1
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Stevens MJ, Rempe SLB. Insight into the K channel's selectivity from binding of K +, Na + and water to N-methylacetamide. Faraday Discuss 2024; 249:195-209. [PMID: 37846738 DOI: 10.1039/d3fd00110e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2023]
Abstract
In potassium channels that conduct K+ selectively over Na+, which sites are occupied by K+ or water and the mechanism of selectivity are unresolved questions. The combination of the energetics and the constraints imposed by the protein structure yield the selective permeation and occupancy. To gain insight into the combination of structure and energetics, we performed density functional theory (DFT) calculations of multiple N-methyl acetamide (NMA) ligands binding to K+ and Na+, relative to hydrated K+ and Na+. NMA is an analogue of the amino acid backbone and provides the carbonyl binding to the ions that occurs in most binding sites of the K+ channel. Unconstrained optimal structures are obtained through geometry optimization calculations of the NMA ligand binding. The complexes formed by 8 NMA binding to the cations have the O atoms positioned in nearly identical locations as the O atoms in the selectivity filter. The transfer free energies between bulk water and K+ or Na+ bound to 8 NMA are almost identical, implying there is no selectivity by a single site. For water optimized with 8 NMA, binding is weak and O atoms are not positioned as in the K+ channel selectivity filter, suggesting that the ions are much more favored than water. Optimal structures of 8 NMA binding with two cations (K+ or Na+) are stable and have lower binding free energy than the optimal structures with just one cation. However, in the Na+ case, the optimal structure deforms and does not match the K+ channel; that is, two bound Na+ are destabilizing. In contrast, the two K+ structure is stabilized and the selectivity free energy favors K+. Overall, this study shows that binding site occupancy and the mechanism for K+ selectivity involves multiple K+ binding in multiple neighboring layers or sites of the K+ channel selectivity filter.
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Affiliation(s)
- Mark J Stevens
- Center for Integrated Nanotechnologies, Sandia National Laboratories, Albuquerque, NM 87185, USA.
| | - Susan L B Rempe
- Center for Integrated Nanotechnologies, Sandia National Laboratories, Albuquerque, NM 87185, USA.
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2
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Yue S, Nandy A, Kulik HJ. Discovering Molecular Coordination Environment Trends for Selective Ion Binding to Molecular Complexes Using Machine Learning. J Phys Chem B 2023. [PMID: 38038675 DOI: 10.1021/acs.jpcb.3c06416] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2023]
Abstract
The design of ion-selective materials with improved separation efficacy and efficiency is paramount, as current technologies fail to meet real-world deployment challenges. Selectivity in these materials can be informed by local ion binding in confined membrane ion channels. In this study, we utilize a data-driven approach to investigate design features in small molecular complexes coordinating ions as simplified models of ion channels. We curate a data set of 563 alkali metal coordinating molecular complexes (i.e., with Li+, Na+, or K+) from the Cambridge Structural Database and calculate differential ion binding energies using density functional theory. Using this information, we probe when and why structures favor exchange with alternate ions. Our analysis reveals that energetic preferences are related to ion size but are largely due to chemical interactions rather than structural reorganization. We identify unique trends in the selectivity for Li+ over other alkali ions, including the presence of N coordination atoms, planar coordination geometry, and small coordinating ring sizes. We use machine learning models to identify the key contributions of both geometric and electronic features in predicting selective ion binding. These physical insights offer preliminary guidance into the design of optimal membranes for ion selectivity.
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Affiliation(s)
- Shuwen Yue
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Aditya Nandy
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Heather J Kulik
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
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3
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Stevens MJ, Rempe SLB. Binding of Li + to Negatively Charged and Neutral Ligands in Polymer Electrolytes. J Phys Chem Lett 2023; 14:10200-10207. [PMID: 37930189 DOI: 10.1021/acs.jpclett.3c02565] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2023]
Abstract
Conceptually, single-ion polymer electrolytes (SIPE) with the anion bound to the polymer could solve major issues in Li-ion batteries, but their conductivity is too low. Experimentally, weakly interacting anionic groups have the best conductivity. To provide a theoretical basis for this result, density functional theory calculations of the optimized geometries and energies are performed for charged ligands used in SIPE. Comparison is made to neutral ligands found in dual-ion conductors, which demonstrate higher conductivity. The free energy differences between adding and subtracting a ligand are small enough for the neutral ligands to have the conductivity seen experimentally. However, charged ligands have large barriers, implying that lithium transport will coincide with the slow polymer diffusion, as observed in experiments. Overall, SIPE will require additional solvent to achieve a sufficiently high conductivity. Additionally, the binding of mono- and bidentate geometries varies, providing a simple and clear reason that polarizable force fields are required for detailed interactions.
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Affiliation(s)
- Mark J Stevens
- Center for Integrated Nanotechnologies, Sandia National Laboratories, Albuquerque, New Mexico 87185, United States
| | - Susan L B Rempe
- Center for Integrated Nanotechnologies, Sandia National Laboratories, Albuquerque, New Mexico 87185, United States
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4
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Stevens MJ, Rempe SLB. Binding of carboxylate and water to monovalent cations. Phys Chem Chem Phys 2023; 25:29881-29893. [PMID: 37889481 DOI: 10.1039/d3cp04200f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2023]
Abstract
The interactions of carboxylate anions with water and cations are important for a wide variety of systems, both biological and synthetic. To gain insight on properties of the local complexes, we apply density functional theory, to treat the complex electrostatic interactions, and investigate mixtures with varied numbers of carboxylate anions (acetate) and waters binding to monovalent cations, Li+, Na+ and K+. The optimal structure with overall lowest free energy contains two acetates and two waters such that the cation is four-fold coordinated, similar to structures found earlier for pure water or pure carboxylate ligands. More generally, the complexes with two acetates have the lowest free energy. In transitioning from the overall optimal state, exchanging an acetate for water has a lower free energy barrier than exchanging water for an acetate. In most cases, the carboxylates are monodentate and in the first solvation shell. As water is added to the system, hydrogen bonding between waters and carboxylate O atoms further stabilizes monodentate structures. These structures, which have strong electrostatic interactions that involve hydrogen bonds of varying strength, are significantly polarized, with ChelpG partial charges that vary substantially as the bonding geometry varies. Overall, these results emphasize the increasing importance of water as a component of binding sites as the number of ligands increases, thus affecting the preferential solvation of specific metal ions and clarifying Hofmeister effects. Finally, structural analysis correlated with free energy analysis supports the idea that binding to more than the preferred number of carboxylates under architectural constraints are a key to ion transport.
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Affiliation(s)
- Mark J Stevens
- Center for Integrated Nanotechnologies, Sandia National Laboratories, Albuquerque, NM 87185, USA.
| | - Susan L B Rempe
- Center for Integrated Nanotechnologies, Sandia National Laboratories, Albuquerque, NM 87185, USA.
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5
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Seiferth D, Tucker SJ, Biggin PC. Limitations of non-polarizable force fields in describing anion binding poses in non-polar synthetic hosts. Phys Chem Chem Phys 2023. [PMID: 37365974 DOI: 10.1039/d3cp00479a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/28/2023]
Abstract
Transmembrane anion transport by synthetic ionophores has received increasing interest not only because of its relevance for understanding endogenous anion transport, but also because of potential implications for therapeutic routes in disease states where chloride transport is impaired. Computational studies can shed light on the binding recognition process and can deepen our mechanistic understanding of them. However, the ability of molecular mechanics methods to properly capture solvation and binding properties of anions is known to be challenging. Consequently, polarizable models have been suggested to improve the accuracy of such calculations. In this study, we calculate binding free energies for different anions to the synthetic ionophore, biotin[6]uril hexamethyl ester in acetonitrile and to biotin[6]uril hexaacid in water by employing non-polarizable and polarizable force fields. Anion binding shows strong solvent dependency consistent with experimental studies. In water, the binding strengths are iodide > bromide > chloride, and reversed in acetonitrile. These trends are well captured by both classes of force fields. However, the free energy profiles obtained from potential of mean force calculations and preferred binding positions of anions depend on the treatment of electrostatics. Results from simulations using the AMOEBA force-field, which recapitulate the observed binding positions, suggest strong effects from multipoles dominate with a smaller contribution from polarization. The oxidation status of the macrocycle was also found to influence anion recognition in water. Overall, these results have implications for the understanding of anion host interactions not just in synthetic ionophores, but also in narrow cavities of biological ion channels.
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Affiliation(s)
- David Seiferth
- Clarendon Laboratory, Department of Physics, University of Oxford, Oxford, OX1 3PU, UK
- Structural Bioinformatics and Computational Biochemistry, Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK.
| | - Stephen J Tucker
- Clarendon Laboratory, Department of Physics, University of Oxford, Oxford, OX1 3PU, UK
- Kavli Institute for Nanoscience Discovery, University of Oxford, Oxford, UK
| | - Philip C Biggin
- Structural Bioinformatics and Computational Biochemistry, Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK.
