca.9b11811] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
![]()
The
structures of three proton-bound dimers (Met2H+, MetTrpH+, and Trp2H+) are
investigated in the gas phase with infrared multiple photon disassociation
(IRMPD) spectroscopy in combination with quantum chemical calculations.
Their IRMPD spectra in the range of 600–1850 cm–1 are obtained experimentally using an FT-ICR mass spectrometer and
the CLIO free electron laser as an IR light source. The most abundant
conformers are elucidated by comparing the IRMPD spectra with harmonic
frequencies obtained at the B3LYP-GD3BJ/6-311++G** level of theory.
Discrepancies between the experimental and theoretical data in the
region of 1500–1700 cm–1 are attributed to
the anharmonicity of the amino bending modes. We confirm the result
of a previous IRMPD study that the structure of gas-phase Trp2H+ is charge-solvated but find that there are more
stable structures than originally reported (Feng, R.; Yin, H.; Kong,
X. Rapid Commun. Mass Spectrom.2016, 30, 24–28). In addition, gas-phase Met2H+ and MetTrpH+ have been revealed to
have charge-solvated structures. For all three dimers, the most stable
conformer is found to be of type A. The spectrum of Met2H+, however, cannot be explained without some abundance
of type B charge-solvated conformers as well as salt-bridged structures.
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Affiliation(s)
- Åke Andersson
- Chalmers University of Technology, 412 96 Gothenburg, Sweden
| | - Mathias Poline
- Department of Physics, Stockholm University, 114 19 Stockholm, Sweden
| | - Meena Kodambattil
- Department of Physics, University of Gothenburg, 405 30 Gothenburg, Sweden.,International School of Photonics, Cochin University of Science and Technology, Kochi, Kerala 682022, India
| | - Oleksii Rebrov
- Department of Physics, Stockholm University, 114 19 Stockholm, Sweden
| | - Estelle Loire
- Laboratoire de Chimie Physique (UMR8000), Université Paris-Sud, CNRS, Université Paris Saclay, Orsay 91405, France
| | - Philippe Maître
- Laboratoire de Chimie Physique (UMR8000), Université Paris-Sud, CNRS, Université Paris Saclay, Orsay 91405, France
| | - Vitali Zhaunerchyk
- Department of Physics, University of Gothenburg, 405 30 Gothenburg, Sweden
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10
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Tang Y, Li D, Cao D, Xu W. Extracting biomolecule collision cross sections from FT-ICR mass spectral line shape. Talanta 2019; 205:120093. [PMID: 31450431 DOI: 10.1016/j.talanta.2019.06.093] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2019] [Revised: 06/19/2019] [Accepted: 06/26/2019] [Indexed: 10/26/2022]
Abstract
To extend the ion structure analysis capability of Fourier transform mass spectrometry (FT-MS), both time-domain and frequency-domain methods have been developed to extract ion collision cross sections (CCS) from high resolution mass spectra in Fourier transform ion cyclotron resonance (FT-ICR) cells. In this study, a new frequency-domain method, namely the line shape fitting method, was proposed to calculate ion CCSs from FT-ICR mass spectra line shape. Besides experimental data, simulated data with precisely controlled signal to noise levels and decay factors were also applied to characterize this method. Compared with the linewidth correction method previously proposed by our group, this line shape fitting method is more tolerant to noise, data length, and sampling rate, thus providing more consistent results. More importantly, CCS measurements of angiotensin I, bradykinin, ubiquitin and cytochrome c show that the resolving power is improved with the new method.
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Affiliation(s)
- Yang Tang
- School of Life Science, Beijing Institute of Technology, Beijing, 100081, China
| | - Dayu Li
- School of Computer Science and Engineering, Northeastern University, Shenyang, 110819, China.
| | - Dong Cao
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Science, Chinese Academy of Science, Beijing 100085, China
| | - Wei Xu
- School of Life Science, Beijing Institute of Technology, Beijing, 100081, China.
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11
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Zhou C, Ieritano C, Hopkins WS. Augmenting Basin-Hopping With Techniques From Unsupervised Machine Learning: Applications in Spectroscopy and Ion Mobility. Front Chem 2019; 7:519. [PMID: 31440497 PMCID: PMC6693329 DOI: 10.3389/fchem.2019.00519] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Accepted: 07/08/2019] [Indexed: 12/17/2022] Open
Abstract
Evolutionary algorithms such as the basin-hopping (BH) algorithm have proven to be useful for difficult non-linear optimization problems with multiple modalities and variables. Applications of these algorithms range from characterization of molecular states in statistical physics and molecular biology to geometric packing problems. A key feature of BH is the fact that one can generate a coarse-grained mapping of a potential energy surface (PES) in terms of local minima. These results can then be utilized to gain insights into molecular dynamics and thermodynamic properties. Here we describe how one can employ concepts from unsupervised machine learning to augment BH PES searches to more efficiently identify local minima and the transition states connecting them. Specifically, we introduce the concepts of similarity indices, hierarchical clustering, and multidimensional scaling to the BH methodology. These same machine learning techniques can be used as tools for interpreting and rationalizing experimental results from spectroscopic and ion mobility investigations (e.g., spectral assignment, dynamic collision cross sections). We exemplify this in two case studies: (1) assigning the infrared multiple photon dissociation spectrum of the protonated serine dimer and (2) determining the temperature-dependent collision cross-section of protonated alanine tripeptide.
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Affiliation(s)
- Ce Zhou
- Department of Chemistry, University of Waterloo, Waterloo, ON, Canada
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12
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Conte R, Gabas F, Botti G, Zhuang Y, Ceotto M. Semiclassical vibrational spectroscopy with Hessian databases. J Chem Phys 2019; 150:244118. [PMID: 31255076 DOI: 10.1063/1.5109086] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
We report on a new approach to ease the computational overhead of ab initio "on-the-fly" semiclassical dynamics simulations for vibrational spectroscopy. The well known bottleneck of such computations lies in the necessity to estimate the Hessian matrix for propagating the semiclassical pre-exponential factor at each step along the dynamics. The procedure proposed here is based on the creation of a dynamical database of Hessians and associated molecular geometries able to speed up calculations while preserving the accuracy of results at a satisfactory level. This new approach can be interfaced to both analytical potential energy surfaces and on-the-fly dynamics, allowing one to study even large systems previously not achievable. We present results obtained for semiclassical vibrational power spectra of methane, glycine, and N-acetyl-L-phenylalaninyl-L-methionine-amide, a molecule of biological interest made of 46 atoms.
