1
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Liu TH, Okuno M. TMAO perturbs intermolecular vibrational motions of water revealed by low-frequency modes. Phys Chem Chem Phys 2024; 26:12397-12405. [PMID: 38619910 DOI: 10.1039/d4cp01025f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/17/2024]
Abstract
Trimethylamine N-oxide (TMAO) as a representative natural osmolyte has received much attention because of its unique properties, including enhancement of hydrogen bonding networks in liquid water and stabilization of three-dimensional structures of proteins in living organisms. As a hydrogen bond maker and/or a protein stabilizer, its hydrated structures and orientation dynamics in aqueous solutions have been investigated by various spectroscopic methods. Particularly, distinct from other natural osmolytes, it has been found that TMAO molecules form complexes with water molecules even at low concentrations, showing extraordinarily long lifetimes and much larger effective dipole moments. In this study, we demonstrated that collective motions of water molecules are closely correlated to TMAO molecules, as revealed by the changes of the librational modes observed in hyper-Raman (HR) spectra in the low-frequency region (<1000 cm-1) for the first time. Based on HR spectra of the TMAO solutions at submolar concentrations, we observed that the librational bands originating from water apparently upshift (∼15 cm-1) upon the addition of TMAO molecules. Compared to the OH stretching band of water showing a negligible downshift (<5 cm-1), the librational bands of water are more sensitive to reflect changes in the hydrogen bonding networks in the TMAO solutions, suggesting formation of transient TMAO-water complexes plays an essential role toward surrounding water molecules in perturbing their librational motions. We expect to provide a supplementary approach to understand that water molecules in TMAO aqueous solutions are strongly affected by TMAO molecules, different from other osmolytes.
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Affiliation(s)
- Tsung-Han Liu
- Department of Basic Science, Graduate School of Arts and Sciences, The University of Tokyo, Meguro, Tokyo 153-8902, Japan.
| | - Masanari Okuno
- Department of Basic Science, Graduate School of Arts and Sciences, The University of Tokyo, Meguro, Tokyo 153-8902, Japan.
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2
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Seo J, Singh R, Ryu J, Choi JH. Molecular Aggregation Behavior and Microscopic Heterogeneity in Binary Osmolyte-Water Solutions. J Chem Inf Model 2024; 64:138-149. [PMID: 37983534 DOI: 10.1021/acs.jcim.3c01382] [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: 11/22/2023]
Abstract
Osmolytes, small organic compounds, play a key role in modulating the protein stability in aqueous solutions, but the operating mechanism of the osmolyte remains inconclusive. Here, we attempt to clarify the mode of osmolyte action by quantitatively estimating the microheterogeneity of osmolyte-water mixtures with the aid of molecular dynamics simulation, graph theoretical analysis, and spatial distribution measurement in the four osmolyte solutions of trimethylamine-N-oxide (TMAO), tetramethylurea (TMU), dimethyl sulfoxide, and urea. TMAO, acting as a protecting osmolyte, tends to remain isolated with no formation of osmolyte aggregates while preferentially interacting with water, but there is a strong aggregation propensity in the denaturant TMU solution, characterized by favored hydrophobic interactions between TMU molecules. Taken together, the mechanism of osmolyte action on protein stability is proposed as a comprehensive one that encompasses the direct interactions between osmolytes and proteins and indirect interactions through the regulation of water properties in the osmolyte-water mixtures.
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Affiliation(s)
- Jiwon Seo
- Department of Chemistry, Gwangju Institute of Science and Technology (GIST), 123 Cheomdangwagi-ro, Buk-gu, Gwangju 61005, Republic of Korea
| | - Ravi Singh
- Department of Chemistry, Gwangju Institute of Science and Technology (GIST), 123 Cheomdangwagi-ro, Buk-gu, Gwangju 61005, Republic of Korea
| | - Jonghyuk Ryu
- Department of Chemistry, Gwangju Institute of Science and Technology (GIST), 123 Cheomdangwagi-ro, Buk-gu, Gwangju 61005, Republic of Korea
| | - Jun-Ho Choi
- Department of Chemistry, Gwangju Institute of Science and Technology (GIST), 123 Cheomdangwagi-ro, Buk-gu, Gwangju 61005, Republic of Korea
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3
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Urbina AS, Slipchenko LV, Ben-Amotz D. Quantifying the Nearly Random Microheterogeneity of Aqueous tert-Butyl Alcohol Solutions Using Vibrational Spectroscopy. J Phys Chem Lett 2023; 14:11376-11383. [PMID: 38078837 DOI: 10.1021/acs.jpclett.3c02603] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2023]
Abstract
The microheterogeneous structure of aqueous tert-butyl alcohol (TBA) solutions is quantified by combining experimental, simulations, and theoretical results. Experimental Raman multivariate curve resolution (Raman-MCR) C-H frequency shift measurements are compared with predictions obtained using combined quantum mechanical and effective fragment potential (QM/EFP) calculations, as well as with molecular dynamics (MD), random mixture (RM), and finite lattice (FL) predictions. The results indicate that the microheterogeneous aggregation in aqueous TBA solutions is slightly less than that predicted by MD simulations performed using either CHARMM generalized force field (CGenFF) or optimized parameters for liquid simulations all atom (OPLS-AA) force fields but slightly more than that in a self-avoiding RM of TBA-like molecules. The results imply that the onset of microheterogeneity in aqueous solutions occurs when solute contact free energies are about an order of magnitude smaller than thermal fluctuations, thus suggesting a fundamental bound of relevance to biological self-assembly.