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6
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Gomez DT, Pratt LR, Asthagiri DN, Rempe SB. Hydrated Anions: From Clusters to Bulk Solution with Quasi-Chemical Theory. Acc Chem Res 2022; 55:2201-2212. [PMID: 35829622 PMCID: PMC9386901 DOI: 10.1021/acs.accounts.2c00078] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The interactions of hydrated ions with molecular and macromolecular solution and interface partners are strong on a chemical energy scale. Here, we recount the foremost ab initio theory for the evaluation of the hydration free energies of ions, namely, quasi-chemical theory (QCT). We focus on anions, particularly halides but also the hydroxide anion, because they have been outstanding challenges for all theories. For example, this work supports understanding the high selectivity for F- over Cl- in fluoride-selective ion channels despite the identical charge and the size similarity of these ions. QCT is built by the identification of inner-shell clusters, separate treatment of those clusters, and then the integration of those results into the broader-scale solution environment. Recent work has focused on a close comparison with mass-spectrometric measurements of ion-hydration equilibria. We delineate how ab initio molecular dynamics (AIMD) calculations on ion-hydration clusters, elementary statistical thermodynamics, and electronic structure calculations on cluster structures sampled from the AIMD calculations obtain just the free energies extracted from the cluster experiments. That theory-experiment comparison has not been attempted before the work discussed here, but the agreement is excellent with moderate computational effort. This agreement reinforces both theory and experiment and provides a numerically accurate inner-shell contribution to QCT. The inner-shell complexes involving heavier halides display strikingly asymmetric hydration clusters. Asymmetric hydration structures can be problematic for the evaluation of the QCT outer-shell contribution with the polarizable continuum model (PCM). Nevertheless, QCT provides a favorable setting for the exploitation of PCM when the inner-shell material shields the ion from the outer solution environment. For the more asymmetrically hydrated, and thus less effectively shielded, heavier halide ions clustered with waters, the PCM is less satisfactory. We therefore investigate an inverse procedure in which the inner-shell structures are sampled from readily available AIMD calculations on the bulk solutions. This inverse procedure is a remarkable improvement; our final results are in close agreement with a standard tabulation of hydration free energies, and the final composite results are independent of the coordination number on the chemical energy scale of relevance, as they should be. Finally, a comparison of anion hydration structure in clusters and bulk solutions from AIMD simulations emphasize some differences: the asymmetries of bulk solution inner-shell structures are moderated compared with clusters but are still present, and inner hydration shells fill to slightly higher average coordination numbers in bulk solution than in clusters.
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Affiliation(s)
- Diego T. Gomez
- Department
of Chemical & Biomolecular Engineering, Tulane University, New Orleans, Louisiana 70118, United States,
| | - Lawrence R. Pratt
- Department
of Chemical & Biomolecular Engineering, Tulane University, New Orleans, Louisiana 70118, United States,
| | - Dilipkumar N. Asthagiri
- Department
of Chemical and Biomolecular Engineering, Rice University, Houston, Texas 77005, United States,
| | - Susan B. Rempe
- Center
for Integrated Nanotechnologies, Sandia
National Laboratories, Albuquerque, New Mexico 87185, United States,
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7
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Sagresti L, Peri L, Ceccarelli G, Brancato G. Stochastic Model of Solvent Exchange in the First Coordination Shell of Aqua Ions. J Chem Theory Comput 2022; 18:3164-3173. [PMID: 35471007 PMCID: PMC9097284 DOI: 10.1021/acs.jctc.2c00181] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Ion microsolvation is a basic, yet fundamental, process of ionic solutions underlying many relevant phenomena in either biological or nanotechnological applications, such as solvent reorganization energy, ion transport, catalytic activity, and so on. As a consequence, it is a topic of extensive investigations by various experimental techniques, ranging from X-ray diffraction to NMR relaxation and from calorimetry to vibrational spectroscopy, and theoretical approaches, especially those based on molecular dynamics (MD) simulations. The conventional microscopic view of ion solvation is usually provided by a "static" cluster model representing the first ion-solvent coordination shell. Despite the merits of such a simple model, however, ion coordination in solution should be better regarded as a complex population of dynamically interchanging molecular configurations. Such a more comprehensive view is more subtle to characterize and often elusive to standard approaches. In this work, we report on an effective computational strategy aiming at providing a detailed picture of solvent coordination and exchange around aqua ions, thus including the main structural, thermodynamic, and dynamic properties of ion microsolvation, such as the most probable first-shell complex structures, the corresponding free energies, the interchanging energy barriers, and the solvent-exchange rates. Assuming the solvent coordination number as an effective reaction coordinate and combining MD simulations with enhanced sampling and master-equation approaches, we propose a stochastic model suitable for properly describing, at the same time, the thermodynamics and kinetics of ion-water coordination. The model is successfully tested toward various divalent ions (Ca2+, Zn2+, Hg2+, and Cd2+) in aqueous solution, considering also the case of a high ionic concentration. Results show a very good agreement with those issuing from brute-force MD simulations, when available, and support the reliable prediction of rare ion-water complexes and slow water exchange rates not easily accessible to usual computational methods.
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Affiliation(s)
- Luca Sagresti
- Scuola Normale Superiore, Piazza Dei Cavalieri 7, I-56126 Pisa, Italy.,Istituto Nazionale di Fisica Nucleare (INFN), Largo Pontecorvo 3, I-56127 Pisa, Italy
| | - Lorenzo Peri
- Scuola Normale Superiore, Piazza Dei Cavalieri 7, I-56126 Pisa, Italy
| | - Giacomo Ceccarelli
- Dipartimento di Fisica, Università di Pisa, Largo Bruno Pontecorvo 3, I-56127 Pisa, Italy
| | - Giuseppe Brancato
- Scuola Normale Superiore, Piazza Dei Cavalieri 7, I-56126 Pisa, Italy.,Istituto Nazionale di Fisica Nucleare (INFN), Largo Pontecorvo 3, I-56127 Pisa, Italy.,Consorzio Interuniversitario per Lo Sviluppo Dei Sistemi a Grande Interfase (CSGI), Via Della Lastruccia 3, I-50019 Sesto Fiorentino (FI), Italy
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8
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Milovanović B, Petković M, Popov I, Etinski M. Water-Mediated Interactions Enhance Alkaline Earth Cation Chelation in Neighboring Cavities of a Cytosine Quartet in the DNA Quadruplex. J Phys Chem B 2021; 125:11996-12005. [PMID: 34694801 DOI: 10.1021/acs.jpcb.1c05598] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Larger Coulombic repulsion between divalent cations compared to the monovalent counterparts dictates the cation-cation distance in the central ion channel of quadruplexes. In this work, density functional theory and a continuum solvation model were employed to study bond energies of alkaline earth cations in adjacent cavities of the central ion channel. Four crystallized tetramolecular quadruplexes with various geometric constraints and structural motifs available in the Protein Data Bank were examined in order to understand how the cation binding affinities could be increased in aqueous solution. A cytosine quartet sandwiched between guanine quartets has a larger bond energy of the second alkaline earth cation in comparison with guanine and uracil quartets. Four highly conserved hydrogen-bonded water molecules in the center of the cytosine quartet are responsible for a higher electrostatic interaction with the cations in comparison with guanines' carbonyl groups. The reported findings are valuable for the design of synthetic quadruplexes templated with divalent cations for optoelectronic applications.
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Affiliation(s)
- Branislav Milovanović
- Faculty of Physical Chemistry, University of Belgrade, Studentski trg 12-16 11000 Belgrade, Serbia
| | - Milena Petković
- Faculty of Physical Chemistry, University of Belgrade, Studentski trg 12-16 11000 Belgrade, Serbia
| | - Igor Popov
- Institute for Multidisciplinary Research, University of Belgrade, Kneza Višeslava 1, 11030 Belgrade, Serbia.,Institut of Physics, University of Belgrade, Pregrevica 118, 11080 Belgrade, Serbia
| | - Mihajlo Etinski
- Faculty of Physical Chemistry, University of Belgrade, Studentski trg 12-16 11000 Belgrade, Serbia
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9
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Shi Y, Doyle CC, Beck TL. Condensed Phase Water Molecular Multipole Moments from Deep Neural Network Models Trained on Ab Initio Simulation Data. J Phys Chem Lett 2021; 12:10310-10317. [PMID: 34662132 DOI: 10.1021/acs.jpclett.1c02328] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Ionic solvation phenomena in liquids involve intense interactions in the inner solvation shell. For interactions beyond the first shell, the ion-solvent interaction energies result from the sum of many smaller-magnitude contributions that can still include polarization effects. Deep neural network (DNN) methods have recently found wide application in developing efficient molecular models that maintain near-quantum accuracy. Here we extend the DeePMD-kit code to produce accurate molecular multipole moments in the bulk and near interfaces. The new method is validated by comparing the DNN moments with those generated by ab initio simulations. The moments are used to compute the electrostatic potential at the center of a molecular-sized hydrophobic cavity in water. The results show that the fields produced by the DNN models are in quantitative agreement with the AIMD-derived values. These efficient methods will open the door to more accurate solvation models for large solutes such as proteins.
