1
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Tolokh IS, Folescu DE, Onufriev AV. Inclusion of Water Multipoles into the Implicit Solvation Framework Leads to Accuracy Gains. J Phys Chem B 2024; 128:5855-5873. [PMID: 38860842 PMCID: PMC11194828 DOI: 10.1021/acs.jpcb.4c00254] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2024] [Revised: 05/28/2024] [Accepted: 05/29/2024] [Indexed: 06/12/2024]
Abstract
The current practical "workhorses" of the atomistic implicit solvation─the Poisson-Boltzmann (PB) and generalized Born (GB) models─face fundamental accuracy limitations. Here, we propose a computationally efficient implicit solvation framework, the Implicit Water Multipole GB (IWM-GB) model, that systematically incorporates the effects of multipole moments of water molecules in the first hydration shell of a solute, beyond the dipole water polarization already present at the PB/GB level. The framework explicitly accounts for coupling between polar and nonpolar contributions to the total solvation energy, which is missing from many implicit solvation models. An implementation of the framework, utilizing the GAFF force field and AM1-BCC atomic partial charges model, is parametrized and tested against the experimental hydration free energies of small molecules from the FreeSolv database. The resulting accuracy on the test set (RMSE ∼ 0.9 kcal/mol) is 12% better than that of the explicit solvation (TIP3P) treatment, which is orders of magnitude slower. We also find that the coupling between polar and nonpolar parts of the solvation free energy is essential to ensuring that several features of the IWM-GB model are physically meaningful, including the sign of the nonpolar contributions.
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Affiliation(s)
- Igor S. Tolokh
- Department
of Computer Science, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Dan E. Folescu
- Department
of Computer Science, Virginia Tech, Blacksburg, Virginia 24061, United States
- Department
of Mathematics, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Alexey V. Onufriev
- Department
of Computer Science, Virginia Tech, Blacksburg, Virginia 24061, United States
- Department
of Physics, Virginia Tech, Blacksburg, Virginia 24061, United States
- Center
for Soft Matter and Biological Physics, Virginia Tech, Blacksburg, Virginia 24061, United States
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2
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Risheh A, Rebel A, Nerenberg PS, Forouzesh N. Calculation of protein-ligand binding entropies using a rule-based molecular fingerprint. Biophys J 2024:S0006-3495(24)00182-6. [PMID: 38481102 DOI: 10.1016/j.bpj.2024.03.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2023] [Revised: 12/21/2023] [Accepted: 03/08/2024] [Indexed: 03/28/2024] Open
Abstract
The use of fast in silico prediction methods for protein-ligand binding free energies holds significant promise for the initial phases of drug development. Numerous traditional physics-based models (e.g., implicit solvent models), however, tend to either neglect or heavily approximate entropic contributions to binding due to their computational complexity. Consequently, such methods often yield imprecise assessments of binding strength. Machine learning models provide accurate predictions and can often outperform physics-based models. They, however, are often prone to overfitting, and the interpretation of their results can be difficult. Physics-guided machine learning models combine the consistency of physics-based models with the accuracy of modern data-driven algorithms. This work integrates physics-based model conformational entropies into a graph convolutional network. We introduce a new neural network architecture (a rule-based graph convolutional network) that generates molecular fingerprints according to predefined rules specifically optimized for binding free energy calculations. Our results on 100 small host-guest systems demonstrate significant improvements in convergence and preventing overfitting. We additionally demonstrate the transferability of our proposed hybrid model by training it on the aforementioned host-guest systems and then testing it on six unrelated protein-ligand systems. Our new model shows little difference in training set accuracy compared to a previous model but an order-of-magnitude improvement in test set accuracy. Finally, we show how the results of our hybrid model can be interpreted in a straightforward fashion.
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Affiliation(s)
- Ali Risheh
- Department of Computer Science, California State University, Los Angeles, California
| | - Alles Rebel
- Department of Computer Science, California State University, Los Angeles, California
| | - Paul S Nerenberg
- Kravis Department of Integrated Sciences, Claremont McKenna College, Claremont, California
| | - Negin Forouzesh
- Department of Computer Science, California State University, Los Angeles, California.
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3
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Khuttan S, Gallicchio E. What to Make of Zero: Resolving the Statistical Noise from Conformational Reorganization in Alchemical Binding Free Energy Estimates with Metadynamics Sampling. J Chem Theory Comput 2024; 20:1489-1501. [PMID: 38252868 PMCID: PMC10867849 DOI: 10.1021/acs.jctc.3c01250] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2023] [Revised: 01/03/2024] [Accepted: 01/03/2024] [Indexed: 01/24/2024]
Abstract
We introduce the self-relative binding free energy (self-RBFE) approach to evaluate the intrinsic statistical variance of dual-topology alchemical binding free energy estimators. The self-RBFE is the relative binding free energy between a ligand and a copy of the same ligand, and its true value is zero. Nevertheless, because the two copies of the ligand move independently, the self-RBFE value produced by a finite-length simulation fluctuates and can be used to measure the variance of the model. The results of this validation provide evidence that a significant fraction of the errors observed in benchmark studies reflect the statistical fluctuations of unconverged estimates rather than the models' accuracy. Furthermore, we find that ligand reorganization is a significant contributing factor to the statistical variance of binding free energy estimates and that metadynamics-accelerated conformational sampling of the torsional degrees of freedom of the ligand can drastically reduce the time to convergence.
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Affiliation(s)
- Sheenam Khuttan
- Department
of Chemistry and Biochemistry, Brooklyn
College of the City University of New York, New York, New York 11210, United States
- Ph.D.
Program in Biochemistry, The Graduate Center
of the City University of New York, New York, New York 10016, United States
| | - Emilio Gallicchio
- Department
of Chemistry and Biochemistry, Brooklyn
College of the City University of New York, New York, New York 11210, United States
- Ph.D.
Program in Biochemistry, The Graduate Center
of the City University of New York, New York, New York 10016, United States
- Ph.D.
Program in Chemistry, The Graduate Center
of the City University of New York, New York, New York 10016, United States
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4
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Setiadi J, Boothroyd S, Slochower DR, Dotson DL, Thompson MW, Wagner JR, Wang LP, Gilson MK. Tuning Potential Functions to Host-Guest Binding Data. J Chem Theory Comput 2024; 20:239-252. [PMID: 38147689 PMCID: PMC10838530 DOI: 10.1021/acs.jctc.3c01050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2023]
Abstract
Software to more rapidly and accurately predict protein-ligand binding affinities is of high interest for early-stage drug discovery, and physics-based methods are among the most widely used technologies for this purpose. The accuracy of these methods depends critically on the accuracy of the potential functions that they use. Potential functions are typically trained against a combination of quantum chemical and experimental data. However, although binding affinities are among the most important quantities to predict, experimental binding affinities have not to date been integrated into the experimental data set used to train potential functions. In recent years, the use of host-guest complexes as simple and tractable models of binding thermodynamics has gained popularity due to their small size and simplicity, relative to protein-ligand systems. Host-guest complexes can also avoid ambiguities that arise in protein-ligand systems such as uncertain protonation states. Thus, experimental host-guest binding data are an appealing additional data type to integrate into the experimental data set used to optimize potential functions. Here, we report the extension of the Open Force Field Evaluator framework to enable the systematic calculation of host-guest binding free energies and their gradients with respect to force field parameters, coupled with the curation of 126 host-guest complexes with available experimental binding free energies. As an initial application of this novel infrastructure, we optimized generalized Born (GB) cavity radii for the OBC2 GB implicit solvent model against experimental data for 36 host-guest systems. This refitting led to a dramatic improvement in accuracy for both the training set and a separate test set with 90 additional host-guest systems. The optimized radii also showed encouraging transferability from host-guest systems to 59 protein-ligand systems. However, the new radii are significantly smaller than the baseline radii and lead to excessively favorable hydration free energies (HFEs). Thus, users of the OBC2 GB model currently may choose between GB cavity radii that yield more accurate binding affinities and GB cavity radii that yield more accurate HFEs. We suspect that achieving good accuracy on both will require more far-reaching adjustments to the GB model. We note that binding free-energy calculations using the OBC2 model in OpenMM gain about a 10× speedup relative to corresponding explicit solvent calculations, suggesting a future role for implicit solvent absolute binding free-energy (ABFE) calculations in virtual compound screening. This study proves the principle of using host-guest systems to train potential functions that are transferrable to protein-ligand systems and provides an infrastructure that enables a range of applications.
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Affiliation(s)
- Jeffry Setiadi
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, 9255 Pharmacy Lane, La Jolla, California 92093, United States
| | - Simon Boothroyd
- Boothroyd Scientific Consulting Ltd., London WC2H 9JQ, U.K
- Psivant Therapeutics, Boston, Massachusetts 02210, United States
| | | | - David L Dotson
- Datryllic LLC, Phoenix, Arizona 85003, United States
- The Open Force Field Consortium, Open Molecular Software Foundation, Davis, California 95616, United States
| | - Matthew W Thompson
- The Open Force Field Consortium, Open Molecular Software Foundation, Davis, California 95616, United States
| | - Jeffrey R Wagner
- The Open Force Field Consortium, Open Molecular Software Foundation, Davis, California 95616, United States
| | - Lee-Ping Wang
- Chemistry Department, University of California Davis, Davis, California 95616, United States
| | - Michael K Gilson
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, 9255 Pharmacy Lane, La Jolla, California 92093, United States
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5
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Kumar P, Bhardwaj VK, Purohit R. Highly robust quantum mechanics and umbrella sampling studies on inclusion complexes of curcumin and β-cyclodextrin. Carbohydr Polym 2024; 323:121432. [PMID: 37940299 DOI: 10.1016/j.carbpol.2023.121432] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Revised: 09/12/2023] [Accepted: 09/23/2023] [Indexed: 11/10/2023]
Abstract
The poor aqueous solubility of curcumin (CUR) obstructs its wide utilization in nutraceuticals, cosmetics, and pharmaceutical companies. This study is dedicated to investigate the stability of CUR inside the hydrophobic pocket of β-cyclodextrin (β-CD), hydroxypropyl-β-CD (HP-β-CD), and 2,6-Di-O-methyl-β-CD (DM-β-CD). Initially, molecular mechanics (MM) calculations and subsequently quantum mechanical (QM) calculations were performed on inclusion complexes to strengthen the MM results. We performed microsecond timescale MD simulations to observe the structural dynamics of CUR inside the cavity of CDs. We elucidated the most stable binding orientations of CUR inside the cavity of CDs based on binding free energy obtained from the Molecular Mechanics Poisson-Boltzmann Surface Area (MM-PBSA) and umbrella sampling simulations. Furthermore, the two-layered ONIOM (B3LYP/6-311+G(2d,p):PM7) method with CPCM implicit water model was used to derive the complete energetics and thermodynamics of inclusion complexes at 1:1 stoichiometry. Each inclusion reaction was exothermic and spontaneous. The chemical reactivity and kinetic stability of inclusion complexes were described by HOMO-LUMO molecular orbital energies. In conclusion, our studies revealed that HP-β-CD had the highest binding affinity for CUR with the most negative complexation energy (-6520.69 kJ/mol) and Gibb's free energy change (-6448.20 kJ/mol). The atomic-level investigation of noncovalent interactions between CUR and the hydroxypropyl groups in HP-β-CD/CUR complex may be helpful to drive new derivatives of HP-β-CD with better host capacity. The computational strategy adopted here might serve as a benchmark for increasing the solubility of numerous clinically significant molecules.
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Affiliation(s)
- Pramod Kumar
- Structural Bioinformatics Lab, Biotechnology Division, CSIR-Institute of Himalayan Bioresource Technology (CSIR-IHBT), Palampur, HP 176061, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad- 201002, India
| | - Vijay Kumar Bhardwaj
- Structural Bioinformatics Lab, Biotechnology Division, CSIR-Institute of Himalayan Bioresource Technology (CSIR-IHBT), Palampur, HP 176061, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad- 201002, India
| | - Rituraj Purohit
- Structural Bioinformatics Lab, Biotechnology Division, CSIR-Institute of Himalayan Bioresource Technology (CSIR-IHBT), Palampur, HP 176061, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad- 201002, India.
