1
|
Cao X, Hummel MH, Wang Y, Simmerling C, Coutsias EA. Exact Analytical Algorithm for the Solvent-Accessible Surface Area and Derivatives in Implicit Solvent Molecular Simulations on GPUs. J Chem Theory Comput 2024; 20:4456-4468. [PMID: 38780181 DOI: 10.1021/acs.jctc.3c01366] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/25/2024]
Abstract
In this paper, we present differentiable solvent-accessible surface area (dSASA), an exact geometric method to calculate SASA analytically along with atomic derivatives on GPUs. The atoms in a molecule are first assigned to tetrahedra in groups of four atoms by Delaunay tetrahedralization adapted for efficient GPU implementation, and the SASA values for atoms and molecules are calculated based on the tetrahedralization information and inclusion-exclusion method. The SASA values from the numerical icosahedral-based method can be reproduced with >98% accuracy for both proteins and RNAs. Having been implemented on GPUs and incorporated into AMBER, we can apply dSASA to implicit solvent molecular dynamics simulations with the inclusion of this nonpolar term. The current GPU version of GB/SA simulations has been accelerated up to nearly 20-fold compared to the CPU version, outperforming LCPO, a commonly used, fast algorithm for calculating SASA, as the system size increases. While we focus on the accuracy of the SASA calculations for proteins and nucleic acids, we also demonstrate stable GB/SA MD mini-protein simulations.
Collapse
Affiliation(s)
- Xin Cao
- Department of Applied Mathematics and Statistics, Stony Brook University, Stony Brook, New York 11794, United States
- Laufer Center for Physical and Quantitative Biology, Stony Brook University, Stony Brook, New York 11794, United States
| | - Michelle H Hummel
- Sandia National Laboratories, Albuquerque, New Mexico 87123, United States
| | - Yuzhang Wang
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794, United States
| | - Carlos Simmerling
- Department of Applied Mathematics and Statistics, Stony Brook University, Stony Brook, New York 11794, United States
- Laufer Center for Physical and Quantitative Biology, Stony Brook University, Stony Brook, New York 11794, United States
| | - Evangelos A Coutsias
- Department of Applied Mathematics and Statistics, Stony Brook University, Stony Brook, New York 11794, United States
- Laufer Center for Physical and Quantitative Biology, Stony Brook University, Stony Brook, New York 11794, United States
| |
Collapse
|
2
|
Cao X, Hummel MH, Wang Y, Simmerling C, Coutsias EA. Exact analytical algorithm for solvent accessible surface area and derivatives in implicit solvent molecular simulations on GPUs. ARXIV 2024:arXiv:2401.10462v2. [PMID: 38313200 PMCID: PMC10836080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 02/06/2024]
Abstract
In this paper, we present dSASA (differentiable SASA), an exact geometric method to calculate solvent accessible surface area (SASA) analytically along with atomic derivatives on GPUs. The atoms in a molecule are first assigned to tetrahedra in groups of four atoms by Delaunay tetrahedrization adapted for efficient GPU implementation and the SASA values for atoms and molecules are calculated based on the tetrahedrization information and inclusion-exclusion method. The SASA values from the numerical icosahedral-based method can be reproduced with more than 98% accuracy for both proteins and RNAs. Having been implemented on GPUs and incorporated into the software Amber, we can apply dSASA to implicit solvent molecular dynamics simulations with inclusion of this nonpolar term. The current GPU version of GB/SA simulations has been accelerated up to nearly 20-fold compared to the CPU version, outperforming LCPO, a commonly used, fast algorithm for calculating SASA, as the system size increases. While we focus on the accuracy of the SASA calculations for proteins and nucleic acids, we also demonstrate stable GB/SA MD mini-protein simulations.
Collapse
Affiliation(s)
- Xin Cao
- Department of Applied Mathematics and Statistics, Stony Brook University, Stony Brook, NY 11794, United States
- Laufer Center for Physical and Quantitative Biology, Stony Brook University, Stony Brook, NY 11794, United States
| | | | - Yuzhang Wang
- Department of Chemistry, Stony Brook University, Stony Brook, NY 11794, United States
| | - Carlos Simmerling
- Department of Chemistry, Stony Brook University, Stony Brook, NY 11794, United States
- Laufer Center for Physical and Quantitative Biology, Stony Brook University, Stony Brook, NY 11794, United States
| | - Evangelos A Coutsias
- Department of Applied Mathematics and Statistics, Stony Brook University, Stony Brook, NY 11794, United States
- Laufer Center for Physical and Quantitative Biology, Stony Brook University, Stony Brook, NY 11794, United States
| |
Collapse
|
3
|
Azizi K, Laio A, Hassanali A. Solvation thermodynamics from cavity shapes of amino acids. PNAS NEXUS 2023; 2:pgad239. [PMID: 37545648 PMCID: PMC10400782 DOI: 10.1093/pnasnexus/pgad239] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Revised: 07/07/2023] [Accepted: 07/17/2023] [Indexed: 08/08/2023]
Abstract
According to common physical chemistry wisdom, the solvent cavities hosting a solute are tightly sewn around it, practically coinciding with its van der Waals surface. Solvation entropy is primarily determined by the surface and the volume of the cavity while enthalpy is determined by the solute-solvent interaction. In this work, we challenge this picture, demonstrating by molecular dynamics simulations that the cavities surrounding the 20 amino acids deviate significantly from the molecular surface. Strikingly, the shape of the cavity alone can be used to predict the solvation free energy, entropy, enthalpy, and hydrophobicity. Solute-solvent interactions involving the different chemical moieties of the amino acid, determine indirectly the cavity shape, and the properties of the branches but do not have to be taken explicitly into account in the prediction model.