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Affiliation(s)
- Yu Shi
- Department of Chemistry, University of Cincinnati, Cincinnati, Ohio 45221-0172, United States
| | - Carrie C Doyle
- Department of Chemistry, University of Cincinnati, Cincinnati, Ohio 45221-0172, United States
| | - Thomas L Beck
- Department of Chemistry, University of Cincinnati, Cincinnati, Ohio 45221-0172, United States
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10
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Asthagiri DN, Paulaitis ME, Pratt LR. Thermodynamics of Hydration from the Perspective of the Molecular Quasichemical Theory of Solutions. J Phys Chem B 2021; 125:8294-8304. [PMID: 34313434 DOI: 10.1021/acs.jpcb.1c04182] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The quasichemical organization of the potential distribution theorem, molecular quasichemical theory (QCT), enables practical calculations and also provides a conceptual framework for molecular hydration phenomena. QCT can be viewed from multiple perspectives: (a) as a way to regularize an ill-conditioned statistical thermodynamic problem; (b) as an introduction of and emphasis on the neighborship characteristics of a solute of interest; or (c) as a way to include accurate electronic structure descriptions of near-neighbor interactions in defensible statistical thermodynamics by clearly defining neighborship clusters. The theory has been applied to solutes of a wide range of chemical complexity, ranging from ions that interact with water with both long-ranged and chemically intricate short-ranged interactions, to solutes that interact with water solely through traditional van der Waals interations, and including water itself. The solutes range in variety from monatomic ions to chemically heterogeneous macromolecules. A notable feature of QCT is that, in applying the theory to this range of solutes, the theory itself provides guidance on the necessary approximations and simplifications that can facilitate the calculations. In this Perspective, we develop these ideas and document them with examples that reveal the insights that can be extracted using the QCT formulation.
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Affiliation(s)
- Dilipkumar N Asthagiri
- Department of Chemical and Biomolecular Engineering, Rice University, Houston, Texas 77005, United States
| | - Michael E Paulaitis
- Center for Nanomedicine, Johns Hopkins School of Medicine, Baltimore, Maryland 21231, United States
| | - Lawrence R Pratt
- Department of Chemical and Biomolecular Engineering, Tulane University, New Orleans, Louisiana 70118, United States
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11
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Gomez DT, Pratt LR, Rogers DM, Rempe SB. Free Energies of Hydrated Halide Anions: High Through-Put Computations on Clusters to Treat Rough Energy-Landscapes. Molecules 2021; 26:molecules26113087. [PMID: 34064203 PMCID: PMC8196753 DOI: 10.3390/molecules26113087] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Revised: 05/04/2021] [Accepted: 05/10/2021] [Indexed: 11/30/2022] Open
Abstract
With a longer-term goal of addressing the comparative behavior of the aqueous halides F−, Cl−, Br−, and I− on the basis of quasi-chemical theory (QCT), here we study structures and free energies of hydration clusters for those anions. We confirm that energetically optimal (H2O)nX clusters, with X = Cl−, Br−, and I−, exhibit surface hydration structures. Computed free energies, based on optimized surface hydration structures utilizing a harmonic approximation, typically (but not always) disagree with experimental free energies. To remedy the harmonic approximation, we utilize single-point electronic structure calculations on cluster geometries sampled from an AIMD (ab initio molecular dynamics) simulation stream. This rough-landscape procedure is broadly satisfactory and suggests unfavorable ligand crowding as the physical effect addressed. Nevertheless, this procedure can break down when n≳4, with the characteristic discrepancy resulting from a relaxed definition of clustering in the identification of (H2O)nX clusters, including ramified structures natural in physical cluster theories. With ramified structures, the central equation for the present rough-landscape approach can acquire some inconsistency. Extension of these physical cluster theories in the direction of QCT should remedy that issue, and should be the next step in this research direction.
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Affiliation(s)
- Diego T. Gomez
- Department of Chemical & Biomolecular Engineering, Tulane University, New Orleans, LA 70118, USA; (D.T.G.); (L.R.P.)
| | - Lawrence R. Pratt
- Department of Chemical & Biomolecular Engineering, Tulane University, New Orleans, LA 70118, USA; (D.T.G.); (L.R.P.)
| | - David M. Rogers
- National Center for Computational Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37830, USA;
| | - Susan B. Rempe
- Center for Integrated Nanotechnologies, Sandia National Laboratories, Albuquerque, NM 87185, USA
- Correspondence: ; Tel.: +1-505-845-0253
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12
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Maerzke KA, Yoon TJ, Jadrich RB, Leiding JA, Currier RP. First-Principles Simulations of CuCl in High-Temperature Water Vapor. J Phys Chem B 2021; 125:4794-4807. [PMID: 33938730 DOI: 10.1021/acs.jpcb.1c00083] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Experimental data suggest that the solubility of copper in high-temperature water vapor is controlled by the formation of hydrated clusters of the form CuCl(H2O)n, where the average number of water molecules in the cluster generally increases with increasing density [Migdisov, A. A.; et al. Geochim. Cosmochim. Acta 2014, 129, 33-53]. However, the precise nature of these clusters is difficult to probe experimentally. Moreover, there are some discrepancies between experimental estimates of average cluster size and prior simulation work [Mei, Y. Geofluids 2018, 2018, 4279124]. We have performed first-principles Monte Carlo (MC) and molecular dynamics (MD) simulations to explore these clusters in finer detail. We find that molecular dynamics is not the most appropriate technique for studying aggregation in vapor phases, even at relatively high temperatures. Specifically, our MD simulations exhibit substantial problems in adequately sampling the equilibrium cluster size distribution. In contrast, MC simulations with specialized cluster moves are able to accurately sample the phase space of hydrogen-bonding vapors. At all densities, we find a stable, slightly distorted linear H2O-Cu-Cl structure, which is in agreement with the earlier simulations, surrounded by a variable number of water molecules. The surrounding water molecules do not form a well-defined second solvation shell but rather a loose network of hydrogen-bonded water with molecular CuCl on the outside edge of the water cluster. We also find a broad distribution of hydration numbers, especially at higher densities. In contrast to previous simulation work but in agreement with experimental data, we find that the average hydration number substantially increases with increasing density. Moreover, the value of the hydration number depends on the choice of cluster definition.
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Affiliation(s)
- Katie A Maerzke
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Tae Jun Yoon
- Materials Physics and Applications Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Ryan B Jadrich
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States.,Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Jeffery A Leiding
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Robert P Currier
- Chemistry Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
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13
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Hpone Myint K, Ding W, Willard AP. The Influence of Spectator Cations on Solvent Reorganization Energy Is a Short-Range Effect. J Phys Chem B 2021; 125:1429-1438. [PMID: 33525875 DOI: 10.1021/acs.jpcb.0c09895] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In this manuscript, we use classical molecular dynamics simulation to explore the origin of specific cation effects on the rates of bulk-phase aqueous electron transfer (ET) reactions. We consider 0.6 M solutions of Cl- and a series of different cations: Li+, Na+, K+, Rb+, and Cs+. We evaluate the collective electrostatic fluctuations that drive Marcus-like ET and find that they are essentially unaffected by changes in the cationic species. This finding implies that the structure making/breaking properties of various cations do not exert a significant influence on bulk-phase ET reactions. We evaluate the role of ion pairing in these specific cation effects and find, unsurprisingly, that model redox anions that are more highly charged tend to pair more effectively with spectator cations than their monovalent counterparts. We demonstrate that this ion pairing significantly affects local electrostatic fluctuations for the anionic redox species and thus conclude that ion pairing is one of the likely sources of rate-dependent cation effects in aqueous ET reactions.