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6
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Agarwala P, Ghosh A, Hazarika P, Acharjee D, Ghosh S, Rout D, Sasmal DK. Unraveling the Interaction of Diflunisal with Cyclodextrin and Lysozyme by Fluorescence Spectroscopy. J Phys Chem B 2023; 127:9710-9723. [PMID: 37917720 DOI: 10.1021/acs.jpcb.3c04295] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2023]
Abstract
Understanding the interaction between the drug:carrier complex and protein is essential for the development of a new drug-delivery system. However, the majority of reports are based on an understanding of interactions between the drug and protein. Here, we present our findings on the interaction of the anti-inflammatory drug diflunisal with the drug carrier cyclodextrin (CD) and the protein lysozyme, utilizing steady-state and time-resolved fluorescence spectroscopy. Our findings reveal a different pattern of molecular interaction between the inclusion complex of β-CD (β-CD) or hydroxypropyl-β-CD (HP-β-CD) (as the host) and diflunisal (as the guest) in the presence of protein lysozyme. The quantum yield for the 1:2 guest:host complex is twice that of the 1:1 guest:host complex, indicating a more stable hydrophobic microenvironment created in the 1:2 complex. Consequently, the nonradiative decay pathway is significantly reduced. The interaction is characterized by ultrafast solvation dynamics and time-resolved fluorescence resonance energy transfer. The solvation dynamics of the lysozyme becomes 10% faster under the condition of binding with the drug, indicating a negligible change in the polar environment after binding. In addition, the fluorescence lifetime of diflunisal (acceptor) is increased by 50% in the presence of the lysozyme (donor), which indicates that the drug molecule is bound to the binding pocket on the surface of the protein, and the average distance between active tryptophan in the hydrophobic region and diflunisal is calculated to be approximately 50 Å. Excitation and emission matrix spectroscopy reveals that the tryptophan emission increases 3-5 times in the presence of both diflunisal and CD. This indicates that the tryptophan of lysozyme may be present in a more hydrophobic environment in the presence of both diflunisal and CD. Our observations on the interaction of diflunisal with β-CD and lysozyme are well supported by molecular dynamics simulation. Results from this study may have an impact on the development of a better drug-delivery system in the future. It also reveals a fundamental molecular mechanism of interaction of the drug-carrier complex with the protein.
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Affiliation(s)
- Pratibha Agarwala
- Department of Chemistry, Indian Institute of Technology Jodhpur, Jodhpur, Rajasthan 342037, India
| | - Arabinda Ghosh
- Department of Computational Biology and Biotechnology, Mahapurusha Srimanta Sankaradeva Viswavidyalaya, Guwahati Unit, Guwahati, Assam 781032, India
| | - Priyanka Hazarika
- Department of Chemistry, Indian Institute of Technology Jodhpur, Jodhpur, Rajasthan 342037, India
| | - Debopam Acharjee
- School of Chemical Sciences, National Institute of Science Education and Research, An OCC of Homi Bhabha National Institute (HBNI), Khurda, Odisha 752050, India
| | - Shirsendu Ghosh
- Department of Chemistry, Gandhi Institute of Technology and Management (GITAM), Hyderabad Campus, Hyderabad 502329, India
| | - Debasish Rout
- Department of Chemistry, Indian Institute of Technology Jodhpur, Jodhpur, Rajasthan 342037, India
| | - Dibyendu K Sasmal
- Department of Chemistry, Indian Institute of Technology Jodhpur, Jodhpur, Rajasthan 342037, India
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7
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Khuttan S, Azimi S, Wu JZ, Dick S, Wu C, Xu H, Gallicchio E. Taming multiple binding poses in alchemical binding free energy prediction: the β-cyclodextrin host-guest SAMPL9 blinded challenge. Phys Chem Chem Phys 2023; 25:24364-24376. [PMID: 37676233 DOI: 10.1039/d3cp02125d] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/08/2023]
Abstract
We apply the Alchemical Transfer Method (ATM) and a bespoke fixed partial charge force field to the SAMPL9 bCD host-guest binding free energy prediction challenge that comprises a combination of complexes formed between five phenothiazine guests and two cyclodextrin hosts. Multiple chemical forms, competing binding poses, and computational modeling challenges pose significant obstacles to obtaining reliable computational predictions for these systems. The phenothiazine guests exist in solution as racemic mixtures of enantiomers related by nitrogen inversions that bind the hosts in various binding poses, each requiring an individual free energy analysis. Due to the large size of the guests and the conformational reorganization of the hosts, which prevent a direct absolute binding free energy route, binding free energies are obtained by a series of absolute and relative binding alchemical steps for each chemical species in each binding pose. Metadynamics-accelerated conformational sampling was found to be necessary to address the poor convergence of some numerical estimates affected by conformational trapping. Despite these challenges, our blinded predictions quantitatively reproduced the experimental affinities for the β-cyclodextrin host and, to a lesser extent, those with a methylated derivative. The work illustrates the challenges of obtaining reliable free energy data in in silico drug design for even seemingly simple systems and introduces some of the technologies available to tackle them.
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Affiliation(s)
- Sheenam Khuttan
- Department of Chemistry, Brooklyn College of the City University of New York, New York, USA.
- PhD Program in Biochemistry, Graduate Center of the City University of New York, USA
| | - Solmaz Azimi
- Department of Chemistry, Brooklyn College of the City University of New York, New York, USA.
- PhD Program in Biochemistry, Graduate Center of the City University of New York, USA
| | - Joe Z Wu
- Department of Chemistry, Brooklyn College of the City University of New York, New York, USA.
- PhD Program in Chemistry, Graduate Center of the City University of New York, USA
| | | | | | | | - Emilio Gallicchio
- Department of Chemistry, Brooklyn College of the City University of New York, New York, USA.
- PhD Program in Biochemistry, Graduate Center of the City University of New York, USA
- PhD Program in Chemistry, Graduate Center of the City University of New York, USA
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8
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Bhardwaj VK, Purohit R. A comparative study on inclusion complex formation between formononetin and β-cyclodextrin derivatives through multiscale classical and umbrella sampling simulations. Carbohydr Polym 2023; 310:120729. [PMID: 36925262 DOI: 10.1016/j.carbpol.2023.120729] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Revised: 01/31/2023] [Accepted: 02/16/2023] [Indexed: 02/22/2023]
Abstract
Formononetin, a naturally occurring isoflavone exhibits a wide range of therapeutic applications including antioxidant, anti-tumor, antiviral, anti-diabetic and neuroprotective activities. However, the low hydro-solubility of formononetin has limited its prospective use in cosmetic, neutraceutical and pharmaceutical industries. Cyclodextrins (CDs), especially β-CD and its derivatives have emerged as promising agents to improve the water solubility of poorly hydrosoluble compounds by the formation of inclusion complexes. We employed multiscale (1000 ns) explicit solvent and umbrella sampling molecular dynamics (MD) simulations to study the interactions and thermodynamic parameters of inclusion complex formation between formononetin and five most commonly used β-CD derivatives. Classical MD simulations revealed two possible binding conformations of formononetin inside the central cavity of hydroxypropyl-β-CD (HP-β-CD), randomly methylated-β-CD (ME-β-CD), and sulfobutylether-β-CD (SBE-β-CD). The binding conformation with the benzopyrone ring of formononetin inside the central cavity of β-CD derivatives was more frequent than the phenyl group occupying the hydrophobic cavity. These interactions were supported by a variety of non-bonded contacts including hydrogen bonds, pi-lone pair, pi-sigma, and pi-alkyl interactions. Formononetin showed favorable end-state MD-driven thermodynamic binding free energies with all the selected β-CD derivatives, except succinyl-β-CD (S-β-CD). Furthermore, umbrella sampling simulations were used to investigate the interactions and thermodynamic parameters of the host-guest inclusion complexes. The SBE-β-CD/formononetin inclusion complex showed the lowest binding energy signifying the highest affinity among all the selected host-guest inclusion complexes. Our study could be used as a standard for analyzing and comparing the ability of different β-CD derivatives to enhance the hydro-solubility of poorly soluble molecules.
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Affiliation(s)
- Vijay Kumar Bhardwaj
- Structural Bioinformatics Lab, CSIR-Institute of Himalayan Bioresource Technology (CSIR-IHBT), Palampur, HP 176061, India; Biotechnology Division, CSIR-IHBT, Palampur, HP 176061, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad- 201002, India
| | - Rituraj Purohit
- Structural Bioinformatics Lab, CSIR-Institute of Himalayan Bioresource Technology (CSIR-IHBT), Palampur, HP 176061, India; Biotechnology Division, CSIR-IHBT, Palampur, HP 176061, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad- 201002, India.
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9
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Odstrcil RE, Dutta P, Liu J. LINES: Log-Probability Estimation via Invertible Neural Networks for Enhanced Sampling. J Chem Theory Comput 2022; 18:6297-6309. [PMID: 36099438 DOI: 10.1021/acs.jctc.2c00254] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
It is very challenging to sample a molecular process with large activation energies using molecular dynamics simulations. Current enhanced sampling methodologies, such as umbrella sampling and metadynamics, rely on the identification of appropriate reaction coordinates for a system. In this paper, we developed a method for log-probability estimation via invertible neural networks for enhanced sampling (LINES). This iterative scheme utilizes a normalizing flow machine learning model to learn the underlying free energy surface (FES) of a system as a function of molecular coordinates and then applies a gradient-based optimization method to the learned normalizing flow to identify reaction coordinates. A biasing potential is then evaluated over a tabulated grid of the reaction coordinate values, which can be applied to the next round of simulations for enhanced sampling, resulting in more efficient sampling. We tested the accuracy and efficiency of the LINES method in sampling the FES using the alanine dipeptide system. We also demonstrated the effectiveness of identification of reaction coordinates through simulation of cyclobutanol unbinding from β-cyclodextrin and the folding/unfolding of CLN025─a variant of the peptide Chignolin. The LINES method can be extended to the study of large-scale protein systems with complex nonlinear reaction pathways.
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Affiliation(s)
- Ryan E Odstrcil
- School of Mechanical and Materials Engineering, Washington State University, Pullman, Washington 99164, United States
| | - Prashanta Dutta
- School of Mechanical and Materials Engineering, Washington State University, Pullman, Washington 99164, United States
| | - Jin Liu
- School of Mechanical and Materials Engineering, Washington State University, Pullman, Washington 99164, United States
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10
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Wang F, Yu W, Popescu C, Ibrahim AA, Yu D, Pearson R, MacKerell AD, Hoag SW. Cholecalciferol complexation with hydroxypropyl-β-cyclodextrin (HPBCD) and its molecular dynamics simulation. Pharm Dev Technol 2022; 27:389-398. [PMID: 35468028 PMCID: PMC9233054 DOI: 10.1080/10837450.2022.2064492] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The focus of the current study is to investigate cholecalciferol (vitamin D3) solubilization by hydroxypropyl-β-cyclodextrin (HPBCD) complexation through experimental and computational studies. Phase solubility diagram of vitamin D3 (completely insoluble in water) has an AP profile revealing a deviation from a linear regression with HPBCD concentration increase. Differential scanning calorimetry (DSC) is the best tool to confirm complex formation by disappearance of cholecalciferol exothermic peak in cholecalciferol-HPBCD complex thermogram, due to its amorphous state by entering HPBCD inner hydrophobic cavity, similarly validated by Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). AP solubility diagram profile can be associated with cholecalciferol-HPBCD complex instability in liquid phase requiring spray drying to bring it to a solid dispersion state (always more stable) illustrated by scanning electron microscopy (SEM). Computational studies led to a deeper understanding and clarification, at molecular level, of the interactions within cholecalciferol-HPBCD complex. Thermodynamics and geometry of the complex were investigated by molecular dynamics (MD) simulation.
