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Subramanian G, Manchanda K, Mo Y, Sathe RY, Bharatam PV. Monovalent cation binding to model systems and the macrocyclic depsipeptide, emodepside. J Comput Chem 2024; 45:2409-2423. [PMID: 38924119 DOI: 10.1002/jcc.27451] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2024] [Revised: 05/13/2024] [Accepted: 06/09/2024] [Indexed: 06/28/2024]
Abstract
This study focuses on the systematic exploration of the emodepside conformations bound to monovalent K+ ion using quantum mechanical density functional theory (DFT) calculations at the M06-2X/6-31+G(d,p) level of theory. Nine conformers of emodepside and their complexes with K+ ion were characterized as stationary points on the potential energy surface. The conformational isomers were examined for their 3D structures, bonding, energetics, and interactions with the cation. A cavitand-like structure (CC) is identified to be the energetically most stable arrangement. To arrive at a better understanding of the K+ ion binding, calculations were initially performed on complexes formed by the K+ and Na+ ions with model ligands (methyl ester and N,N-dimethyl acetamide). Both the natural bond orbital (NBO) method and the block-localized wavefunction (BLW) energy decomposition approach was employed to assess the bonding and energetic contributions stabilizing the ion-bound model complexes. Finally, the solvent effect was evaluated through complete geometry optimizations and energy minimizations for the model ion-ligand complexes and the emodepside-K+ bound complexes using an implicit solvent model mimicking water and DMSO.
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Affiliation(s)
| | - Kanika Manchanda
- Department of Pharmacoinformatics, National Institute of Pharmaceutical Education and Research (NIPER), S.A.S Nagar (Mohali), Punjab, India
| | - Yirong Mo
- Department of Nanoscience, Joint School of Nanoscience and Nanoengineering, University of North Carolina at Greensboro, Greensboro, North Carolina, USA
| | - Rohit Y Sathe
- Department of Biological Sciences and Biotechnology, Institute of Chemical Technology, Mumbai, Maharashtra, India
| | - Prasad V Bharatam
- Department of Medicinal Chemistry, National Institute of Pharmaceutical Education and Research (NIPER), S.A.S Nagar (Mohali), Punjab, India
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2
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Toma H, Tabata JI, Hirata K, Gregoire G, Fujii M, Ishiuchi SI. Micro Solvation Effect of Methanol on Excited-State Dynamics of Protonated Tryptophan and Dopamine. J Phys Chem A 2024; 128:6208-6215. [PMID: 39042432 DOI: 10.1021/acs.jpca.4c03178] [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: 07/24/2024]
Abstract
The electronic and vibrational cryogenic ion spectroscopy of protonated tryptophan (TrpH+) and dopamine (DAH+) complexed with methanol has been recorded. These two biological chromophores exhibit ultrafast photochemistry due to excited-state proton transfer (ESPT). We have established the relationship between the structure of the complexes and their photodynamics and compared them with recent results obtained in hydrated complexes. For TrpH+, there is no substantial change between methanol and water complexes; ESPT is hindered by a single solvent molecule. In the DAH+(MeOH)1 complex, the most stable conformer adopts a structure that prevents the direct interaction of the ammonium group of the side chain with the catechol ring, thus blocking the ESPT reaction. Such a ring structure is indeed a very minor populated conformer in the single-hydrated complex. The change in conformal stability between water and methanol clusters is due to a weak CH-π attractive interaction of the methyl group of methanol with the catechol.
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Affiliation(s)
- Hideo Toma
- Department of Chemistry, School of Science, Tokyo Institute of Technology, 2-12-1 4259 Ookayama, Meguro-ku, Tokyo 152-8550, Japan
| | - Jun-Ichi Tabata
- School of Life Science and Technology, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8503, Japan
| | - Keisuke Hirata
- Department of Chemistry, School of Science, Tokyo Institute of Technology, 2-12-1 4259 Ookayama, Meguro-ku, Tokyo 152-8550, Japan
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsu-ta-cho, Midori-ku, Yokohama 226-8503, Japan
- Tokyo Tech World Research Hub Initiative (WRHI), Institute of Innovation Research, Tokyo Institute of Technology, 4259, Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan
| | - Gilles Gregoire
- Université Paris-Saclay, CNRS, Institut des Sciences Moléculaires d'Orsay, Orsay F-91405, France
- Tokyo Tech World Research Hub Initiative (WRHI), Institute of Innovation Research, Tokyo Institute of Technology, 4259, Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan
| | - Masaaki Fujii
- School of Life Science and Technology, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8503, Japan
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsu-ta-cho, Midori-ku, Yokohama 226-8503, Japan
- Tokyo Tech World Research Hub Initiative (WRHI), Institute of Innovation Research, Tokyo Institute of Technology, 4259, Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan
- Research and Development Initiative, Chuo University, Tokyo 112-8551, Japan
| | - Shun-Ichi Ishiuchi
- Department of Chemistry, School of Science, Tokyo Institute of Technology, 2-12-1 4259 Ookayama, Meguro-ku, Tokyo 152-8550, Japan
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsu-ta-cho, Midori-ku, Yokohama 226-8503, Japan
- Tokyo Tech World Research Hub Initiative (WRHI), Institute of Innovation Research, Tokyo Institute of Technology, 4259, Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan
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3
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Villanueva M, Vega-Chacón J, Picasso G. Comparative analysis of a bulk optode based on a valinomycin ionophore and a nano-optode in micelles with pluronic F-127 for the quantification of potassium in aqueous solutions. ANALYTICAL METHODS : ADVANCING METHODS AND APPLICATIONS 2024; 16:4710-4723. [PMID: 38948955 DOI: 10.1039/d4ay00581c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/02/2024]
Abstract
In this work, two types of optical sensors were prepared for the quantification of potassium: the bulk optode (BO) and nano-optode (NO). The BO was prepared using three main components: the ionophore valinomycin, the ion exchanger tetrakis(4-chlorophenyl) potassium borate (K-TCPB), and the chromoionophore ETH 5294 (CHI). The optimal composition was found to be in a ratio of [1 : 1 : 1]. The NO was prepared by miniaturizing the BO through sonication in surfactant Pluronic F-127. The working range for the linear calibration model of BO was from 10-6 to 1.0 M K+ with a LODBO = 0.31 μM, meanwhile for NO was from 10-4 to 1.0 M K+ with a LODNO = 30.3 μM. Both optodes were tested for selectivity towards K+ in the presence of alkaline and alkaline earth ions, with a selectivity coefficient > 1.0. Furthermore, precision and stability studies of BO and NO were performed for three levels of K+ concentrations, 10-6, 10-3, 1.0 M for BO and 10-4, 10-2, 1.0 M for NO, showing a good homogeneity of the NO in the whole concentration range. However, an excessive variability was obtained for BO at 1.0 M K+. Therefore, the NO represents a potential tool for quantification of K+.