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Affiliation(s)
- Andres S Urbina
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Lyudmila V Slipchenko
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Dor Ben-Amotz
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
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4
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Malik R, Chandra A. Counteracting Effects of Trimethylamine N-Oxide against Urea in Aqueous Solutions: Insights from Theoretical Two-Dimensional Infrared Spectroscopy. J Phys Chem B 2023; 127:7372-7383. [PMID: 37566900 DOI: 10.1021/acs.jpcb.3c03864] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/13/2023]
Abstract
The study of small osmolytes in their aqueous solutions has gained significant attention because of their relevance to structure and thermodynamics of proteins in aqueous media. Special attention has been given to the binary and ternary aqueous solutions of urea and trimethylamine N-oxide (TMAO). Urea is a well-known protein denaturant, while TMAO protects proteins in their native states. Interestingly, TMAO counteracts urea's ability to denature proteins when present in solutions with approximately half of the concentration of urea. Vibrational spectroscopy can improve our understanding of the molecular origin of this counteracting effect because of its sensitivity to local structure and dynamics. We present results of theoretical linear vibrational and two-dimensional infrared (2DIR) spectroscopy of water in the binary and ternary aqueous solutions of TMAO and urea. The 2DIR spectra are calculated using the electronic structure/molecular dynamics approach. The non-Condon effects in spectral transitions are incorporated in the theoretical calculations of 2DIR spectra. It is found that TMAO disrupts the local structure of water, while urea leaves it essentially unaffected. The 2DIR results show that both TMAO and urea slow down the dynamics of spectral diffusion of water. The extent of slowing down is found to be particularly significant for both hydration and bulk water in the presence of TMAO which can be attributed to strong hydrogen bonds between the water and TMAO molecules. The water molecules present in the hydration layer of the solutes in the ternary solutions are found to relax at even slower rates compared to that in their binary solutions in water. The hydrogen bonds between TMAO and urea are found to be not stable. Thus, the counteracting effect of TMAO against urea is seen to take place mainly through water-mediated interactions. Such TMAO-induced effects giving rise to more structured and slower hydrogen-bonded network are successfully captured through 2DIR spectroscopic calculations.
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Affiliation(s)
- Ravi Malik
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, Uttar Pradesh 208016, India
| | - Amalendu Chandra
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, Uttar Pradesh 208016, India
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5
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Malik R, Das B, Chandra A. Theoretical Two Dimensional Infrared Spectroscopy of Aqueous Solutions of tert-Butyl Alcohol: Variation of the Dynamics of Spectral Diffusion along the Percolation Transition. J Phys Chem B 2023; 127:4099-4111. [PMID: 37126459 DOI: 10.1021/acs.jpcb.2c08916] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Binary mixtures of water and tert-butyl alcohol (TBA) are known to exhibit the so-called percolation transition where small clusters of TBA molecules span into large aggregates beyond a threshold concentration of the alcohol. In the present study, we have investigated the linear and two-dimensional infrared spectral features of aqueous solutions of TBA for varying concentration of the alcohol along the percolation transition. The percolation transition is characterized through calculations of intermolecular radial distribution functions and average size of the largest cluster of TBA molecules. It is found that, with variation of alcohol concentration, the radial distribution functions of the central carbon atoms of TBA molecules show a nonmonotonic change in the height of the first peak and also the size of the largest cluster of TBA molecules show a jump in the increase of its size for TBA mole fraction between 0.04 and 0.06 corresponding to a transition from smaller clusters to larger spanning aggregates. However, it is found that the linear infrared spectrum of water does not exhibit any noticeable changes on variation of TBA concentration along the percolation transition. Subsequently, two-dimensional infrared (2DIR) spectra and vibrational frequency time correlation function of water are calculated for all the TBA-water solutions considered in this study. The spectral diffusion of water calculated from 2DIR is found to slow down with increase of the TBA concentration. The time scales of spectral diffusion of water, as characterized by the relaxation of frequency time correlation function, 2DIR metric of central line slope, and also the hydrogen bond time correlation functions, are found to exhibit a noticeable jump along the percolation transition. The hydrophilic group of TBA is found to retard the water dynamics more effectively than the hydrophobic groups. Also, the jump in the dynamical slowdown along the percolation transition is found to be more significant for water molecules at the hydrophilic sites.
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Affiliation(s)
- Ravi Malik
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208016, India
| | - Banshi Das
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208016, India
| | - Amalendu Chandra
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208016, India
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6
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Reddy KD, Biswas R. Theoretical Spectroscopy Aided Validation of the Hydration Structure of Trimethylamine N-Oxide (TMAO). J Phys Chem B 2023; 127:2774-2783. [PMID: 36924339 DOI: 10.1021/acs.jpcb.2c09073] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/18/2023]
Abstract
The molecular-level understanding of the hydration structure of external solutes is extremely challenging. In the context of molecular simulation, particularly sampling proper solvation structure by classical force fields remains always a matter of concern. In the present work, we use theoretical vibrational spectroscopy to understand the microscopic solvation structure of TMAO in water in the cases of five different classical force fields of TMAO. We find that the Netz (J. Phys. Chem. B 2013, 117, 8310-8321) force field agrees better with the experimental results. We also observe that the O-H stretching frequency gets red-shifted compared to the bulk water response, suggesting that the TMAO-water forms stronger hydrogen bonds than water-water. We further investigate the O-H stretching frequency in different solvation shells and the hydrophobic and hydrophilic regions of TMAO. We find that, in the hydrophilic region, O-H stretching frequencies show a strong orientational correlation; however, that is absent in the hydrophobic region. These are further supplemented by hydrogen-bond analysis and local structure index data.
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Affiliation(s)
- Kambham Devendra Reddy
- Department of Chemistry and Center for Atomic, Molecular and Optical Sciences Technologies, Indian Institute of Technology Tirupati, Yerpedu, Tirupati, 517619, Andhra Pradesh, India
| | - Rajib Biswas
- Department of Chemistry and Center for Atomic, Molecular and Optical Sciences Technologies, Indian Institute of Technology Tirupati, Yerpedu, Tirupati, 517619, Andhra Pradesh, India
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7
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Impact and Structure of Water in Aqueous Octanol Mixtures: Hz-GHz Dielectric Relaxation Measurements and Computer Simulations. J Photochem Photobiol A Chem 2023. [DOI: 10.1016/j.jphotochem.2023.114600] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
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8
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Kuroki N, Uchino Y, Funakura T, Mori H. Electronic fluctuation difference between trimethylamine N-oxide and tert-butyl alcohol in water. Sci Rep 2022; 12:19417. [PMID: 36371592 PMCID: PMC9653398 DOI: 10.1038/s41598-022-24049-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Accepted: 11/09/2022] [Indexed: 11/13/2022] Open
Abstract
Although small organic molecules in cells have been considered important to control the functions of proteins, their electronic fluctuation and the intermolecular interaction, which is physicochemical origin of the molecular functions, under physiological conditions, i.e., dilute aqueous solutions (0.18 mol L-1), has never been clarified due to the lack of observation methods with both accuracy and efficiency. Herein, the time evolutions of the interactions in dilute aqueous trimethylamine N-oxide (TMAO) and tert-butyl alcohol (TBA) solutions were analyzed via ab initio molecular dynamics simulations accelerated with the fragment molecular theory. It has been known that TMAO and TBA have similar structures, but opposite physiological functions to stabilize and destabilize proteins. It was clarified that TMAO induced stable polarization and charge-transfer interactions with water molecules near the hydrophilic group, and water molecules were caught even near the CH3- group. Those should affect protein stabilization. Understanding the solution dynamics will contribute to artificial chaperone design in next generation medicine.