Collapse
Affiliation(s)
- Khatereh Azizi
- The Abdus Salam International Centre for Theoretical Physics, Strada Costiera 11, 34151 Trieste, Italy
| | - Alessandro Laio
- The Abdus Salam International Centre for Theoretical Physics, Strada Costiera 11, 34151 Trieste, Italy
- SISSA, Via Bonomea 265, I-34136 Trieste, Italy
| | - Ali Hassanali
- The Abdus Salam International Centre for Theoretical Physics, Strada Costiera 11, 34151 Trieste, Italy
| |
Collapse
|
4
|
Das R, Lindström T, Sharma PR, Chi K, Hsiao BS. Nanocellulose for Sustainable Water Purification. Chem Rev 2022; 122:8936-9031. [PMID: 35330990 DOI: 10.1021/acs.chemrev.1c00683] [Citation(s) in RCA: 56] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Nanocelluloses (NC) are nature-based sustainable biomaterials, which not only possess cellulosic properties but also have the important hallmarks of nanomaterials, such as large surface area, versatile reactive sites or functionalities, and scaffolding stability to host inorganic nanoparticles. This class of nanomaterials offers new opportunities for a broad spectrum of applications for clean water production that were once thought impractical. This Review covers substantial discussions based on evaluative judgments of the recent literature and technical advancements in the fields of coagulation/flocculation, adsorption, photocatalysis, and membrane filtration for water decontamination through proper understanding of fundamental knowledge of NC, such as purity, crystallinity, surface chemistry and charge, suspension rheology, morphology, mechanical properties, and film stability. To supplement these, discussions on low-cost and scalable NC extraction, new characterizations including solution small-angle X-ray scattering evaluation, and structure-property relationships of NC are also reviewed. Identifying knowledge gaps and drawing perspectives could generate guidance to overcome uncertainties associated with the adaptation of NC-enabled water purification technologies. Furthermore, the topics of simultaneous removal of multipollutants disposal and proper handling of post/spent NC are discussed. We believe NC-enabled remediation nanomaterials can be integrated into a broad range of water treatments, greatly improving the cost-effectiveness and sustainability of water purification.
Collapse
Affiliation(s)
- Rasel Das
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794-3400, United States
| | - Tom Lindström
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794-3400, United States.,KTH Royal Institute of Technology, Stockholm 100 44, Sweden
| | - Priyanka R Sharma
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794-3400, United States
| | - Kai Chi
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794-3400, United States
| | - Benjamin S Hsiao
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794-3400, United States
| |
Collapse
|
5
|
Porto CM, Santana LC, Morgon NH. Theoretical investigation of the cooperative effect of solvent: a case study. Phys Chem Chem Phys 2022; 24:14603-14615. [DOI: 10.1039/d1cp05388d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The effect of solvent was investigated at the DFT level, M06-2X/6-31++G(d,p), for the implicit, namely the universal solvent model based on solute electron density (SMD), and hybrid solvation models, and...
Collapse
|
6
|
Identifying hydrophobic protein patches to inform protein interaction interfaces. Proc Natl Acad Sci U S A 2021; 118:2018234118. [PMID: 33526682 DOI: 10.1073/pnas.2018234118] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Interactions between proteins lie at the heart of numerous biological processes and are essential for the proper functioning of the cell. Although the importance of hydrophobic residues in driving protein interactions is universally accepted, a characterization of protein hydrophobicity, which informs its interactions, has remained elusive. The challenge lies in capturing the collective response of the protein hydration waters to the nanoscale chemical and topographical protein patterns, which determine protein hydrophobicity. To address this challenge, here, we employ specialized molecular simulations wherein water molecules are systematically displaced from the protein hydration shell; by identifying protein regions that relinquish their waters more readily than others, we are then able to uncover the most hydrophobic protein patches. Surprisingly, such patches contain a large fraction of polar/charged atoms and have chemical compositions that are similar to the more hydrophilic protein patches. Importantly, we also find a striking correspondence between the most hydrophobic protein patches and regions that mediate protein interactions. Our work thus establishes a computational framework for characterizing the emergent hydrophobicity of amphiphilic solutes, such as proteins, which display nanoscale heterogeneity, and for uncovering their interaction interfaces.
Collapse
|
7
|
Li C, Qin Z, Han W. Bottom-up derived flexible water model with dipole and quadrupole moments for coarse-grained molecular simulations. Phys Chem Chem Phys 2020; 22:27394-27412. [DOI: 10.1039/d0cp04185h] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A bottom-up CG water model is developed to capture the electrostatic multipoles, structural correlation and thermodynamics of water.
Collapse
Affiliation(s)
- Chen Li
- State Key Laboratory of Chemical Genomics
- School of Chemical Biology and Biotechnology
- Peking University Shenzhen Graduate School
- Shenzhen
- China
| | - Zhongyuan Qin
- State Key Laboratory of Chemical Genomics
- School of Chemical Biology and Biotechnology
- Peking University Shenzhen Graduate School
- Shenzhen
- China
| | - Wei Han
- State Key Laboratory of Chemical Genomics
- School of Chemical Biology and Biotechnology
- Peking University Shenzhen Graduate School
- Shenzhen
- China
| |
Collapse
|
8
|
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.
Collapse
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
| |
Collapse
|
9
|
Sexton TM, Tschumper GS. 2-body:Many-body QM:QM study of structures, energetics, and vibrational frequencies for microhydrated halide ions. Mol Phys 2018. [DOI: 10.1080/00268976.2018.1554827] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- Thomas More Sexton
- Department of Chemistry and Biochemistry, University of Mississippi, University, MS, USA
| | - Gregory S. Tschumper
- Department of Chemistry and Biochemistry, University of Mississippi, University, MS, USA
| |
Collapse
|
10
|
Huang H, Simmerling C. Fast Pairwise Approximation of Solvent Accessible Surface Area for Implicit Solvent Simulations of Proteins on CPUs and GPUs. J Chem Theory Comput 2018; 14:5797-5814. [PMID: 30303377 DOI: 10.1021/acs.jctc.8b00413] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We propose a pairwise and readily parallelizable SASA-based nonpolar solvation approach for protein simulations, inspired by our previous pairwise GB polar solvation model development. In this work, we developed a novel function to estimate the atomic and molecular SASAs of proteins, which results in comparable accuracy as the LCPO algorithm in reproducing numerical icosahedral-based SASA values. Implemented in Amber software and tested on consumer GPUs, our pwSASA method reasonably reproduces LCPO simulation results, but accelerates MD simulations up to 30 times compared to the LCPO implementation, which is greatly desirable for protein simulations facing sampling challenges. The value of incorporating the nonpolar term in implicit solvent simulations is explored on a peptide fragment containing the hydrophobic core of HP36 and evaluating thermal stability profiles of four small proteins.