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Affiliation(s)
- Kyaw Hpone Myint
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Wendu Ding
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Adam P Willard
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
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14
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Rahman S, Wineman-Fisher V, Al-Hamdani Y, Tkatchenko A, Varma S. Predictive QM/MM Modeling of Modulations in Protein-Protein Binding by Lysine Methylation. J Mol Biol 2021; 433:166745. [PMID: 33307090 PMCID: PMC9801414 DOI: 10.1016/j.jmb.2020.166745] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 11/25/2020] [Accepted: 12/02/2020] [Indexed: 01/03/2023]
Abstract
Lysine methylation is a key regulator of protein-protein binding. The amine group of lysine can accept up to three methyl groups, and experiments show that protein-protein binding free energies are sensitive to the extent of methylation. These sensitivities have been rationalized in terms of chemical and structural features present in the binding pockets of methyllysine binding domains. However, understanding their specific roles requires an energetic analysis. Here we propose a theoretical framework to combine quantum and molecular mechanics methods, and compute the effect of methylation on protein-protein binding free energies. The advantages of this approach are that it derives contributions from all local non-trivial effects of methylation on induction, polarizability and dispersion directly from self-consistent electron densities, and at the same time determines contributions from well-characterized hydration effects using a computationally efficient classical mean field method. Limitations of the approach are discussed, and we note that predicted free energies of fourteen out of the sixteen cases agree with experiment. Critical assessment of these cases leads to the following overarching principles that drive methylation-state recognition by protein domains. Methylation typically reduces the pairwise interaction between proteins. This biases binding toward lower methylated states. Simultaneously, however, methylation also makes it easier to partially dehydrate proteins and place them in protein-protein complexes. This latter effect biases binding in favor of higher methylated states. The overall effect of methylation on protein-protein binding depends ultimately on the balance between these two effects, which is observed to be tuned via several combinations of local features.
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Affiliation(s)
- Sanim Rahman
- Department of Cell Biology, Microbiology and Molecular Biology, University of South Florida, 4202 E. Fowler Ave., Tampa, FL-33620, USA
| | - Vered Wineman-Fisher
- Department of Cell Biology, Microbiology and Molecular Biology, University of South Florida, 4202 E. Fowler Ave., Tampa, FL-33620, USA
| | - Yasmine Al-Hamdani
- Physics and Materials Science Research Unit, University of Luxembourg, L-1511 Luxembourg, Luxembourg
| | - Alexandre Tkatchenko
- Physics and Materials Science Research Unit, University of Luxembourg, L-1511 Luxembourg, Luxembourg
| | - Sameer Varma
- Department of Cell Biology, Microbiology and Molecular Biology, University of South Florida, 4202 E. Fowler Ave., Tampa, FL-33620, USA,Department of Physics, University of South Florida, 4202 E. Fowler Ave., Tampa, FL-33620, USA,
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15
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Utiramerur S, Paulaitis M. Analysis of Cooperativity and Group Additivity in the Hydration of 1,2-Dimethoxyethane. J Phys Chem B 2021; 125:1660-1666. [DOI: 10.1021/acs.jpcb.0c10729] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Sowmi Utiramerur
- William G. Lowrie Department of Chemical and Biomolecular Engineering, Ohio State University, Columbus, Ohio 43210, United States
| | - Michael Paulaitis
- William G. Lowrie Department of Chemical and Biomolecular Engineering, Ohio State University, Columbus, Ohio 43210, United States
- The Center for Nanomedicine at the Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland 21231, United States
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16
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Absolute ion hydration free energy scale and the surface potential of water via quantum simulation. Proc Natl Acad Sci U S A 2020; 117:30151-30158. [PMID: 33203676 DOI: 10.1073/pnas.2017214117] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
With a goal of determining an absolute free energy scale for ion hydration, quasi-chemical theory and ab initio quantum mechanical simulations are employed to obtain an accurate value for the bulk hydration free energy of the Na+ ion. The free energy is partitioned into three parts: 1) the inner-shell or chemical contribution that includes direct interactions of the ion with nearby waters, 2) the packing free energy that is the work to produce a cavity of size λ in water, and 3) the long-range contribution that involves all interactions outside the inner shell. The interfacial potential contribution to the free energy resides in the long-range term. By averaging cation and anion data for that contribution, cumulant terms of all odd orders in the electrostatic potential are removed. The computed total is then the bulk hydration free energy. Comparison with the experimentally derived real hydration free energy produces an effective surface potential of water in the range -0.4 to -0.5 V. The result is consistent with a variety of experiments concerning acid-base chemistry, ion distributions near hydrophobic interfaces, and electric fields near the surface of water droplets.
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17
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Wineman-Fisher V, Delgado JM, Nagy PR, Jakobsson E, Pandit SA, Varma S. Transferable interactions of Li + and Mg 2+ ions in polarizable models. J Chem Phys 2020; 153:104113. [PMID: 32933310 DOI: 10.1063/5.0022060] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Therapeutic implications of Li+, in many cases, stem from its ability to inhibit certain Mg2+-dependent enzymes, where it interacts with or substitutes for Mg2+. The underlying details of its action are, however, unknown. Molecular simulations can provide insights, but their reliability depends on how well they describe relative interactions of Li+ and Mg2+ with water and other biochemical groups. Here, we explore, benchmark, and recommend improvements to two simulation approaches: the one that employs an all-atom polarizable molecular mechanics (MM) model and the other that uses a hybrid quantum and MM implementation of the quasi-chemical theory (QCT). The strength of the former is that it describes thermal motions explicitly and that of the latter is that it derives local contributions from electron densities. Reference data are taken from the experiment, and also obtained systematically from CCSD(T) theory, followed by a benchmarked vdW-inclusive density functional theory. We find that the QCT model predicts relative hydration energies and structures in agreement with the experiment and without the need for additional parameterization. This implies that accurate descriptions of local interactions are essential. Consistent with this observation, recalibration of local interactions in the MM model, which reduces errors from 10.0 kcal/mol to 1.4 kcal/mol, also fixes aqueous phase properties. Finally, we show that ion-ligand transferability errors in the MM model can be reduced significantly from 10.3 kcal/mol to 1.2 kcal/mol by correcting the ligand's polarization term and by introducing Lennard-Jones cross-terms. In general, this work sets up systematic approaches to evaluate and improve molecular models of ions binding to proteins.
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Affiliation(s)
- Vered Wineman-Fisher
- Department of Cell Biology, Microbiology and Molecular Biology, University of South Florida, Tampa, Florida 33620, USA
| | - Julián Meléndez Delgado
- Department of Cell Biology, Microbiology and Molecular Biology, University of South Florida, Tampa, Florida 33620, USA
| | - Péter R Nagy
- Department of Physical Chemistry and Materials Science, Budapest University of Technology and Economics, P.O. Box 91, H-1521 Budapest, Hungary
| | - Eric Jakobsson
- National Center for Supercomputing Applications, Center for Biophysics and Computational Biology, Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
| | - Sagar A Pandit
- Department of Physics, University of South Florida, Tampa, Florida 33620, USA
| | - Sameer Varma
- Department of Cell Biology, Microbiology and Molecular Biology, University of South Florida, Tampa, Florida 33620, USA
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18
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Maldonado AM, Basdogan Y, Berryman JT, Rempe SB, Keith JA. First-principles modeling of chemistry in mixed solvents: Where to go from here? J Chem Phys 2020; 152:130902. [PMID: 32268733 DOI: 10.1063/1.5143207] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Mixed solvents (i.e., binary or higher order mixtures of ionic or nonionic liquids) play crucial roles in chemical syntheses, separations, and electrochemical devices because they can be tuned for specific reactions and applications. Apart from fully explicit solvation treatments that can be difficult to parameterize or computationally expensive, there is currently no well-established first-principles regimen for reliably modeling atomic-scale chemistry in mixed solvent environments. We offer our perspective on how this process could be achieved in the near future as mixed solvent systems become more explored using theoretical and computational chemistry. We first outline what makes mixed solvent systems far more complex compared to single-component solvents. An overview of current and promising techniques for modeling mixed solvent environments is provided. We focus on so-called hybrid solvation treatments such as the conductor-like screening model for real solvents and the reference interaction site model, which are far less computationally demanding than explicit simulations. We also propose that cluster-continuum approaches rooted in physically rigorous quasi-chemical theory provide a robust, yet practical, route for studying chemical processes in mixed solvents.
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Affiliation(s)
- Alex M Maldonado
- Department of Chemical and Petroleum Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
| | - Yasemin Basdogan
- Department of Chemical and Petroleum Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
| | - Joshua T Berryman
- Department of Physics and Materials Science, University of Luxembourg, L-1511 Luxembourg City, Luxembourg
| | - Susan B Rempe
- Center for Computational Biology and Biophysics, Sandia National Laboratories, Albuquerque, New Mexico 87185, USA
| | - John A Keith
- Department of Chemical and Petroleum Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
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19
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Chaudhari MI, Vanegas JM, Pratt LR, Muralidharan A, Rempe SB. Hydration Mimicry by Membrane Ion Channels. Annu Rev Phys Chem 2020; 71:461-484. [PMID: 32155383 DOI: 10.1146/annurev-physchem-012320-015457] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Ions transiting biomembranes might pass readily from water through ion-specific membrane proteins if these protein channels provide environments similar to the aqueous solution hydration environment. Indeed, bulk aqueous solution is an important reference condition for the ion permeation process. Assessment of this hydration mimicry concept depends on understanding the hydration structure and free energies of metal ions in water in order to provide a comparison for the membrane channel environment. To refine these considerations, we review local hydration structures of ions in bulk water and the molecular quasi-chemical theory that provides hydration free energies. In doing so, we note some current views of ion binding to membrane channels and suggest new physical chemical calculations and experiments that might further clarify the hydration mimicry concept.