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Affiliation(s)
- Nahoko Kuroki
- grid.443595.a0000 0001 2323 0843Department of Applied Chemistry, Faculty of Science and Engineering, Chuo University, Bunkyo-ku, Tokyo, 112-8551 Japan ,grid.419082.60000 0004 1754 9200JST, ACT-X, Kawaguchi, Saitama 332-0012 Japan
| | - Yukina Uchino
- grid.412314.10000 0001 2192 178XDepartment of Chemistry and Biochemistry, Graduate School of Humanities and Sciences, Ochanomizu University, Bunkyo-ku, Tokyo, 112-8610 Japan
| | - Tamon Funakura
- grid.443595.a0000 0001 2323 0843Department of Applied Chemistry, Faculty of Science and Engineering, Chuo University, Bunkyo-ku, Tokyo, 112-8551 Japan
| | - Hirotoshi Mori
- grid.443595.a0000 0001 2323 0843Department of Applied Chemistry, Faculty of Science and Engineering, Chuo University, Bunkyo-ku, Tokyo, 112-8551 Japan ,grid.467196.b0000 0001 2285 6123Department of Theoretical and Computational Molecular Science, Institute for Molecular Science, Myodaiji, Okazaki, 444-8585 Japan
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9
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Baksi A, Biswas R. Dynamical Anomaly of Aqueous Amphiphilic Solutions: Connection to Solution H-Bond Fluctuation Dynamics? ACS OMEGA 2022; 7:10970-10984. [PMID: 35415359 PMCID: PMC8991915 DOI: 10.1021/acsomega.1c06831] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Accepted: 03/11/2022] [Indexed: 06/14/2023]
Abstract
We have investigated the possible connection between "dynamical anomaly" observed in time-resolved fluorescence measurements of reactive and nonreactive solute-centered relaxation dynamics in aqueous binary mixtures of different amphiphiles and the solution intra- and interspecies H-bond fluctuation dynamics. Earlier studies have connected the anomalous thermodynamic properties of binary mixtures at very low amphiphile concentrations to the structural distortion of water. This is termed as "structural anomaly." Interestingly, the abrupt changes in the composition-dependent average rates of solute relaxation dynamics occur at amphiphile mole fractions approximately twice as large as those where structural anomalies appear. We have investigated this anomalous solution dynamical aspect by considering (water + tertiary butanol) as a model system and performed molecular dynamics simulations at several tertiary butanol (TBA) concentrations covering the extremely dilute to the moderately concentrated regimes. The "dynamical anomaly" has been followed via monitoring the composition dependence of the intra- and interspecies H-bond fluctuations and reorientational relaxations of TBA and water molecules. Solution structural aspects have been followed via examining the tetrahedral order parameter, radial and spatial distribution functions, numbers of H bonds per water and TBA molecules, and the respective populations participating in H-bond formation. Our simulations reveal abrupt changes in the H-bond fluctuations and reorientational dynamics and tetrahedral order parameter at amphiphile concentrations differing approximately by a factor of 2 and corroborates well with the steady-state and the time-resolved spectroscopic measurements. This work therefore explains, following a uniform and cogent manner, both the experimentally observed structural and dynamical anomalies in microscopic terms.
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10
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Kadtsyn ED, Nichiporenko VA, Medvedev NN. Volumetric properties of solutions on the perspective of Voronoi tessellation. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2021.118173] [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]
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11
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Roy S, Patra A, Palit DK, Mondal JA. Interaction of Zwitterionic Osmolyte Trimethylamine N-oxide (TMAO) with Molecular Hydrophobes: An Interplay of Hydrophobic and Electrostatic Interactions. J Phys Chem B 2021; 125:10939-10946. [PMID: 34570979 DOI: 10.1021/acs.jpcb.1c05694] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Interaction of trimethylamine N-oxide (TMAO) with charged/uncharged moieties of proteins and lipids is an important elementary step toward the multifaceted biofunctions of TMAO. Using minimum area Raman difference spectroscopy (MA-RDS) of aqueous TMAO (1.0 M) in the presence of deuterated molecular hydrophobes (e.g., deuterated tetramethylammonium cation (d-TMA+) and tert-butylalcohol (d-TBA)), we show that TMAO exhibits two distinct motifs of interaction with the cationic (d-TMA+) and uncharged (d-TBA) hydrophobes. Specifically, the trimethylammonium moiety of TMAO undergoes van der Waals attraction with the tert-butyl group of d-TBA, which is governed by their mutual hydrophobic interaction with water. This makes their methyl groups less exposed to water. In contrast, for the cationic hydrophobe (d-TMA+), TMAO interacts electrostatically via its negatively charged-oxygen, which in turn orients the TMAO-methyls away from the hydrophobe (d-TMA+), keeping them exposed to water.
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Affiliation(s)
- Subhadip Roy
- Radiation & Photochemistry Division, Bhabha Atomic Research Centre, Homi Bhabha National Institute, Trombay, Mumbai 400085, India
| | - Animesh Patra
- School of Chemistry, Centre for Excellence in Basic Sciences, University of Mumbai, Kalina Campus, Santacruz (E), Mumbai 400098, India
| | - Dipak K Palit
- School of Chemistry, Centre for Excellence in Basic Sciences, University of Mumbai, Kalina Campus, Santacruz (E), Mumbai 400098, India
| | - Jahur Alam Mondal
- Radiation & Photochemistry Division, Bhabha Atomic Research Centre, Homi Bhabha National Institute, Trombay, Mumbai 400085, India
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12
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Kadtsyn ED, Nichiporenko VA, Medvedev NN. USING VORONOI DIAGRAMS TO INTERPRET BULK PROPERTIES OF SOLUTIONS. J STRUCT CHEM+ 2021. [DOI: 10.1134/s0022476621010078] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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13
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Maiti A, Daschakraborty S. Effect of TMAO on the Structure and Phase Transition of Lipid Membranes: Potential Role of TMAO in Stabilizing Cell Membranes under Osmotic Stress. J Phys Chem B 2021; 125:1167-1180. [PMID: 33481606 DOI: 10.1021/acs.jpcb.0c08335] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Extremophiles adopt strategies to deal with different environmental stresses, some of which are severely damaging to their cell membrane. To combat high osmotic stress, deep-sea organisms synthesize osmolytes, small polar organic molecules, like trimethylamine-N-oxide (TMAO), and incorporate them in the cell. TMAO is known to protect cells from high osmotic or hydrostatic pressure. Several experimental and simulation studies have revealed the roles of such osmolytes on stabilizing proteins. In contrast, the effect of osmolytes on the lipid membrane is poorly understood and broadly debated. A recent experiment has found strong evidence of the possible role of TMAO in stabilizing lipid membranes. Using the molecular dynamics (MD) simulation technique, we have demonstrated the effect of TMAO on two saturated fully hydrated lipid membranes in their fluid and gel phases. We have captured the impact of TMAO's concentration on the membrane's structural properties along with the fluid/gel phase transition temperatures. On increasing the concentration of TMAO, we see a substantial increase in the packing density of the membrane (estimated by area, thickness, and volume) and enhancement in the orientational order of lipid molecules. Having repulsive interaction with the lipid head group, the TMAO molecules are expelled away from the membrane surface, which induces dehydration of the lipid head groups, increasing the packing density. The addition of TMAO also increases the fluid/gel phase transition temperature of the membrane. All of these results are in close agreement with the experimental observations. This study, therefore, provides a molecular-level understanding of how TMAO can influence the cell membrane of deep-sea organisms and help in combating the osmotic stress condition.