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Affiliation(s)
- Miguel Villanueva
- Technology of Materials for Environmental Remediation (TecMARA) Research Group, Faculty of Sciences, National University of Engineering, Av. Tupac Amaru 210, Lima 15333, Peru.
| | - Jaime Vega-Chacón
- Technology of Materials for Environmental Remediation (TecMARA) Research Group, Faculty of Sciences, National University of Engineering, Av. Tupac Amaru 210, Lima 15333, Peru.
| | - Gino Picasso
- Technology of Materials for Environmental Remediation (TecMARA) Research Group, Faculty of Sciences, National University of Engineering, Av. Tupac Amaru 210, Lima 15333, Peru.
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4
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Terry LM, Foreman MM, Rasmussen AP, McCoy AB, Weber JM. Probing Ion-Receptor Interactions in Halide Complexes of Octamethyl Calix[4]Pyrrole. J Am Chem Soc 2024; 146:12401-12409. [PMID: 38652043 DOI: 10.1021/jacs.3c13445] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/25/2024]
Abstract
Ion receptors are molecular hosts that bind ionic guests, often with great selectivity. The interplay of solvation and ion binding in anion host-guest complexes in solution governs the binding efficiency and selectivity of such ion receptors. To gain molecular-level insight into the intrinsic binding properties of octamethyl calix[4]pyrrole (omC4P) host molecules with halide guest ions, we performed cryogenic ion vibrational spectroscopy (CIVS) of omC4P in complexes with fluoride, chloride, and bromide ions. We interpret the spectra using density functional theory, describing the infrared spectra of these complexes with both harmonic and anharmonic second-order vibrational perturbation theory (VPT2) calculations. The NH stretching modes of the pyrrole moieties serve as sensitive probes of the ion binding properties, as their frequencies encode the ion-receptor interactions. While scaled harmonic spectra reproduce the experimental NH stretching modes of the chloride and bromide complexes in broad strokes, the high proton affinity of fluoride introduces strong anharmonic effects. As a result, the spectrum of F-·omC4P is not even qualitatively captured by harmonic calculations, but it is recovered very well by VPT2 calculations. In addition, the VPT2 calculations recover the intricate coupling of the NH stretching modes with overtones and combination bands of CH stretching and NH bending modes and with low-frequency vibrations of the omC4P macrocycle, which are apparent for all of the halide ion complexes investigated here. A comparison of the CIVS spectra with infrared spectra of solutions of the same ion-receptor complexes in d3-acetonitrile and d6-acetone shows how ion solvation changes the ion-receptor interactions for the different halide ions.
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Affiliation(s)
- Lane M Terry
- JILA and Department of Chemistry, University of Colorado, 440 UCB, Boulder, Colorado 80309-0440, United States
| | - Madison M Foreman
- JILA and Department of Chemistry, University of Colorado, 440 UCB, Boulder, Colorado 80309-0440, United States
| | - Anne P Rasmussen
- JILA and Department of Chemistry, University of Colorado, 440 UCB, Boulder, Colorado 80309-0440, United States
- Department of Physics and Astronomy, Aarhus University, 8000 Aarhus, Denmark
| | - Anne B McCoy
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - J Mathias Weber
- JILA and Department of Chemistry, University of Colorado, 440 UCB, Boulder, Colorado 80309-0440, United States
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Hirata K, Akasaka K, Dopfer O, Ishiuchi SI, Fujii M. Transition from vehicle to Grotthuss proton transfer in a nanosized flask: cryogenic ion spectroscopy of protonated p-aminobenzoic acid solvated with D 2O. Chem Sci 2024; 15:2725-2730. [PMID: 38404372 PMCID: PMC10882521 DOI: 10.1039/d3sc05455a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2023] [Accepted: 01/18/2024] [Indexed: 02/27/2024] Open
Abstract
Proton transfer (PT) is one of the most ubiquitous reactions in chemistry and life science. The unique nature of PT has been rationalized not by the transport of a solvated proton (vehicle mechanism) but by the Grotthuss mechanism in which a proton is transported to the nearest proton acceptor along a hydrogen-bonded network. However, clear experimental evidence of the Grotthuss mechanism has not been reported yet. Herein we show by infrared spectroscopy that a vehicle-type PT occurs in the penta- and hexahydrated clusters of protonated p-aminobenzoic acid, while Grotthuss-type PT is observed in heptahydrated clusters, indicating a change in the PT mechanism depending on the degree of hydration. These findings emphasize the importance of the usually ignored vehicle mechanism as well as the degree of hydration. It highlights the possibility of controlling the PT mechanism by the number of water molecules in chemical and biological environments.