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Affiliation(s)
- Riccardo Conte
- Dipartimento di Chimica, Università degli Studi di Milano, via Golgi 19, 20133 Milano, Italy
| | - Fabio Gabas
- Dipartimento di Chimica, Università degli Studi di Milano, via Golgi 19, 20133 Milano, Italy
| | - Giacomo Botti
- Dipartimento di Chimica, Università degli Studi di Milano, via Golgi 19, 20133 Milano, Italy
| | - Yu Zhuang
- Department of Computer Science, Texas Tech University, Lubbock, Texas 79409-3104, USA
| | - Michele Ceotto
- Dipartimento di Chimica, Università degli Studi di Milano, via Golgi 19, 20133 Milano, Italy
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13
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Linford BD, Le Donne A, Scuderi D, Bodo E, Fridgen TD. Strong intramolecular hydrogen bonding in protonated β-methylaminoalanine: A vibrational spectroscopic and computational study. EUROPEAN JOURNAL OF MASS SPECTROMETRY (CHICHESTER, ENGLAND) 2019; 25:133-141. [PMID: 30563367 DOI: 10.1177/1469066718791998] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The gas-phase structure of protonated β-methylaminoalanine was investigated using infrared multiple photon dissociation spectroscopy in the C-H, N-H, O-H stretching region (2700-3800 cm-1) and the fingerprint region (1000-1900 cm-1). Calculations using density functional theory methods show that the lowest energy structures prefer protonation of the secondary amine. Formation of hydrogen bonds between the primary and secondary amine, and the secondary amine and carboxylic oxygen further stabilize the lowest energy structure. The infrared spectrum of the lowest energy structure originating with harmonic density functional theory has features that generally match the positions of the experimental spectra; however, the overall agreement with the experimental spectrum is poor. Molecular dynamics calculations were used to generate a gas-phase infrared spectrum. With these calculations a reasonable match with the experimental spectrum, especially in the high-energy region, was obtained. The results of the molecular dynamics simulation support the density functional theory calculations, with protonation of the secondary amine and the formation of a hydrogen bond between the protonated secondary amine and the primary amine. This work shows the importance of accounting for anharmonic effects in systems with very strong intramolecular hydrogen bonding.
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Affiliation(s)
- Bryan D Linford
- 1 Department of Chemistry, Memorial University, St John's, Canada
| | - Andrea Le Donne
- 2 Dipartimento di Chimica, Università degli Studi di Roma La Sapienza, Roma, Italy
| | - Debora Scuderi
- 3 Laboratoire de Chimie Physique d'Orsay, Faculté des Sciences, Université Paris Sud, Orsay Cedex, France
| | - Enrico Bodo
- 2 Dipartimento di Chimica, Università degli Studi di Roma La Sapienza, Roma, Italy
| | - Travis D Fridgen
- 1 Department of Chemistry, Memorial University, St John's, Canada
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14
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Lee SS, Lee JU, Oh JH, Park S, Hong Y, Min BK, Lee HHL, Kim HI, Kong X, Lee S, Oh HB. Chiral differentiation of d- and l-isoleucine using permethylated β-cyclodextrin: infrared multiple photon dissociation spectroscopy, ion-mobility mass spectrometry, and DFT calculations. Phys Chem Chem Phys 2018; 20:30428-30436. [PMID: 30499999 DOI: 10.1039/c8cp05617j] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Chiral differentiation of protonated isoleucine (Ile) using permethylated β-cyclodextrin (perCD) in the gas-phase was studied using infrared multiple photon dissociation (IRMPD) spectroscopy, ion-mobility, and density functional theory (DFT) calculations. The gaseous protonated non-covalent complexes of perCD and d-Ile or l-Ile produced by electrospray ionization were interrogated by laser pulses in the wavenumber region of 2650 to 3800 cm-1. The IRMPD spectra showed remarkably different IR spectral features for the d-Ile or l-Ile and perCD non-covalent complexes. However, drift-tube ion-mobility experiments provided only a small difference in their collision cross-sections, and thus a limited separation of the d- and l-Ile complexes. DFT calculations revealed that the chiral distinction of the d- and l-complexes by IRMPD spectroscopy resulted from local interactions of the protonated Ile with perCD. Furthermore, the theoretical results showed that the IR absorption spectra of higher energy conformers (by ∼13.7 kcal mol-1) matched best with the experimentally observed IRMPD spectra. These conformers are speculated to be formed from kinetic-trapping of the solution-phase conformers. This study demonstrated that IRMPD spectroscopy provides an excellent platform for differentiating the subtle chiral difference of a small amino acid in a cyclodextrin-complexation environment; however, drift-tube ion-mobility did not have sufficient resolution to distinguish the chiral difference.
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Affiliation(s)
- Sung-Sik Lee
- Department of Applied Chemistry, Kyung Hee University, Gyeonggi 17104, Republic of Korea.
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15
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Park JJ, Lee CS, Han SY. Proton Transfer Accounting for Anomalous Collision-Induced Dissociation of Proton-Bound Hoogsteen Base Pair of Cytosine and Guanine. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2018; 29:2368-2379. [PMID: 30215166 DOI: 10.1007/s13361-018-2060-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Revised: 08/08/2018] [Accepted: 08/08/2018] [Indexed: 06/08/2023]
Abstract
To understand the anomalous collision-induced dissociation (CID) behavior of the proton-bound Hoogsteen base pair of cytosine (C) and guanine (G), C:H+∙∙∙G, we investigated CID of a homologue series of proton-bound heterodimers of C, 1-methylcytosine, and 5-methylcytosine with G as a common base partner. The CID experiments were performed in an energy-resolved way (ER-CID) under both multiple and near-single collision conditions. The relative stabilities of the protonated complexes examined by ER-CID suggested that the proton-bound complexes produced by electrospray ionization in this study are proton-bound Hoogsteen base pairs. On the other hand, in contrast to the other base pairs, CID of C:H+∙∙∙G exhibited more abundant productions of C:H+, the fragment protonated on the moiety with a smaller proton affinity, than that of G:H+. This appeared to contradict general prediction based on the kinetic method. However, further theoretical exploration of potential energy surfaces found that there can be facile proton transfers in the proton-bound Hoogsteen base pairs during the CID process, which makes the process accessible to an additional product state of O-protonated C for C:H+ fragments. The presence of an additional dissociation channel, which in other words corresponds to twofold degeneracy in the transition state leading to C:H+ fragments, effectively doubles the apparent reaction rate for production of C:H+. In this way, the process gives rise to the anomaly, the observed pronounced formation of C:H+ in the CID of the proton-bound Hoogsteen base pair, C:H+∙∙∙G. Graphical Abstract ᅟ.