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Affiliation(s)
- Mangesh I Chaudhari
- Department of Computational Biology and Biophysics, Sandia National Laboratories, Albuquerque, New Mexico 87185, USA;
| | - Juan M Vanegas
- Department of Computational Biology and Biophysics, Sandia National Laboratories, Albuquerque, New Mexico 87185, USA; .,Current affiliation: Department of Physics, University of Vermont, Burlington, Vermont 05405, USA
| | - L R Pratt
- Department of Chemical and Biomolecular Engineering, Tulane University, New Orleans, Louisiana 70118, USA
| | - Ajay Muralidharan
- Department of Chemical and Biomolecular Engineering, Tulane University, New Orleans, Louisiana 70118, USA.,Current affiliation: Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706, USA
| | - Susan B Rempe
- Department of Computational Biology and Biophysics, Sandia National Laboratories, Albuquerque, New Mexico 87185, USA;
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20
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Asthagiri D, Tomar DS. System Size Dependence of Hydration-Shell Occupancy and Its Implications for Assessing the Hydrophobic and Hydrophilic Contributions to Hydration. J Phys Chem B 2020; 124:798-806. [DOI: 10.1021/acs.jpcb.9b11200] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Affiliation(s)
- Dilipkumar Asthagiri
- Department of Chemical and Biomolecular Engineering, Rice University, Houston, Texas 77005, United States
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21
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Basdogan Y, Groenenboom MC, Henderson E, De S, Rempe SB, Keith JA. Machine Learning-Guided Approach for Studying Solvation Environments. J Chem Theory Comput 2019; 16:633-642. [PMID: 31809056 DOI: 10.1021/acs.jctc.9b00605] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Molecular-level understanding and characterization of solvation environments are often needed across chemistry, biology, and engineering. Toward practical modeling of local solvation effects of any solute in any solvent, we report a static and all-quantum mechanics-based cluster-continuum approach for calculating single-ion solvation free energies. This approach uses a global optimization procedure to identify low-energy molecular clusters with different numbers of explicit solvent molecules and then employs the smooth overlap for atomic positions learning kernel to quantify the similarity between different low-energy solute environments. From these data, we use sketch maps, a nonlinear dimensionality reduction algorithm, to obtain a two-dimensional visual representation of the similarity between solute environments in differently sized microsolvated clusters. After testing this approach on different ions having charges 2+, 1+, 1-, and 2-, we find that the solvation environment around each ion can be seen to usually become more similar in hand with its calculated single-ion solvation free energy. Without needing either dynamics simulations or an a priori knowledge of local solvation structure of the ions, this approach can be used to calculate solvation free energies within 5% of experimental measurements for most cases, and it should be transferable for the study of other systems where dynamics simulations are not easily carried out.
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Affiliation(s)
- Yasemin Basdogan
- Department of Chemical and Petroleum Engineering Swanson School of Engineering , University of Pittsburgh , Pittsburgh 15261 , Pennsylvania , United States
| | - Mitchell C Groenenboom
- Department of Chemical and Petroleum Engineering Swanson School of Engineering , University of Pittsburgh , Pittsburgh 15261 , Pennsylvania , United States
| | - Ethan Henderson
- Department of Chemical and Petroleum Engineering Swanson School of Engineering , University of Pittsburgh , Pittsburgh 15261 , Pennsylvania , United States
| | - Sandip De
- Laboratory of Computational Science and Modelling, Institute of Materials , École Polytechnique Fédérale de Lausanne , Lausanne 1015 , Switzerland
| | - Susan B Rempe
- Department of Nanobiology , Sandia National Laboratories , Albuquerque 87185 , New Mexico , United States
| | - John A Keith
- Department of Chemical and Petroleum Engineering Swanson School of Engineering , University of Pittsburgh , Pittsburgh 15261 , Pennsylvania , United States
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22
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Muralidharan A, Pratt L, Chaudhari M, Rempe S. Quasi-chemical theory for anion hydration and specific ion effects: Cl-(aq) vs. F-(aq). ACTA ACUST UNITED AC 2019. [DOI: 10.1016/j.cpletx.2019.100037] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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23
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Wineman-Fisher V, Al-Hamdani Y, Addou I, Tkatchenko A, Varma S. Ion-Hydroxyl Interactions: From High-Level Quantum Benchmarks to Transferable Polarizable Force Fields. J Chem Theory Comput 2019; 15:2444-2453. [PMID: 30830778 PMCID: PMC6598712 DOI: 10.1021/acs.jctc.8b01198] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Ion descriptors in molecular mechanics models are calibrated against reference data on ion-water interactions. It is then typically assumed that these descriptors will also satisfactorily describe interactions of ions with other functional groups, such as those present in biomolecules. However, several studies now demonstrate that this transferability assumption produces, in many different cases, large errors. Here we address this issue in a representative polarizable model and focus on transferability of cationic interactions from water to a series of alcohols. Both water and alcohols use hydroxyls for ion-coordination, and, therefore, this set of molecules constitutes the simplest possible case of transferability. We obtain gas phase reference data systematically from "gold-standard" quantum Monte Carlo and CCSD(T) methods, followed by benchmarked vdW-corrected DFT. We learn that the original polarizable model yields large gas phase water → alcohol transferability errors - the RMS and maximum errors are 2.3 and 5.1 kcal/mol, respectively. These errors are, nevertheless, systematic in that ion-alcohol interactions are overstabilized, and systematic errors typically imply that some essential physics is either missing or misrepresented. A comprehensive analysis shows that when both low- and high-field responses of ligand dipole polarization are described accurately, then transferability improves significantly - the RMS and maximum errors in the gas phase reduce, respectively, to 0.9 and 2.5 kcal/mol. Additionally, predictions of condensed phase transfer free energies also improve. Nevertheless, within the limits of the extrathermodynamic assumptions necessary to separate experimental estimates of salt dissolution into constituent cationic and anionic contributions, we note that the error in the condensed phase is systematic, which we attribute, at least, partially to the parametrization in long-range electrostatics. Overall, this work demonstrates a rational approach to boosting transferability of ionic interactions that will be applicable broadly to improving other polarizable and nonpolarizable models.
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Affiliation(s)
- Vered Wineman-Fisher
- Department of Cell Biology, Microbiology and Molecular Biology , University of South Florida , Tampa , Florida 33620 , United States
| | - Yasmine Al-Hamdani
- Physics and Materials Science Research Unit , University of Luxembourg , 162a avenue de la Fïancerie , Luxembourg City , L-1511 , Luxembourg
| | - Iqbal Addou
- Department of Cell Biology, Microbiology and Molecular Biology , University of South Florida , Tampa , Florida 33620 , United States
| | - Alexandre Tkatchenko
- Physics and Materials Science Research Unit , University of Luxembourg , 162a avenue de la Fïancerie , Luxembourg City , L-1511 , Luxembourg
| | - Sameer Varma
- Department of Cell Biology, Microbiology and Molecular Biology , University of South Florida , Tampa , Florida 33620 , United States
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24
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Doyle CC, Shi Y, Beck TL. The Importance of the Water Molecular Quadrupole for Estimating Interfacial Potential Shifts Acting on Ions Near the Liquid–Vapor Interface. J Phys Chem B 2019; 123:3348-3358. [DOI: 10.1021/acs.jpcb.9b01289] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Carrie C. Doyle
- Department of Chemistry, University of Cincinnati, Cincinnati, Ohio 45221, United States
| | - Yu Shi
- Department of Chemistry, University of Cincinnati, Cincinnati, Ohio 45221, United States
| | - Thomas L. Beck
- Department of Chemistry, University of Cincinnati, Cincinnati, Ohio 45221, United States
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25
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Friedman R. Simulations of Biomolecules in Electrolyte Solutions. ADVANCED THEORY AND SIMULATIONS 2019. [DOI: 10.1002/adts.201800163] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Ran Friedman
- Department of Chemistry and Biomedical SciencesLinnæus UniversityKalmar SE‐391 82 Sweden
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26
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Muralidharan A, Pratt LR, Chaudhari MI, Rempe SB. Quasi-Chemical Theory with Cluster Sampling from Ab Initio Molecular Dynamics: Fluoride (F -) Anion Hydration. J Phys Chem A 2018; 122:9806-9812. [PMID: 30475612 DOI: 10.1021/acs.jpca.8b08474] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Accurate predictions of the hydration free energy for anions typically has been more challenging than that for cations. Hydrogen bond donation to the anion in hydrated clusters such as F(H2O) n - can lead to delicate structures. Consequently, the energy landscape contains many local minima, even for small clusters, and these minima present a challenge for computational optimization. Utilization of cluster experimental results for the free energies of gas-phase clusters shows that even though anharmonic effects are interesting they need not be of troublesome magnitudes for careful applications of quasi-chemical theory to ion hydration. Energy-optimized cluster structures for anions can leave the central ion highly exposed, and application of implicit solvation models to these structures can incur more serious errors than those for metal cations. Utilizing cluster structures sampled from ab initio molecular dynamics simulations substantially fixes those issues.