Collapse
Affiliation(s)
- He Huang
- Laufer Center for Physical and Quantitative Biology , Stony Brook University , Stony Brook , New York 11794 , United States.,Department of Chemistry , Stony Brook University , Stony Brook , New York 11794 , United States
| | - Carlos Simmerling
- Laufer Center for Physical and Quantitative Biology , Stony Brook University , Stony Brook , New York 11794 , United States.,Department of Chemistry , Stony Brook University , Stony Brook , New York 11794 , United States
| |
Collapse
|
11
|
Hydrophobicity of proteins and nanostructured solutes is governed by topographical and chemical context. Proc Natl Acad Sci U S A 2017; 114:13345-13350. [PMID: 29158409 DOI: 10.1073/pnas.1700092114] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Hydrophobic interactions drive many important biomolecular self-assembly phenomena. However, characterizing hydrophobicity at the nanoscale has remained a challenge due to its nontrivial dependence on the chemistry and topography of biomolecular surfaces. Here we use molecular simulations coupled with enhanced sampling methods to systematically displace water molecules from the hydration shells of nanostructured solutes and calculate the free energetics of interfacial water density fluctuations, which quantify the extent of solute-water adhesion, and therefore solute hydrophobicity. In particular, we characterize the hydrophobicity of curved graphene sheets, self-assembled monolayers (SAMs) with chemical patterns, and mutants of the protein hydrophobin-II. We find that water density fluctuations are enhanced near concave nonpolar surfaces compared with those near flat or convex ones, suggesting that concave surfaces are more hydrophobic. We also find that patterned SAMs and protein mutants, having the same number of nonpolar and polar sites but different geometrical arrangements, can display significantly different strengths of adhesion with water. Specifically, hydroxyl groups reduce the hydrophobicity of methyl-terminated SAMs most effectively not when they are clustered together but when they are separated by one methyl group. Hydrophobin-II mutants show that a charged amino acid reduces the hydrophobicity of a large nonpolar patch when placed at its center, rather than at its edge. Our results highlight the power of water density fluctuations-based measures to characterize the hydrophobicity of nanoscale surfaces and caution against the use of additive approximations, such as the commonly used surface area models or hydropathy scales for characterizing biomolecular hydrophobicity and the associated driving forces of assembly.
Collapse
|
12
|
Brini E, Fennell CJ, Fernandez-Serra M, Hribar-Lee B, Lukšič M, Dill KA. How Water's Properties Are Encoded in Its Molecular Structure and Energies. Chem Rev 2017; 117:12385-12414. [PMID: 28949513 PMCID: PMC5639468 DOI: 10.1021/acs.chemrev.7b00259] [Citation(s) in RCA: 199] [Impact Index Per Article: 28.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Indexed: 11/29/2022]
Abstract
How are water's material properties encoded within the structure of the water molecule? This is pertinent to understanding Earth's living systems, its materials, its geochemistry and geophysics, and a broad spectrum of its industrial chemistry. Water has distinctive liquid and solid properties: It is highly cohesive. It has volumetric anomalies-water's solid (ice) floats on its liquid; pressure can melt the solid rather than freezing the liquid; heating can shrink the liquid. It has more solid phases than other materials. Its supercooled liquid has divergent thermodynamic response functions. Its glassy state is neither fragile nor strong. Its component ions-hydroxide and protons-diffuse much faster than other ions. Aqueous solvation of ions or oils entails large entropies and heat capacities. We review how these properties are encoded within water's molecular structure and energies, as understood from theories, simulations, and experiments. Like simpler liquids, water molecules are nearly spherical and interact with each other through van der Waals forces. Unlike simpler liquids, water's orientation-dependent hydrogen bonding leads to open tetrahedral cage-like structuring that contributes to its remarkable volumetric and thermal properties.