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Affiliation(s)
- Keisuke Hirata
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology 4259 Nagatsuta-cho, Midori-ku Yokohama 226-8503 Japan
- Department of Chemistry, School of Science, Tokyo Institute of Technology 2-12-1 Ookayama, Meguro-ku Tokyo 152-8550 Japan
- International Research Frontiers Initiative, Tokyo Institute of Technology 4259 Nagatsuta-cho, Midori-ku Yokohama 226-8503 Japan
| | - Kyota Akasaka
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology 4259 Nagatsuta-cho, Midori-ku Yokohama 226-8503 Japan
- School of Life Science and Technology, Tokyo Institute of Technology 4259 Nagatsuta-cho, Midori-ku Yokohama Kanagawa 226-8503 Japan
| | - Otto Dopfer
- International Research Frontiers Initiative, Tokyo Institute of Technology 4259 Nagatsuta-cho, Midori-ku Yokohama 226-8503 Japan
- Institut für Optik und Atomare Physik, Technische Universität Berlin Hardenbergstrasse 36 10623 Berlin Germany
| | - Shun-Ichi Ishiuchi
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology 4259 Nagatsuta-cho, Midori-ku Yokohama 226-8503 Japan
- Department of Chemistry, School of Science, Tokyo Institute of Technology 2-12-1 Ookayama, Meguro-ku Tokyo 152-8550 Japan
- International Research Frontiers Initiative, Tokyo Institute of Technology 4259 Nagatsuta-cho, Midori-ku Yokohama 226-8503 Japan
| | - Masaaki Fujii
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology 4259 Nagatsuta-cho, Midori-ku Yokohama 226-8503 Japan
- School of Life Science and Technology, Tokyo Institute of Technology 4259 Nagatsuta-cho, Midori-ku Yokohama Kanagawa 226-8503 Japan
- International Research Frontiers Initiative, Tokyo Institute of Technology 4259 Nagatsuta-cho, Midori-ku Yokohama 226-8503 Japan
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6
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Miyazaki M, Ono M, Otsuka R, Dopfer O, Fujii M. Electronic and vibrational spectroscopies of aromatic clusters with He in a supersonic jet: The case of neutral and cationic phenol-Hen (n = 1 and 2). J Chem Phys 2023; 159:134303. [PMID: 37787127 DOI: 10.1063/5.0169716] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Accepted: 09/15/2023] [Indexed: 10/04/2023] Open
Abstract
Van der Waals clusters composed of He and aromatic molecules provide fundamental information about intermolecular interactions in weakly bound systems. In this study, phenol-helium clusters (PhOH-Hen with n ≤ 2) are characterized for the first time by UV and IR spectroscopies. The S1 ← S0 origin and ionization energy both show small but additive shifts, suggesting π-bound structures of these clusters, a conclusion supported by rotational contour analyses of the S1 origin bands. The OH stretching vibrations of the PhOH moiety in the clusters match with those of bare PhOH in both the S0 and D0 states, illustrating the negligible perturbation of the He atoms on the molecular vibration. Matrix shifts induced by He attachment are discussed based on the observed band positions with the help of complementary quantum chemical calculations. For comparison, the UV and ionization spectra of PhOH-Ne are reported as well.
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Affiliation(s)
- Mitsuhiko Miyazaki
- Natural Science Division, Faculty of Core Research, Ochanomizu University, 2-1-1 Ohtsuka, Bunkyo-ku, Tokyo 112-8610, Japan
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, Yokohama 226-8503, Japan
| | - Megumi Ono
- School of Life Science and Technology, Tokyo Institute of Technology, 4259, Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan
| | - Remina Otsuka
- School of Life Science and Technology, Tokyo Institute of Technology, 4259, Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan
| | - Otto Dopfer
- Institut für Optik und Atomare Physik, Technische Universität Berlin, 10623 Berlin, Germany
- International Research Frontiers Initiative (IRFI), Institute of Innovation Research, Tokyo Institute of Technology, 4259, Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan
| | - Masaaki Fujii
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, Yokohama 226-8503, Japan
- School of Life Science and Technology, Tokyo Institute of Technology, 4259, Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan
- International Research Frontiers Initiative (IRFI), Institute of Innovation Research, Tokyo Institute of Technology, 4259, Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan
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7
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Takayanagi H, Bardaud JX, Hirata K, Brenner V, Gloaguen E, Ishiuchi SI, Fujii M. Stepwise hydration of [CH 3COOMg] + studied by cold ion trap infrared spectroscopy: insights into interactions in the magnesium channel selection filters. Phys Chem Chem Phys 2023; 25:23923-23928. [PMID: 37642502 DOI: 10.1039/d3cp00992k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/31/2023]
Abstract
The magnesium channel controls Mg2+ concentration in the cell and plays an indispensable role in biological functions. The crystal structure of the Magnesium Transport E channel suggested that Mg2+ hydrated by 6 water molecules is transported through a selection filter consisting of COO- groups on two Asp residues. This Mg2+ motion implies successive pairing with -OOC-R and dissociation mediated by water molecules. For another divalent ion, however, it is known that RCOO-⋯Ca2+ cannot be separated even with 12 water molecules. From this discrepancy, we probe the structure of Mg2+(CH3COO-)(H2O)4-17 clusters by measuring the infrared spectra and monitoring the vibrational frequencies of COO- with the help of quantum chemistry calculations. The hydration by (H2O)6 is not enough to induce ion separation, and partially-separated or separated pairs are formed from 10 water molecules at least. These results suggest that the ion separation between Mg2+ and carboxylate ions in the selection-filter of the MgtE channel not only results from water molecules in their first hydration shell, but also from additional factors including water molecules and protein groups in the second solvation shell of Mg2+.