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Affiliation(s)
- A Muralidharan
- Department of Chemical and Biomolecular Engineering , Tulane University , New Orleans , Louisiana 70118 , United States
| | - L R Pratt
- Department of Chemical and Biomolecular Engineering , Tulane University , New Orleans , Louisiana 70118 , United States
| | - M I Chaudhari
- Center for Biological and Engineering Sciences , Sandia National Laboratories , Albuquerque , New Mexico 87185 , United States
| | - S B Rempe
- Center for Biological and Engineering Sciences , Sandia National Laboratories , Albuquerque , New Mexico 87185 , United States
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27
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Chaudhari MI, Rempe SB. Strontium and barium in aqueous solution and a potassium channel binding site. J Chem Phys 2018; 148:222831. [PMID: 29907035 DOI: 10.1063/1.5023130] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Ion hydration structure and free energy establish criteria for understanding selective ion binding in potassium (K+) ion channels and may be significant to understanding blocking mechanisms as well. Recently, we investigated the hydration properties of Ba2+, the most potent blocker of K+ channels among the simple metal ions. Here, we use a similar method of combining ab initio molecular dynamics simulations, statistical mechanical theory, and electronic structure calculations to probe the fundamental hydration properties of Sr2+, which does not block bacterial K+ channels. The radial distribution of water around Sr2+ suggests a stable 8-fold geometry in the local hydration environment, similar to Ba2+. While the predicted hydration free energy of -331.8 kcal/mol is comparable with the experimental result of -334 kcal/mol, the value is significantly more favorable than the -305 kcal/mol hydration free energy of Ba2+. When placed in the innermost K+ channel blocking site, the solvation free energies and lowest energy structures of both Sr2+ and Ba2+ are nearly unchanged compared with their respective hydration properties. This result suggests that the block is not attributable to ion trapping due to +2 charge, and differences in blocking behavior arise due to free energies associated with the exchange of water ligands for channel ligands instead of free energies of transfer from water to the binding site.
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Affiliation(s)
- Mangesh I Chaudhari
- Center for Biological and Engineering Sciences, Sandia National Laboratories, Albuquerque, New Mexico 87185, USA
| | - Susan B Rempe
- Center for Biological and Engineering Sciences, Sandia National Laboratories, Albuquerque, New Mexico 87185, USA
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28
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Chaudhari MI, Rempe SB, Pratt LR. Quasi-chemical theory of F -(aq): The "no split occupancies rule" revisited. J Chem Phys 2018; 147:161728. [PMID: 29096480 DOI: 10.1063/1.4986244] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
We use ab initio molecular dynamics (AIMD) calculations and quasi-chemical theory (QCT) to study the inner-shell structure of F-(aq) and to evaluate that single-ion free energy under standard conditions. Following the "no split occupancies" rule, QCT calculations yield a free energy value of -101 kcal/mol under these conditions, in encouraging agreement with tabulated values (-111 kcal/mol). The AIMD calculations served only to guide the definition of an effective inner-shell constraint. QCT naturally includes quantum mechanical effects that can be concerning in more primitive calculations, including electronic polarizability and induction, electron density transfer, electron correlation, molecular/atomic cooperative interactions generally, molecular flexibility, and zero-point motion. No direct assessment of the contribution of dispersion contributions to the internal energies has been attempted here, however. We anticipate that other aqueous halide ions might be treated successfully with QCT, provided that the structure of the underlying statistical mechanical theory is absorbed, i.e., that the "no split occupancies" rule is recognized.
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Affiliation(s)
- Mangesh I Chaudhari
- Center for Biological and Engineering Sciences, Sandia National Laboratories, Albuquerque, New Mexico 87185, USA
| | - Susan B Rempe
- Center for Biological and Engineering Sciences, Sandia National Laboratories, Albuquerque, New Mexico 87185, USA
| | - Lawrence R Pratt
- Department of Chemical and Biomolecular Engineering, Tulane University, New Orleans, Louisiana 70118, USA
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29
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Dixit PD, Bansal A, Chapman WG, Asthagiri D. Mini-grand canonical ensemble: Chemical potential in the solvation shell. J Chem Phys 2018; 147:164901. [PMID: 29096517 DOI: 10.1063/1.4993178] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Quantifying the statistics of occupancy of solvent molecules in the vicinity of solutes is central to our understanding of solvation phenomena. Number fluctuations in small solvation shells around solutes cannot be described within the macroscopic grand canonical framework using a single chemical potential that represents the solvent bath. In this communication, we hypothesize that molecular-sized observation volumes such as solvation shells are best described by coupling the solvation shell with a mixture of particle baths each with its own chemical potential. We confirm our hypotheses by studying the enhanced fluctuations in the occupancy statistics of hard sphere solvent particles around a distinguished hard sphere solute particle. Connections with established theories of solvation are also discussed.
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Affiliation(s)
- Purushottam D Dixit
- Department of Systems Biology, Columbia University, New York City, New York 10032, USA
| | - Artee Bansal
- Department of Chemical and Biomolecular Engineering, Rice University, Houston, Texas 77251, USA
| | - Walter G Chapman
- Department of Chemical and Biomolecular Engineering, Rice University, Houston, Texas 77251, USA
| | - Dilip Asthagiri
- Department of Chemical and Biomolecular Engineering, Rice University, Houston, Texas 77251, USA
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30
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Chaudhari MI, Muralidharan A, Pratt LR, Rempe SB. Assessment of Simple Models for Molecular Simulation of Ethylene Carbonate and Propylene Carbonate as Solvents for Electrolyte Solutions. Top Curr Chem (Cham) 2018; 376:7. [PMID: 29435669 PMCID: PMC5809610 DOI: 10.1007/s41061-018-0187-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Accepted: 01/23/2018] [Indexed: 01/13/2023]
Abstract
Progress in understanding liquid ethylene carbonate (EC) and propylene carbonate (PC) on the basis of molecular simulation, emphasizing simple models of interatomic forces, is reviewed. Results on the bulk liquids are examined from the perspective of anticipated applications to materials for electrical energy storage devices. Preliminary results on electrochemical double-layer capacitors based on carbon nanotube forests and on model solid-electrolyte interphase (SEI) layers of lithium ion batteries are considered as examples. The basic results discussed suggest that an empirically parameterized, non-polarizable force field can reproduce experimental structural, thermodynamic, and dielectric properties of EC and PC liquids with acceptable accuracy. More sophisticated force fields might include molecular polarizability and Buckingham-model description of inter-atomic overlap repulsions as extensions to Lennard-Jones models of van der Waals interactions. Simple approaches should be similarly successful also for applications to organic molecular ions in EC/PC solutions, but the important case of Li\documentclass[12pt]{minimal}
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\begin{document}$$^+$$\end{document}+ ions in liquid EC/PC solutions, we identify interaction models defined by empirically scaled partial charges for ion-solvent interactions. The empirical adjustments use more basic inputs, electronic structure calculations and ab initio molecular dynamics simulations, and also experimental results on Li\documentclass[12pt]{minimal}
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\begin{document}$$^+$$\end{document}+ thermodynamics and transport in EC/PC solutions. Application of such models to the mechanism of Li\documentclass[12pt]{minimal}
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\begin{document}$$^+$$\end{document}+ transport in glassy SEI models emphasizes the advantage of long time-scale molecular dynamics studies of these non-equilibrium materials.
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Affiliation(s)
- Mangesh I Chaudhari
- Center for Biological and Engineering Sciences, Sandia National Laboratories, Albuquerque, NM 87185, USA
| | - Ajay Muralidharan
- Department of Chemical and Biomolecular Engineering, Tulane University, New Orleans, LA 70118, USA
| | - Lawrence R Pratt
- Department of Chemical and Biomolecular Engineering, Tulane University, New Orleans, LA 70118, USA
| | - Susan B Rempe
- Center for Biological and Engineering Sciences, Sandia National Laboratories, Albuquerque, NM 87185, USA.