Collapse
Affiliation(s)
- Emiliano Brini
- Laufer
Center for Physical and Quantitative Biology, Department of Physics and Astronomy, and Department of
Chemistry, Stony Brook University, Stony Brook, New York 11794, United States
| | - Christopher J. Fennell
- Department
of Chemistry, Oklahoma State University, Stillwater, Oklahoma 74078, United States
| | - Marivi Fernandez-Serra
- Laufer
Center for Physical and Quantitative Biology, Department of Physics and Astronomy, and Department of
Chemistry, Stony Brook University, Stony Brook, New York 11794, United States
| | - Barbara Hribar-Lee
- Faculty
of Chemistry and Chemical Technology, University
of Ljubljana, Večna
pot 113, SI-1000 Ljubljana, Slovenia
| | - Miha Lukšič
- Faculty
of Chemistry and Chemical Technology, University
of Ljubljana, Večna
pot 113, SI-1000 Ljubljana, Slovenia
| | - Ken A. Dill
- Laufer
Center for Physical and Quantitative Biology, Department of Physics and Astronomy, and Department of
Chemistry, Stony Brook University, Stony Brook, New York 11794, United States
| |
Collapse
|
13
|
Molavi Tabrizi A, Goossens S, Mehdizadeh Rahimi A, Cooper CD, Knepley MG, Bardhan JP. Extending the Solvation-Layer Interface Condition Continum Electrostatic Model to a Linearized Poisson–Boltzmann Solvent. J Chem Theory Comput 2017; 13:2897-2914. [DOI: 10.1021/acs.jctc.6b00832] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Amirhossein Molavi Tabrizi
- Department
of Mechanical and Industrial Engineering, Northeastern University, Boston, Massachusetts 02115, United States
| | - Spencer Goossens
- Department
of Mechanical and Industrial Engineering, Northeastern University, Boston, Massachusetts 02115, United States
| | - Ali Mehdizadeh Rahimi
- Department
of Mechanical and Industrial Engineering, Northeastern University, Boston, Massachusetts 02115, United States
| | - Christopher D. Cooper
- Departamento
de Ingeniería Mecánica and Centro Científico
Tecnológico de Valparaíso (CCTVal), Universidad Técnica Federico Santa María, Valparaiso, Chile
| | - Matthew G. Knepley
- Department
of Computational and Applied Mathematics, Rice University, Houston, Texas 77005, United States
| | - Jaydeep P. Bardhan
- Department
of Mechanical and Industrial Engineering, Northeastern University, Boston, Massachusetts 02115, United States
| |
Collapse
|
14
|
Molavi Tabrizi A, Goossens S, Mehdizadeh Rahimi A, Knepley M, Bardhan JP. Predicting solvation free energies and thermodynamics in polar solvents and mixtures using a solvation-layer interface condition. J Chem Phys 2017. [DOI: 10.1063/1.4977037] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Amirhossein Molavi Tabrizi
- Department of Mechanical and Industrial Engineering, Northeastern University, Boston, Massachusetts 02115, USA
| | - Spencer Goossens
- Department of Mechanical and Industrial Engineering, Northeastern University, Boston, Massachusetts 02115, USA
| | - Ali Mehdizadeh Rahimi
- Department of Mechanical and Industrial Engineering, Northeastern University, Boston, Massachusetts 02115, USA
| | - Matthew Knepley
- Department of Computational and Applied Mathematics, Rice University, Houston, Texas 77005, USA
| | - Jaydeep P. Bardhan
- Department of Mechanical and Industrial Engineering, Northeastern University, Boston, Massachusetts 02115, USA
| |
Collapse
|
15
|
Musiani F, Giorgetti A. Protein Aggregation and Molecular Crowding: Perspectives From Multiscale Simulations. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2016; 329:49-77. [PMID: 28109331 DOI: 10.1016/bs.ircmb.2016.08.009] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Cells are extremely crowded environments, thus the use of diluted salted aqueous solutions containing a single protein is too simplistic to mimic the real situation. Macromolecular crowding might affect protein structure, folding, shape, conformational stability, binding of small molecules, enzymatic activity, interactions with cognate biomolecules, and pathological aggregation. The latter phenomenon typically leads to the formation of amyloid fibrils that are linked to several lethal neurodegenerative diseases, but that can also play a functional role in certain organisms. The majority of molecular simulations performed before the last few years were conducted in diluted solutions and were restricted both in the timescales and in the system dimensions by the available computational resources. In recent years, several computational solutions were developed to get close to physiological conditions. In this review we summarize the main computational techniques used to tackle the issue of protein aggregation both in a diluted and in a crowded environment.
Collapse
Affiliation(s)
- F Musiani
- Laboratory of Bioinorganic Chemistry, University of Bologna, Bologna, Italy.
| | - A Giorgetti
- Applied Bioinformatics Group, University of Verona, Verona, Italy.
| |
Collapse
|
16
|
Reif MM, Hünenberger PH. Origin of Asymmetric Solvation Effects for Ions in Water and Organic Solvents Investigated Using Molecular Dynamics Simulations: The Swain Acity-Basity Scale Revisited. J Phys Chem B 2016; 120:8485-517. [PMID: 27173101 DOI: 10.1021/acs.jpcb.6b02156] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The asymmetric solvation of ions can be defined as the tendency of a solvent to preferentially solvate anions over cations or cations over anions, at identical ionic charge magnitudes and effective sizes. Taking water as a reference, these effects are quantified experimentally for many solvents by the relative acity (A) and basity (B) parameters of the Swain scale. The goal of the present study is to investigate the asymmetric solvation of ions using molecular dynamics simulations, and to connect the results to this empirical scale. To this purpose, the charging free energies of alkali and halide ions, and of their hypothetical oppositely charged counterparts, are calculated in a variety of solvents. In a first set of calculations, artificial solvent models are considered that present either a charge or a shape asymmetry at the molecular level. The solvation asymmetry, probed by the difference in charging free energy between the two oppositely charged ions, is found to encompass a term quadratic in the ion charge, related to the different solvation structures around the anion and cation, and a term linear in the ion charge, related to the solvation structure around the uncharged ion-sized cavity. For these simple solvent models, the two terms are systematically counteracting each other, and it is argued that only the quadratic term should be retained when comparing the results of simulations involving physical solvents to experimental data. In a second set of calculations, 16 physical solvents are considered. The theoretical estimates for the acity A are found to correlate very well with the Swain parameters, whereas the correlation for B is very poor. Based on this observation, the Swain scale is reformulated into a new scale involving an asymmetry parameter Σ, positive for acitic solvents and negative for basitic ones, and a polarity parameter Π. This revised scale has the same predictive power as the original scale, but it characterizes asymmetry in an absolute sense, the atomistic simulations playing the role of an extra-thermodynamic assumption, and is optimally compatible with the simulation results. Considering the 55 solvents in the Swain set, it is observed that a moderate basity (Σ between -0.9 and -0.3, related to electronic polarization) represents the baseline for most solvents, while a highly variable acity (Σ between 0.0 and 3.0, related to hydrogen-bond donor capacity modulated by inductive effects) represents a landmark of protic solvents.