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Affiliation(s)
- Hikaru Takayanagi
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, 226-8503, Japan.
- School of Life Science and Technology, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa, 226-8503, Japan
| | - Jean-Xavier Bardaud
- LIDYL, CEA, CNRS, Université Paris Saclay, CEA Saclay, Bât 522, Gif-sur-Yvette 91191, France.
| | - Keisuke Hirata
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, 226-8503, Japan.
- Department of Chemistry, School of Science, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan
| | - Valérie Brenner
- LIDYL, CEA, CNRS, Université Paris Saclay, CEA Saclay, Bât 522, Gif-sur-Yvette 91191, France.
| | - Eric Gloaguen
- LIDYL, CEA, CNRS, Université Paris Saclay, CEA Saclay, Bât 522, Gif-sur-Yvette 91191, France.
| | - Shun-Ichi Ishiuchi
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, 226-8503, Japan.
- Department of Chemistry, School of Science, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan
| | - Masaaki Fujii
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, 226-8503, Japan.
- School of Life Science and Technology, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa, 226-8503, Japan
- IRFI/IPWR, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, 226-8503, Japan
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8
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Vo KX, Hirata K, Lisy JM, Ishiuchi SI, Fujii M. Infrared Spectra of Beauvericin-Alkaline Earth Metal Ion Complexes─Ion Preference to Physiological Ions. J Phys Chem A 2023; 127:7115-7120. [PMID: 37589551 DOI: 10.1021/acs.jpca.3c02783] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/18/2023]
Abstract
Beauvericin (Bv) is a naturally occurring ionophore that selectively transports ions through cell membranes. However, the intrinsic ion selectivity of Bv for alkaline earth metal ions (M2+) is yet to be established due to inconsistent results from condensed phase experiments. Based on fluorescence quenching rates, Ca2+ appears to be preferred while extraction experiments favor Mg2+. In this study, we apply cold ion trap─infrared spectroscopy to Bv-M2+ coupled with electrospray ionization mass spectrometry. The mass spectrum shows that Bv favors binding to physiologically active ions Mg2+ and Ca2+ although it can form complexes with all four alkaline earth metal ions. Infrared spectroscopy, as measured by the H2 tag technique, reveals that Bv binds Mg2+ and Ca2+ ions by six carbonyl oxygens in the center of its cavity. This observation is supported by theoretical calculations. Other alkaline earth metal ions are bound by three carbonyl groups at the amide face. This difference in configuration is consistent with the binding preferences for the alkaline earth metal ions.
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Affiliation(s)
- Kien X Vo
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan
- School of Life Science and Technology, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8503, Japan
| | - Keisuke Hirata
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan
- Department of Chemistry, School of Science, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan
- International Research Frontiers Initiative (IRFI), Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan
| | - James M Lisy
- International Research Frontiers Initiative (IRFI), Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Shun-Ichi Ishiuchi
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan
- Department of Chemistry, School of Science, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan
- International Research Frontiers Initiative (IRFI), Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan
| | - Masaaki Fujii
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan
- School of Life Science and Technology, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8503, Japan
- International Research Frontiers Initiative (IRFI), Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan
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9
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Akasaka K, Hirata K, Haddad F, Dopfer O, Ishiuchi SI, Fujii M. Hydration-induced protomer switching in p-aminobenzoic acid studied by cold double ion trap infrared spectroscopy. Phys Chem Chem Phys 2023; 25:4481-4488. [PMID: 36514975 DOI: 10.1039/d2cp04497h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Para-Aminobenzoic acid (PABA) is a benchmark molecule to study solvent-induced proton site switching. Protonation of the carboxy and amino groups of PABA generates O- and N-protomers of PABAH+, respectively. Ion mobility mass spectrometry (IMS) and infrared photodissociation (IRPD) studies have claimed that the O-protomer most stable in the gas phase is converted to the N-protomer most stable in solution upon hydration with six water molecules in the gas-phase cluster. However, the threshold size has remained ambiguous because the arrival time distributions in the IMS experiments exhibit multiple peaks. On the other hand, IRPD spectroscopy could not detect the N-protomer for smaller hydrated clusters because of broad background due to annealing required to reduce kinetic trapping. Herein, we report the threshold size for O → N protomer switching without ambiguity using IR spectroscopy in a double ion trap spectrometer from 1300 to 1800 cm-1. The pure O-protomer is prepared by electrospray, and size-specific hydrated clusters are formed in a reaction ion trap. The resulting clusters are transferred into a second cryogenic ion trap and the distribution of O- and N-protomers is determined by mid-IR spectroscopy without broadening. The threshold to promote O → N protomer switching is indeed five water molecules. It is smaller than the value reported previously, and as a result, its pentahydrated structure does not support the Grotthuss mechanism proposed previously. The extent of O → N proton transfer is evaluated by collision-assisted stripping IR spectroscopy, and the N-protomer population increases with the number of water molecules. This result is consistent with the dominant population of the N-protomer in aqueous solution.