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Affiliation(s)
- Jeong Ju Park
- Department of Nanochemistry, Gachon University, 1342 Seongnam-daero, Sujeong-gu, Seongnam-si, Gyeonggi-do, 13120, Republic of Korea
| | - Choong Sik Lee
- Scientific Investigation Laboratory, Ministry of National Defense, 22 Itaewon-ro, Yongsan-gu, Seoul, 04383, Republic of Korea
| | - Sang Yun Han
- Department of Nanochemistry, Gachon University, 1342 Seongnam-daero, Sujeong-gu, Seongnam-si, Gyeonggi-do, 13120, Republic of Korea.
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Gabas F, Di Liberto G, Conte R, Ceotto M. Protonated glycine supramolecular systems: the need for quantum dynamics. Chem Sci 2018; 9:7894-7901. [PMID: 30542548 PMCID: PMC6237109 DOI: 10.1039/c8sc03041c] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Accepted: 09/16/2018] [Indexed: 02/02/2023] Open
Abstract
Quantum mechanical simulations unequivocally explain experimental IR spectra of protonated supramolecular systems.
IR spectroscopy is one of the most commonly employed techniques to study molecular vibrations and interactions. However, characterization of experimental IR spectra is not always straightforward. This is the case of protonated glycine supramolecular systems like Gly2H+ and (GlyH + nH2), whose IR spectra raise questions which have still to find definitive answers even after theoretical spectroscopy investigations. Specifically, the assignment of the conformer responsible for the spectrum of the protonated glycine dimer (Gly2H+) has led to much controversy and it is still debated, while structural hypotheses formulated to explain the main experimental spectral features of (GlyH + nH2) systems have not been theoretically confirmed. We demonstrate that simulations must account for quantum dynamical effects in order to resolve these open issues. This is achieved by means of our divide-and-conquer semiclassical initial value representation technique, which approximates the quantum dynamics of high dimensional systems with remarkable accuracy and outperforms not only the commonly employed but unfit scaled-harmonic approaches, but also pure classical dynamics simulations. Besides the specific insights concerning the two particular cases presented here, the general conclusion is that, due to the widespread presence of protonated systems in chemistry, quantum dynamics may play a prominent role and should not be totally overlooked even when dealing with large systems including biological structures.
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Affiliation(s)
- Fabio Gabas
- Dipartimento di Chimica , Università degli Studi di Milano , via Golgi 19 , 20133 Milano , Italy . ;
| | - Giovanni Di Liberto
- Dipartimento di Chimica , Università degli Studi di Milano , via Golgi 19 , 20133 Milano , Italy . ;
| | - Riccardo Conte
- Dipartimento di Chimica , Università degli Studi di Milano , via Golgi 19 , 20133 Milano , Italy . ;
| | - Michele Ceotto
- Dipartimento di Chimica , Università degli Studi di Milano , via Golgi 19 , 20133 Milano , Italy . ;
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Ma L, Ren J, Feng R, Zhang K, Kong X. Structural characterizations of protonated homodimers of amino acids: Revealed by infrared multiple photon dissociation (IRMPD) spectroscopy and theoretical calculations. CHINESE CHEM LETT 2018. [DOI: 10.1016/j.cclet.2018.02.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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18
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Fritsche L, Bach A, Miloglyadova L, Tsybizova A, Chen P. A 4 K FT-ICR cell for infrared ion spectroscopy. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2018; 89:063119. [PMID: 29960550 DOI: 10.1063/1.5026973] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We present the design of the newly constructed cryogenic Fourier-transform ion cyclotron resonance (FT-ICR) ion trap for infrared ion spectroscopy. Trapped ions are collisionally cooled by the pulsed introduction of buffer gas into the cell. Using different buffer gases and cell temperatures, we record action spectra of weakly bound neutral gas-analyte complexes with an IR laser source. We show for the first time that ion-He complexes can be observed in an ICR cell at temperatures around 4 K. We compare the experimental vibrational spectra of Ag(PPh3)2+ obtained by tagging with different neutral gases: He, Ne, Ar, H2, and N2 to computed vibrational spectra. Furthermore, the conditions necessary for the formation of neutral tags within an ICR ion trap are studied.
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Affiliation(s)
- Lukas Fritsche
- Laboratorium für Organische Chemie, ETH Zurich, Vladimir-Prelog-Weg 2, CH-8093 Zürich, Switzerland
| | - Andreas Bach
- Laboratorium für Organische Chemie, ETH Zurich, Vladimir-Prelog-Weg 2, CH-8093 Zürich, Switzerland
| | - Larisa Miloglyadova
- Laboratorium für Organische Chemie, ETH Zurich, Vladimir-Prelog-Weg 2, CH-8093 Zürich, Switzerland
| | - Alexandra Tsybizova
- Laboratorium für Organische Chemie, ETH Zurich, Vladimir-Prelog-Weg 2, CH-8093 Zürich, Switzerland
| | - Peter Chen
- Laboratorium für Organische Chemie, ETH Zurich, Vladimir-Prelog-Weg 2, CH-8093 Zürich, Switzerland
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19
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Lee SS, Park S, Hong Y, Lee JU, Kim JH, Yoon D, Kong X, Lee S, Oh HB. Chiral differentiation of d- and l-alanine by permethylated β-cyclodextrin: IRMPD spectroscopy and DFT methods. Phys Chem Chem Phys 2018; 19:14729-14737. [PMID: 28540941 DOI: 10.1039/c7cp01085k] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The gaseous chiral differentiation of alanine by permethylated β-cyclodextrin was studied using IRMPD spectroscopy and density functional theory calculations. The protonated non-covalent complexes of permethylated β-cyclodextrin and d- or l-alanine were mass-selected and investigated by IR laser pulses in the wavelength region of 2650-3800 cm-1. The remarkably different features of the IRMPD spectra for d- and l-alanine are described, and their origin is elucidated by quantum chemical calculations. We show that the differentiation of the experimentally observed spectral features is the result of different local interactions of d- and l-alanine with permethylated β-cyclodextrin. We also assign the extremely high-frequency (>3700 cm-1) bands in the observed spectra to the stretch motions of completely isolated alanine -OH groups.
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Affiliation(s)
- Sung-Sik Lee
- Department of Applied Chemistry, Kyung Hee University, Gyeonggi 446-701, Republic of Korea.
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Heiles S, Berden G, Oomens J, Williams ER. Competition between salt bridge and non-zwitterionic structures in deprotonated amino acid dimers. Phys Chem Chem Phys 2018; 20:15641-15652. [DOI: 10.1039/c8cp01458b] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The effect of side chain functional groups on salt bridge structures in deprotonated amino acid homodimers is investigated using both infrared multiple photon dissociation spectroscopy between 650 and 1850 cm−1 and theory.