Collapse
Affiliation(s)
- Maria M Reif
- Physics Department (T38), Technische Universität München , D-85748 Garching, Germany
| | | |
Collapse
|
17
|
Yao Y, Berkowitz ML, Kanai Y. Communication: Modeling of concentration dependent water diffusivity in ionic solutions: Role of intermolecular charge transfer. J Chem Phys 2015; 143:241101. [DOI: 10.1063/1.4938083] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Affiliation(s)
- Yi Yao
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
| | - Max L. Berkowitz
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
| | - Yosuke Kanai
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
| |
Collapse
|
18
|
Reif MM, Oostenbrink C. Toward the correction of effective electrostatic forces in explicit-solvent molecular dynamics simulations: restraints on solvent-generated electrostatic potential and solvent polarization. Theor Chem Acc 2015; 134:2. [PMID: 26097404 PMCID: PMC4470580 DOI: 10.1007/s00214-014-1600-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2014] [Accepted: 11/19/2014] [Indexed: 11/26/2022]
Abstract
Despite considerable advances in computing power, atomistic simulations under nonperiodic boundary conditions, with Coulombic electrostatic interactions and in systems large enough to reduce finite-size associated errors in thermodynamic quantities to within the thermal energy, are still not affordable. As a result, periodic boundary conditions, systems of microscopic size and effective electrostatic interaction functions are frequently resorted to. Ensuing artifacts in thermodynamic quantities are nowadays routinely corrected a posteriori, but the underlying configurational sampling still descends from spurious forces. The present study addresses this problem through the introduction of on-the-fly corrections to the physical forces during an atomistic molecular dynamics simulation. Two different approaches are suggested, where the force corrections are derived from special potential energy terms. In the first approach, the solvent-generated electrostatic potential sampled at a given atom site is restrained to a target value involving corrections for electrostatic artifacts. In the second approach, the long-range regime of the solvent polarization around a given atom site is restrained to the Born polarization, i.e., the solvent polarization corresponding to the ideal situation of a macroscopic system under nonperiodic boundary conditions and governed by Coulombic electrostatic interactions. The restraints are applied to the explicit-water simulation of a hydrated sodium ion, and the effect of the restraints on the structural and energetic properties of the solvent is illustrated. Furthermore, by means of the calculation of the charging free energy of a hydrated sodium ion, it is shown how the electrostatic potential restraint translates into the on-the-fly consideration of the corresponding free-energy correction terms. It is discussed how the restraints can be generalized to situations involving several solute particles. Although the present study considers a very simple system only, it is an important step toward the on-the-fly elimination of finite-size and approximate-electrostatic artifacts during atomistic molecular dynamics simulations.
Collapse
Affiliation(s)
- Maria M. Reif
- Institute for Molecular Modeling and Simulation, University of Natural Resources and Life Sciences, Vienna, Muthgasse 18, 1190 Vienna, Austria
| | - Chris Oostenbrink
- Institute for Molecular Modeling and Simulation, University of Natural Resources and Life Sciences, Vienna, Muthgasse 18, 1190 Vienna, Austria
| |
Collapse
|
19
|
Starovoytov ON, Liu Y, Tan L, Yang S. Effects of the hydroxyl group on phenyl based ligand/ERRγ protein binding. Chem Res Toxicol 2014; 27:1371-9. [PMID: 25098505 PMCID: PMC4137991 DOI: 10.1021/tx500082r] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Bisphenol-A (4,4'-dihydroxy-2,2-diphenylpropane, BPA, or BPA-A) and its derivatives, when exposed to humans, may affect functions of multiple organs by specific binding to the human estrogen-related receptor γ (ERRγ). We carried out atomistic molecular dynamics (MD) simulations of three ligand compounds including BPA-A, 4-α-cumylphenol (BPA-C), and 2,2-diphenylpropane (BPA-D) binding to the ligand binding domain (LBD) of a human ERRγ to study the structures and energies associated with the binding. We used the implicit Molecular Mechanics/Poisson-Boltzmann Surface Area (MM/PBSA) method to estimate the free energies of binding for the phenyl based compound/ERRγ systems. The addition of hydroxyl groups to the aromatic ring had only a minor effect on binding structures and a significant effect on ligand/protein binding energy in an aqueous solution. Free binding energies of BPA-D to the ERRγ were found to be considerably less than those of BPA-A and BPA-C to the ERRγ. These results are well correlated with those from experiments where no binding affinities were determined in the BPA-D/ERRγ complex. No conformational change was observed for the helix 12 (H-12) of ERRγ upon binding of these compounds preserving an active transcriptional conformation state.
Collapse
Affiliation(s)
- Oleg N Starovoytov
- Department of Chemistry, Wayne State University , Detroit, Michigan 48202, United States
| | | | | | | |
Collapse
|
20
|
Miguel ELM, Silva PL, Pliego JR. Theoretical Prediction of pKa in Methanol: Testing SM8 and SMD Models for Carboxylic Acids, Phenols, and Amines. J Phys Chem B 2014; 118:5730-9. [DOI: 10.1021/jp501379p] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Elizabeth L. M. Miguel
- Departamento de Ciências
Naturais, Universidade Federal de São João del-Rei, 36301-160, São João del-Rei, MG, Brazil
| | - Poliana L. Silva
- Departamento de Ciências
Naturais, Universidade Federal de São João del-Rei, 36301-160, São João del-Rei, MG, Brazil
| | - Josefredo R. Pliego
- Departamento de Ciências
Naturais, Universidade Federal de São João del-Rei, 36301-160, São João del-Rei, MG, Brazil
| |
Collapse
|
21
|
Smith C, Kong H. Cross-linkable liposomes stabilize a magnetic resonance contrast-enhancing polymeric fastener. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:3697-3704. [PMID: 24635565 PMCID: PMC3983383 DOI: 10.1021/la500412r] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/30/2014] [Revised: 03/09/2014] [Indexed: 06/03/2023]
Abstract
Liposomes are commonly used to deliver drugs and contrast agents to their target site in a controlled manner. One of the greatest obstacles in the performance of such delivery vehicles is their stability in the presence of serum. Here, we demonstrate a method to stabilize a class of liposomes that load gadolinium, a magnetic resonance (MR) contrast agent, as a model cargo on their surfaces. We hypothesized that the sequential adsorption of a gadolinium-binding chitosan fastener on the liposome surface followed by covalent cross-linking of the lipid bilayer would provide enhanced stability and improved MR signal in the presence of human serum. To investigate this hypothesis, liposomes composed of diyne-containing lipids were assembled and functionalized via chitosan conjugated with a hydrophobic anchor and diethylenetriaminepentaacetic acid (DTPA). This postadsorption cross-linking strategy served to stabilize the thermodynamically favorable association between liposome and polymeric fastener. Furthermore, the chitosan-coated, cross-linked liposomes proved more effective as delivery vehicles of gadolinium than uncross-linked liposomes due to the reduced liposome degradation and chitosan desorption. Overall, this study demonstrates a useful method to stabilize a broad class of particles used for systemic delivery of various molecular payloads.