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Affiliation(s)
- Kyota Akasaka
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, 226-8503, Japan. .,School of Life Science and Technology, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa, 226-8503, Japan
| | - Keisuke Hirata
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, 226-8503, Japan. .,Department of Chemistry, School of Science, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan.,International Research Frontiers Initiative, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, 226-8503, Japan.
| | - Fuad Haddad
- Institut für Optik und Atomare Physik, Technische Universität Berlin, Hardenbergstrasse 36, 10623 Berlin, Germany
| | - Otto Dopfer
- International Research Frontiers Initiative, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, 226-8503, Japan. .,Institut für Optik und Atomare Physik, Technische Universität Berlin, Hardenbergstrasse 36, 10623 Berlin, Germany
| | - Shun-Ichi Ishiuchi
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, 226-8503, Japan. .,Department of Chemistry, School of Science, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan.,International Research Frontiers Initiative, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, 226-8503, Japan.
| | - Masaaki Fujii
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, 226-8503, Japan. .,School of Life Science and Technology, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa, 226-8503, Japan.,International Research Frontiers Initiative, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, 226-8503, Japan.
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10
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Molina F, Dezalay J, Tabata JI, Soorkia S, Broquier M, Hirata K, Ishiuchi SI, Fujii M, Grégoire G. Conformer-selective Photodynamics of TrpH + -H 2 O. Chemphyschem 2023; 24:e202200561. [PMID: 36177693 PMCID: PMC10092157 DOI: 10.1002/cphc.202200561] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Revised: 09/06/2022] [Indexed: 01/20/2023]
Abstract
The photodynamics of protonated tryptophan and its mono hydrated complex TrpH+ -H2 O has been revisited. A combination of steady-state IR and UV cryogenic ion spectroscopies with picosecond pump-probe photodissociation experiments sheds new lights on the deactivation processes of TrpH+ and conformer-selected TrpH+ -H2 O complex, supported by quantum chemistry calculations at the DFT and coupled-cluster levels for the ground and excited states, respectively. TrpH+ excited at the band origin exhibits a transient of less than 100 ps, assigned to the lifetime of the excited state proton transfer (ESPT) structure. The two experimentally observed conformers of TrpH+ -H2 O have been assigned. A striking result arises from the conformer-selective photodynamics of TrpH+ -H2 O, in which a single water molecule inserted in between the ammonium and the indole ring hinders the barrierless ESPT reaction responsible for the ultra-fast deactivation process observed in the other conformer and in bare TrpH+ .
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Affiliation(s)
- Franco Molina
- Université Paris-Saclay, CNRS, Institut des Sciences Moléculaires d'Orsay, 91405, Orsay, France.,INFIQC (CONICET-UNC). Departamento de Fisicoquímica, Fac. de Ciencias Químicas. Centro Láser de Ciencias Moleculares., Universidad Nacional de Córdoba, Ciudad Universitaria Pabellón Argentina, X5000HUA, Córdoba, Argentina
| | - Jordan Dezalay
- Université Paris-Saclay, CNRS, Institut des Sciences Moléculaires d'Orsay, 91405, Orsay, France
| | - Jun-Ichi Tabata
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsu-ta-cho, Midori-ku, Yokohama, 226-8503, Japan.,School of Life Science and Technology, Tokyo Institute of Technology, 4259 Nagatsu-ta-cho, Midori-ku, Yokohama, 226-8503, Japan
| | - Satchin Soorkia
- Université Paris-Saclay, CNRS, Institut des Sciences Moléculaires d'Orsay, 91405, Orsay, France
| | - Michel Broquier
- Université Paris-Saclay, CNRS, Institut des Sciences Moléculaires d'Orsay, 91405, Orsay, France
| | - Keisuke Hirata
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsu-ta-cho, Midori-ku, Yokohama, 226-8503, Japan.,Department of Chemistry, School of Science, Tokyo Institute of Technology, 2-12-1 4259 Ookayama, Meguro-ku, Tokyo, 152-8550, Japan.,Tokyo Tech World Research Hub Initiative (WRHI), Institute of Innovation Research, Tokyo Institute of Technology, 4259, Nagatsuta-cho, Midori-ku, Yokohama, 226-8503, Japan
| | - Shun-Ichi Ishiuchi
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsu-ta-cho, Midori-ku, Yokohama, 226-8503, Japan.,Department of Chemistry, School of Science, Tokyo Institute of Technology, 2-12-1 4259 Ookayama, Meguro-ku, Tokyo, 152-8550, Japan.,Tokyo Tech World Research Hub Initiative (WRHI), Institute of Innovation Research, Tokyo Institute of Technology, 4259, Nagatsuta-cho, Midori-ku, Yokohama, 226-8503, Japan
| | - Masaaki Fujii
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsu-ta-cho, Midori-ku, Yokohama, 226-8503, Japan.,Tokyo Tech World Research Hub Initiative (WRHI), Institute of Innovation Research, Tokyo Institute of Technology, 4259, Nagatsuta-cho, Midori-ku, Yokohama, 226-8503, Japan.,School of Life Science and Technology, Tokyo Institute of Technology, 4259 Nagatsu-ta-cho, Midori-ku, Yokohama, 226-8503, Japan
| | - Gilles Grégoire
- Université Paris-Saclay, CNRS, Institut des Sciences Moléculaires d'Orsay, 91405, Orsay, France.,Tokyo Tech World Research Hub Initiative (WRHI), Institute of Innovation Research, Tokyo Institute of Technology, 4259, Nagatsuta-cho, Midori-ku, Yokohama, 226-8503, Japan
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11
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Hirata K, Sato E, Lisy JM, Ishiuchi SI, Fujii M. Cation-responsive cavity expansion of valinomycin revealed by cryogenic ion trap infrared spectroscopy. Phys Chem Chem Phys 2023; 25:1075-1080. [PMID: 36519454 DOI: 10.1039/d2cp04570b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Valinomycin (VM) is a natural K+-selective ionophore that transports K+ through the cell membrane. VM captures K+ in its central cavity with a C3-symmetric β-turn-like backbone. Although the binding affinity is drastically decreased for the VM-sodium (Na+VM) complex with respect to K+VM, VM holds relatively high affinity to Rb+ and Cs+. The high affinity for larger ions irrespective of ionic size seems to conflict with the expected optimal size matching model and raises questions on what factors determine ion selectivity. A combination of infrared spectroscopy with supporting computational calculations reveals that VM can accommodate larger Rb+ and Cs+ by flexibly changing its cavity size with the elongation of its folded β-turn-like backbone. The high affinity to Rb+ and Cs+ can be ascribed to a size-dependent cavity expansion. These findings provide a new perspective on molecular recognition and selectivity beyond the conventional size matching model.