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Affiliation(s)
- Archita Maiti
- Department of Chemistry, Indian Institute of Technology Patna, Patna, Bihar 801106, India
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14
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Choudhary A, Chandra A. Spatially resolved structure and dynamics of the hydration shell of pyridine in sub- and supercritical water. J Mol Liq 2019. [DOI: 10.1016/j.molliq.2019.110881] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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15
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Overduin SD, Perera A, Patey GN. Structural behavior of aqueous t-butanol solutions from large-scale molecular dynamics simulations. J Chem Phys 2019; 150:184504. [PMID: 31091933 DOI: 10.1063/1.5097011] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Large-scale molecular dynamics simulations are reported for aqueous t-butanol (TBA) solutions. The CHARMM generalized force field (CGenFF) for TBA is combined with the TIP4P/2005 model for water. Unlike many other common TBA models, the CGenFF model is miscible with water in all proportions at 300 K. The main purpose of this work is to investigate the existence and nature of a microheterogeneous structure in aqueous TBA solutions. Our simulations of large systems (128 000 and 256 000 particles) at TBA mole fractions of 0.06 and 0.1 clearly reveal the existence of long-range correlations (>10 nm) that show significant variations on long time scales (∼50 ns). We associate these long-range slowly varying correlations with the existence of supramolecular domainlike structures that consist of TBA-rich and water-rich regions. This structure is always present but continually changing in time, giving rise to long-range slowly varying pair correlation functions. We find that this behavior appears to have little influence on the single particle dynamics; the diffusion coefficients of both TBA and water molecules lie in the usual liquid state regime, and mean square displacements provide no indication of anomalous diffusion. Using our large system simulations, we are able to reliably calculate small angle x-ray scattering and small angle neutron scattering spectra, except at a very low wave vector, and the results agree well with recent experiments. However, this paper shows that simulation of the relatively simple TBA/water system remains challenging. This is particularly true if one wishes to obtain properties such as Kirkwood-Buff factors, or scattering functions at a low wave vector, which strongly depend on the long-range behavior of the pair correlations.
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Affiliation(s)
- S D Overduin
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - Aurélien Perera
- Laboratoire de Physique Théorique de la Matière Condensée (UMR CNRS 7600), Université Pierre et Marie Curie, 4 Place Jussieu, F75252 Paris Cedex 05, France
| | - G N Patey
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
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16
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Bandyopadhyay D, Kamble Y, Choudhury N. How Different Are the Characteristics of Aqueous Solutions of tert-Butyl Alcohol and Trimethylamine-N-Oxide? A Molecular Dynamics Simulation Study. J Phys Chem B 2018; 122:8220-8232. [DOI: 10.1021/acs.jpcb.8b02411] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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17
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Banik D, Bhattacharya S, Datta PK, Sarkar N. Anomalous Dynamics in tert-Butyl Alcohol-Water and Trimethylamine N-Oxide-Water Binary Mixtures: A Femtosecond Transient Absorption Study. ACS OMEGA 2018; 3:383-392. [PMID: 31457899 PMCID: PMC6641418 DOI: 10.1021/acsomega.7b01595] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Accepted: 12/27/2017] [Indexed: 05/17/2023]
Abstract
In this article, we have investigated the unusual dynamics of tert-butyl alcohol (TBA)-water and trimethylamine N-oxide (TMAO)-water binary mixtures using solvation dynamics as a tool. For this purpose, femtosecond transient absorption spectroscopy has been employed. Although these two molecules are isosteres to each other, a significant difference in water dynamics has been observed. The solvation times in TBA-water binary mixtures are found to be between 1.5 and 15.5 ps. On the contrary, we have observed very fast dynamics in TMAO-water binary mixtures (between 210 and 600 fs). Interestingly, unusual retardation in dynamics is observed at 0.10 mole fraction of TBA and TMAO in both the binary mixtures.
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Affiliation(s)
- Debasis Banik
- Department
of Chemistry and Department of Physics, Indian Institute
of Technology, Kharagpur 721302, West Bengal, India
| | - Sayantan Bhattacharya
- Department
of Chemistry and Department of Physics, Indian Institute
of Technology, Kharagpur 721302, West Bengal, India
| | - Prasanta Kumar Datta
- Department
of Chemistry and Department of Physics, Indian Institute
of Technology, Kharagpur 721302, West Bengal, India
- E-mail: (P.K.D.)
| | - Nilmoni Sarkar
- Department
of Chemistry and Department of Physics, Indian Institute
of Technology, Kharagpur 721302, West Bengal, India
- E-mail: . Phone: +91-3222-283332. Fax: 91-3222-255303 (N.S.)
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18
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Stirnemann G, Duboué-Dijon E, Laage D. Ab Initio Simulations of Water Dynamics in Aqueous TMAO Solutions: Temperature and Concentration Effects. J Phys Chem B 2017; 121:11189-11197. [PMID: 29200289 DOI: 10.1021/acs.jpcb.7b09989] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We use ab initio molecular dynamics simulation to study the effect of hydrophobic groups on the dynamics of water molecules in aqueous solutions of trimethylamine N-oxide (TMAO). We show that hydrophobic groups induce a moderate (<2-fold) slowdown of water reorientation and hydrogen-bond dynamics in dilute solutions, but that this slowdown rapidly increases with solute concentration. In addition, the slowdown factor is found to vary very little with temperature, thus suggesting an entropic origin. All of these results are in quantitative agreement with prior classical molecular dynamics simulations and with the previously suggested excluded-volume model. The hydrophilic TMAO headgroup is found to affect water dynamics more strongly than the hydrophobic moiety, and the magnitude of this slowdown is very sensitive to the strength of the water-solute hydrogen-bond.
