1
|
Gheta SKO, Bonin A, Gerlach T, Göller AH. Predicting absolute aqueous solubility by applying a machine learning model for an artificially liquid-state as proxy for the solid-state. J Comput Aided Mol Des 2023; 37:765-789. [PMID: 37878216 DOI: 10.1007/s10822-023-00538-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Accepted: 10/02/2023] [Indexed: 10/26/2023]
Abstract
In this study, we use machine learning algorithms with QM-derived COSMO-RS descriptors, along with Morgan fingerprints, to predict the absolute solubility of drug-like compounds. The QM-derived descriptors account for the molecular properties of the solute, i.e., the solute-solute interactions in an artificial-liquid-state (super-cooled liquid), and the solute-solvent interactions in solution. We employ two main approaches to predict solubility: (i) a hypothetical pathway that involves melting the solute at room temperature T = T¯ ([Formula: see text]) and mixing the artificially liquid solute into the solvent ([Formula: see text]). In this approach [Formula: see text] is predicted using machine learning models, and the [Formula: see text] is obtained from COSMO-RS calculations; (ii) direct solubility prediction using machine learning algorithms. The models were trained on a large number of Bayer in-house compounds for which water solubility data is available at physiological pH of 6.5 and ambient temperature. We also evaluated our models using external datasets from a solubility challenge. Our models present great improvements compared to the absolute solubility prediction with the QSAR model for the artificial liquid state as implemented in the COSMOtherm software, for both in-house and external datasets. We are furthermore able to demonstrate the superiority of QM-derived descriptors compared to cheminformatics descriptors. We finally present low-cost alternative models using fragment-based COSMOquick calculations with only marginal reduction in the quality of predicted solubility.
Collapse
Affiliation(s)
- Sadra Kashef Ol Gheta
- Bayer AG, Pharmaceuticals, R&D, Computational Molecular Design, 42096, Wuppertal, Germany
| | - Anne Bonin
- Bayer AG, Pharmaceuticals, R&D, Computational Molecular Design, 42096, Wuppertal, Germany
| | - Thomas Gerlach
- Bayer AG, Crop Science, R&D, Digital Transformation, 40789, Monheim, Germany
- Bayer AG, Engineering & Technology, Thermal Separation Technologies, 51368, Leverkusen, Germany
| | - Andreas H Göller
- Bayer AG, Pharmaceuticals, R&D, Computational Molecular Design, 42096, Wuppertal, Germany.
| |
Collapse
|
2
|
Champion C, Gall R, Ries B, Rieder SR, Barros EP, Riniker S. Accelerating Alchemical Free Energy Prediction Using a Multistate Method: Application to Multiple Kinases. J Chem Inf Model 2023; 63:7133-7147. [PMID: 37948537 PMCID: PMC10685456 DOI: 10.1021/acs.jcim.3c01469] [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] [Received: 09/13/2023] [Revised: 10/23/2023] [Accepted: 10/23/2023] [Indexed: 11/12/2023]
Abstract
Alchemical free-energy methods based on molecular dynamics (MD) simulations have become important tools to identify modifications of small organic molecules that improve their protein binding affinity during lead optimization. The routine application of pairwise free-energy methods to rank potential binders from best to worst is impacted by the combinatorial increase in calculations to perform when the number of molecules to assess grows. To address this fundamental limitation, our group has developed replica-exchange enveloping distribution sampling (RE-EDS), a pathway-independent multistate method, enabling the calculation of alchemical free-energy differences between multiple ligands (N > 2) from a single MD simulation. In this work, we apply the method to a set of four kinases with diverse binding pockets and their corresponding inhibitors (42 in total), chosen to showcase the general applicability of RE-EDS in prospective drug design campaigns. We show that for the targets studied, RE-EDS is able to model up to 13 ligands simultaneously with high sampling efficiency, leading to a substantial decrease in computational cost when compared to pairwise methods.
Collapse
Affiliation(s)
- Candide Champion
- Department of Chemistry and
Applied Biosciences, ETH Zürich, Vladimir-Prelog-Weg 2, 8093 Zürich, Switzerland
| | - René Gall
- Department of Chemistry and
Applied Biosciences, ETH Zürich, Vladimir-Prelog-Weg 2, 8093 Zürich, Switzerland
| | | | - Salomé R. Rieder
- Department of Chemistry and
Applied Biosciences, ETH Zürich, Vladimir-Prelog-Weg 2, 8093 Zürich, Switzerland
| | - Emilia P. Barros
- Department of Chemistry and
Applied Biosciences, ETH Zürich, Vladimir-Prelog-Weg 2, 8093 Zürich, Switzerland
| | - Sereina Riniker
- Department of Chemistry and
Applied Biosciences, ETH Zürich, Vladimir-Prelog-Weg 2, 8093 Zürich, Switzerland
| |
Collapse
|
3
|
Gracia Carmona O, Oostenbrink C. Accelerated Enveloping Distribution Sampling (AEDS) Allows for Efficient Sampling of Orthogonal Degrees of Freedom. J Chem Inf Model 2023; 63:197-207. [PMID: 36512416 PMCID: PMC9832482 DOI: 10.1021/acs.jcim.2c01272] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
One of the most challenging aspects in the molecular simulation of proteins is the study of slowly relaxing processes, such as loop rearrangements or ligands that adopt different conformations in the binding site. State-of-the-art methods used to calculate binding free energies rely on performing several short simulations (lambda steps), in which the ligand is slowly transformed into the endstates of interest. This makes capturing the slowly relaxing processes even more difficult, as they would need to be observed in all of the lambda steps. One attractive alternative is the use of a reference state capable of sampling all of the endstates of interest in a single simulation. However, the energy barriers between the states can be too high to overcome, thus hindering the sampling of all of the relevant conformations. Accelerated enveloping distribution sampling (AEDS) is a recently developed reference state technique that circumvents the high-energy-barrier challenge by adding a boosting potential that flattens the energy landscape without distorting the energy minima. In the present work, we apply AEDS to the well-studied benchmark system T4 lysozyme L99A. The T4 lysozyme L99A mutant contains a hydrophobic pocket in which there is a valine (valine 111), whose conformation influences the binding efficiencies of the different ligands. Incorrectly sampling the dihedral angle can lead to errors in predicted binding free energies of up to 16 kJ mol-1. This protein constitutes an ideal scenario to showcase the advantages and challenges when using AEDS in the presence of slow relaxing processes. We show that AEDS is able to successfully sample the relevant degrees of freedom, providing accurate binding free energies, without the need of previous information of the system in the form of collective variables. Additionally, we showcase the capabilities of AEDS to efficiently screen a set of ligands. These results represent a promising first step toward the development of free-energy methods that can respond to more intricate molecular events.
Collapse
|
4
|
Wang X, Ham S, Zhou W, Qiao R. Adsorption of rhodamine 6G and choline on gold electrodes: a molecular dynamics study. NANOTECHNOLOGY 2022; 34:025501. [PMID: 36195059 DOI: 10.1088/1361-6528/ac973b] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2022] [Accepted: 10/04/2022] [Indexed: 06/16/2023]
Abstract
The adsorption of analyte molecules on nano-optoelectrodes (e.g. a combined nanoantenna and nanoelectrode device) significantly affects the signal characteristics in surface-enhanced Raman scattering (SERS) measurements. Understanding how different molecules adsorb on electrodes and their electrical potential modulation helps interpret SERS measurements better. We use molecular dynamics simulations to investigate the adsorption of prototypical analyte molecules (rhodamine 6G and choline) on gold electrodes with negative, neutral, and positive surface charges. We show that both molecules can readily adsorb on gold surfaces at all surface charge densities studied. Nevertheless, the configurations of the adsorbed molecules can differ for different surface charge densities, and adsorption can also change a molecule's conformation. Rhodamine 6G molecules adsorb more strongly than choline molecules, and the adsorption of both molecules is affected by electrode charge in 0.25 M NaCl solutions. The mechanisms of these observations are elucidated, and their implications for voltage-modulated SERS measurements are discussed.