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Affiliation(s)
- Keisuke Hirata
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, 226-8503, Japan. .,Department of Chemistry, School of Science, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo, 152-8550, Japan
| | - Eiko Sato
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, 226-8503, Japan. .,School of Life Science and Technology, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa, 226-8503, Japan
| | - James M Lisy
- International Research Frontiers Initiative (IRFI), Institute of Innovative Research, Tokyo Institute of Technology, 4259, Nagatsuta-cho, Midori-ku, Yokohama, 226-8503, Japan.,Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA.
| | - Shun-Ichi Ishiuchi
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, 226-8503, Japan. .,Department of Chemistry, School of Science, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo, 152-8550, Japan
| | - Masaaki Fujii
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, 226-8503, Japan. .,Department of Chemistry, School of Science, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo, 152-8550, Japan.,International Research Frontiers Initiative (IRFI), Institute of Innovative Research, Tokyo Institute of Technology, 4259, Nagatsuta-cho, Midori-ku, Yokohama, 226-8503, Japan
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12
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Vo KX, Hirata K, Lisy JM, Ishiuchi SI, Fujii M. Na + Selective Binding by Beauvericin and Its Mechanism Studied by Mass-Coupled Cold Ion Trap Infrared Spectroscopy. J Phys Chem Lett 2022; 13:11330-11334. [PMID: 36454047 DOI: 10.1021/acs.jpclett.2c02814] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Beauvericin (Bv) is a cyclic hexadepsipeptide mycotoxin that selectively transports ions across cell membranes. Characterization of its intrinsic ion affinity has been complicated by different previous results in condensed phases and biological membranes. We report the marked specificity between alkali metal ions by Bv using experimental and computational methods. Mass spectrometry shows Bv readily binds all five alkali ions; however, the complex with Na+ is the most abundant species, indicating a strong binding preference. Gas phase infrared spectroscopy and theoretical calculations show that Li+, K+, Rb+, and Cs+ are coordinated by three amide carbonyl oxygens on the N-methylamino-l-phenylalanyl face. Selectivity for Na+ is achieved as Bv sequesters Na+ in the center of its cavity formed by three amide carbonyl and three ester carbonyl groups, a configuration unique among alkali metal ions. This finding provides insight into the correlation between selectivity and conformation of Bv, essential for development of this mycotoxin.
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Affiliation(s)
- Kien X Vo
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan
- School of Life Science and Technology, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8503, Japan
| | - Keisuke Hirata
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan
- Department of Chemistry, School of Science, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan
- International Research Frontiers Initiative (IRFI), Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan
| | - James M Lisy
- International Research Frontiers Initiative (IRFI), Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Shun-Ichi Ishiuchi
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan
- Department of Chemistry, School of Science, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan
- International Research Frontiers Initiative (IRFI), Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan
| | - Masaaki Fujii
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan
- School of Life Science and Technology, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8503, Japan
- International Research Frontiers Initiative (IRFI), Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan
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13
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Foreman MM, Weber JM. Ion Binding Site Structure and the Role of Water in Alkaline Earth EDTA Complexes. J Phys Chem Lett 2022; 13:8558-8563. [PMID: 36067512 DOI: 10.1021/acs.jpclett.2c02391] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
The interactions between molecular hosts and ionic guests and their dependence on the chemical environment are challenging to disentangle from solution data alone. The vibrational spectra of cold complexes of ethylenediaminetetraacetic acid (EDTA) chelating alkaline earth dications in vacuo encode structural characteristics of these complexes and their dependence on the size of the bound ion. The correlation between metal binding geometry and the relative intensities of vibrational bands of the carboxylate groups forming the binding pocket allows us to characterize water-induced changes in molecular geometry. The evolution of these structural markers from bare ions to water adducts to aqueous solution illustrates the role of water for the structure of ion binding sites in chelators. The binding pocket of EDTA opens up in aqueous solution, bringing the bound ion closer to the mouth of the binding site and leading to an increased exposure of the ion to the chemical environment.