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Affiliation(s)
- Guillaume Stirnemann
- CNRS Laboratoire de Biochimie Théorique, Institut de Biologie Physico-Chimique, Univ. Paris Diderot, Sorbonne Paris Cité, PSL Research University , 13 rue Pierre et Marie Curie, 75005 Paris, France
| | - Elise Duboué-Dijon
- PASTEUR, Département de Chimie, École Normale Supérieure, PSL Research University, Sorbonne Universités, UPMC Univ. Paris 06, CNRS , 75005 Paris, France
| | - Damien Laage
- PASTEUR, Département de Chimie, École Normale Supérieure, PSL Research University, Sorbonne Universités, UPMC Univ. Paris 06, CNRS , 75005 Paris, France
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19
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Anikeenko A, Kadtsyn E, Medvedev N. Statistical geometry characterization of global structure of TMAO and TBA aqueous solutions. J Mol Liq 2017. [DOI: 10.1016/j.molliq.2017.06.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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20
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Overduin SD, Patey GN. Comparison of simulation and experimental results for a model aqueous tert-butanol solution. J Chem Phys 2017; 147:024503. [DOI: 10.1063/1.4990505] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- S. D. Overduin
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - G. N. Patey
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
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21
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Three-dimensional Morphology and X-ray Scattering Structure of Aqueous tert-Butanol Mixtures: A Molecular Dynamics Study. J CHEM SCI 2017. [DOI: 10.1007/s12039-016-1207-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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22
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Ohto T, Hunger J, Backus EHG, Mizukami W, Bonn M, Nagata Y. Trimethylamine-N-oxide: its hydration structure, surface activity, and biological function, viewed by vibrational spectroscopy and molecular dynamics simulations. Phys Chem Chem Phys 2017; 19:6909-6920. [DOI: 10.1039/c6cp07284d] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Vibrational spectroscopy and molecular simulations revealed the hydrophilicity and hydrophobicity of TMAO in aqueous solution.
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Affiliation(s)
- Tatsuhiko Ohto
- Graduate School of Engineering Science
- Osaka University
- Toyonaka
- Japan
| | | | | | - Wataru Mizukami
- Department of Energy and Material Sciences
- Faculty of Engineering Sciences
- Kyushu University
- Fukuoka
- Japan
| | - Mischa Bonn
- Max Planck Institute for Polymer Research
- 55128 Mainz
- Germany
| | - Yuki Nagata
- Max Planck Institute for Polymer Research
- 55128 Mainz
- Germany
- Department of Theoretical and Computational Molecular Science
- Institute for Molecular Science
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23
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Fedotova MV, Kruchinin SE, Chuev GN. Hydration structure of osmolyte TMAO: concentration/pressure-induced response. NEW J CHEM 2017. [DOI: 10.1039/c6nj03296f] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The effect of solute concentration/pressure on the TMAO hydration structure was studied to understand its protective action under abiotic stressors.
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Affiliation(s)
- Marina V. Fedotova
- G.A. Krestov Institute of Solution Chemistry
- The Russian Academy of Sciences
- Ivanovo
- Russia
| | - Sergey E. Kruchinin
- G.A. Krestov Institute of Solution Chemistry
- The Russian Academy of Sciences
- Ivanovo
- Russia
| | - Gennady N. Chuev
- Institute of Theoretical and Experimental Biophysics
- The Russian Academy of Sciences
- Pushchino
- Russia
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24
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INDRA SANDIPA, BISWAS RANJIT. Is dynamic heterogeneity of water in presence of a protein denaturing agent different from that in presence of a protein stabilizer? A molecular dynamics simulation study. J CHEM SCI 2016. [DOI: 10.1007/s12039-016-1194-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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25
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Borgohain G, Paul S. Temperature-mediated switching of protectant-denaturant behavior of trimethylamine-N-oxide and consequences on protein stability from a replica exchange molecular dynamics simulation study. MOLECULAR SIMULATION 2016. [DOI: 10.1080/08927022.2016.1233546] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- Gargi Borgohain
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati, India
| | - Sandip Paul
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati, India
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26
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Rodríguez-Ropero F, Rötzscher P, van der Vegt NFA. Comparison of Different TMAO Force Fields and Their Impact on the Folding Equilibrium of a Hydrophobic Polymer. J Phys Chem B 2016; 120:8757-67. [DOI: 10.1021/acs.jpcb.6b04100] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Francisco Rodríguez-Ropero
- Eduard-Zintl-Institut für
Anorganische und Physikalische Chemie and Center of Smart Interfaces, Technische Universität Darmstadt, Alarich-Weiss-Straße 10, 64287, Darmstadt, Germany
| | - Philipp Rötzscher
- Eduard-Zintl-Institut für
Anorganische und Physikalische Chemie and Center of Smart Interfaces, Technische Universität Darmstadt, Alarich-Weiss-Straße 10, 64287, Darmstadt, Germany
| | - Nico F. A. van der Vegt
- Eduard-Zintl-Institut für
Anorganische und Physikalische Chemie and Center of Smart Interfaces, Technische Universität Darmstadt, Alarich-Weiss-Straße 10, 64287, Darmstadt, Germany
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27
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Affiliation(s)
- Sandip Paul
- Department of Chemistry, Indian Institute of Technology, Guwahati, India
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28
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Comez L, Paolantoni M, Corezzi S, Lupi L, Sassi P, Morresi A, Fioretto D. Aqueous solvation of amphiphilic molecules by extended depolarized light scattering: the case of trimethylamine-N-oxide. Phys Chem Chem Phys 2016; 18:8881-9. [PMID: 26958663 DOI: 10.1039/c5cp04357c] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Hydrophilic and hydrophobic interactions strongly affect the solvation dynamics of biomolecules. To understand their role, small model systems are generally employed to simplify the investigations. In this study the amphiphile trimethylamine N-oxide (TMAO) is chosen as an exemplar, and studied by means of extended frequency range depolarized light scattering (EDLS) experiments as a function of solute concentration. This technique proves to be a suitable tool for investigating different aspects of aqueous solvation, being able at the same time to provide information about relaxation processes and vibrational modes of solvent and solute. In the case study of TMAO, we find that the relaxation dynamics of hydration water is moderately retarded compared to the bulk, and the perturbation induced by the solute on surrounding water is confined to the first hydration shell. The results highlight the hydrophobic character of TMAO in its interaction with water. The number of molecules taking part in the solvation process decreases as the solute concentration increases, following a trend consistent with the hydration water-sharing model, and suggesting that aggregation between solute molecules is negligible. Finally, the analysis of the resonant modes in the THz region and the comparison with the corresponding results obtained for the isosteric molecule tert-butyl alcohol (TBA) allow us to provide new insights into the different solvating properties of these two biologically relevant molecules.