Collapse
Affiliation(s)
- Cartney
E. Smith
- Department
of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, Illinois, 61801 United States
| | - Hyunjoon Kong
- Department
of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, Illinois, 61801 United States
- Institute
for Genomic Biology, University of Illinois
at Urbana-Champaign, 1206 West Gregory Drive, Urbana, Illinois 61801, United
States
| |
Collapse
|
22
|
Lukšič M, Fennell CJ, Dill KA. Using interpolation for fast and accurate calculation of ion-ion interactions. J Phys Chem B 2014; 118:8017-25. [PMID: 24625086 PMCID: PMC4142335 DOI: 10.1021/jp501141j] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
We perform extensive molecular dynamics (MD) simulations between pairs of ions of various diameters (2-5.5 Å in increments of 0.5 Å) and charge (+1 or -1) interacting in explicit water (TIP3P) under ambient conditions. We extract their potentials of mean force (PMFs). We develop an interpolation scheme, called i-PMF, that is capable of capturing the full set of PMFs for arbitrary combinations of ion sizes ranging from 2 to 5.5 Å. The advantage of the interpolation process is computational cost. Whereas it can take 100 h to simulate each PMF by MD, we can compute an equivalently accurate i-PMF in seconds. This process may be useful for rapid and accurate calculation of the strengths of salt bridges and the effects of bridging waters in biomolecular simulations. We also find that our data is consistent with Collins' "law of matching affinities" of ion solubilities: small-small or large-large ion pairs are poorly soluble in water, whereas small-large are highly soluble.
Collapse
Affiliation(s)
- Miha Lukšič
- Laufer Center for Physical and Quantitative Biology, Stony Brook University , Stony Brook, New York 11794-5252, United States
| | | | | |
Collapse
|
23
|
Li L, Dill KA, Fennell CJ. Testing the semi-explicit assembly model of aqueous solvation in the SAMPL4 challenge. J Comput Aided Mol Des 2014; 28:259-64. [PMID: 24474161 DOI: 10.1007/s10822-014-9712-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2013] [Accepted: 01/16/2014] [Indexed: 12/14/2022]
Abstract
Here, we test a method, called semi-explicit assembly (SEA), that computes the solvation free energies of molecules in water in the SAMPL4 blind test challenge. SEA was developed with the intention of being as accurate as explicit-solvent models, but much faster to compute. It is accurate because it uses pre-simulations of simple spheres in explicit solvent to obtain structural and thermodynamic quantities, and it is fast because it parses solute free energies into regionally additive quantities. SAMPL4 provided us the opportunity to make new tests of SEA. Our tests here lead us to the following conclusions: (1) The newest version, called Field-SEA, which gives improved predictions for highly charged ions, is shown here to perform as well as the earlier versions (dipolar and quadrupolar SEA) on this broad blind SAMPL4 test set. (2) We find that both the past and present SEA models give solvation free energies that are as accurate as TIP3P. (3) Using a new approach for force field parameter optimization, we developed improved hydroxyl parameters that ensure consistency with neat-solvent dielectric constants, and found that they led to improved solvation free energies for hydroxyl-containing compounds in SAMPL4. We also learned that these hydroxyl parameters are not just fixing solvent exposed oxygens in a general sense, and therefore do not improve predictions for carbonyl or carboxylic-acid groups. Other such functional groups will need their own independent optimizations for potential improvements. Overall, these tests in SAMPL4 indicate that SEA is an accurate, general and fast new approach to computing solvation free energies.
Collapse
Affiliation(s)
- Libo Li
- Departments of Chemistry and Physics, Laufer Center for Physical and Quantitative Biology, Stony Brook University, Stony Brook, NY, 11794, USA
| | | | | |
Collapse
|
24
|
Li L, Fennell CJ, Dill KA. Field-SEA: a model for computing the solvation free energies of nonpolar, polar, and charged solutes in water. J Phys Chem B 2013; 118:6431-7. [PMID: 24299013 PMCID: PMC4065164 DOI: 10.1021/jp4115139] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
![]()
Previous
work describes a computational solvation model called semi-explicit
assembly (SEA). The SEA water model computes the free energies of
solvation of nonpolar and polar solutes in water with good efficiency
and accuracy. However, SEA gives systematic errors in the solvation
free energies of ions and charged solutes. Here, we describe field-SEA,
an improved treatment that gives accurate solvation free energies
of charged solutes, including monatomic and polyatomic ions and model
dipeptides, as well as nonpolar and polar molecules. Field-SEA is
computationally inexpensive for a given solute because explicit-solvent
model simulations are relegated to a precomputation step and because
it represents solvating waters in terms of a solute’s free-energy
field. In essence, field-SEA approximates the physics of explicit-model
simulations within a computationally efficient framework. A key finding
is that an atom’s solvation shell inherits characteristics
of a neighboring atom, especially strongly charged neighbors. Field-SEA
may be useful where there is a need for solvation free-energy computations
that are faster than explicit-solvent simulations and more accurate
than traditional implicit-solvent simulations for a wide range of
solutes.