Collapse
Affiliation(s)
- Xin Wang
- Department of Mechanical Engineering, Virginia Tech, Blacksburg, VA 24061, United States of America
| | - Seokgyun Ham
- Department of Mechanical Engineering, Virginia Tech, Blacksburg, VA 24061, United States of America
| | - Wei Zhou
- Department of Electrical and Computer Engineering Virginia Tech, Blacksburg, VA 24061, United States of America
| | - Rui Qiao
- Department of Mechanical Engineering, Virginia Tech, Blacksburg, VA 24061, United States of America
| |
Collapse
|
5
|
Patel LA, Chau P, Debesai S, Darwin L, Neale C. Drug Discovery by Automated Adaptation of Chemical Structure and Identity. J Chem Theory Comput 2022; 18:5006-5024. [PMID: 35834740 DOI: 10.1021/acs.jctc.1c01271] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Computer-aided drug design offers the potential to dramatically reduce the cost and effort required for drug discovery. While screening-based methods are valuable in the early stages of hit identification, they are frequently succeeded by iterative, hypothesis-driven computations that require recurrent investment of human time and intuition. To increase automation, we introduce a computational method for lead refinement that combines concerted dynamics of the ligand/protein complex via molecular dynamics simulations with integrated Monte Carlo-based changes in the chemical formula of the ligand. This approach, which we refer to as ligand-exchange Monte Carlo molecular dynamics, accounts for solvent- and entropy-based contributions to competitive binding free energies by coupling the energetics of bound and unbound states during the ligand-exchange attempt. Quantitative comparison of relative binding free energies to reference values from free energy perturbation, conducted in vacuum, indicates that ligand-exchange Monte Carlo molecular dynamics simulations sample relevant conformational ensembles and are capable of identifying strongly binding compounds. Additional simulations demonstrate the use of an implicit solvent model. We speculate that the use of chemical graphs in which exchanges are only permitted between ligands with sufficient similarity may enable an automated search to capture some of the benefits provided by human intuition during hypothesis-guided lead refinement.
Collapse
|
6
|
Sowlati-Hashjin S, Gandhi A, Garton M. Dawn of a New Era for Membrane Protein Design. BIODESIGN RESEARCH 2022; 2022:9791435. [PMID: 37850134 PMCID: PMC10521746 DOI: 10.34133/2022/9791435] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Accepted: 03/20/2022] [Indexed: 10/19/2023] Open
Abstract
A major advancement has recently occurred in the ability to predict protein secondary structure from sequence using artificial neural networks. This new accessibility to high-quality predicted structures provides a big opportunity for the protein design community. It is particularly welcome for membrane protein design, where the scarcity of solved structures has been a major limitation of the field for decades. Here, we review the work done to date on the membrane protein design and set out established and emerging tools that can be used to most effectively exploit this new access to structures.
Collapse
Affiliation(s)
- Shahin Sowlati-Hashjin
- Institute of Biomedical Engineering, University of Toronto, 164 College Street, Toronto, ON, Canada, M5S 3E2
| | - Aanshi Gandhi
- Institute of Biomedical Engineering, University of Toronto, 164 College Street, Toronto, ON, Canada, M5S 3E2
| | - Michael Garton
- Institute of Biomedical Engineering, University of Toronto, 164 College Street, Toronto, ON, Canada, M5S 3E2
| |
Collapse
|
7
|
Fortuna A, Costa PJ. Optimized Halogen Atomic Radii for PBSA Calculations Using Off-Center Point Charges. J Chem Inf Model 2021; 61:3361-3375. [PMID: 34185532 DOI: 10.1021/acs.jcim.1c00177] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
In force-field methods, the usage of off-center point charges, also called extra points (EPs), is a common strategy to tackle the anisotropy of the electrostatic potential of covalently bonded halogens (X), thus allowing the description of halogen bonds (XBs) at the molecular mechanics/molecular dynamics (MM/MD) level. Diverse EP implementations exist in the literature differing on the charge sets and/or the X-EP distances. Poisson-Boltzmann and surface area (PBSA) calculations can be used to obtain solvation free energies (ΔGsolv) of small molecules, often to compute binding free energies (ΔGbind) at the MM-PBSA level. This method depends, among other parameters, on the empirical assignment of atomic radii (PB radii). Given the multiplicity of off-center point-charge models and the lack of specific PB radii for halogens compatible with such implementations, in this work, we assessed the performance of PBSA calculations for the estimation of ΔGsolv values in water (ΔGhyd), also conducting an optimization of the halogen PB radii (Cl, Br, and I) for each EP model. We not only expand the usage of EP models in the scope of the general AMBER force field (GAFF) but also provide the first optimized halogen PB radii in the context of the CHARMM general force field (CGenFF), thus contributing to improving the description of halogenated compounds in PBSA calculations.
Collapse
Affiliation(s)
- Andreia Fortuna
- BioISI-Biosystems & Integrative Sciences Institute, Faculty of Sciences, University of Lisboa, 1749-016 Lisboa, Portugal.,Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, University of Lisbon, Av. Professor Gama Pinto, 1649-003 Lisbon, Portugal
| | - Paulo J Costa
- BioISI-Biosystems & Integrative Sciences Institute, Faculty of Sciences, University of Lisboa, 1749-016 Lisboa, Portugal
| |
Collapse
|
8
|
Song LF, Merz KM. Evolution of Alchemical Free Energy Methods in Drug Discovery. J Chem Inf Model 2020; 60:5308-5318. [DOI: 10.1021/acs.jcim.0c00547] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Lin Frank Song
- Department of Chemistry and Department of Biochemistry and Molecular Biology, Michigan State University, 578 S. Shaw Lane, East Lansing, Michigan 48824, United States
| | - Kenneth M. Merz
- Department of Chemistry and Department of Biochemistry and Molecular Biology, Michigan State University, 578 S. Shaw Lane, East Lansing, Michigan 48824, United States
| |
Collapse
|
9
|
Liu Y, Pezeshkian W, Barnoud J, de Vries AH, Marrink SJ. Coupling Coarse-Grained to Fine-Grained Models via Hamiltonian Replica Exchange. J Chem Theory Comput 2020; 16:5313-5322. [PMID: 32569465 PMCID: PMC7426904 DOI: 10.1021/acs.jctc.0c00429] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
![]()
The energy landscape of biomolecular
systems contains many local
minima that are separated by high energy barriers. Sampling this landscape
in molecular dynamics simulations is a challenging task and often
requires the use of enhanced sampling techniques. Here, we increase
the sampling efficiency by coupling the fine-grained (FG) GROMOS force
field to the coarse-grained (CG) Martini force field via the Hamiltonian
replica exchange method (HREM). We tested the efficiency of this procedure
using a lutein/octane system. In traditional simulations, cis–trans
transitions of lutein are barely observed due to the high energy barrier
separating these states. However, many of these transitions are sampled
with our HREM scheme. The proposed method offers new possibilities
for enhanced sampling of biomolecular conformations, making use of
CG models without compromising the accuracy of the FG model.