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Affiliation(s)
- L Comez
- IOM-CNR c/o Dipartimento di Fisica e Geologia, Università di Perugia, Via Pascoli, I-06123 Perugia, Italy. and Dipartimento di Fisica e Geologia, Università di Perugia, Via Pascoli, I-06123 Perugia, Italy
| | - M Paolantoni
- Dipartimento di Chimica, Biologia e Biotecnologie, Università di Perugia, Via Elce di Sotto 8, I-06123 Perugia, Italy
| | - S Corezzi
- Dipartimento di Fisica e Geologia, Università di Perugia, Via Pascoli, I-06123 Perugia, Italy
| | - L Lupi
- Department of Chemistry, The University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112-0850, USA
| | - P Sassi
- Dipartimento di Chimica, Biologia e Biotecnologie, Università di Perugia, Via Elce di Sotto 8, I-06123 Perugia, Italy
| | - A Morresi
- Dipartimento di Chimica, Biologia e Biotecnologie, Università di Perugia, Via Elce di Sotto 8, I-06123 Perugia, Italy
| | - D Fioretto
- Dipartimento di Fisica e Geologia, Università di Perugia, Via Pascoli, I-06123 Perugia, Italy and Centro di Eccellenza sui Materiali Innovativi Nanostrutturati (CEMIN), Università di Perugia, Via Elce di Sotto 8, I-06123 Perugia, Italy
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29
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Das S, Paul S. Mechanism of Hydrotropic Action of Hydrotrope Sodium Cumene Sulfonate on the Solubility of Di-t-Butyl-Methane: A Molecular Dynamics Simulation Study. J Phys Chem B 2016; 120:173-83. [PMID: 26684411 DOI: 10.1021/acs.jpcb.5b09668] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Hydrotropes are special class of amphiphilic molecules that have an ability to solubilize the insoluble or sparingly soluble molecules in water. To find out the mechanism of hydrotropic action of hydrotropes on hydrophobic molecules, we have carried out classical molecular dynamics simulation of hydrophobic solute di-t-butyl-methane (DTBM) and hydrotrope sodium cumene sulfonate (SCS) in water with a regime of SCS concentrations. Our study demonstrates that, above the minimum hydrotrope concentration (MHC), the self-aggregation of SCS starts, and it creates a micellar-like environment in which the hydrophobic tail part of SCS points inward while its hydrophilic sulfonate group points outward to make favorable contact with water molecules. The formation of the hydrophobic core of SCS cluster creates a hydrophobic environment where the hydrophobic DTBM molecules are encapsulated. Interestingly, the determination of average water-SCS hydrogen bonds further suggests that the aggregate formation of SCS molecules has a negligible influence on it. Moreover, the calculations of Flory-Huggins interaction parameters also reveal favorable interactions between hydrotrope SCS and solute DTBM molecules. The implications of these findings on the mechanism of hydrotrope assisted enhanced solubility of hydrophobic molecules are discussed.
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Affiliation(s)
- Shubhadip Das
- Department of Chemistry, Indian Institute of Technology , Guwahati, Assam 781039, India
| | - Sandip Paul
- Department of Chemistry, Indian Institute of Technology , Guwahati, Assam 781039, India
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30
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Knake L, Schwaab G, Kartaschew K, Havenith M. Solvation Dynamics of Trimethylamine N-Oxide in Aqueous Solution Probed by Terahertz Spectroscopy. J Phys Chem B 2015. [PMID: 26214376 DOI: 10.1021/acs.jpcb.5b04152] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We have studied the hydration dynamics of trimethylamine N-oxide (TMAO) in aqueous solution using a combination of concentration-dependent terahertz/far-infrared (THz/FIR) and Raman spectroscopic techniques. Terahertz/FIR absorption was measured using narrowband (76-93 cm(-1)) p-Ge laser and broad band (30-400 cm(-1)) Fourier transform spectroscopy. We used principal component analysis in combination with a semi-ideal chemical equilibrium model to dissect the spectra into linear and nonlinear contributions of the solvated solute extinction. We attribute the linear part to the average extinction and Raman scattering of TMAO-water aggregates with approximately 3-4 water strongly hydrogen bonded to TMAO. An additional nonlinear concentration dependence indicates a decrease of the number of attached water molecules with increasing TMAO concentrations due to a shift in association equilibria. The Raman spectra reveal a frequency shift of the (narrowband) intramolecular vibrations with decreasing dilution. Based on the results of a detailed analysis and isotopic substitution, the experimentally observed absorption bands at 0, 176, and 388 cm(-1) could be assigned to water relaxation modes, an intermolecular TMAO-H2O stretch, and the C-N-C bending mode, respectively. Our results provide evidence for a local modification of the water structure.