Collapse
Affiliation(s)
- Libo Li
- Laufer Center for Physical and Quantitative Biology, and Departments of Physics and Chemistry, Stony Brook University , Stony Brook, New York 11794, United States
| | | | | |
Collapse
|
25
|
May A, Pool R, van Dijk E, Bijlard J, Abeln S, Heringa J, Feenstra KA. Coarse-grained versus atomistic simulations: realistic interaction free energies for real proteins. ACTA ACUST UNITED AC 2013; 30:326-34. [PMID: 24273239 DOI: 10.1093/bioinformatics/btt675] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
MOTIVATION To assess whether two proteins will interact under physiological conditions, information on the interaction free energy is needed. Statistical learning techniques and docking methods for predicting protein-protein interactions cannot quantitatively estimate binding free energies. Full atomistic molecular simulation methods do have this potential, but are completely unfeasible for large-scale applications in terms of computational cost required. Here we investigate whether applying coarse-grained (CG) molecular dynamics simulations is a viable alternative for complexes of known structure. RESULTS We calculate the free energy barrier with respect to the bound state based on molecular dynamics simulations using both a full atomistic and a CG force field for the TCR-pMHC complex and the MP1-p14 scaffolding complex. We find that the free energy barriers from the CG simulations are of similar accuracy as those from the full atomistic ones, while achieving a speedup of >500-fold. We also observe that extensive sampling is extremely important to obtain accurate free energy barriers, which is only within reach for the CG models. Finally, we show that the CG model preserves biological relevance of the interactions: (i) we observe a strong correlation between evolutionary likelihood of mutations and the impact on the free energy barrier with respect to the bound state; and (ii) we confirm the dominant role of the interface core in these interactions. Therefore, our results suggest that CG molecular simulations can realistically be used for the accurate prediction of protein-protein interaction strength. AVAILABILITY AND IMPLEMENTATION The python analysis framework and data files are available for download at http://www.ibi.vu.nl/downloads/bioinformatics-2013-btt675.tgz.
Collapse
Affiliation(s)
- Ali May
- Centre for Integrative Bioinformatics (IBIVU), VU University Amsterdam, Amsterdam Institute for Molecules Medicines and Systems (AIMMS), VU University Amsterdam, Department of Preventive Dentistry, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and VU University Amsterdam, Netherlands Bioinformatics Centre (NBIC), Geert Grooteplein 28 6525 GA Nijmegen, The Netherlands and Department of Biological Psychology, VU University Amsterdam, 1081 HV Amsterdam, The Netherlands
| | | | | | | | | | | | | |
Collapse
|
26
|
Desmond JL, Rodger PM, Walsh TR. Testing the inter-operability of the CHARMM and SPC/Fw force fields for conformational sampling. MOLECULAR SIMULATION 2013. [DOI: 10.1080/08927022.2013.824574] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
|
27
|
Sun Z, Zhang W, Ji M, Hartsock R, Gaffney KJ. Contact Ion Pair Formation between Hard Acids and Soft Bases in Aqueous Solutions Observed with 2DIR Spectroscopy. J Phys Chem B 2013; 117:15306-12. [DOI: 10.1021/jp4033854] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Affiliation(s)
- Zheng Sun
- PULSE Institute, SLAC National Accelerator
Laboratory, Stanford University, Stanford,
California 94305, United
States
| | - Wenkai Zhang
- PULSE Institute, SLAC National Accelerator
Laboratory, Stanford University, Stanford,
California 94305, United
States
| | - Minbiao Ji
- PULSE Institute, SLAC National Accelerator
Laboratory, Stanford University, Stanford,
California 94305, United
States
| | - Robert Hartsock
- PULSE Institute, SLAC National Accelerator
Laboratory, Stanford University, Stanford,
California 94305, United
States
| | - Kelly J. Gaffney
- PULSE Institute, SLAC National Accelerator
Laboratory, Stanford University, Stanford,
California 94305, United
States
| |
Collapse
|
28
|
Harano Y, Roth R, Chiba S. A morphometric approach for the accurate solvation thermodynamics of proteins and ligands. J Comput Chem 2013; 34:1969-74. [DOI: 10.1002/jcc.23348] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2013] [Revised: 05/01/2013] [Accepted: 05/10/2013] [Indexed: 11/08/2022]
Affiliation(s)
- Yuichi Harano
- Institute for Protein Research; Osaka University; 3-2 Yamadaoka; Suita; Osaka; 565-0871; Japan
| | - Roland Roth
- Institut für Theoretische Physik; Universität Tübingen; Auf der Morgenstelle 14; 72076 Tübingen; Germany
| | - Shuntaro Chiba
- Center for Biological Resources and Informatics; Tokyo Institute of Technology; Yokohama; 226-8501; Japan
| |
Collapse
|
29
|
Ahmed A, Sandler SI. Hydration Free Energies of Multifunctional Nitroaromatic Compounds. J Chem Theory Comput 2013; 9:2774-85. [DOI: 10.1021/ct3011002] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- Alauddin Ahmed
- Department
of Chemical and Biomolecular Engineering,
University of Delaware, Newark, Delaware 19716, United States
| | - Stanley I. Sandler
- Department
of Chemical and Biomolecular Engineering,
University of Delaware, Newark, Delaware 19716, United States
| |
Collapse
|
30
|
Ahmed A, Sandler SI. Physicochemical Properties of Hazardous Energetic Compounds from Molecular Simulation. J Chem Theory Comput 2013; 9:2389-97. [DOI: 10.1021/ct301129x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Affiliation(s)
- Alauddin Ahmed
- Center for Molecular and Engineering Thermodynamics,
Department of Chemical and Biomolecular Engineering, University of
Delaware, Newark, Delaware 19716, United States
| | - Stanley I. Sandler
- Center for Molecular and Engineering Thermodynamics,
Department of Chemical and Biomolecular Engineering, University of
Delaware, Newark, Delaware 19716, United States
| |
Collapse
|
31
|
Bardhan JP, Jungwirth P, Makowski L. Affine-response model of molecular solvation of ions: Accurate predictions of asymmetric charging free energies. J Chem Phys 2013; 137:124101. [PMID: 23020318 DOI: 10.1063/1.4752735] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Two mechanisms have been proposed to drive asymmetric solvent response to a solute charge: a static potential contribution similar to the liquid-vapor potential, and a steric contribution associated with a water molecule's structure and charge distribution. In this work, we use free-energy perturbation molecular-dynamics calculations in explicit water to show that these mechanisms act in complementary regimes; the large static potential (∼44 kJ/mol/e) dominates asymmetric response for deeply buried charges, and the steric contribution dominates for charges near the solute-solvent interface. Therefore, both mechanisms must be included in order to fully account for asymmetric solvation in general. Our calculations suggest that the steric contribution leads to a remarkable deviation from the popular "linear response" model in which the reaction potential changes linearly as a function of charge. In fact, the potential varies in a piecewise-linear fashion, i.e., with different proportionality constants depending on the sign of the charge. This discrepancy is significant even when the charge is completely buried, and holds for solutes larger than single atoms. Together, these mechanisms suggest that implicit-solvent models can be improved using a combination of affine response (an offset due to the static potential) and piecewise-linear response (due to the steric contribution).