Collapse
Affiliation(s)
- Yang Liu
- Groningen Biomolecular Sciences and Biotechnology Institute and the Zernike Institute for Advanced Material, University of Groningen, Groningen 9747 AG, The Netherlands
| | - Weria Pezeshkian
- Groningen Biomolecular Sciences and Biotechnology Institute and the Zernike Institute for Advanced Material, University of Groningen, Groningen 9747 AG, The Netherlands
| | - Jonathan Barnoud
- Groningen Biomolecular Sciences and Biotechnology Institute and the Zernike Institute for Advanced Material, University of Groningen, Groningen 9747 AG, The Netherlands
| | - Alex H de Vries
- Groningen Biomolecular Sciences and Biotechnology Institute and the Zernike Institute for Advanced Material, University of Groningen, Groningen 9747 AG, The Netherlands
| | - Siewert J Marrink
- Groningen Biomolecular Sciences and Biotechnology Institute and the Zernike Institute for Advanced Material, University of Groningen, Groningen 9747 AG, The Netherlands
| |
Collapse
|
10
|
Paul TJ, Vilseck JZ, Hayes RL, Brooks CL. Exploring pH Dependent Host/Guest Binding Affinities. J Phys Chem B 2020; 124:6520-6528. [PMID: 32628482 DOI: 10.1021/acs.jpcb.0c03671] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
When the electrostatic environment surrounding binding partners changes between unbound and bound states, the net uptake or release of a proton is possible by either binding partner. This process is pH-dependent in that the free energy required to uptake or release the proton varies with pH. This pH-dependence is typically not considered in conventional free energy methods where the use of fixed protonation states is the norm. In the present paper, we apply a simple two-step approach to calculate the pH-dependent binding free energy of a model cucubit[7]uril host/guest system. By use of λ-dynamics with an enhanced sampling protocol, adaptive landscape flattening, pKa shifts and reference binding free energies upon complexation were determined. This information enables the construction of pH-dependent binding profiles that accurately capture the pKa shifts and reproduce binding free energies at the different pH conditions that were observed experimentally. Our calculations illustrate a general framework for computing pH-dependent binding free energies but also point to some issues in modeling the molecular charge distributions within this series of molecules with CGenFF. However, by introducing some minor charge modifications to the CGenFF force field, we saw significant improvement in accuracy of the calculated pKa shifts.
Collapse
|
11
|
Ibarra AA, Bartlett GJ, Hegedüs Z, Dutt S, Hobor F, Horner KA, Hetherington K, Spence K, Nelson A, Edwards TA, Woolfson DN, Sessions RB, Wilson AJ. Predicting and Experimentally Validating Hot-Spot Residues at Protein-Protein Interfaces. ACS Chem Biol 2019; 14:2252-2263. [PMID: 31525028 PMCID: PMC6804253 DOI: 10.1021/acschembio.9b00560] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
![]()
Protein–protein
interactions (PPIs) are vital to all biological
processes. These interactions are often dynamic, sometimes transient,
typically occur over large topographically shallow protein surfaces,
and can exhibit a broad range of affinities. Considerable progress
has been made in determining PPI structures. However, given the above
properties, understanding the key determinants of their thermodynamic
stability remains a challenge in chemical biology. An improved ability
to identify and engineer PPIs would advance understanding of biological
mechanisms and mutant phenotypes and also provide a firmer foundation
for inhibitor design. In silico prediction of PPI
hot-spot amino acids using computational alanine scanning (CAS) offers
a rapid approach for predicting key residues that drive protein–protein
association. This can be applied to all known PPI structures; however
there is a trade-off between throughput and accuracy. Here we describe
a comparative analysis of multiple CAS methods, which highlights effective
approaches to improve the accuracy of predicting hot-spot residues.
Alongside this, we introduce a new method, BUDE Alanine Scanning,
which can be applied to single structures from crystallography and
to structural ensembles from NMR or molecular dynamics data. The comparative
analyses facilitate accurate prediction of hot-spots that we validate
experimentally with three diverse targets: NOXA-B/MCL-1 (an α-helix-mediated
PPI), SIMS/SUMO, and GKAP/SHANK-PDZ (both β-strand-mediated
interactions). Finally, the approach is applied to the accurate prediction
of hot-spot residues at a topographically novel Affimer/BCL-xL protein–protein interface.
Collapse
Affiliation(s)
- Amaurys A. Ibarra
- School of Biochemistry, University of Bristol, Medical Sciences Building, University Walk, Bristol BS8 1TD, U.K
| | - Gail J. Bartlett
- School of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, U.K
| | - Zsöfia Hegedüs
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K
- Astbury Centre for Structural Molecular Biology, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K
| | - Som Dutt
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K
- Astbury Centre for Structural Molecular Biology, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K
| | - Fruzsina Hobor
- Astbury Centre for Structural Molecular Biology, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K
- School of Molecular and Cellular Biology, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K
| | - Katherine A. Horner
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K
- Astbury Centre for Structural Molecular Biology, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K
| | - Kristina Hetherington
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K
- Astbury Centre for Structural Molecular Biology, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K
| | - Kirstin Spence
- Astbury Centre for Structural Molecular Biology, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K
- School of Molecular and Cellular Biology, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K
| | - Adam Nelson
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K
- Astbury Centre for Structural Molecular Biology, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K
| | - Thomas A. Edwards
- Astbury Centre for Structural Molecular Biology, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K
- School of Molecular and Cellular Biology, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K
| | - Derek N. Woolfson
- School of Biochemistry, University of Bristol, Medical Sciences Building, University Walk, Bristol BS8 1TD, U.K
- School of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, U.K
- BrisSynBio, University of Bristol, Life Sciences Building, Tyndall Avenue, Bristol BS8 1TQ, U.K
| | - Richard B. Sessions
- School of Biochemistry, University of Bristol, Medical Sciences Building, University Walk, Bristol BS8 1TD, U.K
- BrisSynBio, University of Bristol, Life Sciences Building, Tyndall Avenue, Bristol BS8 1TQ, U.K
| | - Andrew J. Wilson
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K
- Astbury Centre for Structural Molecular Biology, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K
| |
Collapse
|
12
|
Song LF, Lee TS, Zhu C, York DM, Merz KM. Using AMBER18 for Relative Free Energy Calculations. J Chem Inf Model 2019; 59:3128-3135. [PMID: 31244091 DOI: 10.1021/acs.jcim.9b00105] [Citation(s) in RCA: 121] [Impact Index Per Article: 24.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
With renewed interest in free energy methods in contemporary structure-based drug design, there is a pressing need to validate against multiple targets and force fields to assess the overall ability of these methods to accurately predict relative binding free energies. We computed relative binding free energies using graphics processing unit accelerated thermodynamic integration (GPU-TI) on a data set originally assembled by Schrödinger, Inc. Using their GPU free energy code (FEP+) and the OPLS2.1 force field combined with the REST2 enhanced sampling approach, these authors obtained an overall MUE of 0.9 kcal/mol and an overall RMSD of 1.14 kcal/mol. In our study using GPU-TI from AMBER with the AMBER14SB/GAFF1.8 force field but without enhanced sampling, we obtained an overall MUE of 1.17 kcal/mol and an overall RMSD of 1.50 kcal/mol for the 330 perturbations contained in this data set. A more detailed analysis of our results suggested that the observed differences between the two studies arise from differences in sampling protocols along with differences in the force fields employed. Future work should address the problem of establishing benchmark quality results with robust statistical error bars obtained through multiple independent runs and enhanced sampling, which is possible with the GPU-accelerated features in AMBER.