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Affiliation(s)
- Sven Heiles
- Department of Chemistry
- University of California
- Berkeley
- USA
- Institute of Inorganic and Analytical Chemistry
| | - Giel Berden
- Radboud University
- Institute for Molecules and Materials
- FELIX Laboratory
- 6525 ED Nijmegen
- The Netherlands
| | - Jos Oomens
- Radboud University
- Institute for Molecules and Materials
- FELIX Laboratory
- 6525 ED Nijmegen
- The Netherlands
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21
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Yang Y, Liao G, Kong X. Charge-state Resolved Infrared Multiple Photon Dissociation (IRMPD) Spectroscopy of Ubiquitin Ions in the Gas Phase. Sci Rep 2017; 7:16592. [PMID: 29185478 PMCID: PMC5707388 DOI: 10.1038/s41598-017-16831-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Accepted: 11/16/2017] [Indexed: 11/25/2022] Open
Abstract
In this study, we obtained for the first time the direct infrared multiple photon dissociation (IRMPD) spectra of ubiquitin ions in the range 2700-3750 cm-1. Ubiquitin ions with different charge states showed absorption in the two regions of 2940-3000 cm-1 and 3280-3400 cm-1. The increase of the charge state of ubiquitin ions broadened the absorption peak on the high-frequency side in the second region, indicating some hydrogen bonds were weakened due to Coulomb interaction. It is also found that the relative intensity of the absorption peak in the first region compared to the absorption peak in the second region increased with increasing charge state, making the IRMPD spectra charge-state resolved. Although it is usually reasonable to suggest the origin of the absorption in the range 2940-3000 cm-1 as the C-H bond stretching modes, the results show significantly reduced absorption after the deuteration of all labile hydrogen atoms. A possible explanation for this is that the coupling coefficients between the C-H vibrational mode and other selective modes decreased greatly after the deuteration, reducing the rate of energy redistribution and probability of consecutive IR absorption.
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Affiliation(s)
- Yijie Yang
- State Key Laboratory and Institute of Elemento-Organic Chemistry, College of Chemistry, Nankai University, Tianjin, 300071, China
| | - Guanhua Liao
- State Key Laboratory and Institute of Elemento-Organic Chemistry, College of Chemistry, Nankai University, Tianjin, 300071, China
| | - Xianglei Kong
- State Key Laboratory and Institute of Elemento-Organic Chemistry, College of Chemistry, Nankai University, Tianjin, 300071, China.
- Collaborative Innovation Center of Chemical Science and Engineering, Nankai University, Tianjin, 300071, China.
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22
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Jun J, Han SY. Theoretical exploration of gas-phase conformers of proton-bound non-covalent heterodimers of guanine and cytosine rare tautomers: structures and energies. Theor Chem Acc 2017. [DOI: 10.1007/s00214-017-2165-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
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23
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Filippi A, Fraschetti C, Guarcini L, Zazza C, Ema T, Speranza M. Spectroscopic Discrimination of Diastereomeric Complexes Involving an Axially Chiral Receptor. Chemphyschem 2017; 18:2475-2481. [DOI: 10.1002/cphc.201700732] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Indexed: 01/20/2023]
Affiliation(s)
- Antonello Filippi
- Università di Roma “La Sapienza”; Dipartimento di Chimica e Tecnologie del Farmaco; P.le A. Moro, 5 Roma 00185 Italy
| | - Caterina Fraschetti
- Università di Roma “La Sapienza”; Dipartimento di Chimica e Tecnologie del Farmaco; P.le A. Moro, 5 Roma 00185 Italy
| | - Laura Guarcini
- Università di Roma “La Sapienza”; Dipartimento di Chimica e Tecnologie del Farmaco; P.le A. Moro, 5 Roma 00185 Italy
| | - Costantino Zazza
- Università di Roma “La Sapienza”; Dipartimento di Chimica e Tecnologie del Farmaco; P.le A. Moro, 5 Roma 00185 Italy
| | - Tadashi Ema
- Graduate School of Natural Sciences and Technology; Okayama University; Tsushima Okayama 700-8530 Japan
| | - Maurizio Speranza
- Università di Roma “La Sapienza”; Dipartimento di Chimica e Tecnologie del Farmaco; P.le A. Moro, 5 Roma 00185 Italy
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Pan H, Mondal S, Yang CH, Liu K. Imaging characterization of the rapid adiabatic passage in a source-rotatable, crossed-beam scattering experiment. J Chem Phys 2017; 147:013928. [DOI: 10.1063/1.4982615] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Huilin Pan
- Institute of Atomic and Molecular Sciences, Academia Sinica, P.O. Box 23-166, Taipei 10617, Taiwan
| | - Sohidul Mondal
- Institute of Atomic and Molecular Sciences, Academia Sinica, P.O. Box 23-166, Taipei 10617, Taiwan
| | - Chung-Hsin Yang
- Institute of Atomic and Molecular Sciences, Academia Sinica, P.O. Box 23-166, Taipei 10617, Taiwan
| | - Kopin Liu
- Institute of Atomic and Molecular Sciences, Academia Sinica, P.O. Box 23-166, Taipei 10617, Taiwan
- Department of Physics, National Taiwan University, Taipei 10617, Taiwan
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25
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Ren J, Wang YY, Feng RX, Kong XL. Investigation of l / d -threonine substituted l -serine octamer ions by mass spectrometry and infrared photodissociation spectroscopy. CHINESE CHEM LETT 2017. [DOI: 10.1016/j.cclet.2016.10.032] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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26
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Tandem Mass Spectrometry. Mass Spectrom (Tokyo) 2017. [DOI: 10.1007/978-3-319-54398-7_9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
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27
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Barnes L, Schindler B, Compagnon I, Allouche AR. Fast and accurate hybrid QM//MM approach for computing anharmonic corrections to vibrational frequencies. J Mol Model 2016; 22:285. [DOI: 10.1007/s00894-016-3135-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2016] [Accepted: 10/09/2016] [Indexed: 10/20/2022]
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28
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Schwing K, Gerhards M. Investigations on isolated peptides by combined IR/UV spectroscopy in a molecular beam – structure, aggregation, solvation and molecular recognition. INT REV PHYS CHEM 2016. [DOI: 10.1080/0144235x.2016.1229331] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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29
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Feng R, Yin H, Kong X. Structure of protonated tryptophan dimer in the gas phase investigated by IRPD spectroscopy and theoretical calculations. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2016; 30 Suppl 1:24-28. [PMID: 27539410 DOI: 10.1002/rcm.7615] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
RATIONAL In addition to proton affinity (PA), side chains may also have an effect on the structures of amino acid complex ions in the gas phase. A previous study showed that the most stable isomer of Pro2 H(+) favored a salt-bridged structure. Tryptophan has a PA close to that of proline, but a quite different side chain. Thus, it will be interesting to discover whether the salt-bridged or charge-solvated conformation is energetically more favorable for Trp2 H(+) in the gas phase. METHODS The infrared photodissociation (IRPD) spectrum of Trp2 H(+) was obtained using a Fourier transform ion cyclotron resonance mass spectrometer equipped with a tunable OPO laser. The non-covalent cluster ions were generated by electrospray ionization. Structural optimization and frequency calculation of the selected isomers were performed at the M062X/6-311++G(d,p) level. RESULTS The experimental IRPD spectrum of Trp2 H(+) was reported in the region of 2700-3750 cm(-1) . Theoretical calculations show that the most stable isomer has a charge-solvated structure. Its energy was found to be 9 kcal/mol lower than that of the most stable salt-bridged isomer. The experimental spectrum is consistent with the predicted spectra of the most stable charge-solvated structures. Temperature effect on the stability of isomers was also evaluated and it was revealed that the contribution from salt-bridged isomers can be neglected at a temperature of 300 K. CONCLUSIONS Combining the method of IRPD spectroscopy with theoretical calculations, the structures of Trp2 H(+) were investigated. It is shown that the structures of Trp2 H(+) are dominated by charge-solvated forms. The results also indicate that the side chain may considerably affect the stability of the zwitterionic forms. Copyright © 2016 John Wiley & Sons, Ltd.