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31
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Duignan TT, Baer MD, Schenter GK, Mundy CJ. Real single ion solvation free energies with quantum mechanical simulation. Chem Sci 2017; 8:6131-6140. [PMID: 28989643 PMCID: PMC5625628 DOI: 10.1039/c7sc02138k] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Accepted: 05/26/2017] [Indexed: 01/11/2023] Open
Abstract
Single ion solvation free energies are one of the most important properties of electrolyte solutions and yet there is ongoing debate about what these values are. Only the values for neutral ion pairs are known. Here, we use DFT interaction potentials with molecular dynamics simulation (DFT-MD) combined with a modified version of the quasi-chemical theory (QCT) to calculate these energies for the lithium and fluoride ions. A method to correct for the error in the DFT functional is developed and very good agreement with the experimental value for the lithium fluoride pair is obtained. Moreover, this method partitions the energies into physically intuitive terms such as surface potential, cavity and charging energies which are amenable to descriptions with reduced models. Our research suggests that lithium's solvation free energy is dominated by the free energetics of a charged hard sphere, whereas fluoride exhibits significant quantum mechanical behavior that cannot be simply described with a reduced model.
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Affiliation(s)
- Timothy T Duignan
- Physical Science Division , Pacific Northwest National Laboratory , P.O. Box 999 , Richland , Washington 99352 , USA . ; Tel: +1 509 3756940
| | - Marcel D Baer
- Physical Science Division , Pacific Northwest National Laboratory , P.O. Box 999 , Richland , Washington 99352 , USA . ; Tel: +1 509 3756940
| | - Gregory K Schenter
- Physical Science Division , Pacific Northwest National Laboratory , P.O. Box 999 , Richland , Washington 99352 , USA . ; Tel: +1 509 3756940
| | - Christopher J Mundy
- Physical Science Division , Pacific Northwest National Laboratory , P.O. Box 999 , Richland , Washington 99352 , USA . ; Tel: +1 509 3756940
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32
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Chaudhari MI, Pratt LR, Rempe SB. Utility of chemical computations in predicting solution free energies of metal ions. MOLECULAR SIMULATION 2017. [DOI: 10.1080/08927022.2017.1342127] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- Mangesh I. Chaudhari
- Center for Biological and Engineering Sciences, Sandia National Laboratories, Albuquerque, NM, USA
| | - Lawrence R. Pratt
- Department of Chemical and Biomolecular Engineering, Tulane University, New Orleans, LA, USA
| | - Susan B. Rempe
- Center for Biological and Engineering Sciences, Sandia National Laboratories, Albuquerque, NM, USA
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33
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Chaudhari MI, Nair JR, Pratt LR, Soto FA, Balbuena PB, Rempe SB. Scaling Atomic Partial Charges of Carbonate Solvents for Lithium Ion Solvation and Diffusion. J Chem Theory Comput 2016; 12:5709-5718. [DOI: 10.1021/acs.jctc.6b00824] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Mangesh I. Chaudhari
- Center
for Biological and Engineering Sciences, Sandia National Laboratories, Albuquerque, New Mexico 87185, United States
| | - Jijeesh R. Nair
- Department
of Applied Science and Technology, Politecnico di Torino, Turin 10129, Italy
| | - Lawrence R. Pratt
- Department
of Chemical and Biomolecular Engineering, Tulane University, New Orleans, Louisiana 70118, United States
| | - Fernando A. Soto
- Department of Chemical Engineering, Texas A&M University, College Station, Texas 77843, United States
| | - Perla B. Balbuena
- Department of Chemical Engineering, Texas A&M University, College Station, Texas 77843, United States
| | - Susan B. Rempe
- Center
for Biological and Engineering Sciences, Sandia National Laboratories, Albuquerque, New Mexico 87185, United States
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34
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Manin N, da Silva MC, Zdravkovic I, Eliseeva O, Dyshin A, Yaşar O, Salahub DR, Kolker AM, Kiselev MG, Noskov SY. LiCl solvation in N-methyl-acetamide (NMA) as a model for understanding Li(+) binding to an amide plane. Phys Chem Chem Phys 2016; 18:4191-200. [PMID: 26784370 DOI: 10.1039/c5cp04847h] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The thermodynamics of ion solvation in non-aqueous solvents remains of great significance for understanding cellular transport and ion homeostasis for the design of novel ion-selective materials and applications in molecular pharmacology. Molecular simulations play pivotal roles in connecting experimental measurements to the microscopic structures of liquids. One of the most useful and versatile mimetic systems for understanding biological ion transport is N-methyl-acetamide (NMA). A plethora of theoretical studies for ion solvation in NMA have appeared recently, but further progress is limited by two factors. One is an apparent lack of experimental data on solubility and thermodynamics of solvation for a broad panel of 1 : 1 salts over an appropriate temperature and concentration range. The second concern is more substantial and has to do with the limitations hardwired in the additive (fixed charge) approximations used for most of the existing force-fields. In this submission, we report on the experimental evaluation of LiCl solvation in NMA over a broad range of concentrations and temperatures and compare the results with those of MD simulations with several additive and one polarizable force-field (Drude). By comparing our simulations and experimental results to density functional theory computations, we discuss the limiting factors in existing potential functions. To evaluate the possible implications of explicit and implicit polarizability treatments on ion permeation across biological channels, we performed potential of mean force (PMF) computations for Li(+) transport through a model narrow ion channel with additive and polarizable force-fields.
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Affiliation(s)
- Nikolai Manin
- G.A. Krestov Institute for Solution Chemistry, Russian Academy of Sciences, Akademicheskaya str, 1, Ivanovo, 153045, Russia.
| | - Mauricio C da Silva
- Centre for Molecular Simulation, BI-447, University of Calgary, 2500 University Drive NW, Calgary, AB T3A 2T3, Canada. and Department of Chemistry, University of Calgary, 2500 University Drive NW, Calgary, AB T2N 1N4, Canada
| | - Igor Zdravkovic
- Centre for Molecular Simulation, BI-447, University of Calgary, 2500 University Drive NW, Calgary, AB T3A 2T3, Canada. and Department of Biological Sciences, University of Calgary, 2500 University Drive NW, Calgary, AB T3A 2T3, Canada
| | - Olga Eliseeva
- G.A. Krestov Institute for Solution Chemistry, Russian Academy of Sciences, Akademicheskaya str, 1, Ivanovo, 153045, Russia.
| | - Alexey Dyshin
- G.A. Krestov Institute for Solution Chemistry, Russian Academy of Sciences, Akademicheskaya str, 1, Ivanovo, 153045, Russia.
| | - Orhan Yaşar
- Centre for Molecular Simulation, BI-447, University of Calgary, 2500 University Drive NW, Calgary, AB T3A 2T3, Canada. and Department of Biological Sciences, University of Calgary, 2500 University Drive NW, Calgary, AB T3A 2T3, Canada
| | - Dennis R Salahub
- Centre for Molecular Simulation, BI-447, University of Calgary, 2500 University Drive NW, Calgary, AB T3A 2T3, Canada. and Department of Chemistry, University of Calgary, 2500 University Drive NW, Calgary, AB T2N 1N4, Canada
| | - Arkadiy M Kolker
- G.A. Krestov Institute for Solution Chemistry, Russian Academy of Sciences, Akademicheskaya str, 1, Ivanovo, 153045, Russia.
| | - Michael G Kiselev
- G.A. Krestov Institute for Solution Chemistry, Russian Academy of Sciences, Akademicheskaya str, 1, Ivanovo, 153045, Russia.
| | - Sergei Yu Noskov
- Centre for Molecular Simulation, BI-447, University of Calgary, 2500 University Drive NW, Calgary, AB T3A 2T3, Canada. and Department of Biological Sciences, University of Calgary, 2500 University Drive NW, Calgary, AB T3A 2T3, Canada
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35
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Soniat M, Rogers DM, Rempe SB. Dispersion- and Exchange-Corrected Density Functional Theory for Sodium Ion Hydration. J Chem Theory Comput 2016; 11:2958-67. [PMID: 26575733 DOI: 10.1021/acs.jctc.5b00357] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
A challenge in density functional theory is developing functionals that simultaneously describe intermolecular electron correlation and electron delocalization. Recent exchange-correlation functionals address those two issues by adding corrections important at long ranges: an atom-centered pairwise dispersion term to account for correlation and a modified long-range component of the electron exchange term to correct for delocalization. Here we investigate how those corrections influence the accuracy of binding free energy predictions for sodium-water clusters. We find that the dual-corrected ωB97X-D functional gives cluster binding energies closest to high-level ab initio methods (CCSD(T)). Binding energy decomposition shows that the ωB97X-D functional predicts the smallest ion-water (pairwise) interaction energy and larger multibody contributions for a four-water cluster than most other functionals - a trend consistent with CCSD(T) results. Also, ωB97X-D produces the smallest amounts of charge transfer and the least polarizable waters of the density functionals studied, which mimics the lower polarizability of CCSD. When compared with experimental binding free energies, however, the exchange-corrected CAM-B3LYP functional performs best (error <1 kcal/mol), possibly because of its parametrization to experimental formation enthalpies. For clusters containing more than four waters, "split-shell" coordination must be considered to obtain accurate free energies in comparison with experiment.