Collapse
Affiliation(s)
- Lin Frank Song
- Department of Chemistry and the Department of Biochemistry and Molecular Biology , Michigan State University , 578 S. Shaw Lane , East Lansing , Michigan 48824 , United States
| | - Tai-Sung Lee
- Laboratory for Biomolecular Simulation Research, Institute for Quantitative Biomedicine and Department of Chemistry and Chemical Biology , Rutgers University , Piscataway , New Jersey 08854 , United States
| | - Chun Zhu
- Department of Chemistry and the Department of Biochemistry and Molecular Biology , Michigan State University , 578 S. Shaw Lane , East Lansing , Michigan 48824 , United States
| | - Darrin M York
- Laboratory for Biomolecular Simulation Research, Institute for Quantitative Biomedicine and Department of Chemistry and Chemical Biology , Rutgers University , Piscataway , New Jersey 08854 , United States
| | - Kenneth M Merz
- Department of Chemistry and the Department of Biochemistry and Molecular Biology , Michigan State University , 578 S. Shaw Lane , East Lansing , Michigan 48824 , United States.,Institute for Cyber Enabled Research , Michigan State University , 567 Wilson Road, Room 1440 , East Lansing , Michigan 48824 , United States
| |
Collapse
|
13
|
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.
Collapse
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
| |
Collapse
|
14
|
Hahn DF, Hünenberger PH. Alchemical Free-Energy Calculations by Multiple-Replica λ-Dynamics: The Conveyor Belt Thermodynamic Integration Scheme. J Chem Theory Comput 2019; 15:2392-2419. [PMID: 30821973 DOI: 10.1021/acs.jctc.8b00782] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
A new method is proposed to calculate alchemical free-energy differences based on molecular dynamics (MD) simulations, called the conveyor belt thermodynamic integration (CBTI) scheme. As in thermodynamic integration (TI), K replicas of the system are simulated at different values of the alchemical coupling parameter λ. The number K is taken to be even, and the replicas are equally spaced on a forward-turn-backward-turn path, akin to a conveyor belt (CB) between the two physical end-states; and as in λ-dynamics (λD), the λ-values associated with the individual systems evolve in time along the simulation. However, they do so in a concerted fashion, determined by the evolution of a single dynamical variable Λ of period 2π controlling the advance of the entire CB. Thus, a change of Λ is always associated with K/2 equispaced replicas moving forward and K/2 equispaced replicas moving backward along λ. As a result, the effective free-energy profile of the replica system along Λ is periodic of period 2 πK-1, and the magnitude of its variations decreases rapidly upon increasing K, at least as K-1 in the limit of large K. When a sufficient number of replicas is used, these variations become small, which enables a complete and quasi-homogeneous coverage of the λ-range by the replica system, without application of any biasing potential. If desired, a memory-based biasing potential can still be added to further homogenize the sampling, the preoptimization of which is computationally inexpensive. The final free-energy profile along λ is calculated similarly to TI, by binning of the Hamiltonian λ-derivative as a function of λ considering all replicas simultaneously, followed by quadrature integration. The associated quadrature error can be kept very low owing to the continuous and quasi-homogeneous λ-sampling. The CBTI scheme can be viewed as a continuous/deterministic/dynamical analog of the Hamiltonian replica-exchange/permutation (HRE/HRP) schemes or as a correlated multiple-replica analog of the λD or λ-local elevation umbrella sampling (λ-LEUS) schemes. Compared to TI, it shares the advantage of the latter schemes in terms of enhanced orthogonal sampling, i.e. the availability of variable-λ paths to circumvent conformational barriers present at specific λ-values. Compared to HRE/HRP, it permits a deterministic and continuous sampling of the λ-range, is expected to be less sensitive to possible artifacts of the thermo- and barostating schemes, and bypasses the need to carefully preselect a λ-ladder and a swapping-attempt frequency. Compared to λ-LEUS, it eliminates (or drastically reduces) the dead time associated with the preoptimization of a biasing potential. The goal of this article is to provide the mathematical/physical formulation of the proposed CBTI scheme, along with an initial application of the method to the calculation of the hydration free energy of methanol.
Collapse
Affiliation(s)
- David F Hahn
- Laboratory of Physical Chemistry, Department of Chemistry and Applied Biosciences , ETH Zürich , Vladimir-Prelog-Weg 2 , 8093 Zürich , Switzerland
| | - Philippe H Hünenberger
- Laboratory of Physical Chemistry, Department of Chemistry and Applied Biosciences , ETH Zürich , Vladimir-Prelog-Weg 2 , 8093 Zürich , Switzerland
| |
Collapse
|
15
|
Cole DJ, Cabeza de Vaca I, Jorgensen WL. Computation of protein-ligand binding free energies using quantum mechanical bespoke force fields. MEDCHEMCOMM 2019; 10:1116-1120. [PMID: 31391883 DOI: 10.1039/c9md00017h] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Accepted: 02/26/2019] [Indexed: 12/17/2022]
Abstract
A quantum mechanical bespoke molecular mechanics force field is derived for the L99A mutant of T4 lysozyme and used to compute absolute binding free energies of six benzene analogs to the protein. Promising agreement between theory and experiment highlights the potential for future use of system-specific force fields in computer-aided drug design.
Collapse
Affiliation(s)
- Daniel J Cole
- School of Natural and Environmental Sciences , Newcastle University , Newcastle upon Tyne NE1 7RU , UK .
| | - Israel Cabeza de Vaca
- Department of Chemistry , Yale University , New Haven , Connecticut 06520-8107 , USA
| | - William L Jorgensen
- Department of Chemistry , Yale University , New Haven , Connecticut 06520-8107 , USA
| |
Collapse
|
16
|
Garton M, Corbi-Verge C, Hu Y, Nim S, Tarasova N, Sherborne B, Kim PM. Rapid and accurate structure-based therapeutic peptide design using GPU accelerated thermodynamic integration. Proteins 2019; 87:236-244. [PMID: 30520126 DOI: 10.1002/prot.25644] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Revised: 10/30/2018] [Accepted: 11/29/2018] [Indexed: 11/07/2022]
Abstract
Peptide-based therapeutics are an alternative to small molecule drugs as they offer superior specificity, lower toxicity, and easy synthesis. Here we present an approach that leverages the dramatic performance increase afforded by the recent arrival of GPU accelerated thermodynamic integration (TI). GPU TI facilitates very fast, highly accurate binding affinity optimization of peptides against therapeutic targets. We benchmarked TI predictions using published peptide binding optimization studies. Prediction of mutations involving charged side-chains was found to be less accurate than for non-charged, and use of a more complex 3-step TI protocol was found to boost accuracy in these cases. Using the 3-step protocol for non-charged side-chains either had no effect or was detrimental. We use the benchmarked pipeline to optimize a peptide binding to our recently discovered cancer target: EME1. TI calculations predict beneficial mutations using both canonical and non-canonical amino acids. We validate these predictions using fluorescence polarization and confirm that binding affinity is increased. We further demonstrate that this increase translates to a significant reduction in pancreatic cancer cell viability.