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Affiliation(s)
- Ruxia Feng
- State Key Laboratory and Institute of Elemento-Organic Chemistry, Nankai University, Tianjin, 300071, China
| | - Hong Yin
- State Key Laboratory and Institute of Elemento-Organic Chemistry, Nankai University, Tianjin, 300071, China
| | - Xianglei Kong
- State Key Laboratory and Institute of Elemento-Organic Chemistry, Nankai University, Tianjin, 300071, China
- Collaborative Innovation Center of Chemical Science and Engineering, Nankai University, Tianjin, 300071, China
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30
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Feng RX, Mu L, Yang SM, Kong XL. Structure of Pro 4 H + investigated by infrared photodissociation (IRPD) spectroscopy and theoretical calculations. CHINESE CHEM LETT 2016. [DOI: 10.1016/j.cclet.2016.02.027] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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31
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Pearson WL, Contreras C, Powell D, Berden G, Oomens J, Bendiak B, Eyler JR. Differentiation of Rubidiated Methyl-d-Glycoside Stereoisomers by Infrared Multiple-Photon Dissociation Spectroscopy in the O–H and C–H Stretching Regions. J Phys Chem B 2015; 119:12970-81. [DOI: 10.1021/acs.jpcb.5b06563] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Wright L. Pearson
- Department
of Chemistry, University of Florida, Gainesville, Florida 32611-7200, United States
| | - Cesar Contreras
- Department
of Chemistry, University of Florida, Gainesville, Florida 32611-7200, United States
| | - David Powell
- Department
of Chemistry, University of Florida, Gainesville, Florida 32611-7200, United States
| | - Giel Berden
- Radboud University, Institute for Molecules and
Materials, FELIX Laboratory, Toernooiveld 7c, 6525 ED Nijmegen, The Netherlands
| | - Jos Oomens
- Radboud University, Institute for Molecules and
Materials, FELIX Laboratory, Toernooiveld 7c, 6525 ED Nijmegen, The Netherlands
- University of Amsterdam, Science
Park 904, 1098XH Amsterdam, The Netherlands
| | - Brad Bendiak
- Department
of Cell and Developmental Biology and Program in Structural Biology
and Biochemistry, University of Colorado Health Sciences Center, Denver, Colorado 80045, United States
| | - John R. Eyler
- Department
of Chemistry, University of Florida, Gainesville, Florida 32611-7200, United States
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Yin H, Kong X. Structure of Protonated Threonine Dimers in the Gas Phase: Salt-Bridged or Charge-Solvated? JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2015; 26:1455-1461. [PMID: 26111520 DOI: 10.1007/s13361-015-1194-y] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2015] [Revised: 05/04/2015] [Accepted: 05/14/2015] [Indexed: 06/04/2023]
Abstract
For homodimers of amino acids, their salt-bridged structures are gradually stabilized as the proton affinity of the component amino acid increases. Threonine has a proton affinity value located in the middle of the list of 20 natural amino acids. Thus, identifying whether the most stable isomer of protonated threonine dimer (Thr(2)H(+)) has a charge-solvated or salt-bridged structure is important and helpful for understanding the structures of other homodimers. By combining infrared photodissociation (IRPD) spectroscopy and theoretical calculations, the structures of Thr(2)H(+) were investigated. Based on calculations at the M062X/6-311++G(d,p)//M062X/6-311++G(d,p) level, the most stable isomer of Thr(2)H(+) was computed to be a charge-solvated structure, with an energy 3.87 kcal/mol lower than the most stable salt-bridged isomer. The predicted infrared spectrum is in good agreement with the experimental spectrum. To evaluate the temperature effect on the distribution of different isomers, the relative concentrations of the six isomers of Thr(2)H(+) were calculated at different temperatures, according to their partition functions and enthalpies. The results show that the isomers are dominated by charge-solvated structures at a temperature of 300 K.
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Affiliation(s)
- Hong Yin
- State Key Laboratory and Institute of Elemento-Organic Chemistry, Nankai University, Tianjin, 300071, China
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Alahmadi YJ, Gholami A, Fridgen TD. The protonated and sodiated dimers of proline studied by IRMPD spectroscopy in the N-H and O-H stretching region and computational methods. Phys Chem Chem Phys 2015; 16:26855-63. [PMID: 25375752 DOI: 10.1039/c4cp03104k] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
IRMPD spectroscopy and computational chemistry techniques have been used to determine that the proton- and sodium-bound dimers of proline exist as a mixture of a number of different structures. Simulated annealing computations were found to be helpful in determining the unique structures of the protonated and sodiated dimers, augmenting chemical intuition. The experimental and computational results are consistent with the proton-bound dimer of N-protonated proline bound to zwitterionic proline. There was no spectroscopic evidence in the 3200-3800 cm(-1) region for a canonical structure which is predicted to have a weak N-H stretch at about 3440 cm(-1). A well resolved band at 1733 cm(-1) from a previous spectroscopic study (DOI: 10.1021/ja068715a ) was reassigned from a high energy canonical isomer to the C=O stretch of a lower energy zwitterionic structure. This band is a free carboxylate C=O stretch where protonated proline is hydrogen bonded to the other carboxylate oxygen which is also involved in an intramolecular hydrogen bond. Fifteen structures of the sodium bound proline dimer were computed to be within 10 kJ mol(-1) of Gibbs energy and eight structures were within 5 kJ mol(-1). None of these structures can be ruled out based on the experimental IRMPD spectrum. They all have an N-H stretching band predicted in a position that agrees with the experimental spectrum. However, only structures where one of the proline monomers is in the canonical form and having a free O-H bond can produce the band at ∼3600 cm(-1).