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Affiliation(s)
- Fang Wang
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, MD, USA
| | - Wenbo Yu
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, MD, USA
- University of Maryland School of Pharmacy, University of Maryland Computer Aided Drug Design Center, Baltimore, MD, USA
| | | | - Ahmed Ashour Ibrahim
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, MD, USA
| | - Dongyue Yu
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, MD, USA
| | - Ryan Pearson
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, MD, USA
| | - Alexander D. MacKerell
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, MD, USA
- University of Maryland School of Pharmacy, University of Maryland Computer Aided Drug Design Center, Baltimore, MD, USA
| | - Stephen W. Hoag
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, MD, USA
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11
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Sun Q, Biswas A, Vijayan RSK, Craveur P, Forli S, Olson AJ, Castaner AE, Kirby KA, Sarafianos SG, Deng N, Levy R. Structure-based virtual screening workflow to identify antivirals targeting HIV-1 capsid. J Comput Aided Mol Des 2022; 36:193-203. [PMID: 35262811 PMCID: PMC8904208 DOI: 10.1007/s10822-022-00446-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Accepted: 02/24/2022] [Indexed: 02/07/2023]
Abstract
We have identified novel HIV-1 capsid inhibitors targeting the PF74 binding site. Acting as the building block of the HIV-1 capsid core, the HIV-1 capsid protein plays an important role in the viral life cycle and is an attractive target for antiviral development. A structure-based virtual screening workflow for hit identification was employed, which includes docking 1.6 million commercially-available drug-like compounds from the ZINC database to the capsid dimer, followed by applying two absolute binding free energy (ABFE) filters on the 500 top-ranked molecules from docking. The first employs the Binding Energy Distribution Analysis Method (BEDAM) in implicit solvent. The top-ranked compounds are then refined using the Double Decoupling method in explicit solvent. Both docking and BEDAM refinement were carried out on the IBM World Community Grid as part of the FightAIDS@Home project. Using this virtual screening workflow, we identified 24 molecules with calculated binding free energies between − 6 and − 12 kcal/mol. We performed thermal shift assays on these molecules to examine their potential effects on the stability of HIV-1 capsid hexamer and found that two compounds, ZINC520357473 and ZINC4119064 increased the melting point of the latter by 14.8 °C and 33 °C, respectively. These results support the conclusion that the two ZINC compounds are primary hits targeting the capsid dimer interface. Our simulations also suggest that the two hit molecules may bind at the capsid dimer interface by occupying a new sub-pocket that has not been exploited by existing CA inhibitors. The possible causes for why other top-scored compounds suggested by ABFE filters failed to show measurable activity are discussed.
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Affiliation(s)
- Qinfang Sun
- Center for Biophysics and Computational Biology and Department of Chemistry, Temple University, Philadelphia, PA, 19122, USA
| | - Avik Biswas
- Center for Biophysics and Computational Biology and Department of Chemistry, Temple University, Philadelphia, PA, 19122, USA
| | - R S K Vijayan
- Institute for Applied Cancer Science, MD Anderson Cancer Center, Houston, TX, 77030, USA
| | - Pierrick Craveur
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA, 92037, USA
| | - Stefano Forli
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA, 92037, USA
| | - Arthur J Olson
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA, 92037, USA
| | - Andres Emanuelli Castaner
- Laboratory of Biochemical Pharmacology, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA, 30322, USA.,Children's Healthcare of Atlanta, Atlanta, GA, 30322, USA
| | - Karen A Kirby
- Laboratory of Biochemical Pharmacology, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA, 30322, USA.,Children's Healthcare of Atlanta, Atlanta, GA, 30322, USA
| | - Stefan G Sarafianos
- Laboratory of Biochemical Pharmacology, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA, 30322, USA.,Children's Healthcare of Atlanta, Atlanta, GA, 30322, USA
| | - Nanjie Deng
- Department of Chemistry and Physical Sciences, Pace University, New York, NY, 10038, USA.
| | - Ronald Levy
- Center for Biophysics and Computational Biology and Department of Chemistry, Temple University, Philadelphia, PA, 19122, USA
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12
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Wickstrom L, Gallicchio E, Chen L, Kurtzman T, Deng N. Developing end-point methods for absolute binding free energy calculation using the Boltzmann-quasiharmonic model. Phys Chem Chem Phys 2022; 24:6037-6052. [PMID: 35212338 PMCID: PMC9044818 DOI: 10.1039/d1cp05075c] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Understanding the physical forces underlying receptor-ligand binding requires robust methods for analyzing the binding thermodynamics. In end-point binding free energy methods the binding free energy is naturally decomposable into physically intuitive contributions such as the solvation free energy and configurational entropy that can provide insights. Here we present a new end-point method called EE-BQH (Effective Energy-Boltzmann-Quasiharmonic) which combines the Boltzmann-Quasiharmonic model for configurational entropy with different solvation free energy methods, such as the continuum solvent PBSA model and the integral equation-based 3D-RISM, to estimate the absolute binding free energy. We compare EE-BQH with other treatments of configurational entropy such as Quasiharmonic models in internal coordinates (QHIC) and in Cartesian coordinates (QHCC), and Normal Mode analysis (NMA), by testing them on the octa acids host-guest complexes from the SAMPL8 blind challenge. The accuracies in the calculated absolute binding free energies strongly depend on the configurational entropy and solvation free energy methods used. QHIC and BQH yield the best agreements with the established potential of mean force (PMF) estimates, with R2 of ∼0.7 and mean unsigned error of ∼1.7 kcal mol-1. These results from the end-point calculations are also in similar agreement with experiments. While 3D-RISM in combination with QHIC or BQH lead to reasonable correlations with the PMF results and experiments, the calculated absolute binding free energies are underestimated by ∼5 kcal mol-1. While the binding is accompanied by a significant reduction in the ligand translational/rotational entropy, the change in the torsional entropy in these host-guest systems is slightly positive. Compared with BQH, QHIC underestimates the reduction of configurational entropy because of the non-Gaussian probability distributions in the ligand rotation and a small number of torsions. The study highlights the crucial role of configurational entropy in determining binding and demonstrates the potential of using the new end-point method to provide insights in more complex protein-ligand systems.
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Affiliation(s)
- Lauren Wickstrom
- Borough of Manhattan Community College, The City University of New York, Department of Science, New York, New York, USA
| | - Emilio Gallicchio
- Department of Chemistry, Brooklyn College, The City University of New York, Brooklyn, New York, USA.,PhD Program in Chemistry, Graduate Center of the City University of New York, New York, USA.,PhD Program in Biochemistry, Graduate Center of the City University of New York, New York, USA
| | - Lieyang Chen
- PhD Program in Chemistry, Graduate Center of the City University of New York, New York, USA.,PhD Program in Biochemistry, Graduate Center of the City University of New York, New York, USA.,Department of Chemistry, Lehman College, The City University of New York, Bronx, New York, USA
| | - Tom Kurtzman
- PhD Program in Chemistry, Graduate Center of the City University of New York, New York, USA.,PhD Program in Biochemistry, Graduate Center of the City University of New York, New York, USA.,Department of Chemistry, Lehman College, The City University of New York, Bronx, New York, USA
| | - Nanjie Deng
- Department of Chemistry and Physical Sciences, Pace University, New York, New York, USA.
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13
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Suárez D, Díaz N. Amphiphilic cyclodextrins: Dimerization and diazepam binding explored by molecular dynamics simulations. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2021.118457] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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14
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Parks FC, Sheetz EG, Stutsman SR, Lutolli A, Debnath S, Raghavachari K, Flood AH. Revealing the Hidden Costs of Organization in Host-Guest Chemistry Using Chloride-Binding Foldamers and Their Solvent Dependence. J Am Chem Soc 2022; 144:1274-1287. [PMID: 35015538 DOI: 10.1021/jacs.1c10758] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Preorganization is a key concept in supramolecular chemistry. Preorganized receptors enhance binding by minimizing the organization costs associated with adopting the conformation needed to orient the binding sites toward the guest. Conversely, poorly organized receptors show affinities below what is possible based on the potential of their specific binding interactions. Despite the fact that the organization energy is paid each time like a tax, its value has never been measured directly, though many compounds have been developed to measure its effects. We present a method to quantify the hidden costs of receptor organization by independently measuring the contribution it makes to chloride complexation by a flexible foldameric receptor. This method uses folding energy to approximate organization energy and relies on measurement of the coil-helix equilibrium as a function of solvent. We also rely on the finding, established with rigid receptors, that affinity is inversely related to the solvent dielectric and expect the same for the foldamer's helically organized state. Increasing solvent polarity across nine dichloromethane-acetonitrile mixtures we see an unusual V-shape in affinity (decrease then increase). Quantitatively, this shape arises from weakened hydrogen-bonding interactions with solvent polarity followed by solvent-driven folding into an organized helix. We confirm that dielectric screening impacts the stability of host-guest complexes of flexible foldamers just like rigid receptors. These results experimentally verify the canonical model of binding (affinity depends on the sum of organization and noncovalent interactions). The picture of how solvent impacts complex stability and conformational organization thereby helps lay the groundwork for de novo receptor design.
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Affiliation(s)
- Fred C Parks
- Department of Chemistry, Indiana University, 800 East Kirkwood Avenue, Bloomington, Indiana 47405, United States
| | - Edward G Sheetz
- Department of Chemistry, Indiana University, 800 East Kirkwood Avenue, Bloomington, Indiana 47405, United States
| | - Sydney R Stutsman
- Department of Chemistry, Indiana University, 800 East Kirkwood Avenue, Bloomington, Indiana 47405, United States
| | - Alketa Lutolli
- Department of Chemistry, Indiana University, 800 East Kirkwood Avenue, Bloomington, Indiana 47405, United States
| | - Sibali Debnath
- Department of Chemistry, Indiana University, 800 East Kirkwood Avenue, Bloomington, Indiana 47405, United States
| | - Krishnan Raghavachari
- Department of Chemistry, Indiana University, 800 East Kirkwood Avenue, Bloomington, Indiana 47405, United States
| | - Amar H Flood
- Department of Chemistry, Indiana University, 800 East Kirkwood Avenue, Bloomington, Indiana 47405, United States
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15
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Al-Thiabat MG, Gazzali AM, Mohtar N, Murugaiyah V, Kamarulzaman EE, Yap BK, Rahman NA, Othman R, Wahab HA. Conjugated β-Cyclodextrin Enhances the Affinity of Folic Acid towards FRα: Molecular Dynamics Study. Molecules 2021; 26:5304. [PMID: 34500740 PMCID: PMC8434473 DOI: 10.3390/molecules26175304] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Revised: 08/13/2021] [Accepted: 08/16/2021] [Indexed: 12/02/2022] Open
Abstract
Drug targeting is a progressive area of research with folate receptor alpha (FRα) receiving significant attention as a biological marker in cancer drug delivery. The binding affinity of folic acid (FA) to the FRα active site provides a basis for recognition of FRα. In this study, FA was conjugated to beta-cyclodextrin (βCD) and subjected to in silico analysis (molecular docking and molecular dynamics (MD) simulation (100 ns)) to investigate the affinity and stability for the conjugated system compared to unconjugated and apo systems (ligand free). Docking studies revealed that the conjugated FA bound into the active site of FRα with a docking score (free binding energy < -15 kcal/mol), with a similar binding pose to that of unconjugated FA. Subsequent analyses from molecular dynamics (MD) simulations, root mean square deviation (RMSD), root mean square fluctuation (RMSF), and radius of gyration (Rg) demonstrated that FA and FA-βCDs created more dynamically stable systems with FRα than the apo-FRα system. All systems reached equilibrium with stable RMSD values ranging from 1.9-2.4 Å and the average residual fluctuation values of the FRα backbone atoms for all residues (except for terminal residues ARG8, THR9, THR214, and LEU215) were less than 2.1 Å with a consistent Rg value of around 16.8 Å throughout the MD simulation time (0-100 ns). The conjugation with βCD improved the stability and decreased the mobility of all the residues (except residues 149-151) compared to FA-FRα and apo-FRα systems. Further analysis of H-bonds, binding free energy (MM-PBSA), and per residue decomposition energy revealed that besides APS81, residues HIS20, TRP102, HIS135, TRP138, TRP140, and TRP171 were shown to have more favourable energy contributions in the holo systems than in the apo-FRα system, and these residues might have a direct role in increasing the stability of holo systems.
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Affiliation(s)
- Mohammad G. Al-Thiabat
- School of Pharmaceutical Sciences, Universiti Sains Malaysia, George Town 11800, Malaysia; (M.G.A.-T.); (A.M.G.); (N.M.); (V.M.); (E.E.K.); (B.K.Y.)
- Pharmaceutical Design and Simulation (PHDS) Laboratory, School of Pharmaceutical Sciences, Universiti Sains Malaysia, George Town 11800, Malaysia
| | - Amirah Mohd Gazzali
- School of Pharmaceutical Sciences, Universiti Sains Malaysia, George Town 11800, Malaysia; (M.G.A.-T.); (A.M.G.); (N.M.); (V.M.); (E.E.K.); (B.K.Y.)
| | - Noratiqah Mohtar
- School of Pharmaceutical Sciences, Universiti Sains Malaysia, George Town 11800, Malaysia; (M.G.A.-T.); (A.M.G.); (N.M.); (V.M.); (E.E.K.); (B.K.Y.)
| | - Vikneswaran Murugaiyah
- School of Pharmaceutical Sciences, Universiti Sains Malaysia, George Town 11800, Malaysia; (M.G.A.-T.); (A.M.G.); (N.M.); (V.M.); (E.E.K.); (B.K.Y.)
| | - Ezatul Ezleen Kamarulzaman
- School of Pharmaceutical Sciences, Universiti Sains Malaysia, George Town 11800, Malaysia; (M.G.A.-T.); (A.M.G.); (N.M.); (V.M.); (E.E.K.); (B.K.Y.)
| | - Beow Keat Yap
- School of Pharmaceutical Sciences, Universiti Sains Malaysia, George Town 11800, Malaysia; (M.G.A.-T.); (A.M.G.); (N.M.); (V.M.); (E.E.K.); (B.K.Y.)
| | - Noorsaadah Abd Rahman
- Department of Chemistry, Faculty of Science, Universiti Malaya, Kuala Lumpur 50603, Malaysia;
| | - Rozana Othman
- Center for Natural Products Research and Drug Discovery (CENAR), Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Universiti Malaya, Kuala Lumpur 50603, Malaysia
| | - Habibah A. Wahab
- School of Pharmaceutical Sciences, Universiti Sains Malaysia, George Town 11800, Malaysia; (M.G.A.-T.); (A.M.G.); (N.M.); (V.M.); (E.E.K.); (B.K.Y.)