Collapse
Affiliation(s)
- Michael Garton
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, Canada
| | - Carles Corbi-Verge
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, Canada
| | - Yuan Hu
- Merck & Co., Inc., Kenilworth, New Jersey.,Alkermes Inc., Waltham, Massachusetts
| | - Satra Nim
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, Canada
| | - Nadya Tarasova
- Cancer and Inflammation Program, Center for Cancer Research, National Cancer Institute-Frederick, Frederick, Maryland
| | | | - Philip M Kim
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, Canada.,Department of Computer Science, University of Toronto, Toronto, Canada
| |
Collapse
|
17
|
A computational approach for designing D-proteins with non-canonical amino acid optimised binding affinity. PLoS One 2017; 12:e0187524. [PMID: 29108013 PMCID: PMC5673230 DOI: 10.1371/journal.pone.0187524] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2017] [Accepted: 10/21/2017] [Indexed: 01/08/2023] Open
Abstract
Redesigning protein surface topology to improve target binding holds great promise in the search for highly selective therapeutics. While significant binding improvements can be achieved using natural amino acids, the introduction of non-canonical residues vastly increases sequence space and thus the chance to significantly out-compete native partners. The potency of protein inhibitors can be further enhanced by synthesising mirror image, D-amino versions. This renders them non-immunogenic and makes them highly resistant to proteolytic degradation. Current experimental design methods often preclude the use of D-amino acids and non-canonical amino acids for a variety of reasons. To address this, we build an in silico pipeline for D-protein designs featuring non-canonical amino acids. For a test scaffold we use an existing D-protein inhibitor of VEGF: D-RFX001. We benchmark the approach by recapitulating previous experimental optimisation with canonical amino acids. Subsequent incorporation of non-canonical amino acids allows designs that are predicted to improve binding affinity by up to -7.18 kcal/mol.
Collapse
|
18
|
Abstract
Binding free energy calculations based on molecular simulations provide predicted affinities for biomolecular complexes. These calculations begin with a detailed description of a system, including its chemical composition and the interactions among its components. Simulations of the system are then used to compute thermodynamic information, such as binding affinities. Because of their promise for guiding molecular design, these calculations have recently begun to see widespread applications in early-stage drug discovery. However, many hurdles remain in making them a robust and reliable tool. In this review, we highlight key challenges of these calculations, discuss some examples of these challenges, and call for the designation of standard community benchmark test systems that will help the research community generate and evaluate progress. In our view, progress will require careful assessment and evaluation of new methods, force fields, and modeling innovations on well-characterized benchmark systems, and we lay out our vision for how this can be achieved.
Collapse
Affiliation(s)
- David L Mobley
- Department of Pharmaceutical Sciences and Department of Chemistry, University of California, Irvine, California 92697;
| | - Michael K Gilson
- Skaggs School of Pharmacy and Pharmaceutical Sciences and Center for Drug Discovery Innovation, University of California, San Diego, La Jolla, California 92093;
| |
Collapse
|
19
|
Wang J, Jang Y, Khedkar JK, Koo JY, Kim Y, Lee CJ, Rhee YM, Kim K. How Does Solvation Affect the Binding of Hydrophilic Amino Saccharides to Cucurbit[7]uril with Exceptional Anomeric Selectivity? Chemistry 2016; 22:15791-15799. [PMID: 27632939 DOI: 10.1002/chem.201602810] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Indexed: 01/06/2023]
Abstract
Cucurbit[7]uril (CB[7]) is known to bind strongly to hydrophilic amino saccharide guests with exceptional α-anomer selectivities under aqueous conditions. Single-crystal X-ray crystallography and computational methods were used to elucidate the reason behind this interesting phenomenon. The crystal structures of protonated galactosamine (GalN) and glucosamine (GluN) complexes confirm the inclusion of α anomers inside CB[7] and disclose the details of the host-guest binding. Whereas computed gas-phase structures agree with these crystal structures, gas-phase binding free energies show preferences for the β-anomer complexes over their α counterparts, in striking contrast to the experimental results under aqueous conditions. However, when the solvation effect is considered, the binding structures drastically change and the preference for the α anomers is recovered. The α anomers also tend to bind more tightly and leave less space in the CB[7] cavity toward inclusion of only one water molecule, whereas loosely bound β anomers leave more space toward accommodating two water molecules, with markedly different hydrogen-bonding natures. Surprisingly, entropy seems to contribute significantly to both anomeric discrimination and binding. This suggests that of all the driving factors for the strong complexation of the hydrophilic amino saccharide guests, water mediation plays a crucial role in the anomer discrimination.
Collapse
Affiliation(s)
- Jianping Wang
- Center for Self-assembly and Complexity, Institute for Basic Science (IBS), 77 Cheongam-Ro, Nam-Gu, Pohang, 37673, Republic of Korea
| | - Yoonjung Jang
- Center for Self-assembly and Complexity, Institute for Basic Science (IBS), 77 Cheongam-Ro, Nam-Gu, Pohang, 37673, Republic of Korea.,Department of Chemistry, Pohang University of Science and Technology, 77 Cheongam-Ro, Nam-Gu, Pohang, 37673, Republic of Korea
| | - Jayshree K Khedkar
- Center for Self-assembly and Complexity, Institute for Basic Science (IBS), 77 Cheongam-Ro, Nam-Gu, Pohang, 37673, Republic of Korea
| | - Jin Young Koo
- Division of Advanced Materials Science, Pohang University of Science and Technology, 77 Cheongam-Ro, Nam-Gu, Pohang, 37673, Republic of Korea
| | - Yonghwi Kim
- Center for Self-assembly and Complexity, Institute for Basic Science (IBS), 77 Cheongam-Ro, Nam-Gu, Pohang, 37673, Republic of Korea
| | - Chang Jun Lee
- Center for Self-assembly and Complexity, Institute for Basic Science (IBS), 77 Cheongam-Ro, Nam-Gu, Pohang, 37673, Republic of Korea
| | - Young Min Rhee
- Center for Self-assembly and Complexity, Institute for Basic Science (IBS), 77 Cheongam-Ro, Nam-Gu, Pohang, 37673, Republic of Korea. .,Department of Chemistry, Pohang University of Science and Technology, 77 Cheongam-Ro, Nam-Gu, Pohang, 37673, Republic of Korea.
| | - Kimoon Kim
- Center for Self-assembly and Complexity, Institute for Basic Science (IBS), 77 Cheongam-Ro, Nam-Gu, Pohang, 37673, Republic of Korea. .,Department of Chemistry, Pohang University of Science and Technology, 77 Cheongam-Ro, Nam-Gu, Pohang, 37673, Republic of Korea. .,Division of Advanced Materials Science, Pohang University of Science and Technology, 77 Cheongam-Ro, Nam-Gu, Pohang, 37673, Republic of Korea.
| |
Collapse
|
20
|
Bieler NS, Tschopp JP, Hünenberger PH. Multistate λ-local-elevation umbrella-sampling (MS-λ-LEUS): method and application to the complexation of cations by crown ethers. J Chem Theory Comput 2016; 11:2575-88. [PMID: 26575556 DOI: 10.1021/acs.jctc.5b00118] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
An extension of the λ-local-elevation umbrella-sampling (λ-LEUS) scheme [ Bieler et al. J. Chem. Theory Comput. 2014 , 10 , 3006 ] is proposed to handle the multistate (MS) situation, i.e. the calculation of the relative free energies of multiple physical states based on a single simulation. The key element of the MS-λ-LEUS approach is to use a single coupling variable Λ controlling successive pairwise mutations between the states of interest in a cyclic fashion. The Λ variable is propagated dynamically as an extended-system variable, using a coordinate transformation with plateaus and a memory-based biasing potential as in λ-LEUS. Compared to other available MS schemes (one-step perturbation, enveloping distribution sampling and conventional λ-dynamics) the proposed method presents a number of important advantages, namely: (i) the physical states are visited explicitly and over finite time periods; (ii) the extent of unphysical space required to ensure transitions is kept minimal and, in particular, one-dimensional; (iii) the setup protocol solely requires the topologies of the physical states; and (iv) the method only requires limited modifications in a simulation code capable of handling two-state mutations. As an initial application, the absolute binding free energies of five alkali cations to three crown ethers in three different solvents are calculated. The results are found to reproduce qualitatively the main experimental trends and, in particular, the experimental selectivity of 18C6 for K(+) in water and methanol, which is interpreted in terms of opposing trends along the cation series between the solvation free energy of the cation and the direct electrostatic interactions within the complex.