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Lee SS, Park S, Kim JY, Kim HR, Lee S, Oh HB. Infrared multiple photon dissociation spectroscopy and density functional theory (DFT) studies of protonated permethylated β-cyclodextrin-water non-covalent complexes. Phys Chem Chem Phys 2015; 16:8376-83. [PMID: 24658048 DOI: 10.1039/c3cp54841d] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We present infrared multiple photon dissociation (IRMPD) spectroscopy and quantum chemical calculation results for the protonated permethylated β-cyclodextrin (CD)-water non-covalent complex, the simplest β-CD non-covalent complex, in the gas-phase. The IRMPD spectrum in the region 2700-3750 cm(-1) consisted of three strong peaks at 3096, 3315, and 3490 cm(-1). These spectral features in the experimental IRMPD spectrum were compared with a large set of infrared absorption spectra predicted using density functional theory (DFT) calculations for the protonated β-CD-water complex. Complex III (see ), in which the water molecule (at the primary rim) and the proton (at the secondary rim) were separated, was found to suitably reflect the main spectral characteristics found in the experimental IRMPD spectrum. The absence of the homodromic hydrogen bond ring, due to replacement of hydroxyl groups with methoxy groups in permethylated β-CD, rendered the primary rim open compared with the unmodified β-CD 'one-gate-closed' lowest energy conformer. This study demonstrates that IRMPD studies combined with DFT theoretical calculations can be a good method for studying molecular interactions of large host-guest pairs.
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Affiliation(s)
- Sung-Sik Lee
- Department of Applied Chemistry, Kyung Hee University, Gyeonggi 446-701, Korea.
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35
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Lorenz UJ, Rizzo TR. Structural melting of an amino acid dimer upon intersystem crossing. J Am Chem Soc 2014; 136:14974-80. [PMID: 25250642 DOI: 10.1021/ja507981p] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
We present a spectroscopic investigation of the excited-state dynamics of the phenylalanine (Phe)/serine (Ser) protonated dimer in the gas phase. Using an ultraviolet (UV) laser pulse, we promote individual isomers to the S1 state and probe their fate with an infrared (IR) pulse. We find that the S1 state has a lifetime of ~70 ns and undergoes intersystem crossing (ISC) to the T1 state. Time-resolved IR spectra allow us to follow the structural evolution of the dimer. In the S1 state, the different isomers retain the hydrogen-bonding pattern of the ground state. Intersystem crossing triggers a sudden increase of the vibrational energy, so that the dimers can overcome isomerization barriers and explore large parts of the potential energy surface (PES). Their broad IR spectra largely resemble one another and indicate that the dimers adopt a molten structure.
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Affiliation(s)
- Ulrich J Lorenz
- Laboratoire de Chimie Physique Moléculaire, École Polytechnique Fédérale de Lausanne , CH-1015 Lausanne, Switzerland
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36
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Kong X. Reinvestigation of the structure of protonated lysine dimer. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2014; 25:422-426. [PMID: 24420385 DOI: 10.1007/s13361-013-0801-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2013] [Revised: 11/30/2013] [Accepted: 12/03/2013] [Indexed: 06/03/2023]
Abstract
To better understand inconsistencies between the predicted infrared (IR) spectra of previously suggested isomers of Lys2H(+) reported by Wu et al. (J. Am. Soc. Mass Spectrom. 22:1651-1659, 18) and the experimental IR photon dissociation (IRPD) spectrum obtained by Oh et al. (J. Am. Chem. Soc. 127:4076-4083, 4), the structure of Lys2H(+) was reinvestigated using IRPD spectroscopy in the extended region 2700-3700 cm(-1) and theoretical calculations. The new experimental IRPD spectrum is in good agreement with Oh's spectrum in the corresponding wavelength range. Based on calculations at the MP2/6-311++G(d,p)//B3LYP/6-311++G(d,p) and MP2/6-31 + G(d,p)//MP2/6-31 + G(d,p) levels, a new salt-bridged isomer, ZW1, was found to be the most stable isomer; it is more energetically favored than the previously suggested charge-solvated isomer LL-CS01 by 10 or 26 kJ mol(-1). Although the calculated IR spectrum of ZW1 is in good agreement with the experimental one in the range 2700-3700 cm(-1), it is in poor agreement with the previous IRPD spectrum in the range 1000-1900 cm(-1). This investigation shows that the intermolecular interactions inside the dimer are more complex than previously supposed. It is possible that both salt-bridged and charge-solvated isomers of Lys2H(+) are stable in the gas phase, and the isomers generated during ionization are sensitive to the experimental conditions.