- Pharmaceutical Design and Simulation (PHDS) Laboratory, School of Pharmaceutical Sciences, Universiti Sains Malaysia, George Town 11800, Malaysia
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16
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Spoel D, Zhang J, Zhang H. Quantitative predictions from molecular simulations using explicit or implicit interactions. WIRES COMPUTATIONAL MOLECULAR SCIENCE 2021. [DOI: 10.1002/wcms.1560] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Affiliation(s)
- David Spoel
- Uppsala Center for Computational Chemistry, Science for Life Laboratory, Department of Cell and Molecular Biology Uppsala University Uppsala Sweden
| | - Jin Zhang
- Department of Chemistry Southern University of Science and Technology Shenzhen China
| | - Haiyang Zhang
- Department of Biological Science and Engineering, School of Chemistry and Biological Engineering University of Science and Technology Beijing Beijing China
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17
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Samuelsen L, Holm R, Schönbeck C. Specific Buffers Affect the Stability of a Charged Cyclodextrin Complex Via Competitive Binding and Ionic Strength. J Pharm Sci 2021; 110:2661-2668. [PMID: 33607189 DOI: 10.1016/j.xphs.2021.02.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 01/27/2021] [Accepted: 02/08/2021] [Indexed: 11/25/2022]
Abstract
The effect of 11 buffers as well as the effect of ionic strength were investigated on the binding between the bile salt taurochenodeoxycholate and the ionic sulfobutylether-β-cyclodextrin. The investigations showed that both ionic strength and competitive binding affected the stability constant. The stability constant for the sulfobutylether-β-cyclodextrin complex increased from 34,400 M-1 to 114,000 M-1 as the ionic strength of the solution increased to 0.15 M. Keeping the ionic strength constant, the stability constant for the complex depended on the buffer in the solution, with citric and succinic acid reducing the stability constant. The reduction in the stability constant by buffers was related to a competitive mechanism. The results showed that, when accounting for the variation in ionic strength between the buffers, three groupings of buffers existed. All carboxylic acid buffers decreased the stability constant of the sulfobutylether-β-cyclodextrin complex, relative to the effect observed by altering the ionic strength, whereas the other buffers only affected the stability constant in terms of the changes in ionic strength. Both buffer species and ionic strength impacted the stability of ionic cyclodextrin complexes, hence, it is important to be aware of these effects when working with, comparing and reporting stability constants.
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Affiliation(s)
- Lisa Samuelsen
- Department of Science and Environment, Roskilde University, Roskilde, Denmark
| | - René Holm
- Department of Science and Environment, Roskilde University, Roskilde, Denmark; Drug Product Development, Janssen Research and Development, Johnson & Johnson, Beerse, Belgium.
| | - Christian Schönbeck
- Department of Science and Environment, Roskilde University, Roskilde, Denmark
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18
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Kasavajhala K, Lam K, Simmerling C. Exploring Protocols to Build Reservoirs to Accelerate Temperature Replica Exchange MD Simulations. J Chem Theory Comput 2020; 16:7776-7799. [PMID: 33142060 DOI: 10.1021/acs.jctc.0c00513] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Temperature replica exchange molecular dynamics (REMD) is a widely used enhanced sampling method for accelerating biomolecular simulations. During the past 2 decades, several variants of REMD have been developed to further improve the rate of conformational sampling of REMD. One such variant, reservoir REMD (RREMD), was shown to improve the rate of conformational sampling by around 5-20×. Despite the significant increase in the sampling speed, RREMD methods have not been widely used because of the difficulties in building the reservoir and also because of the code not being available on the graphics processing units (GPUs). In this work, we ported the Amber RREMD code onto GPUs making it 20× faster than the central processing unit code. Then, we explored protocols for building Boltzmann-weighted reservoirs as well as non-Boltzmann reservoirs and tested how each choice affects the accuracy of the resulting RREMD simulations. We show that, using the recommended protocols outlined here, RREMD simulations can accurately reproduce Boltzmann-weighted ensembles obtained by much more expensive conventional temperature-based REMD simulations, with at least 15× faster convergence rates even for larger proteins (>50 amino acids) compared to conventional REMD.
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Affiliation(s)
- Koushik Kasavajhala
- Department of Chemistry, 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
| | - Kenneth Lam
- Molecular and Cellular Biology, 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
| | - Carlos Simmerling
- Department of Chemistry, 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
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19
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Qianzhu H, Welegedara AP, Williamson H, McGrath AE, Mahawaththa MC, Dixon NE, Otting G, Huber T. Genetic Encoding of para-Pentafluorosulfanyl Phenylalanine: A Highly Hydrophobic and Strongly Electronegative Group for Stable Protein Interactions. J Am Chem Soc 2020; 142:17277-17281. [DOI: 10.1021/jacs.0c07976] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Haocheng Qianzhu
- Research School of Chemistry, Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Adarshi P. Welegedara
- Research School of Chemistry, Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Holly Williamson
- Research School of Chemistry, Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Amy E. McGrath
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, New South Wales 2522, Australia
| | - Mithun C. Mahawaththa
- Research School of Chemistry, Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Nicholas E. Dixon
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, New South Wales 2522, Australia
| | - Gottfried Otting
- Research School of Chemistry, Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Thomas Huber
- Research School of Chemistry, Australian National University, Canberra, Australian Capital Territory 2601, Australia
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20
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Forouzesh N, Mukhopadhyay A, Watson LT, Onufriev AV. Multidimensional Global Optimization and Robustness Analysis in the Context of Protein-Ligand Binding. J Chem Theory Comput 2020; 16:4669-4684. [PMID: 32450041 PMCID: PMC8594251 DOI: 10.1021/acs.jctc.0c00142] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Accuracy of protein-ligand binding free energy calculations utilizing implicit solvent models is critically affected by parameters of the underlying dielectric boundary, specifically, the atomic and water probe radii. Here, a global multidimensional optimization pipeline is developed to find optimal atomic radii specifically for protein-ligand binding calculations in implicit solvent. The computational pipeline has these three key components: (1) a massively parallel implementation of a deterministic global optimization algorithm (VTDIRECT95), (2) an accurate yet reasonably fast generalized Born implicit solvent model (GBNSR6), and (3) a novel robustness metric that helps distinguish between nearly degenerate local minima via a postprocessing step of the optimization. A graph-based "kT-connectivity" approach to explore and visualize the multidimensional energy landscape is proposed: local minima that can be reached from the global minimum without exceeding a given energy threshold (kT) are considered to be connected. As an illustration of the capabilities of the optimization pipeline, we apply it to find a global optimum in the space of just five radii: four atomic (O, H, N, and C) radii and water probe radius. The optimized radii, ρW = 1.37 Å, ρC = 1.40 Å, ρH = 1.55 Å, ρN = 2.35 Å, and ρO = 1.28 Å, lead to a closer agreement of electrostatic binding free energies with the explicit solvent reference than two commonly used sets of radii previously optimized for small molecules. At the same time, the ability of the optimizer to find the global optimum reveals fundamental limits of the common two-dielectric implicit solvation model: the computed electrostatic binding free energies are still almost 4 kcal/mol away from the explicit solvent reference. The proposed computational approach opens the possibility to further improve the accuracy of practical computational protocols for binding free energy calculations.
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Affiliation(s)
- Negin Forouzesh
- Department of Computer Science, Virginia Polytechnic Institute & State University, Blacksburg, Virginia 24061, United States
| | - Abhishek Mukhopadhyay
- Department of Physics, Virginia Polytechnic Institute & State University, Blacksburg, Virginia 24061, United States
| | - Layne T Watson
- Department of Computer Science, Virginia Polytechnic Institute & State University, Blacksburg, Virginia 24061, United States
- Department of Mathematics, Virginia Polytechnic Institute & State University, Blacksburg, Virginia 24061, United States
- Department of Aerospace and Ocean Engineering, Virginia Polytechnic Institute & State University, Blacksburg, Virginia 24061, United States
- Center for Soft Matter and Biological Physics, Virginia Polytechnic Institute & State University, Blacksburg, Virginia 24061, United States
| | - Alexey V Onufriev
- Department of Computer Science, Virginia Polytechnic Institute & State University, Blacksburg, Virginia 24061, United States
- Department of Physics, Virginia Polytechnic Institute & State University, Blacksburg, Virginia 24061, United States
- Center for Soft Matter and Biological Physics, Virginia Polytechnic Institute & State University, Blacksburg, Virginia 24061, United States
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21
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Sakae Y, Zhang BW, Levy RM, Deng N. Absolute Protein Binding Free Energy Simulations for Ligands with Multiple Poses, a Thermodynamic Path That Avoids Exhaustive Enumeration of the Poses. J Comput Chem 2020; 41:56-68. [PMID: 31621932 PMCID: PMC7140983 DOI: 10.1002/jcc.26078] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Revised: 08/07/2019] [Accepted: 08/31/2019] [Indexed: 12/28/2022]
Abstract
We propose a free energy calculation method for receptor-ligand binding, which have multiple binding poses that avoids exhaustive enumeration of the poses. For systems with multiple binding poses, the standard procedure is to enumerate orientations of the binding poses, restrain the ligand to each orientation, and then, calculate the binding free energies for each binding pose. In this study, we modify a part of the thermodynamic cycle in order to sample a broader conformational space of the ligand in the binding site. This modification leads to more accurate free energy calculation without performing separate free energy simulations for each binding pose. We applied our modification to simple model host-guest systems as a test, which have only two binding poses, by using a single decoupling method (SDM) in implicit solvent. The results showed that the binding free energies obtained from our method without knowing the two binding poses were in good agreement with the benchmark results obtained by explicit enumeration of the binding poses. Our method is applicable to other alchemical binding free energy calculation methods such as the double decoupling method (DDM) in explicit solvent. We performed a calculation for a protein-ligand system with explicit solvent using our modified thermodynamic path. The results of the free energy simulation along our modified path were in good agreement with the results of conventional DDM, which requires a separate binding free energy calculation for each of the binding poses of the example of phenol binding to T4 lysozyme in explicit solvent. © 2019 Wiley Periodicals, Inc.
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Affiliation(s)
- Yoshitake Sakae
- Center for Biophysics and Computational Biology, Temple University, Philadelphia, Pennsylvania, 19122
| | - Bin W Zhang
- Center for Biophysics and Computational Biology, Temple University, Philadelphia, Pennsylvania, 19122
| | - Ronald M Levy
- Center for Biophysics and Computational Biology, Temple University, Philadelphia, Pennsylvania, 19122
- Department of Chemistry, Institute for Computational Molecular Science, Temple University, Philadelphia, Pennsylvania, 19122
| | - Nanjie Deng
- Department of Chemistry and Physical Sciences, Pace University, New York, New York, 10038
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22
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He P, Sarkar S, Gallicchio E, Kurtzman T, Wickstrom L. Role of Displacing Confined Solvent in the Conformational Equilibrium of β-Cyclodextrin. J Phys Chem B 2019; 123:8378-8386. [PMID: 31509409 DOI: 10.1021/acs.jpcb.9b07028] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
This study investigates the role of hydration and its relationship to the conformational equilibrium of the host molecule β-cyclodextrin. Molecular dynamics simulations indicate that the unbound β-cyclodextrin exhibits two state behavior in explicit solvent due to the opening and closing of its cavity. In implicit solvent, these transitions are not observed, and there is one dominant conformation of β-cyclodextrin with an open cavity. Based on these observations, we investigate the hypothesis that the expulsion of thermodynamically unfavorable water molecules into the bulk plays an important role in controlling the accessibility of the closed macrostate at room temperature. We compare the results of the molecular mechanics analytical generalized Born plus nonpolar solvation approach to those obtained through grid inhomogeneous solvation theory analysis with explicit solvation to elucidate the thermodynamic forces at play. The work illustrates the use of continuum solvent models to tease out solvation effects related to the inhomogeneity and the molecular nature of water and demonstrates the key role of the thermodynamics of enclosed hydration in driving the conformational equilibrium of molecules in solution.