Collapse
Affiliation(s)
- Jaydeep P Bardhan
- Department of Molecular Biophysics and Physiology, Rush University Medical Center, Chicago, Illinois 60612, USA
| | | | | |
Collapse
|
32
|
Guo Z, Li B, Dzubiella J, Cheng LT, McCammon JA, Che J. Evaluation of Hydration Free Energy by Level-Set Variational Implicit-Solvent Model with Coulomb-Field Approximation. J Chem Theory Comput 2013; 9:1778-1787. [PMID: 23505345 PMCID: PMC3596957 DOI: 10.1021/ct301087w] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2012] [Indexed: 01/22/2023]
Abstract
![]()
In this article, we systematically apply a novel implicit-solvent
model, the variational implicit-solvent model (VISM) together with
the Coulomb-Field Approximation (CFA), to calculate the hydration
free energy of a large set of small organic molecules. Because these
molecules have been studied in detail by molecular dynamics simulations
and other implicit-solvent models, they provide a good benchmark for
evaluating the performance of VISM-CFA. With all-atom Amber force
field parameters, VISM-CFA is able to reproduce well not only the
experimental and MD simulated total hydration free energy but also
the polar and nonpolar contributions individually. The correlation
between VISM-CFA and experiments is R2 = 0.763 for the total hydration free energy, with a root-mean-square
deviation (RMSD) of 1.83 kcal/mol, and the correlation to results
from TIP3P explicit water MD simulations is R2 = 0.839 with a RMSD = 1.36 kcal/mol. In addition, we demonstrate
that VISM captures dewetting phenomena in the p53/MDM2 complex and
hydrophobic characteristics in the system. This work demonstrates
that the level-set VISM-CFA can be used to study the energetic behavior
of realistic molecular systems with complicated geometries in solvation,
protein–ligand binding, protein–protein association,
and protein folding processes.
Collapse
Affiliation(s)
- Zuojun Guo
- Genomics Institute of the Novartis Research Foundation, 10675 John Jay Hopkins Drive, San Diego, California 92121, United States
| | | | | | | | | | | |
Collapse
|
33
|
Abstract
Linear solvation theories are well established to describe electrostatic hydration of small solutes when the hydration free energy is dominated by the electrostatic free energy of the solute multipole. In contrast, hydration of nanometer solutes is driven by surface hydration. We address the question of whether the linear-response thermodynamics established for small multipolar solutes applies to surface hydration. To this end, molecular dynamics simulations are carried out on a model C180 solute that carries no global multipole, but the surface of which is decorated with radially pointing dipoles. Linear response is dramatically violated in this case. Further, two crossovers in the solvation thermodynamics are discovered as the surface polarity is increased. Both transformations produce strongly nonlinear solvation response. The second, more collective, crossover leads to a dramatic slowing down of the interfacial dynamics, reaching the time-scales of nanoseconds. Our picture offers the possibility of flipping water domains at interfaces of nanoparticles and biomolecules.
Collapse
Affiliation(s)
- Allan D Friesen
- Center for Biological Physics, Arizona State University, P.O. Box 871504, Tempe, Arizona 85287-1504, United States
| | - Dmitry V Matyushov
- Center for Biological Physics, Arizona State University, P.O. Box 871504, Tempe, Arizona 85287-1504, United States
| |
Collapse
|
34
|
Abstract
Coarse-grained (CG) models have proven to be very effective tools in the study of phenomena or systems that involve large time- and length-scales. By decreasing the degrees of freedom in the system and using softer interactions than seen in atomistic models, larger timesteps can be used and much longer simulation times can be studied. CG simulations are widely used to study systems of biological importance that are beyond the reach of atomistic simulation, necessitating a computationally efficient and accurate CG model for water. In this review, we discuss the methods used for developing CG water models and the relative advantages and disadvantages of the resulting models. In general, CG water models differ with regards to how many waters each CG group or bead represents, whether analytical or tabular potentials have been used to describe the interactions, and how the model incorporates electrostatic interactions. Finally, how the models are parameterized depends on their application, so, while some are fitted to experimental properties such as surface tension and density, others are fitted to radial distribution functions extracted from atomistic simulations.
Collapse
Affiliation(s)
| | - Clare McCabe
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville TN 37235-1604
- Department of Chemistry, Vanderbilt University, Nashville TN 37235-1604
| |
Collapse
|
35
|
|