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Affiliation(s)
- Madison M Foreman
- JILA and Department of Chemistry, University of Colorado, 440 UCB, Boulder, Colorado 80309-0440, United States
| | - J Mathias Weber
- JILA and Department of Chemistry, University of Colorado, 440 UCB, Boulder, Colorado 80309-0440, United States
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14
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Yamaguchi K, Hirata K, Ishiuchi SI, Fujii M. Ultraviolet and infrared spectra of mono-, di- and tri-hydrated clusters of protonated noradrenaline – Solvation and conformational variations. Chem Phys Lett 2022. [DOI: 10.1016/j.cplett.2022.140014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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15
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Hirata K, Kasai KI, Yoshizawa K, Grégoire G, Ishiuchi SI, Fujii M. Excited state dynamics of protonated dopamine: hydration and conformation effects. Phys Chem Chem Phys 2022; 24:10737-10744. [PMID: 35389419 DOI: 10.1039/d2cp00543c] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Electronic and vibrational spectroscopy in a cryogenic ion trap has been applied to protonated dopamine water clusters and assigned with the help of quantum chemistry calculations performed in the ground and electronic excited states. A dramatic hydration effect is observed when dopamine is solvated by three water molecules. The broad electronic spectra recorded for the bare and small water clusters containing protonated dopamine turn to sharp, well-resolved vibronic transitions in the 1-3 complex. This reflects the change induced by hydration in the photodynamics of protonated dopamine which is initially controlled by an excited state proton transfer (ESPT) reaction from the ammonium group toward the catechol ring. Interestingly, conformer selectivity is revealed in the 1-3 complex which shows two low lying energy conformers for which the ESPT reaction is prevented or not depending on the H-bond network formed between the dopamine and water molecules.
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Affiliation(s)
- Keisuke Hirata
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsu-ta-cho, Midori-ku, Yokohama, 226-8503, Japan. .,Department of Chemistry, School of Science, Tokyo Institute of Technology, 2-12-1 4259 Ookayama, Meguro-ku, Tokyo, 152-8550, Japan.,Tokyo Tech World Research Hub Initiative (WRHI), Institute of Innovation Research, Tokyo Institute of Technology, 4259, Nagatsuta-cho, Midori-ku, Yokohama, 226-8503, Japan.
| | - Ken-Ichi Kasai
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsu-ta-cho, Midori-ku, Yokohama, 226-8503, Japan. .,School of Life Science and Technology, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa, 226-8503, Japan
| | - Koki Yoshizawa
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsu-ta-cho, Midori-ku, Yokohama, 226-8503, Japan. .,School of Life Science and Technology, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa, 226-8503, Japan
| | - Gilles Grégoire
- Tokyo Tech World Research Hub Initiative (WRHI), Institute of Innovation Research, Tokyo Institute of Technology, 4259, Nagatsuta-cho, Midori-ku, Yokohama, 226-8503, Japan. .,Université Paris-Saclay, CNRS, Institut des Sciences Moléculaires d'Orsay, F-91405 Orsay, France
| | - Shun-Ichi Ishiuchi
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsu-ta-cho, Midori-ku, Yokohama, 226-8503, Japan. .,Department of Chemistry, School of Science, Tokyo Institute of Technology, 2-12-1 4259 Ookayama, Meguro-ku, Tokyo, 152-8550, Japan.,Tokyo Tech World Research Hub Initiative (WRHI), Institute of Innovation Research, Tokyo Institute of Technology, 4259, Nagatsuta-cho, Midori-ku, Yokohama, 226-8503, Japan.
| | - Masaaki Fujii
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsu-ta-cho, Midori-ku, Yokohama, 226-8503, Japan. .,Tokyo Tech World Research Hub Initiative (WRHI), Institute of Innovation Research, Tokyo Institute of Technology, 4259, Nagatsuta-cho, Midori-ku, Yokohama, 226-8503, Japan. .,School of Life Science and Technology, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa, 226-8503, Japan
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16
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Oluwatoba DS, Islam MF, Som B, Sindt AJ, Smith MD, Shimizu LS, Do TD. Evaluating the Effects of Metal Adduction and Charge Isomerism on Ion-Mobility Measurements using m-Xylene Macrocycles as Models. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2022; 33:840-850. [PMID: 35471025 DOI: 10.1021/jasms.2c00033] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Gas-phase ion-mobility spectrometry provides a unique platform to study the effect of mobile charge(s) or charge location on collisional cross section and ion separation. Here, we evaluate the effects of cation/anion adduction in a series of xylene and pyridyl macrocycles that contain ureas and thioureas. We explore how zinc binding led to unexpected deprotonation of the thiourea macrocyclic host in positive polarity ionization and subsequently how charge isomerism due to cation (zinc metal) and anion (chloride counterion) adduction or proton competition among acceptors can affect the measured collisional cross sections in helium and nitrogen buffer gases. Our approach uses synthetic chemistry to design macrocycle targets and a combination of ion-mobility spectrometry mass spectrometry experiments and quantum mechanics calculations to characterize their structural properties. We demonstrate that charge isomerism significantly improves ion-mobility resolution and allows for determination of the metal binding mechanism in metal-inclusion macrocyclic complexes. Additionally, charge isomers can be populated in molecules where individual protons are shared between acceptors. In these cases, interactions via drift gas collisions magnify the conformational differences. Finally, for the macrocyclic systems we report here, charge isomers are observed in both helium and nitrogen drift gases with similar resolution. The separation factor does not simply increase with increasing drift gas polarizability. Our study sheds light on important properties of charge isomerism and offers strategies to take advantage of this phenomenon in analytical separations.