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Affiliation(s)
- Peng He
- Center for Biophysics & Computational Biology/ICMS, Department of Chemistry , Temple University , Philadelphia , Pennsylvania 19122 , United States
| | - Sheila Sarkar
- Department of Science , Borough of Manhattan Community College, The City University of New York , New York , New York 10007 , United States
| | - Emilio Gallicchio
- Department of Chemistry , Brooklyn College, The City University of New York , Brooklyn , New York 11210 , United States.,Ph.D. Programs in Chemistry & Biochemistry , The Graduate Center of the City University of New York , 365 Fifth Avenue , New York , New York 10016 , United States
| | - Tom Kurtzman
- Department of Chemistry , Lehman College, The City University of New York , Bronx , New York 10468 , United States.,Ph.D. Programs in Chemistry & Biochemistry , The Graduate Center of the City University of New York , 365 Fifth Avenue , New York , New York 10016 , United States
| | - Lauren Wickstrom
- Department of Science , Borough of Manhattan Community College, The City University of New York , New York , New York 10007 , United States
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23
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Xia J, Flynn W, Gallicchio E, Uplinger K, Armstrong JD, Forli S, Olson AJ, Levy RM. Massive-Scale Binding Free Energy Simulations of HIV Integrase Complexes Using Asynchronous Replica Exchange Framework Implemented on the IBM WCG Distributed Network. J Chem Inf Model 2019; 59:1382-1397. [PMID: 30758197 PMCID: PMC6496938 DOI: 10.1021/acs.jcim.8b00817] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
To perform massive-scale replica exchange molecular dynamics (REMD) simulations for calculating binding free energies of protein-ligand complexes, we implemented the asynchronous replica exchange (AsyncRE) framework of the binding energy distribution analysis method (BEDAM) in implicit solvent on the IBM World Community Grid (WCG) and optimized the simulation parameters to reduce the overhead and improve the prediction power of the WCG AsyncRE simulations. We also performed the first massive-scale binding free energy calculations using the WCG distributed computing grid and 301 ligands from the SAMPL4 challenge for large-scale binding free energy predictions of HIV-1 integrase complexes. In total there are ∼10000 simulated complexes, ∼1 million replicas, and ∼2000 μs of aggregated MD simulations. Running AsyncRE MD simulations on the WCG requires accepting a trade-off between the number of replicas that can be run (breadth) and the number of full RE cycles that can be completed per replica (depth). As compared with synchronous Replica Exchange (SyncRE) running on tightly coupled clusters like XSEDE, on the WCG many more replicas can be launched simultaneously on heterogeneous distributed hardware, but each full RE cycle requires more overhead. We compared the WCG results with that from AutoDock and more advanced RE simulations including the use of flattening potentials to accelerate sampling of selected degrees of freedom of ligands and/or receptors related to slow dynamics due to high energy barriers. We propose a suitable strategy of RE simulations to refine high throughput docking results which can be matched to corresponding computing resources: from HPC clusters, to small or medium-size distributed campus grids, and finally to massive-scale computing networks including millions of CPUs like the resources available on the WCG.
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Affiliation(s)
- Junchao Xia
- Center for Biophysics and Computational Biology and Department of Physics , Temple University , Philadelphia , Pennsylvania 19122 , United States
| | - William Flynn
- Center for Biophysics and Computational Biology and Department of Chemistry , Temple University , Philadelphia , Pennsylvania 19122 , United States
| | - Emilio Gallicchio
- Department of Chemistry , CUNY Brooklyn College , Brooklyn , New York 11210 , United States
| | - Keith Uplinger
- IBM WCG Team, 1177 South Belt Line Road , Coppell , Texas 75019 , United States
| | - Jonathan D Armstrong
- IBM WCG Team, 11400 Burnet Road , 0453B129, Austin , Texas 78758 , United States
| | - Stefano Forli
- Department of Integrative Structural and Computational Biology , The Scripps Research Institute , La Jolla , California 92037-1000 , United States
| | - Arthur J Olson
- Department of Integrative Structural and Computational Biology , The Scripps Research Institute , La Jolla , California 92037-1000 , United States
| | - Ronald M Levy
- Center for Biophysics and Computational Biology and Department of Chemistry , Temple University , Philadelphia , Pennsylvania 19122 , United States
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24
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You W, Tang Z, Chang CEA. Potential Mean Force from Umbrella Sampling Simulations: What Can We Learn and What Is Missed? J Chem Theory Comput 2019; 15:2433-2443. [PMID: 30811931 PMCID: PMC6456367 DOI: 10.1021/acs.jctc.8b01142] [Citation(s) in RCA: 75] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Changes in free energy provide valuable information for molecular recognition, including both ligand-receptor binding thermodynamics and kinetics. Umbrella sampling (US), a widely used free energy calculation method, has long been used to explore the dissociation process of ligand-receptor systems and compute binding free energy. In existing publications, the binding free energy computed from the potential of mean force (PMF) with US simulation mostly yielded "ball park" values with experimental data. However, the computed PMF values are highly influenced by factors such as initial conformations and/or trajectories provided, the reaction coordinate, and sampling of conformational space in each US window. These critical factors have rarely been carefully studied. Here we used US to study the guest aspirin and 1-butanol dissociation processes of β-cyclodextrin (β-CD) and an inhibitor SB2 dissociation from a p38α mitogen-activated protein kinase (MAPK) complex. For β-CD, we used three different β-CD conformations to generate the dissociation path with US windows. For p38α, we generated the dissociation pathway by using accelerated molecular dynamics followed by conformational relaxing with short conventional MD, steered MD, and manual pulling. We found that, even for small β-CD complexes, different β-CD conformations altered the height of the PMF, but the pattern of PMF was not affected if the MD sampling in each US window was well-converged. Because changing the macrocyclic ring conformation needs to rotate dihedral angles in the ring, a bound ligand largely restrains the motion of cyclodextrin. Therefore, once a guest is in the binding site, cyclodextrin cannot freely change its initial conformation, resulting in different absolute heights of the PMF, which cannot be overcome by running excessively long MD simulations for each US window. Moreover, if the US simulations were not converged, the important barrier and minimum were missed. For ligand-protein systems, our studies also suggest that the dissociation trajectories modeled by an enhanced sampling method must maintain a natural molecular movement to avoid biased PMF plots when using US simulations.
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Affiliation(s)
- Wanli You
- Department of Chemistry, University of California, Riverside, California 92521, United States
| | - Zhiye Tang
- Department of Chemistry, University of California, Riverside, California 92521, United States
| | - Chia-en A. Chang
- Department of Chemistry, University of California, Riverside, California 92521, United States
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25
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Zhang BW, Arasteh S, Levy RM. The UWHAM and SWHAM Software Package. Sci Rep 2019; 9:2803. [PMID: 30808938 PMCID: PMC6391495 DOI: 10.1038/s41598-019-39420-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Accepted: 01/21/2019] [Indexed: 11/09/2022] Open
Abstract
We introduce the UWHAM (binless weighted histogram analysis method) and SWHAM (stochastic UWHAM) software package that can be used to estimate the density of states and free energy differences based on the data generated by multi-state simulations. The programs used to solve the UWHAM equations are written in the C++ language and operated via the command line interface. In this paper, first we review the theoretical bases of UWHAM, its stochastic solver RE-SWHAM (replica exchange-like SWHAM)and ST-SWHAM (serial tempering-like SWHAM). Then we provide a tutorial with examples that explains how to apply the UWHAM program package to analyze the data generated by different types of multi-state simulations: umbrella sampling, replica exchange, free energy perturbation simulations, etc. The tutorial examples also show that the UWHAM equations can be solved stochastically by applying the RE-SWHAM and ST-SWHAM programs when the data ensemble is large. If the simulations at some states are far from equilibrium, the Stratified RE-SWHAM program can be applied to obtain the equilibrium distribution of the state of interest. All the source codes and the tutorial examples are available from our group's web page: https://ronlevygroup.cst.temple.edu/software/UWHAM_and_SWHAM_webpage/index.html .
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Affiliation(s)
- Bin W Zhang
- Center for Biophysics and Computational Biology, Department of Chemistry and Institute for Computational Molecular Science, Temple University, Philadelphia, Pennsylvania, 19122, United States.
| | - Shima Arasteh
- Center for Biophysics and Computational Biology, Department of Chemistry and Institute for Computational Molecular Science, Temple University, Philadelphia, Pennsylvania, 19122, United States
| | - Ronald M Levy
- Center for Biophysics and Computational Biology, Department of Chemistry and Institute for Computational Molecular Science, Temple University, Philadelphia, Pennsylvania, 19122, United States
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26
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Suárez D, Díaz N. Affinity Calculations of Cyclodextrin Host-Guest Complexes: Assessment of Strengths and Weaknesses of End-Point Free Energy Methods. J Chem Inf Model 2019; 59:421-440. [PMID: 30566348 DOI: 10.1021/acs.jcim.8b00805] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The end-point methods like MM/PBSA or MM/GBSA estimate the free energy of a biomolecule by combining its molecular mechanics energy with solvation free energy and entropy terms. On the one hand, their performance largely depends on the particular system of interest, and despite numerous attempts to improve their reliability that have resulted in many variants, there is still no clear alternative to improve their accuracy. On the other hand, the relatively small cyclodextrin host-guest complexes, for which high-quality binding calorimetric data are usually available, are becoming reference models for testing the accuracy of free energy methods. In this work, we further assess the performance of various MM/PBSA-like approaches as applied to cyclodextrin complexes. To this end, we select a set of complexes between β-cyclodextrin and 57 small organic molecules that has been previously studied with the binding energy distribution analysis method in combination with an implicit solvent model ( Wickstrom, L.; He, P.; Gallicchio, E.; Levy, R. M. J. Chem. Theory Comput. 2013 , 9 , 3136 - 3150 ). For each complex, a conventional 1.0 μs molecular dynamics simulation in explicit solvent is performed. Then we employ semiempirical quantum chemical calculations, several variants of the MM-PB(GB)SA methods, entropy estimations, etc., to assess the reliability of the end-point affinity calculations. The best end-point protocol in this study, which combines DFTB3 energies with entropy corrections, yields estimations of the binding free energies that still have substantial errors (RMSE = 2.2 kcal/mol), but it exhibits a good prediction capacity in terms of ligand ranking ( R2 = 0.66) that is close to or even better than that of rigorous free energy methodologies. Our results can be helpful to discriminate between the intrinsic limitations of the end-point methods and other sources of error, such as the underlying energy and continuum solvation methods.