Collapse
Affiliation(s)
- Noah S Bieler
- Laboratory of Physical Chemistry, ETH Zürich , CH-8093 Zürich, Zürich, Switzerland
| | - Jan P Tschopp
- Laboratory of Physical Chemistry, ETH Zürich , CH-8093 Zürich, Zürich, Switzerland
| | | |
Collapse
|
21
|
Mentes A, Deng NJ, Vijayan RSK, Xia J, Gallicchio E, Levy RM. Binding Energy Distribution Analysis Method: Hamiltonian Replica Exchange with Torsional Flattening for Binding Mode Prediction and Binding Free Energy Estimation. J Chem Theory Comput 2016; 12:2459-70. [PMID: 27070865 PMCID: PMC4862910 DOI: 10.1021/acs.jctc.6b00134] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Molecular dynamics modeling of complex biological systems is limited by finite simulation time. The simulations are often trapped close to local energy minima separated by high energy barriers. Here, we introduce Hamiltonian replica exchange (H-REMD) with torsional flattening in the Binding Energy Distribution Analysis Method (BEDAM), to reduce energy barriers along torsional degrees of freedom and accelerate sampling of intramolecular degrees of freedom relevant to protein-ligand binding. The method is tested on a standard benchmark (T4 Lysozyme/L99A/p-xylene complex) and on a library of HIV-1 integrase complexes derived from the SAMPL4 blind challenge. We applied the torsional flattening strategy to 26 of the 53 known binders to the HIV Integrase LEDGF site found to have a binding energy landscape funneled toward the crystal structure. We show that our approach samples the conformational space more efficiently than the original method without flattening when starting from a poorly docked pose with incorrect ligand dihedral angle conformations. In these unfavorable cases convergence to a binding pose within 2-3 Å from the crystallographic pose is obtained within a few nanoseconds of the Hamiltonian replica exchange simulation. We found that torsional flattening is insufficient in cases where trapping is due to factors other than torsional energy, such as the formation of incorrect intramolecular hydrogen bonds and stacking. Work is in progress to generalize the approach to handle these cases and thereby make it more widely applicable.
Collapse
Affiliation(s)
- Ahmet Mentes
- Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122, United States
- Center for Biophysics and Computational Biology and Institute for Computational Molecular Science, Temple University, Philadelphia, Pennsylvania 19122, United States
| | - Nan-Jie Deng
- Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122, United States
- Center for Biophysics and Computational Biology and Institute for Computational Molecular Science, Temple University, Philadelphia, Pennsylvania 19122, United States
| | - R. S. K. Vijayan
- Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122, United States
- Center for Biophysics and Computational Biology and Institute for Computational Molecular Science, Temple University, Philadelphia, Pennsylvania 19122, United States
| | - Junchao Xia
- Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122, United States
- Center for Biophysics and Computational Biology and Institute for Computational Molecular Science, Temple University, Philadelphia, Pennsylvania 19122, United States
| | - Emilio Gallicchio
- Department of Chemistry, Brooklyn College, The City University of New York, Brooklyn, New York 11210, United States
| | - Ronald M. Levy
- Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122, United States
- Center for Biophysics and Computational Biology and Institute for Computational Molecular Science, Temple University, Philadelphia, Pennsylvania 19122, United States
| |
Collapse
|
22
|
Cole DJ, Vilseck JZ, Tirado-Rives J, Payne MC, Jorgensen WL. Biomolecular Force Field Parameterization via Atoms-in-Molecule Electron Density Partitioning. J Chem Theory Comput 2016; 12:2312-23. [PMID: 27057643 PMCID: PMC4864407 DOI: 10.1021/acs.jctc.6b00027] [Citation(s) in RCA: 91] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
![]()
Molecular mechanics
force fields, which are commonly used in biomolecular
modeling and computer-aided drug design, typically treat nonbonded
interactions using a limited library of empirical parameters that
are developed for small molecules. This approach does not account
for polarization in larger molecules or proteins, and the parametrization
process is labor-intensive. Using linear-scaling density functional
theory and atoms-in-molecule electron density partitioning, environment-specific
charges and Lennard-Jones parameters are derived directly from quantum
mechanical calculations for use in biomolecular modeling of organic
and biomolecular systems. The proposed methods significantly reduce
the number of empirical parameters needed to construct molecular mechanics
force fields, naturally include polarization effects in charge and
Lennard-Jones parameters, and scale well to systems comprised of thousands
of atoms, including proteins. The feasibility and benefits of this
approach are demonstrated by computing free energies of hydration,
properties of pure liquids, and the relative binding free energies
of indole and benzofuran to the L99A mutant of T4 lysozyme.
Collapse
Affiliation(s)
- Daniel J Cole
- Department of Chemistry, Yale University , New Haven, Connecticut 06520-8107, United States.,TCM Group, Cavendish Laboratory, 19 JJ Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - Jonah Z Vilseck
- Department of Chemistry, Yale University , New Haven, Connecticut 06520-8107, United States
| | - Julian Tirado-Rives
- Department of Chemistry, Yale University , New Haven, Connecticut 06520-8107, United States
| | - Mike C Payne
- TCM Group, Cavendish Laboratory, 19 JJ Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - William L Jorgensen
- Department of Chemistry, Yale University , New Haven, Connecticut 06520-8107, United States
| |
Collapse
|
23
|
Gu J, Li H, Wang X. A Self-Adaptive Steered Molecular Dynamics Method Based on Minimization of Stretching Force Reveals the Binding Affinity of Protein-Ligand Complexes. Molecules 2015; 20:19236-51. [PMID: 26506335 PMCID: PMC6332444 DOI: 10.3390/molecules201019236] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Revised: 10/14/2015] [Accepted: 10/14/2015] [Indexed: 01/22/2023] Open
Abstract
Binding affinity prediction of protein–ligand complexes has attracted widespread interest. In this study, a self-adaptive steered molecular dynamics (SMD) method is proposed to reveal the binding affinity of protein–ligand complexes. The SMD method is executed through adjusting pulling direction to find an optimum trajectory of ligand dissociation, which is realized by minimizing the stretching force automatically. The SMD method is then used to simulate the dissociations of 19 common protein–ligand complexes which are derived from two homology families, and the binding free energy values are gained through experimental techniques. Results show that the proposed SMD method follows a different dissociation pathway with lower a rupture force and energy barrier when compared with the conventional SMD method, and further analysis indicates the rupture forces of the complexes in the same protein family correlate well with their binding free energy, which reveals the possibility of using the proposed SMD method to identify the active ligand.
Collapse
Affiliation(s)
- Junfeng Gu
- State Key Laboratory of Structural Analysis for Industrial Equipment, Department of Engineering Mechanics, Dalian University of Technology, Dalian 116023, China.
| | - Hongxia Li
- School of Mechanical Engineering, Dalian University of Technology, Dalian 116023, China.
| | - Xicheng Wang
- State Key Laboratory of Structural Analysis for Industrial Equipment, Department of Engineering Mechanics, Dalian University of Technology, Dalian 116023, China.
| |
Collapse
|
24
|
Luitz M, Bomblies R, Ostermeir K, Zacharias M. Exploring biomolecular dynamics and interactions using advanced sampling methods. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2015; 27:323101. [PMID: 26194626 DOI: 10.1088/0953-8984/27/32/323101] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Molecular dynamics (MD) and Monte Carlo (MC) simulations have emerged as a valuable tool to investigate statistical mechanics and kinetics of biomolecules and synthetic soft matter materials. However, major limitations for routine applications are due to the accuracy of the molecular mechanics force field and due to the maximum simulation time that can be achieved in current simulations studies. For improving the sampling a number of advanced sampling approaches have been designed in recent years. In particular, variants of the parallel tempering replica-exchange methodology are widely used in many simulation studies. Recent methodological advancements and a discussion of specific aims and advantages are given. This includes improved free energy simulation approaches and conformational search applications.