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Affiliation(s)
- Damilola S Oluwatoba
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Md Faizul Islam
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States
| | - Bozumeh Som
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States
- Department of Chemistry, University of Ghana, P.O. Box LG 56, Legon, Accra, Ghana
| | - Ammon J Sindt
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States
| | - Mark D Smith
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States
| | - Linda S Shimizu
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States
| | - Thanh D Do
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, United States
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17
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Takeda N, Hirata K, Tsuruta K, Santis GD, Xantheas SS, Ishiuchi SI, Fujii M. Gas phase protonated nicotine is a mixture of pyridine- and pyrrolidine-protonated conformers: implications for its native structure in the nicotinic acetylcholine receptor. Phys Chem Chem Phys 2021; 24:5786-5793. [PMID: 34939632 DOI: 10.1039/d1cp05175j] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The infrared (IR) spectra of gas phase protonated nicotine has been measured in the never-before probed N-H "fingerprint region" (3200-3500 cm-1). The protonated molecules generated by an electrospray source are thermalized in the first ion trap with water vapor and He gas at a pre-determined temperature prior to being probed by IR spectroscopy in the second ion trap at 4 K. The IR spectra exhibit two N-H stretching bands which are assigned to the pyridine and pyrrolidine protomers with the aid of high-level electronic structure calculations. This finding is in sharp contrast to previous spectroscopic studies that suggested a single population of the pyridine protomer. The relative populations of the two protomers vary by changing the temperature of the thermalizing trap from 180-300 K. The relative conformer populations at 240 K and 300 K are well reproduced by the theoretical calculations, unequivocally determining that gas phase nicotine is a 3 : 2 mixture of both pyridine and pyrrolidine protomers at room temperature. The thermalizing anhydrous vapor does not result in any population change. It rather demonstrates the catalytic role of water in achieving equilibrium between the two protomers. The combination of IR spectroscopy and electronic structure calculations establish the small energy difference between the pyridine and pyrrolidine protomers in nicotine. One of the gas phase nicotine pyrrolidine protomers has the closest conformational resemblance among all low-lying energy isomers with the X-ray structure of nicotine in the nicotinic acetylcholine receptor (nAChR).
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Affiliation(s)
- Naoya Takeda
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, 226-8503, Japan. .,School of Life Science and Technology, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa, 226-8503, Japan
| | - Keisuke Hirata
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, 226-8503, Japan. .,Department of Chemistry, School of Science, Tokyo Institute of Technology, 2-12-1 4259 Ookayama, Meguro-ku, Tokyo, 152-8550, Japan. .,Tokyo Tech World Research Hub Initiative (WRHI), Institute of Innovation Research, Tokyo Institute of Technology, 4259, Nagatsuta-cho, Midori-ku, Yokohama, 226-8503, Japan.
| | - Kazuya Tsuruta
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, 226-8503, Japan. .,School of Life Science and Technology, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa, 226-8503, Japan
| | - Garrett D Santis
- Department of Chemistry, University of Washington, Seattle, WA 98195, USA
| | - Sotiris S Xantheas
- Tokyo Tech World Research Hub Initiative (WRHI), Institute of Innovation Research, Tokyo Institute of Technology, 4259, Nagatsuta-cho, Midori-ku, Yokohama, 226-8503, Japan. .,Department of Chemistry, University of Washington, Seattle, WA 98195, USA.,Advanced Computing, Mathematics and Data Division, Pacific Northwest National Laboratory, 902 Battelle Boulevard, P.O. Box 999, MS K1-83, Richland, WA 99352, USA
| | - Shun-Ichi Ishiuchi
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, 226-8503, Japan. .,Department of Chemistry, School of Science, Tokyo Institute of Technology, 2-12-1 4259 Ookayama, Meguro-ku, Tokyo, 152-8550, Japan. .,Tokyo Tech World Research Hub Initiative (WRHI), Institute of Innovation Research, Tokyo Institute of Technology, 4259, Nagatsuta-cho, Midori-ku, Yokohama, 226-8503, Japan.
| | - Masaaki Fujii
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, 226-8503, Japan. .,School of Life Science and Technology, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa, 226-8503, Japan.,Tokyo Tech World Research Hub Initiative (WRHI), Institute of Innovation Research, Tokyo Institute of Technology, 4259, Nagatsuta-cho, Midori-ku, Yokohama, 226-8503, Japan.
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18
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Hirata K, Kasai KI, Grégoire G, Ishiuchi SI, Fujii M. Hydration-controlled excited-state relaxation in protonated dopamine studied by cryogenic ion spectroscopy. J Chem Phys 2021; 155:151101. [PMID: 34686064 DOI: 10.1063/5.0066919] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Ultraviolet (UV) and infrared (IR) spectra of protonated dopamine (DAH+) and its hydrated clusters DAH+(H2O)1-3 are measured by cryogenic ion spectroscopy. DAH+ monomer and hydrated clusters with up to two water molecules show a broad UV spectrum, while it turns to a sharp, well-resolved one for DAH+-(H2O)3. Excited state calculations of DAH+(H2O)3 reproduce these spectral features. The conformer-selected IR spectrum of DAH+(H2O)3 is measured by IR dip spectroscopy, and its structure is assigned with the help of quantum chemical calculations. The excited state lifetime of DAH+ is much shorter than 20 ps, the cross correlation of the ps lasers, revealing a fast relaxation dynamics. The minimal energy path along the NH → π proton transfer coordinate exhibits a low energy barrier in the monomer, while this path is blocked by the high energy barrier in DAH+(H2O)3. It is concluded that the excited state proton transfer in DAH+ is inhibited by water-insertion.
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Affiliation(s)
- Keisuke Hirata
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsu-ta-cho, Midori-ku, Yokohama 226-8503, Japan
| | - Ken-Ichi Kasai
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsu-ta-cho, Midori-ku, Yokohama 226-8503, Japan
| | - Gilles Grégoire
- Tokyo Tech World Research Hub Initiative (WRHI), Institute of Innovation Research, Tokyo Institute of Technology, 4259, Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan
| | - Shun-Ichi Ishiuchi
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsu-ta-cho, Midori-ku, Yokohama 226-8503, Japan
| | - Masaaki Fujii
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsu-ta-cho, Midori-ku, Yokohama 226-8503, Japan
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