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Affiliation(s)
- Marielle Soniat
- Department of Chemistry, University of New Orleans , 2000 Lakeshore Drive, New Orleans, Louisiana 70148, United States
| | - David M Rogers
- Center for Biological and Engineering Sciences, Sandia National Laboratories , Albuquerque, New Mexico 87123, United States.,Department of Chemistry, University of South Florida , Tampa, Florida 33620, United States
| | - Susan B Rempe
- Center for Biological and Engineering Sciences, Sandia National Laboratories , Albuquerque, New Mexico 87123, United States
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36
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Toward a quantitative theory of Hofmeister phenomena: From quantum effects to thermodynamics. Curr Opin Colloid Interface Sci 2016. [DOI: 10.1016/j.cocis.2016.06.015] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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37
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Wheatley RW, Juers DH, Lev BB, Huber RE, Noskov SY. Elucidating factors important for monovalent cation selectivity in enzymes: E. coli β-galactosidase as a model. Phys Chem Chem Phys 2016; 17:10899-909. [PMID: 25820412 DOI: 10.1039/c4cp04952g] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Many enzymes require a specific monovalent cation (M(+)), that is either Na(+) or K(+), for optimal activity. While high selectivity M(+) sites in transport proteins have been extensively studied, enzyme M(+) binding sites generally have lower selectivity and are less characterized. Here we study the M(+) binding site of the model enzyme E. coli β-galactosidase, which is about 10 fold selective for Na(+) over K(+). Combining data from X-ray crystallography and computational models, we find the electrostatic environment predominates in defining the Na(+) selectivity. In this lower selectivity site rather subtle influences on the electrostatic environment become significant, including the induced polarization effects of the M(+) on the coordinating ligands and the effect of second coordination shell residues on the charge distribution of the primary ligands. This work expands the knowledge of ion selectivity in proteins to denote novel mechanisms important for the selectivity of M(+) sites in enzymes.
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Affiliation(s)
- Robert W Wheatley
- Division of Biochemistry, Department of Biological Sciences, University of Calgary, 2500 University Drive NW, Calgary, AB T2N 1N4, Canada
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38
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Baer MD, Mundy CJ. Local Aqueous Solvation Structure Around Ca2+ During Ca2+···Cl– Pair Formation. J Phys Chem B 2016; 120:1885-93. [DOI: 10.1021/acs.jpcb.5b09579] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Marcel D. Baer
- Physical Science Division, Pacific Northwest National Laboratory, Richland, Washington 99354, United States
| | - Christopher J. Mundy
- Physical Science Division, Pacific Northwest National Laboratory, Richland, Washington 99354, United States
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39
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Abstract
The hydration structure of Ba(2+) ion is important for understanding blocking mechanisms in potassium ion channels. Here, we combine statistical mechanical theory, ab initio molecular dynamics simulations, and electronic structure methods to calculate the hydration free energy and local hydration structure of Ba(2+)(aq). The predicted hydration free energy (-304 ± 1 kcal/mol) agrees with the experimental value (-303 kcal/mol) when a maximally occupied, unimodal inner solvation shell is treated. In the local environment defined by the first shell of hydrating waters, Ba(2+) is directly and stably coordinated by eight (8) waters. Octa-coordination resembles the crystal structure of Ba(2+) and K(+) bound in potassium ion channels, but differs from the local hydration structure of K(+)(aq) determined earlier.
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Affiliation(s)
- Mangesh I Chaudhari
- †Center for Biological and Engineering Sciences, Sandia National Laboratories, Albuquerque, New Mexico 87185, United States
| | - Marielle Soniat
- ‡Department of Chemistry, University of New Orleans, New Orleans, Louisiana 70148, United States
| | - Susan B Rempe
- †Center for Biological and Engineering Sciences, Sandia National Laboratories, Albuquerque, New Mexico 87185, United States
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40
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Rogers DM, Kent MS, Rempe SB. Molecular basis of endosomal-membrane association for the dengue virus envelope protein. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1848:1041-52. [DOI: 10.1016/j.bbamem.2014.12.018] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2014] [Revised: 12/05/2014] [Accepted: 12/19/2014] [Indexed: 11/15/2022]
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41
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Chaudhari MI, Sabo D, Pratt LR, Rempe SB. Hydration of Kr(aq) in Dilute and Concentrated Solutions. J Phys Chem B 2014; 119:9098-102. [DOI: 10.1021/jp508866h] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Affiliation(s)
- Mangesh I. Chaudhari
- Center
for Biological and
Material Sciences, Sandia National Laboratories, Albuquerque, New Mexico 87123, United States
| | - Dubravko Sabo
- Department of Chemistry, New York University, New York, New York 10003, United States
| | - Lawrence R. Pratt
- Department of Chemical
and
Biomolecular Engineering, Tulane University, New Orleans, Louisiana 70118, United States
| | - Susan B. Rempe
- Center for Biological and
Material Sciences, Sandia National Laboratories, Albuquerque, New Mexico 87185, United States
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42
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Pollard T, Beck TL. Quasichemical analysis of the cluster-pair approximation for the thermodynamics of proton hydration. J Chem Phys 2014; 140:224507. [DOI: 10.1063/1.4881602] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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43
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Dixit PD, Dill KA. Inferring Microscopic Kinetic Rates from Stationary State Distributions. J Chem Theory Comput 2014; 10:3002-3005. [PMID: 25136269 PMCID: PMC4132853 DOI: 10.1021/ct5001389] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2014] [Indexed: 02/03/2023]
Abstract
![]()
We
present a principled approach for estimating the matrix of microscopic
transition probabilities among states of a Markov process, given only
its stationary state population distribution and a single average
global kinetic observable. We adapt Maximum Caliber, a variational
principle in which the path entropy is maximized over the distribution
of all possible trajectories, subject to basic kinetic constraints
and some average dynamical observables. We illustrate the method by
computing the solvation dynamics of water molecules from molecular
dynamics trajectories.
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Affiliation(s)
- Purushottam D Dixit
- Department of Systems Biology, Columbia University , New York, New York 10032, United States
| | - Ken A Dill
- Department of Systems Biology, Columbia University , New York, New York 10032, United States
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44
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Zhang W, You X, Pratt LR. Multiscale Theory in the Molecular Simulation of Electrolyte Solutions. J Phys Chem B 2014; 118:7730-8. [DOI: 10.1021/jp410310m] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Affiliation(s)
- W. Zhang
- Department of Chemical and Biomolecular
Engineering, Tulane University, New Orleans, Lousiana 70118, United States
| | - X. You
- Department of Chemical and Biomolecular
Engineering, Tulane University, New Orleans, Lousiana 70118, United States
| | - L. R. Pratt
- Department of Chemical and Biomolecular
Engineering, Tulane University, New Orleans, Lousiana 70118, United States
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45
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Sepehr F, Paddison SJ. The solvation structure and thermodynamics of aqueous vanadium cations. Chem Phys Lett 2013. [DOI: 10.1016/j.cplett.2013.08.089] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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46
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Shi Y, Beck TL. Length scales and interfacial potentials in ion hydration. J Chem Phys 2013; 139:044504. [DOI: 10.1063/1.4814070] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
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47
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You X, Chaudhari MI, Pratt LR, Pesika N, Aritakula KM, Rick SW. Interfaces of propylene carbonate. J Chem Phys 2013; 138:114708. [DOI: 10.1063/1.4794792] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Affiliation(s)
- Xinli You
- Department of Chemical and Biomolecular Engineering, Tulane University, New Orleans, Louisiana 70118, USA.
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48
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Beck TL. The influence of water interfacial potentials on ion hydration in bulk water and near interfaces. Chem Phys Lett 2013. [DOI: 10.1016/j.cplett.2013.01.008] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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49
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Sabo D, Jiao D, Varma S, Pratt LR, Rempe SB. Case study of Rb+(aq), quasi-chemical theory of ion hydration, and the no split occupancies rule. ACTA ACUST UNITED AC 2013. [DOI: 10.1039/c3pc90009f] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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50
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Zhu P, Pratt LR, Papadopoulos KD. Pairing of 1-hexyl-3-methylimidazolium and tetrafluoroborate ions in n-pentanol. J Chem Phys 2012; 137:174501. [DOI: 10.1063/1.4764296] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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