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Affiliation(s)
- Xianglei Kong
- State Key Laboratory and Institute of Elemento-Organic Chemistry, Nankai University, Collaborative Innovation Center of Chemical Science and Engineering, 300071, Tianjin, China,
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37
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Rijs AM, Oomens J. IR Spectroscopic Techniques to Study Isolated Biomolecules. Top Curr Chem (Cham) 2014; 364:1-42. [DOI: 10.1007/128_2014_621] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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38
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Liao G, Yang Y, Kong X. Chirality effects on proline-substituted serine octamers revealed by infrared photodissociation spectroscopy. Phys Chem Chem Phys 2014; 16:1554-8. [DOI: 10.1039/c3cp53469c] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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39
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Schmidt J, Kass SR. Zwitterion vs Neutral Structures of Amino Acids Stabilized by a Negatively Charged Site: Infrared Photodissociation and Computations of Proline–Chloride Anion. J Phys Chem A 2013; 117:4863-9. [DOI: 10.1021/jp402267c] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
- Jacob Schmidt
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Steven R. Kass
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, United States
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40
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Lanucara F, Crestoni ME, Chiavarino B, Fornarini S, Hernandez O, Scuderi D, Maitre P. Infrared spectroscopy of nucleotides in the gas phase 2. The protonated cyclic 3′,5′-adenosine monophosphate. RSC Adv 2013. [DOI: 10.1039/c3ra41117f] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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41
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Sunahori FX, Yang G, Kitova EN, Klassen JS, Xu Y. Chirality recognition of the protonated serine dimer and octamer by infrared multiphoton dissociation spectroscopy. Phys Chem Chem Phys 2013; 15:1873-86. [DOI: 10.1039/c2cp43296j] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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42
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Dunbar RC, Steill JD, Polfer NC, Oomens J. Metal Cation Binding to Gas-Phase Pentaalanine: Divalent Ions Restructure the Complex. J Phys Chem A 2012; 117:1094-101. [DOI: 10.1021/jp304256f] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Robert C. Dunbar
- Chemistry Department, Case Western Reserve University, Cleveland,
Ohio 44106, United States
| | - Jeffrey D. Steill
- FOM-Institute for Plasma Physics Rijnhuizen, Edisonbaan 14, NL-3439 MN
Nieuwegein, The Netherlands
| | - Nicolas C. Polfer
- Chemistry Department, University of Florida, Gainesville,
Florida, United States
| | - Jos Oomens
- FOM-Institute for Plasma Physics Rijnhuizen, Edisonbaan 14, NL-3439 MN
Nieuwegein, The Netherlands
- University of Amsterdam, Science Park
904, 1098XH Amsterdam, The Netherlands
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43
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Lorenz UJ, Rizzo TR. Multiple Isomers and Protonation Sites of the Phenylalanine/Serine Dimer. J Am Chem Soc 2012; 134:11053-5. [DOI: 10.1021/ja3023708] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Ulrich J. Lorenz
- Laboratoire
de Chimie Physique Moléculaire, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne,
Switzerland
| | - Thomas R. Rizzo
- Laboratoire
de Chimie Physique Moléculaire, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne,
Switzerland
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44
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Filippi A, Fraschetti C, Piccirillo S, Rondino F, Botta B, D'Acquarica I, Calcaterra A, Speranza M. Chirality effects on the IRMPD spectra of basket resorcinarene/nucleoside complexes. Chemistry 2012; 18:8320-8. [PMID: 22696428 DOI: 10.1002/chem.201200614] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2012] [Indexed: 11/12/2022]
Abstract
The IRMPD spectra of the ESI-formed proton-bound complexes of the R,R,R,R- and S,S,S,S-enantiomers of a bis(diamido)-bridged basket resorcin[4]arene (R and S) with cytosine (1), cytidine (2), and cytarabine (3) were measured in the region 2800-3600 cm(-1). Comparison of the IRMPD spectra with the corresponding ONIOM (B3LYP/6-31(d):UFF)-calculated absorption frequencies allowed the assessment of the vibrational modes that are responsible for the observed spectroscopic features. All of the complexes investigated, apart from [R⋅H⋅3](+), showed similar IRMPD spectra, which points to similar structural and conformational landscapes. Their IRMPD spectra agree with the formation of several isomeric structures in the ESI source, wherein the N(3)-protonated guest establishes noncovalent interactions with the host amidocarbonyl groups that are either oriented inside the host cavity or outside it between one of the bridged side-chains and the upper aromatic nucleus. The IRMPD spectrum of the [R⋅H⋅3](+) complex was clearly different from the others. This difference is attributed to the effect of intramolecular hydrogen-bonding interactions between the C(2')-OH group and the aglycone oxygen atom of the nucleosidic guest upon repulsive interactions between the same oxygen atom and the aromatic rings of the host.
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Affiliation(s)
- Antonello Filippi
- Dipartimento di Chimica e Tecnologie del Farmaco, Università di Roma La Sapienza, 00185 Roma, Italy
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45
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Leavitt CM, Wolk AB, Fournier JA, Kamrath MZ, Garand E, Van Stipdonk MJ, Johnson MA. Isomer-Specific IR-IR Double Resonance Spectroscopy of D2-Tagged Protonated Dipeptides Prepared in a Cryogenic Ion Trap. J Phys Chem Lett 2012; 3:1099-105. [PMID: 26288043 DOI: 10.1021/jz3003074] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Isomer-specific vibrational predissociation spectra are reported for the gas-phase GlySarH(+) and SarSarH(+) [Gly = glycine; Sar = sarcosine] ions prepared by electrospray ionization and tagged with weakly bound D2 adducts using a cryogenic ion trap. The contributions of individual isomers to the overlapping vibrational band patterns are completely isolated using a pump-probe photochemical hole-burning scheme involving two tunable infrared lasers and two stages of mass selection (hence IR(2)MS(2)). These patterns are then assigned by comparison with harmonic (MP2/6-311+G(d,p)) spectra for various possible conformers. Both systems occur in two conformations based on cis and trans configurations with respect to the amide bond. In addition to the usual single intramolecular hydrogen bond motif between the protonated amine and the nearby amide oxygen atom, cis-SarSarH(+) adopts a previous unreported conformation in which both amino NH's act as H-bond donors. The correlated red shifts in the NH donor and C═O acceptor components of the NH···O═C linkage to the acid group are unambiguously assigned in the double H-bonded conformer.