Collapse
Affiliation(s)
- Manuel Luitz
- Physik-Department T38, Technische Universität München, James Franck Str. 1, 85748 Garching, Germany
| | | | | | | |
Collapse
|
25
|
Ferenczy GG. Computation of Drug-Binding Thermodynamics. THERMODYNAMICS AND KINETICS OF DRUG BINDING 2015. [DOI: 10.1002/9783527673025.ch3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
|
26
|
Hadden JA, Tessier MB, Fadda E, Woods RJ. Calculating binding free energies for protein-carbohydrate complexes. Methods Mol Biol 2015; 1273:431-65. [PMID: 25753724 DOI: 10.1007/978-1-4939-2343-4_26] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
A variety of computational techniques may be applied to compute theoretical binding free energies for protein-carbohydrate complexes. Elucidation of the intermolecular interactions, as well as the thermodynamic effects, that contribute to the relative strength of receptor binding can shed light on biomolecular recognition, and the resulting initiation or inhibition of a biological process. Three types of free energy methods are discussed here, including MM-PB/GBSA, thermodynamic integration, and a non-equilibrium alternative utilizing SMD. Throughout this chapter, the well-known concanavalin A lectin is employed as a model system to demonstrate the application of these methods to the special case of carbohydrate binding.
Collapse
Affiliation(s)
- Jodi A Hadden
- Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Road, Athens, GA, 30602, USA
| | | | | | | |
Collapse
|
27
|
Sun X, Ågren H, Tu Y. Functional Water Molecules in Rhodopsin Activation. J Phys Chem B 2014; 118:10863-73. [DOI: 10.1021/jp505180t] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Affiliation(s)
- Xianqiang Sun
- Division of Theoretical Chemistry
and Biology, School of Biotechnology, KTH Royal Institute of Technology, S-106 91 Stockholm, Sweden
| | - Hans Ågren
- Division of Theoretical Chemistry
and Biology, School of Biotechnology, KTH Royal Institute of Technology, S-106 91 Stockholm, Sweden
| | - Yaoquan Tu
- Division of Theoretical Chemistry
and Biology, School of Biotechnology, KTH Royal Institute of Technology, S-106 91 Stockholm, Sweden
| |
Collapse
|
28
|
George Priya Doss C, Rajith B, Chakraboty C, Balaji V, Magesh R, Gowthami B, Menon S, Swati M, Trivedi M, Paul J, Vasan R, Das M. In silico profiling and structural insights of missense mutations in RET protein kinase domain by molecular dynamics and docking approach. MOLECULAR BIOSYSTEMS 2013; 10:421-36. [PMID: 24336963 DOI: 10.1039/c3mb70427k] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
A major challenge remaining in drug design efforts towards protein kinase is due to the development of drug resistance initiated by the missense mutations in the kinase catalytic domain. Gain or loss of function mutations in the REarranged during Transfection (RET) tyrosine kinase gene have been associated with the development of a wide range of human associated cancers and Hirschsprung's disease. However, to what extent these mutations might affect bio-molecular functions remains unclear. In this article, the functionally significant mutations in RET were screened with the aid of various sequence and structure based in silico prediction methods. We mapped the deleterious mutants, modelled mutant proteins and deciphered the impact of mutations on drug binding mechanisms in the RET crystal structure of PDB ID: with the potential inhibitor vandetanib by docking analysis. Furthermore, molecular dynamics simulations were undertaken to understand the mechanistic action of cancer associated mutations in altering the protein kinase structure, dynamics, and stability. According to our results, the overall effect of V804M, M918T and S922Y were destabilizing and mostly alter the electrostatic component of the binding energy. Specifically, the mutation of gatekeeper residue valine 804 present in the ATP binding pocket affects the protein stability and confers resistance to the drug vandetanib, which was consistent with previously published experimental results. Overall, our findings may provide useful structural insights for in-depth understanding of the molecular mechanism underlying RET mutation and developing effective drugs.
Collapse
Affiliation(s)
- C George Priya Doss
- Medical Biotechnology Division, School of Biosciences and Technology, VIT University, Vellore 632014, Tamil Nadu, India.
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
29
|
Ostermeir K, Zacharias M. Hamiltonian replica-exchange simulations with adaptive biasing of peptide backbone and side chain dihedral angles. J Comput Chem 2013; 35:150-8. [PMID: 24318649 DOI: 10.1002/jcc.23476] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Revised: 09/13/2013] [Accepted: 10/07/2013] [Indexed: 11/07/2022]
Abstract
A Hamiltonian Replica-Exchange Molecular Dynamics (REMD) simulation method has been developed that employs a two-dimensional backbone and one-dimensional side chain biasing potential specifically to promote conformational transitions in peptides. To exploit the replica framework optimally, the level of the biasing potential in each replica was appropriately adapted during the simulations. This resulted in both high exchange rates between neighboring replicas and improved occupancy/flow of all conformers in each replica. The performance of the approach was tested on several peptide and protein systems and compared with regular MD simulations and previous REMD studies. Improved sampling of relevant conformational states was observed for unrestrained protein and peptide folding simulations as well as for refinement of a loop structure with restricted mobility of loop flanking protein regions.
Collapse
Affiliation(s)
- Katja Ostermeir
- Physik-Department T38, Technische Universität München, James Franck Str. 1, 85748, Garching, Germany
| | | |
Collapse
|
30
|
Zhu S, Travis SM, Elcock AH. Accurate calculation of mutational effects on the thermodynamics of inhibitor binding to p38α MAP kinase: a combined computational and experimental study. J Chem Theory Comput 2013; 9:3151-3164. [PMID: 23914145 PMCID: PMC3731164 DOI: 10.1021/ct400104x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
A major current challenge for drug design efforts focused on protein kinases is the development of drug resistance caused by spontaneous mutations in the kinase catalytic domain. The ubiquity of this problem means that it would be advantageous to develop fast, effective computational methods that could be used to determine the effects of potential resistance-causing mutations before they arise in a clinical setting. With this long-term goal in mind, we have conducted a combined experimental and computational study of the thermodynamic effects of active-site mutations on a well-characterized and high-affinity interaction between a protein kinase and a small-molecule inhibitor. Specifically, we developed a fluorescence-based assay to measure the binding free energy of the small-molecule inhibitor, SB203580, to the p38α MAP kinase and used it measure the inhibitor's affinity for five different kinase mutants involving two residues (Val38 and Ala51) that contact the inhibitor in the crystal structure of the inhibitor-kinase complex. We then conducted long, explicit-solvent thermodynamic integration (TI) simulations in an attempt to reproduce the experimental relative binding affinities of the inhibitor for the five mutants; in total, a combined simulation time of 18.5 μs was obtained. Two widely used force fields - OPLS-AA/L and Amber ff99SB-ILDN - were tested in the TI simulations. Both force fields produced excellent agreement with experiment for three of the five mutants; simulations performed with the OPLS-AA/L force field, however, produced qualitatively incorrect results for the constructs that contained an A51V mutation. Interestingly, the discrepancies with the OPLS-AA/L force field could be rectified by the imposition of position restraints on the atoms of the protein backbone and the inhibitor without destroying the agreement for other mutations; the ability to reproduce experiment depended, however, upon the strength of the restraints' force constant. Imposition of position restraints in corresponding simulations that used the Amber ff99SB-ILDN force field had little effect on their ability to match experiment. Overall, the study shows that both force fields can work well for predicting the effects of active-site mutations on small molecule binding affinities and demonstrates how a direct combination of experiment and computation can be a powerful strategy for developing an understanding of protein-inhibitor interactions.