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Affiliation(s)
- Dimas Suárez
- Departamento de Química Física y Analítica , Universidad de Oviedo , Avda. Julián Clavería 8 , Oviedo , Asturias 33006 , Spain
| | - Natalia Díaz
- Departamento de Química Física y Analítica , Universidad de Oviedo , Avda. Julián Clavería 8 , Oviedo , Asturias 33006 , Spain
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27
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Kilburg D, Gallicchio E. Analytical Model of the Free Energy of Alchemical Molecular Binding. J Chem Theory Comput 2018; 14:6183-6196. [DOI: 10.1021/acs.jctc.8b00967] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Affiliation(s)
- Denise Kilburg
- Department of Chemistry, Brooklyn College of the City University of New York, Brooklyn, New York 11210, United States
| | - Emilio Gallicchio
- Department of Chemistry, Brooklyn College of the City University of New York, Brooklyn, New York 11210, United States
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28
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Chen Y, Zuo Z, Dai X, Xiao P, Fang X, Wang X, Wang W, Ding CF. Gas-phase complexation of α-/β-cyclodextrin with amino acids studied by ion mobility-mass spectrometry and molecular dynamics simulations. Talanta 2018; 186:1-7. [DOI: 10.1016/j.talanta.2018.04.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Revised: 03/28/2018] [Accepted: 04/01/2018] [Indexed: 01/11/2023]
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29
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Xia J, Flynn W, Levy RM. Improving Prediction Accuracy of Binding Free Energies and Poses of HIV Integrase Complexes Using the Binding Energy Distribution Analysis Method with Flattening Potentials. J Chem Inf Model 2018; 58:1356-1371. [PMID: 29927237 PMCID: PMC6287956 DOI: 10.1021/acs.jcim.8b00194] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
To accelerate conformation sampling of slow dynamics from receptor or ligand, we introduced flattening potentials on selected bonded and nonbonded intramolecular interactions to the binding energy distribution analysis method (BEDAM) for calculating absolute binding free energies of protein-ligand complexes using an implicit solvent model and implemented flattening BEDAM using the asynchronous replica exchange (AsyncRE) framework for performing large scale replica exchange molecular dynamics (REMD) simulations. The advantage of using the flattening feature to reduce high energy barriers was exhibited first by the p-xylene-T4 lysozyme complex, where the intramolecular interactions of a protein side chain on the binding site were flattened to accelerate the conformational transition of the side chain from the trans to the gauche state when the p-xylene ligand is present in the binding site. Much more extensive flattening BEDAM simulations were performed for 53 experimental binders and 248 nonbinders of HIV-1 integrase which formed the SAMPL4 challenge, with the total simulation time of 24.3 μs. We demonstrated that the flattening BEDAM simulations not only substantially increase the number of true positives (and reduce false negatives) but also improve the prediction accuracy of binding poses of experimental binders. Furthermore, the values of area under the curve (AUC) of receiver operating characteristic (ROC) and the enrichment factors at 20% cutoff calculated from the flattening BEDAM simulations were improved significantly in comparison with that of simulations without flattening as we previously reported for the whole SAMPL4 database. Detailed analysis found that the improved ability to discriminate the binding free energies between the binders and nonbinders is due to the fact that the flattening simulations reduce the reorganization free energy penalties of binders and decrease the overlap of binding free energy distributions of binders relative to that of nonbinders. This happens because the conformational ensemble distributions for both the ligand and protein in solution match those at the fully coupled (complex) state more closely when the systems are more fully sampled after the flattening potentials are applied to the intermediate states.
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Affiliation(s)
- Junchao Xia
- Center for Biophysics and Computational Biology and Department of Physics , Temple University , Philadelphia , Pennsylvania 19122 , United States
| | - William Flynn
- Center for Biophysics and Computational Biology and Department of Chemistry , Temple University , Philadelphia , Pennsylvania 19122 , United States
| | - Ronald M Levy
- Center for Biophysics and Computational Biology and Department of Chemistry , Temple University , Philadelphia , Pennsylvania 19122 , United States
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30
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Toward Expanded Diversity of Host–Guest Interactions via Synthesis and Characterization of Cyclodextrin Derivatives. J SOLUTION CHEM 2018. [DOI: 10.1007/s10953-018-0769-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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31
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Gebhardt J, Kleist C, Jakobtorweihen S, Hansen N. Validation and Comparison of Force Fields for Native Cyclodextrins in Aqueous Solution. J Phys Chem B 2018; 122:1608-1626. [PMID: 29287148 DOI: 10.1021/acs.jpcb.7b11808] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Molecular dynamics simulations of native α-, β-, and γ-cyclodextrin in aqueous solution have been conducted with the goal to investigate the performance of the CHARMM36 force field, the AMBER-compatible q4md-CD force field, and five variants of the GROMOS force field. The properties analyzed are structural parameters derived from X-ray diffraction and NMR experiments as well as hydrogen bonds and hydration patterns, including hydration free enthalpies. Recent revisions of the torsional-angle parameters for carbohydrate systems within the GROMOS family of force fields lead to a significant improvement of the agreement between simulated and experimental NMR data. Therefore, we recommend using the variant 53A6GLYC instead of 53A6 and 56A6CARBO_R or 2016H66 instead of 56A6CARBO to simulate cyclodextrins in solution. The CHARMM36 and q4md-CD force fields show a similar performance as the three recommended GROMOS parameter sets. A significant difference is the more flexible nature of the cyclodextrins modeled with the CHARMM36 and q4md-CD force fields compared to the three recommended GROMOS parameter sets.
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Affiliation(s)
- Julia Gebhardt
- Institute of Thermodynamics and Thermal Process Engineering, University of Stuttgart , D-70569 Stuttgart, Germany
| | - Catharina Kleist
- Institute of Thermal Separation Processes, Hamburg University of Technology , D-21073 Hamburg, Germany
| | - Sven Jakobtorweihen
- Institute of Thermal Separation Processes, Hamburg University of Technology , D-21073 Hamburg, Germany
| | - Niels Hansen
- Institute of Thermodynamics and Thermal Process Engineering, University of Stuttgart , D-70569 Stuttgart, Germany
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32
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Tang Z, Chang CEA. Binding Thermodynamics and Kinetics Calculations Using Chemical Host and Guest: A Comprehensive Picture of Molecular Recognition. J Chem Theory Comput 2018; 14:303-318. [PMID: 29149564 PMCID: PMC5920803 DOI: 10.1021/acs.jctc.7b00899] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Understanding the fine balance between changes of entropy and enthalpy and the competition between a guest and water molecules in molecular binding is crucial in fundamental studies and practical applications. Experiments provide measurements. However, illustrating the binding/unbinding processes gives a complete picture of molecular recognition not directly available from experiments, and computational methods bridge the gaps. Here, we investigated guest association/dissociation with β-cyclodextrin (β-CD) by using microsecond-time-scale molecular dynamics (MD) simulations, postanalysis and numerical calculations. We computed association and dissociation rate constants, enthalpy, and solvent and solute entropy of binding. All the computed values of kon, koff, ΔH, ΔS, and ΔG using GAFF-CD and q4MD-CD force fields for β-CD could be compared with experimental data directly and agreed reasonably with experiment findings. In addition, our study further interprets experiments. Both force fields resulted in similar computed ΔG from independently computed kinetics rates, ΔG = -RT ln(kon·C0/koff), and thermodynamics properties, ΔG = ΔH - TΔS. The water entropy calculations show that the entropy gain of desolvating water molecules are a major driving force, and both force fields have the same strength of nonpolar attractions between solutes and β-CD as well. Water molecules play a crucial role in guest binding to β-CD. However, collective water/β-CD motions could contribute to different computed kon and ΔH values by different force fields, mainly because the parameters of β-CD provide different motions of β-CD, hydrogen-bond networks of water molecules in the cavity of free β-CD, and strength of desolvation penalty. As a result, q4MD-CD suggests that guest binding is mostly driven by enthalpy, while GAFF-CD shows that gaining entropy is the major driving force of binding. The study deepens our understanding of ligand-receptor recognition and suggests strategies for force field parametrization for accurately modeling molecular systems.
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Affiliation(s)
- Zhiye Tang
- Department of Chemistry, University of California, Riverside, California 92521, United States
| | - Chia-en A. Chang
- Department of Chemistry, University of California, Riverside, California 92521, United States
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33
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Lapelosa M. Conformational dynamics and free energy of BHRF1 binding to Bim BH3. Biophys Chem 2018; 232:22-28. [DOI: 10.1016/j.bpc.2017.11.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Revised: 11/06/2017] [Accepted: 11/07/2017] [Indexed: 01/10/2023]
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34
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Giovannelli E, Cioni M, Procacci P, Cardini G, Pagliai M, Volkov V, Chelli R. Binding Free Energies of Host–Guest Systems by Nonequilibrium Alchemical Simulations with Constrained Dynamics: Illustrative Calculations and Numerical Validation. J Chem Theory Comput 2017; 13:5887-5899. [DOI: 10.1021/acs.jctc.7b00595] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Edoardo Giovannelli
- Dipartimento
di Chimica, Università di Firenze, Via della Lastruccia 3, I-50019 Sesto Fiorentino, Italy
| | - Matteo Cioni
- Dipartimento
di Chimica, Università di Firenze, Via della Lastruccia 3, I-50019 Sesto Fiorentino, Italy
| | - Piero Procacci
- Dipartimento
di Chimica, Università di Firenze, Via della Lastruccia 3, I-50019 Sesto Fiorentino, Italy
| | - Gianni Cardini
- Dipartimento
di Chimica, Università di Firenze, Via della Lastruccia 3, I-50019 Sesto Fiorentino, Italy
| | - Marco Pagliai
- Dipartimento
di Chimica, Università di Firenze, Via della Lastruccia 3, I-50019 Sesto Fiorentino, Italy
| | - Victor Volkov
- Dipartimento
di Chimica, Università di Firenze, Via della Lastruccia 3, I-50019 Sesto Fiorentino, Italy
| | - Riccardo Chelli
- Interdisciplinary
Biomedical Research Center, School of Science and Technology, Nottingham Trent University, Clifton Lane, Nottingham NG11 8NS, U.K
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35
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Onufriev AV, Izadi S. Water models for biomolecular simulations. WILEY INTERDISCIPLINARY REVIEWS-COMPUTATIONAL MOLECULAR SCIENCE 2017. [DOI: 10.1002/wcms.1347] [Citation(s) in RCA: 94] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Alexey V. Onufriev
- Department of Physics; Virginia Tech; Blacksburg VA USA
- Department of Computer Science; Virginia Tech; Blacksburg VA USA
- Center for Soft Matter and Biological Physics; Virginia Tech; Blacksburg VA USA
| | - Saeed Izadi
- Early Stage Pharmaceutical Development; Genentech Inc.; South San Francisco, CA USA
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36
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Current trends in molecular modeling methods applied to the study of cyclodextrin complexes. J INCL PHENOM MACRO 2017. [DOI: 10.1007/s10847-017-0763-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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37
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Henriksen NM, Gilson MK. Evaluating Force Field Performance in Thermodynamic Calculations of Cyclodextrin Host-Guest Binding: Water Models, Partial Charges, and Host Force Field Parameters. J Chem Theory Comput 2017; 13:4253-4269. [PMID: 28696692 PMCID: PMC5606194 DOI: 10.1021/acs.jctc.7b00359] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
![]()
Computational
prediction of noncovalent binding free energies with
methods based on molecular mechanical force fields has become increasingly
routine in drug discovery projects, where they promise to speed the
discovery of small molecule ligands to bind targeted proteins with
high affinity. Because the reliability of free energy methods still
has significant room for improvement, new force fields, or modifications
of existing ones, are regularly introduced with the aim of improving
the accuracy of molecular simulations. However, comparatively little
work has been done to systematically assess how well force fields
perform, particularly in relation to the calculation of binding affinities.
Hardware advances have made these calculations feasible, but comprehensive
force field assessments for protein–ligand sized systems still
remain costly. Here, we turn to cyclodextrin host–guest systems,
which feature many hallmarks of protein–ligand binding interactions
but are generally much more tractable due to their small size. We
present absolute binding free energy and enthalpy calculations, using
the attach-pull-release (APR) approach, on a set of 43 cyclodextrin-guest
pairs for which experimental ITC data are available. The test set
comprises both α- and β-cyclodextrin hosts binding a series
of small organic guests, each with one of three functional groups:
ammonium, alcohol, or carboxylate. Four water models are considered
(TIP3P, TIP4Pew, SPC/E, and OPC), along with two partial charge assignment
procedures (RESP and AM1-BCC) and two cyclodextrin host force fields.
The results suggest a complex set of considerations when choosing
a force field for biomolecular simulations. For example, some force
field combinations clearly outperform others at the binding enthalpy
calculations but not for the binding free energy. Additionally, a
force field combination which we expected to be the worst performer
gave the most accurate binding free energies – but the least
accurate binding enthalpies. The results have implications for the
development of improved force fields, and we propose this test set,
and potential future elaborations of it, as a powerful validation
suite to evaluate new force fields and help guide future force field
development.
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Affiliation(s)
- Niel M Henriksen
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego , La Jolla, California 92093-0736, United States
| | - Michael K Gilson
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego , La Jolla, California 92093-0736, United States
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38
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Levy RM, Cui D, Zhang BW, Matubayasi N. Relationship between Solvation Thermodynamics from IST and DFT Perspectives. J Phys Chem B 2017; 121:3825-3841. [PMID: 28186751 DOI: 10.1021/acs.jpcb.6b12889] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Inhomogeneous solvation theory (IST) and classical density functional theory (DFT) each provide a framework for relating distribution functions of solutions to their thermodynamic properties. As reviewed in this work, both IST and DFT can be formulated in a way that use two "end point" simulations, one of the pure solvent and the other of the solution, to determine the solute chemical potential and other thermodynamic properties of the solution and of subvolumes in regions local to the solute containing hydrating waters. In contrast to IST, where expressions for the excess energy and entropy of solution are the object of analysis, in the DFT end point formulation of the problem, the solute-solvent potential of mean force (PMF) plays a central role. The indirect part of the PMF corresponds to the lowest order (1-body) truncation of the IST expression. Because the PMF is a free energy function, powerful numerical methods can be used to estimate it. We show that the DFT expressions for the solute excess chemical potential can be written in a form which is local, involving integrals only over regions proximate to the solute. The DFT end point route to estimating solvation free energies provides an alternative path to that of IST for analyzing solvation effects on molecular recognition and conformational changes in solution, which can lead to new insights. In order to illustrate the kind of information that is contained in the solute-solvent PMF, we have carried out simulations of β-cyclodextrin in water. This solute is a well studied "host" molecule to which "guest" molecules bind; host-guest systems serve as models for molecular recognition. We illustrate the range of values the direct and indirect parts of the solute-solvent PMF can have as a water molecule is brought to the interface of β-cyclodextrin from the bulk; we discuss the "competition" between these two terms, and the role it plays in molecular recognition.