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Affiliation(s)
- Christopher M Leavitt
- †Sterling Chemistry Laboratory, Yale University, P.O. Box 208107, New Haven, Connecticut 06520, United States
| | - Arron B Wolk
- †Sterling Chemistry Laboratory, Yale University, P.O. Box 208107, New Haven, Connecticut 06520, United States
| | - Joseph A Fournier
- †Sterling Chemistry Laboratory, Yale University, P.O. Box 208107, New Haven, Connecticut 06520, United States
| | - Michael Z Kamrath
- †Sterling Chemistry Laboratory, Yale University, P.O. Box 208107, New Haven, Connecticut 06520, United States
| | - Etienne Garand
- †Sterling Chemistry Laboratory, Yale University, P.O. Box 208107, New Haven, Connecticut 06520, United States
| | - Michael J Van Stipdonk
- ‡Department of Chemistry, Lawrence University, 711 East Boldt Way, Appleton, Wisconsin 54911, United States
| | - Mark A Johnson
- †Sterling Chemistry Laboratory, Yale University, P.O. Box 208107, New Haven, Connecticut 06520, United States
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46
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Shmilovits-Ofir M, Gerber RB. Proton Transfer and Dissociation of GlyLysH+ following O–H and N–H Stretching Mode Excitations: Dynamics Simulations. J Am Chem Soc 2011; 133:16510-7. [DOI: 10.1021/ja205634b] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Michaela Shmilovits-Ofir
- Department of Physical Chemistry and the Fritz Haber Research Center, The Hebrew University, Jerusalem 91904, Israel
| | - R. Benny Gerber
- Department of Physical Chemistry and the Fritz Haber Research Center, The Hebrew University, Jerusalem 91904, Israel
- Department of Chemistry, University of California, Irvine, California 92697-2025, United States
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47
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Burt MB, Decker SGA, Atkins CG, Rowsell M, Peremans A, Fridgen TD. Structures of bare and hydrated [Pb(aminoacid-H)]+ complexes using infrared multiple photon dissociation spectroscopy. J Phys Chem B 2011; 115:11506-18. [PMID: 21875029 DOI: 10.1021/jp2068655] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Infrared multiple-photon dissociation (IRMPD) spectroscopy was used to determine the gas-phase structures of deprotonated Pb(2+)/amino acid (Aa) complexes with and without a solvent molecule present. Five amino acid complexes with side chains containing only carbon and hydrogen (Ala, Val, Leu, Ile, Pro) and one with a basic side chain (Lys) were compared. These experiments demonstrated that all [Pb(Aa-H)](+) complexes have Pb(2+) covalently bound between the amine nitrogen and carbonyl oxygen. The nonhydrated complexes containing Ala, Val, Leu, Ile, and Pro are amine-deprotonated, whereas the one containing Lys is deprotonated at its carboxylic acid. The difference is attributed to the polar and basic side chain of lysine, which helps stabilize Pb(2+). IRMPD spectroscopy was also performed on the monohydrated analogues of the [Pb(Aa-H)](+) complexes. The [Pb(Aa-H)H(2)O](+) complexes, where Aa = Ala, Val, Leu, and Ile, exhibited two N-H stretches as well as a carboxylic acid O-H and a PbO-H stretch. Hence, their structures are monohydrated versions of the amine-deprotonated [Pb(Aa-H)](+) complexes where a proton transfer has occurred from the lead-bound water to the deprotonated amine. The IRMPD spectrum and calculations suggest that [Pb(Pro-H)H(2)O](+) has a hydrated carboxylate salt structure. The structure of [Pb(Lys-H)H(2)O](+) was also carboxyl-deprotonated, but Pb(2+) is bound to the carbonyl oxygen and the amine nitrogen, with one of the protons belonging to the water transferred to the basic side chain. This results in an intramolecular hydrogen bond that does not absorb in the region of the spectrum probed in these experiments. The IRMPD spectra and structural characterizations were confirmed and aided by infrared spectra calculated at the B3LYP/6-31+G(d,p) level of theory and 298 K enthalpies and Gibbs energies using the MP2(full)/6-311++G(2d,2p) method on the B3LYP geometries.
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Affiliation(s)
- Michael B Burt
- Department of Chemistry, Memorial University of Newfoundland, St. John's, Newfoundland and Labrador, Canada, A1B 3X7
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48
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Wang D, Gulyuz K, Stedwell CN, Polfer NC. Diagnostic NH and OH vibrations for oxazolone and diketopiperazine structures: b2 from protonated triglycine. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2011; 22:1197-1203. [PMID: 21953102 DOI: 10.1007/s13361-011-0147-3] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2011] [Revised: 04/03/2011] [Accepted: 04/04/2011] [Indexed: 05/31/2023]
Abstract
We present infrared multiple photon dissociation (IRMPD) spectra in the hydrogen stretching region of the simplest b fragment, b(2) from protonated triglycine, contrasted to that of protonated cyclo(Gly-Gly). Both spectra confirm the presence of intense, diagnostic vibrations linked to the site of proton attachment. Protonated cyclo(Gly-Gly) serves as a reference spectrum for the diketopiperazine structure, showing a diagnostic O-H(+) stretch of the protonated carbonyl group at 3585 cm(-1). Conversely, b(2) from protonated triglycine exhibits a strong band at 3345 cm(-1), associated with the N-H stretching mode of the protonated oxazolone ring structure. Other weaker N-H stretches can also be discerned, such as the amino NH(2) and amide NH bands. These results demonstrate the usefulness of the hydrogen stretching region, and hence benchtop optical parametric oscillator/amplifier (OPO/A) set-ups, in making structural assignments of product ions in collision-induced dissociation (CID) of peptides.
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Affiliation(s)
- Da Wang
- Department of Chemistry, University of Florida, Gainesville, FL 32611-7200, USA
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49
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Schmidt J, Meyer MM, Spector I, Kass SR. Infrared Multiphoton Dissociation Spectroscopy Study of Protonated p-Aminobenzoic Acid: Does Electrospray Ionization Afford the Amino- or Carboxy-Protonated Ion? J Phys Chem A 2011; 115:7625-32. [DOI: 10.1021/jp203829z] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Jacob Schmidt
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Matthew M. Meyer
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Ivan Spector
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Steven R. Kass
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, United States
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50
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Dunbar RC, Steill JD, Oomens J. Encapsulation of metal cations by the PhePhe ligand: a cation-π ion cage. J Am Chem Soc 2011; 133:9376-86. [PMID: 21553844 DOI: 10.1021/ja200219q] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Structures and binding thermochemistry are investigated for protonated PhePhe and for complexes of PhePhe with the alkaline-earth ions Ba(2+) and Ca(2+), the alkali-metal ions Li(+), Na(+), K(+), and Cs(+), and the transition-metal ion Ag(+). The two neighboring aromatic side chains open the possibility of a novel encapsulation motif of the metal ion in a double cation-π configuration, which is found to be realized for the alkaline-earth complexes and, in a variant form, for the Ag(+) complex. Experimentally, complexes are formed by electrospray ionization, trapped in an FT-ICR mass spectrometer, and characterized by infrared multiple photon dissociation (IRMPD) spectroscopy using the free electron laser FELIX. Interpretation is assisted by thermochemical and IR spectral calculations using density functional theory (DFT). The IRMPD spectrum of protonated PhePhe is reproduced with good fidelity by the calculated spectrum of the most stable conformation, although the additional presence of the secondmost stable conformation is not excluded. All metal-ion complexes have charge-solvated binding modes, with zwitterion (salt bridge) forms being much less stable. The amide oxygen always coordinates to the metal ion, as well as at least one phenyl ring (cation-π interaction). At least one additional chelation site is always occupied, which may be either the amino nitrogen or the carboxy carbonyl oxygen. The alkaline-earth complexes prefer a highly compact caged structure with both phenyl rings providing cation-π stabilization in a "sandwich" configuration (OORR chelation). The alkali-metal complexes prefer open-cage structures with only one cation-π interaction, except perhaps Cs(+). The Ag(+) complex shows a unique preference for the closed-cage amino-bound NORR structure. Ligand-driven perturbations of normal-mode frequencies are generally found to correlate linearly with metal-ion binding energy.
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Affiliation(s)
- Robert C Dunbar
- Chemistry Department, Case Western Reserve University, Cleveland, Ohio 44106, USA.
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