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Affiliation(s)
- Lukas Knake
- Department of Physical Chemistry II, Ruhr-University Bochum , 44780 Bochum, Germany
| | - Gerhard Schwaab
- Department of Physical Chemistry II, Ruhr-University Bochum , 44780 Bochum, Germany
| | | | - Martina Havenith
- Department of Physical Chemistry II, Ruhr-University Bochum , 44780 Bochum, Germany
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31
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Usui K, Hunger J, Sulpizi M, Ohto T, Bonn M, Nagata Y. Ab Initio Liquid Water Dynamics in Aqueous TMAO Solution. J Phys Chem B 2015; 119:10597-606. [DOI: 10.1021/acs.jpcb.5b02579] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Kota Usui
- Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany
| | - Johannes Hunger
- Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany
| | - Marialore Sulpizi
- Johannes Gutenberg University Mainz, Staudingerweg 7, 55099 Mainz, Germany
| | - Tatsuhiko Ohto
- Graduate
School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan
| | - Mischa Bonn
- Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany
| | - Yuki Nagata
- Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany
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32
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Banerjee S, Furtado J, Bagchi B. Fluctuating micro-heterogeneity in water–tert-butyl alcohol mixtures and lambda-type divergence of the mean cluster size with phase transition-like multiple anomalies. J Chem Phys 2014; 140:194502. [DOI: 10.1063/1.4874637] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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33
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Bruździak P, Panuszko A, Stangret J. Influence of Osmolytes on Protein and Water Structure: A Step To Understanding the Mechanism of Protein Stabilization. J Phys Chem B 2013; 117:11502-8. [DOI: 10.1021/jp404780c] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Piotr Bruździak
- Department of Physical Chemistry, Chemical Faculty, Gdańsk University of Technology, Narutowicza 11/12, 80-233 Gdańsk, Poland
| | - Aneta Panuszko
- Department of Physical Chemistry, Chemical Faculty, Gdańsk University of Technology, Narutowicza 11/12, 80-233 Gdańsk, Poland
| | - Janusz Stangret
- Department of Physical Chemistry, Chemical Faculty, Gdańsk University of Technology, Narutowicza 11/12, 80-233 Gdańsk, Poland
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34
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Larini L, Shea JE. Double Resolution Model for Studying TMAO/Water Effective Interactions. J Phys Chem B 2013; 117:13268-77. [DOI: 10.1021/jp403635g] [Citation(s) in RCA: 82] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Affiliation(s)
- Luca Larini
- Department of Chemistry
and Biochemistry
and of Physics, University of California, Santa Barbara, Santa Barbara, California 93106, United
States
| | - Joan-Emma Shea
- Department of Chemistry
and Biochemistry
and of Physics, University of California, Santa Barbara, Santa Barbara, California 93106, United
States
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35
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Fiore A, Venkateshwaran V, Garde S. Trimethylamine N-oxide (TMAO) and tert-butyl alcohol (TBA) at hydrophobic interfaces: insights from molecular dynamics simulations. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:8017-8024. [PMID: 23687932 DOI: 10.1021/la401203r] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
TMAO, a potent osmolyte, and TBA, a denaturant, have similar molecular architecture but somewhat different chemistry. We employ extensive molecular dynamics simulations to quantify their behavior at vapor-water and octane-water interfaces. We show that interfacial structure-density and orientation-and their dependence on solution concentration are markedly different for the two molecules. TMAO molecules are moderately surface active and adopt orientations with their N-O vector approximately parallel to the aqueous interface. That is, not all methyl groups of TMAO at the interface point away from the water phase. In contrast, TBA molecules act as molecular amphiphiles, are highly surface active, and, at low concentrations, adopt orientations with their methyl groups pointing away and the C-O vector pointing directly into water. The behavior of TMAO at aqueous interfaces is only weakly dependent on its solution concentration, whereas that of TBA depends strongly on concentration. We show that this concentration dependence arises from their different hydrogen bonding capabilities-TMAO can only accept hydrogen bonds from water, whereas TBA can accept (donate) hydrogen bonds from (to) water or other TBA molecules. The ability to self-associate, particularly visible in TBA molecules in the interfacial layer, allows them to sample a broad range of orientations at higher concentrations. In light of the role of TMAO and TBA in biomolecular stability, our results provide a reference with which to compare their behavior near biological interfaces. Also, given the ubiquity of aqueous interfaces in biology, chemistry, and technology, our results may be useful in the design of interfacially active small molecules with the aim to control their orientations and interactions.
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Affiliation(s)
- Andrew Fiore
- The Howard P. Isermann Department of Chemical and Biological Engineering and The Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, New York 12180, USA
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36
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37
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Wilcox DS, Rankin BM, Ben-Amotz D. Distinguishing aggregation from random mixing in aqueous t-butyl alcohol solutions. Faraday Discuss 2013; 167:177-90. [DOI: 10.1039/c3fd00086a] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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38
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Sarma R, Paul S. The effect of aqueous solutions of trimethylamine-N-oxide on pressure induced modifications of hydrophobic interactions. J Chem Phys 2012; 137:094502. [DOI: 10.1063/1.4748101] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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39
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Gupta R, Patey GN. Aggregation in dilute aqueous tert-butyl alcohol solutions: Insights from large-scale simulations. J Chem Phys 2012; 137:034509. [DOI: 10.1063/1.4731248] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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40
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Paul S, Patey GN. Influence of urea on tert-butyl alcohol aggregation in aqueous solutions. J Phys Chem B 2012; 116:4991-5001. [PMID: 22480288 DOI: 10.1021/jp300792p] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Ternary solutions consisting of urea, tert-butyl alcohol (TBA), and water are investigated employing molecular dynamics simulations. The main purpose of the present paper is to investigate the effect of urea on TBA aggregation and by extension its influence on hydrophobic interactions. The aggregation of TBA can be detected from the concentration dependence of structural properties such as first-shell TBA-water coordination numbers and TBA-TBA hydrogen-bond numbers, as well as through changes in the translational diffusion coefficients of TBA. It is found that urea acts to delay the association of TBA to concentrations greater than those required to cause TBA aggregation in binary TBA-water systems. It is shown that urea acts through a direct mechanism, whereby it preferentially binds to TBA replacing water from the first coordination shell. TBA-urea hydrogen bonds can be as strong as, or stronger than, those of TBA-water, and urea binds to both the hydrophilic and hydrophobic moieties of TBA. Our observations are qualitatively consistent with experimental results for urea-TBA-water solutions and with recent simulation studies of urea's action as a protein denaturant.
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Affiliation(s)
- Sandip Paul
- Department of Chemistry, Indian Institute of Technology , Guwahati, Assam, India-781039
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41
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Hunger J, Tielrooij KJ, Buchner R, Bonn M, Bakker HJ. Complex Formation in Aqueous Trimethylamine-N-oxide (TMAO) Solutions. J Phys Chem B 2012; 116:4783-95. [DOI: 10.1021/jp212542q] [Citation(s) in RCA: 115] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Johannes Hunger
- FOM Institute AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz,
Germany
| | | | - Richard Buchner
- Institut für
Physikalische
und Theoretische Chemie, Universität Regensburg, 93040 Regensburg, Germany
| | - Mischa Bonn
- FOM Institute AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz,
Germany
| | - Huib J. Bakker
- FOM Institute AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands
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42
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Nagy PI. Structure simulations for the 0.22 and 1 molar aqueous dimethylammonium chloride solutions. Phys Chem Chem Phys 2012; 14:849-57. [PMID: 22108699 DOI: 10.1039/c1cp22604e] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Affiliation(s)
- Peter I Nagy
- Center for Drug Design and Development, The University of Toledo, Toledo, OH 43606-3390, USA.