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Affiliation(s)
- Ronald M Levy
- Center for Biophysics and Computational Biology, Department of Chemistry, and Institute for Computational Molecular Science, Temple University , Philadelphia, Pennsylvania 19122, United States
| | - Di Cui
- Center for Biophysics and Computational Biology, Department of Chemistry, and Institute for Computational Molecular Science, Temple University , Philadelphia, Pennsylvania 19122, United States
| | - Bin W Zhang
- Center for Biophysics and Computational Biology, Department of Chemistry, and Institute for Computational Molecular Science, Temple University , Philadelphia, Pennsylvania 19122, United States
| | - Nobuyuki Matubayasi
- Division of Chemical Engineering, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan and Elements Strategy Initiative for Catalysts and Batteries, Kyoto University , Katsura, Kyoto 615-8520, Japan
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39
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Abdolmaleki A, Ghasemi F, Ghasemi JB. Computer-aided drug design to explore cyclodextrin therapeutics and biomedical applications. Chem Biol Drug Des 2017; 89:257-268. [DOI: 10.1111/cbdd.12825] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Revised: 06/28/2016] [Accepted: 07/04/2016] [Indexed: 12/22/2022]
Affiliation(s)
- Azizeh Abdolmaleki
- Department of Chemistry; Faculty of Sciences; Toyserkan Branch; Islamic Azad University; Toyserkan Iran
| | | | - Jahan B. Ghasemi
- Drug Design in Silico Lab.; Chemistry Faculty; University of Tehran; Tehran Iran
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40
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Tang Z, Roberts CC, Chang CEA. Understanding ligand-receptor non-covalent binding kinetics using molecular modeling. FRONT BIOSCI-LANDMRK 2017; 22:960-981. [PMID: 27814657 PMCID: PMC5470370 DOI: 10.2741/4527] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Kinetic properties may serve as critical differentiators and predictors of drug efficacy and safety, in addition to the traditionally focused binding affinity. However the quantitative structure-kinetics relationship (QSKR) for modeling and ligand design is still poorly understood. This review provides an introduction to the kinetics of drug binding from a fundamental chemistry perspective. We focus on recent developments of computational tools and their applications to non-covalent binding kinetics.
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Affiliation(s)
- Zhiye Tang
- Department of Chemistry, University of California, Riverside, CA 92521
| | | | - Chia-En A Chang
- Department of Chemistry, University of California, Riverside, CA 92521,
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41
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Pal RK, Haider K, Kaur D, Flynn W, Xia J, Levy RM, Taran T, Wickstrom L, Kurtzman T, Gallicchio E. A combined treatment of hydration and dynamical effects for the modeling of host-guest binding thermodynamics: the SAMPL5 blinded challenge. J Comput Aided Mol Des 2017; 31:29-44. [PMID: 27696239 PMCID: PMC5477994 DOI: 10.1007/s10822-016-9956-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Accepted: 08/25/2016] [Indexed: 01/02/2023]
Abstract
As part of the SAMPL5 blinded experiment, we computed the absolute binding free energies of 22 host-guest complexes employing a novel approach based on the BEDAM single-decoupling alchemical free energy protocol with parallel replica exchange conformational sampling and the AGBNP2 implicit solvation model specifically customized to treat the effect of water displacement as modeled by the Hydration Site Analysis method with explicit solvation. Initial predictions were affected by the lack of treatment of ionic charge screening, which is very significant for these highly charged hosts, and resulted in poor relative ranking of negatively versus positively charged guests. Binding free energies obtained with Debye-Hückel treatment of salt effects were in good agreement with experimental measurements. Water displacement effects contributed favorably and very significantly to the observed binding affinities; without it, the modeling predictions would have grossly underestimated binding. The work validates the implicit/explicit solvation approach employed here and it shows that comprehensive physical models can be effective at predicting binding affinities of molecular complexes requiring accurate treatment of conformational dynamics and hydration.
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Affiliation(s)
- Rajat Kumar Pal
- Department of Chemistry, Brooklyn College, 2900 Bedford Avenue, Brooklyn, New York, 11210, USA
- Ph.D. Program in Biochemistry, The Graduate Center of the City University of New York, New York, NY, 10016, USA
| | - Kamran Haider
- Department of Chemistry, Lehman College, The City University of New York, 250 Bedford Park Blvd. West, Bronx, New York, NY, 10468, USA
| | - Divya Kaur
- Ph.D. Program in Chemistry, The Graduate Center of the City University of New York, New York, NY, 10016, USA
| | - William Flynn
- Center for Biophysics and Computational Biology, Institute of Computational Molecular Science and Department of Chemistry, Temple University, Philadelphia, PA, USA
- Department of Physics and Astronomy, Rutgers University, Piscataway, NJ, 08854, USA
| | - Junchao Xia
- Center for Biophysics and Computational Biology, Institute of Computational Molecular Science and Department of Chemistry, Temple University, Philadelphia, PA, USA
| | - Ronald M Levy
- Center for Biophysics and Computational Biology, Institute of Computational Molecular Science and Department of Chemistry, Temple University, Philadelphia, PA, USA
| | - Tetiana Taran
- Borough of Manhattan Community College, Department of Science, The City University of New York, 199 Chambers Street, New York, NY, 10007, USA
| | - Lauren Wickstrom
- Borough of Manhattan Community College, Department of Science, The City University of New York, 199 Chambers Street, New York, NY, 10007, USA
| | - Tom Kurtzman
- Department of Chemistry, Lehman College, The City University of New York, 250 Bedford Park Blvd. West, Bronx, New York, NY, 10468, USA
- Ph.D. Program in Biochemistry, The Graduate Center of the City University of New York, New York, NY, 10016, USA
- Ph.D. Program in Chemistry, The Graduate Center of the City University of New York, New York, NY, 10016, USA
| | - Emilio Gallicchio
- Department of Chemistry, Brooklyn College, 2900 Bedford Avenue, Brooklyn, New York, 11210, USA.
- Ph.D. Program in Biochemistry, The Graduate Center of the City University of New York, New York, NY, 10016, USA.
- Ph.D. Program in Chemistry, The Graduate Center of the City University of New York, New York, NY, 10016, USA.
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42
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Harris RC, Deng N, Levy RM, Ishizuka R, Matubayasi N. Computing conformational free energy differences in explicit solvent: An efficient thermodynamic cycle using an auxiliary potential and a free energy functional constructed from the end points. J Comput Chem 2016; 38:1198-1208. [PMID: 28008630 DOI: 10.1002/jcc.24668] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Revised: 09/02/2016] [Accepted: 10/26/2016] [Indexed: 01/17/2023]
Abstract
Many biomolecules undergo conformational changes associated with allostery or ligand binding. Observing these changes in computer simulations is difficult if their timescales are long. These calculations can be accelerated by observing the transition on an auxiliary free energy surface with a simpler Hamiltonian and connecting this free energy surface to the target free energy surface with free energy calculations. Here, we show that the free energy legs of the cycle can be replaced with energy representation (ER) density functional approximations. We compute: (1) The conformational free energy changes for alanine dipeptide transitioning from the right-handed free energy basin to the left-handed basin and (2) the free energy difference between the open and closed conformations of β-cyclodextrin, a "host" molecule that serves as a model for molecular recognition in host-guest binding. β-cyclodextrin contains 147 atoms compared to 22 atoms for alanine dipeptide, making β-cyclodextrin a large molecule for which to compute solvation free energies by free energy perturbation or integration methods and the largest system for which the ER method has been compared to exact free energy methods. The ER method replaced the 28 simulations to compute each coupling free energy with two endpoint simulations, reducing the computational time for the alanine dipeptide calculation by about 70% and for the β-cyclodextrin by > 95%. The method works even when the distribution of conformations on the auxiliary free energy surface differs substantially from that on the target free energy surface, although some degree of overlap between the two surfaces is required. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Robert C Harris
- Department of Chemistry and Center for Biophysics and Computational Biology and Institute for Computational Molecular Science, Temple University, Philadelphia, Pennsylvania, 19122
| | - Nanjie Deng
- Department of Chemistry and Center for Biophysics and Computational Biology and Institute for Computational Molecular Science, Temple University, Philadelphia, Pennsylvania, 19122.,Department of Chemistry and Physical Sciences, Dyson College of Arts and Sciences, Pace University, New York, New York, 10038
| | - Ronald M Levy
- Department of Chemistry and Center for Biophysics and Computational Biology and Institute for Computational Molecular Science, Temple University, Philadelphia, Pennsylvania, 19122
| | - Ryosuke Ishizuka
- Division of Chemical Engineering, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka, 560-8531, Japan
| | - Nobuyuki Matubayasi
- Division of Chemical Engineering, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka, 560-8531, Japan.,Elements Strategy Initiative for Catalysts and Batteries, Kyoto University, Katsura, Kyoto, 615-8520, Japan
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43
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Tan Z, Xia J, Zhang BW, Levy RM. Locally weighted histogram analysis and stochastic solution for large-scale multi-state free energy estimation. J Chem Phys 2016; 144:034107. [PMID: 26801020 DOI: 10.1063/1.4939768] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
The weighted histogram analysis method (WHAM) including its binless extension has been developed independently in several different contexts, and widely used in chemistry, physics, and statistics, for computing free energies and expectations from multiple ensembles. However, this method, while statistically efficient, is computationally costly or even infeasible when a large number, hundreds or more, of distributions are studied. We develop a locally WHAM (local WHAM) from the perspective of simulations of simulations (SOS), using generalized serial tempering (GST) to resample simulated data from multiple ensembles. The local WHAM equations based on one jump attempt per GST cycle can be solved by optimization algorithms orders of magnitude faster than standard implementations of global WHAM, but yield similarly accurate estimates of free energies to global WHAM estimates. Moreover, we propose an adaptive SOS procedure for solving local WHAM equations stochastically when multiple jump attempts are performed per GST cycle. Such a stochastic procedure can lead to more accurate estimates of equilibrium distributions than local WHAM with one jump attempt per cycle. The proposed methods are broadly applicable when the original data to be "WHAMMED" are obtained properly by any sampling algorithm including serial tempering and parallel tempering (replica exchange). To illustrate the methods, we estimated absolute binding free energies and binding energy distributions using the binding energy distribution analysis method from one and two dimensional replica exchange molecular dynamics simulations for the beta-cyclodextrin-heptanoate host-guest system. In addition to the computational advantage of handling large datasets, our two dimensional WHAM analysis also demonstrates that accurate results similar to those from well-converged data can be obtained from simulations for which sampling is limited and not fully equilibrated.