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43
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Mazur K, Heisler IA, Meech SR. Aqueous solvation of amphiphilic solutes: concentration and temperature dependent study of the ultrafast polarisability relaxation dynamics. Phys Chem Chem Phys 2012; 14:6343-51. [DOI: 10.1039/c2cp23806c] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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44
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Rogachev AY, Burger P. Bonding situation and N–O-bond strengths in amine-N-oxides—a combined experimental and theoretical study. Phys Chem Chem Phys 2012; 14:1985-2000. [DOI: 10.1039/c2cp22341d] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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45
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Graziano G. A rationale for the contrasting activity (towards globular proteins) of tert-butyl alcohol and trimethylamine N-oxide. Phys Chem Chem Phys 2012; 14:13088-94. [DOI: 10.1039/c2cp41363a] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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46
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Gupta R, Patey GN. Association and microheterogeneity in aqueous 2-butoxyethanol solutions. J Phys Chem B 2011; 115:15323-31. [PMID: 22082133 DOI: 10.1021/jp209905g] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Molecular dynamics simulations are employed to investigate aggregation and microheterogeneity in dilute solutions of 2-butoxyethanol (BE) in water. The BE concentration is varied from near infinite dilution to the mole fraction X(BE) = 0.04. It was found that large systems (32,000 molecules) are necessary to accommodate the BE aggregates that form in this concentration range. Simulations were performed with two different force fields, and similar results were obtained. At very low concentration, BE aggregation is not observed, but evidence is found for intramolecular hydrogen bonds (between the hydroxyl hydrogen and the ether oxygen of the same BE molecule) that form five-member ring configurations, similar to those reported in experimental studies of BE in nonaqueous solvent. Initial signs of BE association appear at X(BE) ≈ 0.005, after which aggregation occurs rapidly, with aggregates that can be described as micelle-like being fully formed at X(BE) ≈ 0.02. This concentration agrees well with many experimental studies of aggregation in BE-water solutions. Between X(BE) = 0.02 and 0.04, the aggregates appear to grow a little in size, but the basic structure remains the same. At long range, the various pair correlation functions show clear density oscillations associated with BE aggregation. This allows us to identify the length scales of the existing microheterogeneity and to estimate the size of the BE aggregates. If we assume spherical aggregates, then our estimate of the radius at X(BE) = 0.04 (~42 Å) is close to estimates obtained from light scattering and small-angle neutron scattering experiments.
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Affiliation(s)
- Rini Gupta
- Department of Chemistry, University of British Columbia, Vancouver BC, Canada, V6T 1Z1
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47
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Subramanian D, Anisimov MA. Resolving the mystery of aqueous solutions of tertiary butyl alcohol. J Phys Chem B 2011; 115:9179-83. [PMID: 21671661 DOI: 10.1021/jp2041795] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
We have resolved a long-standing issue in the discussion on the origin of the mesoscale inhomogeneities observed in aqueous solutions of tertiary butyl alcohol (TBA). We have shown that the formation of stable mesoscale particles (of about 100 nm in size) can be triggered by the addition of trace amounts of propylene oxide (an impurity expected to be present in all commercial samples of TBA) to a solution, which was previously filtered at a low temperature to remove these inhomogeneities. We hypothesize that these particles are aggregates of mixed clathrate-hydrates that are formed through the stabilization of fluctuations of the intrinsic structure in TBA aqueous solutions by the clathrate-forming ability of propylene oxide.
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Affiliation(s)
- Deepa Subramanian
- Department of Chemical and Biomolecular Engineering, University of Maryland, College Park, Maryland 20742, USA
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Munroe KL, Magers DH, Hammer NI. Raman spectroscopic signatures of noncovalent interactions between trimethylamine N-oxide (TMAO) and water. J Phys Chem B 2011; 115:7699-707. [PMID: 21598992 DOI: 10.1021/jp203840w] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The effects of hydration on vibrational normal modes of trimethylamine N-oxide (TMAO) are investigated by Raman spectroscopy and electronic structure computations. Microsolvated networks of water are observed to induce either red or blue shifts in the normal modes of TMAO with increasing water concentration and to also exhibit distinct spectral signatures. By taking advantage of the selective and gradual nature of the water-induced shifts and using comparisons to theoretical predictions, the assignments of TMAO's normal modes are re-examined and the structure of the hydrogen-bonded network in the vicinity of TMAO is elucidated. Agreement between experiment and theory suggests that the oxygen atom in TMAO accepts on average at least three hydrogen bonds from neighboring water molecules and that water molecules are likely not directly interacting with TMAO's methyl groups.
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Affiliation(s)
- Katherine L Munroe
- Department of Chemistry and Biochemistry, University of Mississippi, University, Mississippi 38677, USA
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49
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Koga Y, Westh P, Nishikawa K, Subramanian S. Is a Methyl Group Always Hydrophobic? Hydrophilicity of Trimethylamine-N-oxide, Tetramethyl Urea and Tetramethylammonium Ion. J Phys Chem B 2011; 115:2995-3002. [DOI: 10.1021/jp108347b] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Yoshikata Koga
- Department of Chemistry, The University of British Columbia, Vancouver, BC Canada V6T 1Z1
- Suiteki Juku (Water Drop Institute), Vancouver, BC Canada V6R 2P5
| | - Peter Westh
- NSM Research for Functional Biomaterials, Roskilde University, Roskilde DK-4000 Denmark
| | - Keiko Nishikawa
- Graduate School of Advanced Integration Sciences, Chiba University, Chiba 263-8522 Japan
| | - S. Subramanian
- Department of Chemistry, The University of British Columbia, Vancouver, BC Canada V6T 1Z1
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50
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Stirnemann G, Sterpone F, Laage D. Dynamics of Water in Concentrated Solutions of Amphiphiles: Key Roles of Local Structure and Aggregation. J Phys Chem B 2011; 115:3254-62. [DOI: 10.1021/jp112001d] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Guillaume Stirnemann
- Ecole Normale Supérieure, Chemistry Department, UMR CNRS-ENS-UPMC 8640, 24 rue Lhomond, 75005 Paris, France
| | - Fabio Sterpone
- Ecole Normale Supérieure, Chemistry Department, UMR CNRS-ENS-UPMC 8640, 24 rue Lhomond, 75005 Paris, France
| | - Damien Laage
- Ecole Normale Supérieure, Chemistry Department, UMR CNRS-ENS-UPMC 8640, 24 rue Lhomond, 75005 Paris, France
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