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Affiliation(s)
- Zhiqiang Tan
- Department of Statistics, Rutgers University, Piscataway, New Jersey 08854, USA
| | - Junchao Xia
- Center for Biophysics and Computational Biology, Department of Chemistry and Institute for Computational Molecular Science, Temple University, Philadelphia, Pennsylvania 19122, USA
| | - Bin W Zhang
- Center for Biophysics and Computational Biology, Department of Chemistry and Institute for Computational Molecular Science, Temple University, Philadelphia, Pennsylvania 19122, USA
| | - Ronald M Levy
- Center for Biophysics and Computational Biology, Department of Chemistry and Institute for Computational Molecular Science, Temple University, Philadelphia, Pennsylvania 19122, USA
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44
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Zhang H, Yin C, Yan H, van der Spoel D. Evaluation of Generalized Born Models for Large Scale Affinity Prediction of Cyclodextrin Host–Guest Complexes. J Chem Inf Model 2016; 56:2080-2092. [DOI: 10.1021/acs.jcim.6b00418] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Haiyang Zhang
- Department
of Biological Science and Engineering, School of Chemistry and Biological
Engineering, University of Science and Technology Beijing, 100083 Beijing, China
| | - Chunhua Yin
- Department
of Biological Science and Engineering, School of Chemistry and Biological
Engineering, University of Science and Technology Beijing, 100083 Beijing, China
| | - Hai Yan
- Department
of Biological Science and Engineering, School of Chemistry and Biological
Engineering, University of Science and Technology Beijing, 100083 Beijing, China
| | - David van der Spoel
- Uppsala
Center for Computational Chemistry, Science for Life Laboratory, Department
of Cell and Molecular Biology, Uppsala University, Husargatan 3, Box
596, SE-75124 Uppsala, Sweden
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45
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Zhang B, D’Erasmo M, Murelli RP, Gallicchio E. Free Energy-Based Virtual Screening and Optimization of RNase H Inhibitors of HIV-1 Reverse Transcriptase. ACS OMEGA 2016; 1:435-447. [PMID: 27713931 PMCID: PMC5046171 DOI: 10.1021/acsomega.6b00123] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/11/2016] [Accepted: 09/07/2016] [Indexed: 06/06/2023]
Abstract
We report the results of a binding free energy-based virtual screening campaign of a library of 77 α-hydroxytropolone derivatives against the challenging RNase H active site of the reverse transcriptase (RT) enzyme of human immunodeficiency virus-1. Multiple protonation states, rotamer states, and binding modalities of each compound were individually evaluated. The work involved more than 300 individual absolute alchemical binding free energy parallel molecular dynamics calculations and over 1 million CPU hours on national computing clusters and a local campus computational grid. The thermodynamic and structural measures obtained in this work rationalize a series of characteristics of this system useful for guiding future synthetic and biochemical efforts. The free energy model identified key ligand-dependent entropic and conformational reorganization processes difficult to capture using standard docking and scoring approaches. Binding free energy-based optimization of the lead compounds emerging from the virtual screen has yielded four compounds with very favorable binding properties, which will be the subject of further experimental investigations. This work is one of the few reported applications of advanced-binding free energy models to large-scale virtual screening and optimization projects. It further demonstrates that, with suitable algorithms and automation, advanced-binding free energy models can have a useful role in early-stage drug-discovery programs.
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Affiliation(s)
- Baofeng Zhang
- Department
of Chemistry, Brooklyn
College, City University of New York, Brooklyn, New York 11210, United States
| | - Michael
P. D’Erasmo
- Department
of Chemistry, Brooklyn
College, City University of New York, Brooklyn, New York 11210, United States
- Ph.D. Program in Chemistry and Ph.D. Program in
Biochemistry, The Graduate Center of the
City University of New York, New
York, New York 10016, United States
| | - Ryan P. Murelli
- Department
of Chemistry, Brooklyn
College, City University of New York, Brooklyn, New York 11210, United States
- Ph.D. Program in Chemistry and Ph.D. Program in
Biochemistry, The Graduate Center of the
City University of New York, New
York, New York 10016, United States
| | - Emilio Gallicchio
- Department
of Chemistry, Brooklyn
College, City University of New York, Brooklyn, New York 11210, United States
- Ph.D. Program in Chemistry and Ph.D. Program in
Biochemistry, The Graduate Center of the
City University of New York, New
York, New York 10016, United States
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46
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Di Marino D, D'Annessa I, Tancredi H, Bagni C, Gallicchio E. A unique binding mode of the eukaryotic translation initiation factor 4E for guiding the design of novel peptide inhibitors. Protein Sci 2016; 24:1370-82. [PMID: 26013047 DOI: 10.1002/pro.2708] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Revised: 05/12/2015] [Accepted: 05/14/2015] [Indexed: 12/24/2022]
Abstract
The interaction between the eukaryotic translation initiation factor 4E (eIF4E) and eIF4E binding proteins (4E-BP) is a promising template for the inhibition of eIF4E and the treatment of diseases such as cancer and a spectrum of autism disorders, including the Fragile X syndrome (FXS). Here, we report an atomically detailed model of the complex between eIF4E and a peptide fragment of a 4E-BP, the cytoplasmic Fragile X interacting protein (CYFIP1). This model was generated using computer simulations with enhanced sampling from an alchemical replica exchange approach and validated using long molecular dynamics simulations. 4E-BP proteins act as post-transcriptional regulators by binding to eIF4E and preventing mRNA translation. Dysregulation of eIF4E activity has been linked to cancer, FXS, and autism spectrum disorders. Therefore, the study of the mechanism of inhibition of eIF4E by 4E-BPs is key to the development of drug therapies targeting this regulatory pathways. The results obtained in this work indicate that CYFIP1 interacts with eIF4E by an unique mode not shared by other 4E-BP proteins and elucidate the mechanism by which CYFIP1 interacts with eIF4E despite having a sequence binding motif significantly different from most 4E-BPs. Our study suggests an alternative strategy for the design of eIF4E inhibitor peptides with superior potency and specificity than currently available.
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Affiliation(s)
- Daniele Di Marino
- Department of Chemistry, Brooklyn College of the City University of New York, Brooklyn, New York, 11210
| | - Ilda D'Annessa
- Department of Biology, University of Rome Tor Vergata, Rome, Italy
| | - Holly Tancredi
- Department of Chemistry, Brooklyn College of the City University of New York, Brooklyn, New York, 11210.,Department of Computer Science, Brooklyn College of the City University of New York, Brooklyn, New York, 11210
| | - Claudia Bagni
- VIB Center for the Biology of Disease, Leuven, Belgium.,Center for Human Genetics and Leuven Institute for Neurodegenerative Diseases (LIND), Leuven, Belgium.,Department of Biomedicine and Prevention, University of Rome Tor Vergata, Rome, Italy
| | - Emilio Gallicchio
- Department of Chemistry, Brooklyn College of the City University of New York, Brooklyn, New York, 11210
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47
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Zhang BW, Dai W, Gallicchio E, He P, Xia J, Tan Z, Levy RM. Simulating Replica Exchange: Markov State Models, Proposal Schemes, and the Infinite Swapping Limit. J Phys Chem B 2016; 120:8289-301. [PMID: 27079355 DOI: 10.1021/acs.jpcb.6b02015] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Replica exchange molecular dynamics is a multicanonical simulation technique commonly used to enhance the sampling of solvated biomolecules on rugged free energy landscapes. While replica exchange is relatively easy to implement, there are many unanswered questions about how to use this technique most efficiently, especially because it is frequently the case in practice that replica exchange simulations are not fully converged. A replica exchange cycle consists of a series of molecular dynamics steps of a set of replicas moving under different Hamiltonians or at different thermodynamic states followed by one or more replica exchange attempts to swap replicas among the different states. How the replica exchange cycle is constructed affects how rapidly the system equilibrates. We have constructed a Markov state model of replica exchange (MSMRE) using long molecular dynamics simulations of a host-guest binding system as an example, in order to study how different implementations of the replica exchange cycle can affect the sampling efficiency. We analyze how the number of replica exchange attempts per cycle, the number of MD steps per cycle, and the interaction between the two parameters affects the largest implied time scale of the MSMRE simulation. The infinite swapping limit is an important concept in replica exchange. We show how to estimate the infinite swapping limit from the diagonal elements of the exchange transition matrix constructed from MSMRE "simulations of simulations" as well as from relatively short runs of the actual replica exchange simulations.
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Affiliation(s)
- Bin W Zhang
- Center for Biophysics and Computational Biology, Department of Chemistry and Institute for Computational Molecular Science, Temple University , Philadelphia, Pennsylvania 19122, United States
| | - Wei Dai
- Department of Physics and Astronomy, Rutgers, the State University of New Jersey , Piscataway, New Jersey 08854, United States
| | - Emilio Gallicchio
- Department of Chemistry, Brooklyn College of the City University of New York , Brooklyn, New York 11210, United States
| | - Peng He
- Center for Biophysics and Computational Biology, Department of Chemistry and Institute for Computational Molecular Science, Temple University , Philadelphia, Pennsylvania 19122, United States
| | - Junchao Xia
- Center for Biophysics and Computational Biology, Department of Chemistry and Institute for Computational Molecular Science, Temple University , Philadelphia, Pennsylvania 19122, United States
| | - Zhiqiang Tan
- Department of Statistics, Rutgers, the State University of New Jersey , Piscataway, New Jersey 08854, United States
| | - Ronald M Levy
- Center for Biophysics and Computational Biology, Department of Chemistry and Institute for Computational Molecular Science, Temple University , Philadelphia, Pennsylvania 19122, United States
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48
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Exploring host–guest complexation mechanisms by a molecular dynamics/quantum mechanics/continuum solvent model approach. Chem Phys Lett 2016. [DOI: 10.1016/j.cplett.2016.02.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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49
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Gallicchio E, Xia J, Flynn WF, Zhang B, Samlalsingh S, Mentes A, Levy RM. Asynchronous Replica Exchange Software for Grid and Heterogeneous Computing. COMPUTER PHYSICS COMMUNICATIONS 2015; 196:236-246. [PMID: 27103749 PMCID: PMC4834714 DOI: 10.1016/j.cpc.2015.06.010] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Parallel replica exchange sampling is an extended ensemble technique often used to accelerate the exploration of the conformational ensemble of atomistic molecular simulations of chemical systems. Inter-process communication and coordination requirements have historically discouraged the deployment of replica exchange on distributed and heterogeneous resources. Here we describe the architecture of a software (named ASyncRE) for performing asynchronous replica exchange molecular simulations on volunteered computing grids and heterogeneous high performance clusters. The asynchronous replica exchange algorithm on which the software is based avoids centralized synchronization steps and the need for direct communication between remote processes. It allows molecular dynamics threads to progress at different rates and enables parameter exchanges among arbitrary sets of replicas independently from other replicas. ASyncRE is written in Python following a modular design conducive to extensions to various replica exchange schemes and molecular dynamics engines. Applications of the software for the modeling of association equilibria of supramolecular and macromolecular complexes on BOINC campus computational grids and on the CPU/MIC heterogeneous hardware of the XSEDE Stampede supercomputer are illustrated. They show the ability of ASyncRE to utilize large grids of desktop computers running the Windows, MacOS, and/or Linux operating systems as well as collections of high performance heterogeneous hardware devices.
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Affiliation(s)
- Emilio Gallicchio
- Department of Chemistry, Brooklyn College of the City University of New York, Brooklyn, NY
| | - Junchao Xia
- Center for Biophysics and Computational Biology, Institute of Computational Molecular Science and Department of Chemistry, Temple University, Philadelphia PA
| | - William F. Flynn
- Center for Biophysics and Computational Biology, Institute of Computational Molecular Science and Department of Chemistry, Temple University, Philadelphia PA
| | - Baofeng Zhang
- Department of Chemistry, Brooklyn College of the City University of New York, Brooklyn, NY
| | - Sade Samlalsingh
- Department of Chemistry, Brooklyn College of the City University of New York, Brooklyn, NY
| | - Ahmet Mentes
- Center for Biophysics and Computational Biology, Institute of Computational Molecular Science and Department of Chemistry, Temple University, Philadelphia PA
| | - Ronald M. Levy
- Center for Biophysics and Computational Biology, Institute of Computational Molecular Science and Department of Chemistry, Temple University, Philadelphia PA
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50
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Abstract
The weighted histogram analysis method (WHAM) and unbinned versions such as the multistate Bennett acceptance ratio (MBAR) and unbinned WHAM (UWHAM) are widely used to compute free energies and expectations from data generated by independent or coupled parallel simulations. Here we introduce a replica exchange-like algorithm (RE-SWHAM) that can be used to solve the UWHAM equations stochastically. This method is capable of analyzing large data sets generated by hundreds or even thousands of parallel simulations that are too large to be "WHAMMED" using standard methods. We illustrate the method by applying it to obtain free energy weights for each of the 240 states in a simulation of host-guest ligand binding containing ∼3.5 × 10(7) data elements collected from 16 parallel Hamiltonian replica exchange simulations, performed at 15 temperatures. In addition to using much less memory, RE-SWHAM showed a nearly 80-fold improvement in computational time compared with UWHAM.
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Affiliation(s)
- Bin W. Zhang
- Center for Biophysics and Computational Biology, Department of Chemistry and Institute for Computational Molecular Science, Temple University, Philadelphia 19122
| | - Junchao Xia
- Center for Biophysics and Computational Biology, Department of Chemistry and Institute for Computational Molecular Science, Temple University, Philadelphia 19122
| | - Zhiqiang Tan
- Department of Statistics, Rutgers University, Piscataway, New Jersey 08854
| | - Ronald M. Levy
- Center for Biophysics and Computational Biology, Department of Chemistry and Institute for Computational Molecular Science, Temple University, Philadelphia 19122
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