Collapse
Affiliation(s)
- Shun Zhu
- Department of Biochemistry, University of Iowa, Iowa City, IA 52242
| | | | | |
Collapse
|
31
|
Advanced replica-exchange sampling to study the flexibility and plasticity of peptides and proteins. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2013; 1834:847-53. [PMID: 23298543 DOI: 10.1016/j.bbapap.2012.12.016] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2012] [Revised: 12/23/2012] [Accepted: 12/24/2012] [Indexed: 11/20/2022]
Abstract
Molecular dynamics (MD) simulations are ideally suited to investigate protein and peptide plasticity and flexibility simultaneously at high spatial (atomic) and high time resolution. However, the applicability is still limited by the force field accuracy and by the maximum simulation time that can be routinely achieved in current MD simulations. In order to improve the sampling the replica-exchange (REMD) methodology has become popular and is now the most widely applied advanced sampling approach. Many variants of the REMD method have been designed to reduce the computational demand or to enhance sampling along specific sets of conformational variables. An overview on recent methodological advances and discussion of specific aims and advantages of the approaches will be given. Applications in the area of free energy simulations and advanced sampling of intrinsically disordered peptides and proteins will also be discussed. This article is part of a Special Issue entitled: The emerging dynamic view of proteins: Protein plasticity in allostery, evolution and self-assembly.
Collapse
|
32
|
Mobley DL, Klimovich PV. Perspective: Alchemical free energy calculations for drug discovery. J Chem Phys 2012; 137:230901. [PMID: 23267463 PMCID: PMC3537745 DOI: 10.1063/1.4769292] [Citation(s) in RCA: 159] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2012] [Accepted: 11/15/2012] [Indexed: 02/06/2023] Open
Abstract
Computational techniques see widespread use in pharmaceutical drug discovery, but typically prove unreliable in predicting trends in protein-ligand binding. Alchemical free energy calculations seek to change that by providing rigorous binding free energies from molecular simulations. Given adequate sampling and an accurate enough force field, these techniques yield accurate free energy estimates. Recent innovations in alchemical techniques have sparked a resurgence of interest in these calculations. Still, many obstacles stand in the way of their routine application in a drug discovery context, including the one we focus on here, sampling. Sampling of binding modes poses a particular challenge as binding modes are often separated by large energy barriers, leading to slow transitions. Binding modes are difficult to predict, and in some cases multiple binding modes may contribute to binding. In view of these hurdles, we present a framework for dealing carefully with uncertainty in binding mode or conformation in the context of free energy calculations. With careful sampling, free energy techniques show considerable promise for aiding drug discovery.
Collapse
Affiliation(s)
- David L Mobley
- Department of Chemistry, University of New Orleans, 2000 Lakeshore Drive, New Orleans, Louisiana 70148, USA.
| | | |
Collapse
|
33
|
Ripoll DR, Khavrutskii IV, Chaudhury S, Liu J, Kuschner RA, Wallqvist A, Reifman J. Quantitative predictions of binding free energy changes in drug-resistant influenza neuraminidase. PLoS Comput Biol 2012; 8:e1002665. [PMID: 22956900 PMCID: PMC3431292 DOI: 10.1371/journal.pcbi.1002665] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2012] [Accepted: 07/15/2012] [Indexed: 12/26/2022] Open
Abstract
Quantitatively predicting changes in drug sensitivity associated with residue mutations is a major challenge in structural biology. By expanding the limits of free energy calculations, we successfully identified mutations in influenza neuraminidase (NA) that confer drug resistance to two antiviral drugs, zanamivir and oseltamivir. We augmented molecular dynamics (MD) with Hamiltonian Replica Exchange and calculated binding free energy changes for H274Y, N294S, and Y252H mutants. Based on experimental data, our calculations achieved high accuracy and precision compared with results from established computational methods. Analysis of 15 µs of aggregated MD trajectories provided insights into the molecular mechanisms underlying drug resistance that are at odds with current interpretations of the crystallographic data. Contrary to the notion that resistance is caused by mutant-induced changes in hydrophobicity of the binding pocket, our simulations showed that drug resistance mutations in NA led to subtle rearrangements in the protein structure and its dynamics that together alter the active-site electrostatic environment and modulate inhibitor binding. Importantly, different mutations confer resistance through different conformational changes, suggesting that a generalized mechanism for NA drug resistance is unlikely. The capacity of the influenza virus to rapidly mutate and render resistance to a handful of FDA approved neuraminidase (NA) inhibitors represents a significant human health concern. To gain an atomic-level understanding of the mechanisms behind drug resistance, we applied a novel computational approach to characterize resistant NA mutations. These results are comparable in accuracy and precision with the best experimental measurements presently available. To the best of our knowledge, this is the first time that a rigorous computational method has attained the level of certainty needed to predict subtle changes in binding free energies conferred by mutations. Analysis of our simulation data provided a thorough description of the thermodynamics of the binding process for different NA-inhibitor complexes, with findings that in some cases challenge current views based on interpretations of the crystallographic data. While we did not find a generalized mechanism of NA resistance, we identified key differences between oseltamivir and zanamivir that discriminate their responses to the three mutations we considered, namely H274Y, N294S and Y252H. It is worth noting that our approach can be broadly applied to predict resistant mutations to existing and newly developed drugs in other important drug targets.
Collapse
Affiliation(s)
- Daniel R. Ripoll
- Department of Defense Biotechnology High Performance Computing Software Applications Institute, Telemedicine and Advanced Technology Research Center, US Army Medical Research and Materiel Command, Fort Detrick, Frederick, Maryland, United States of America
| | - Ilja V. Khavrutskii
- Department of Defense Biotechnology High Performance Computing Software Applications Institute, Telemedicine and Advanced Technology Research Center, US Army Medical Research and Materiel Command, Fort Detrick, Frederick, Maryland, United States of America
| | - Sidhartha Chaudhury
- Department of Defense Biotechnology High Performance Computing Software Applications Institute, Telemedicine and Advanced Technology Research Center, US Army Medical Research and Materiel Command, Fort Detrick, Frederick, Maryland, United States of America
| | - Jin Liu
- Department of Defense Biotechnology High Performance Computing Software Applications Institute, Telemedicine and Advanced Technology Research Center, US Army Medical Research and Materiel Command, Fort Detrick, Frederick, Maryland, United States of America
| | - Robert A. Kuschner
- Walter Reed Army Institute of Research, Emerging Infectious Diseases Research Unit, Silver Spring, Maryland, United States of America
| | - Anders Wallqvist
- Department of Defense Biotechnology High Performance Computing Software Applications Institute, Telemedicine and Advanced Technology Research Center, US Army Medical Research and Materiel Command, Fort Detrick, Frederick, Maryland, United States of America
| | - Jaques Reifman
- Department of Defense Biotechnology High Performance Computing Software Applications Institute, Telemedicine and Advanced Technology Research Center, US Army Medical Research and Materiel Command, Fort Detrick, Frederick, Maryland, United States of America
- * E-mail:
| |
Collapse
|
34
|
Cardellina JH, Roxas-Duncan VI, Montgomery V, Eccard V, Campbell Y, Hu X, Khavrutskii I, Tawa GJ, Wallqvist A, Gloer JB, Phatak NL, Höller U, Soman AG, Joshi BK, Hein SM, Wicklow DT, Smith LA. Fungal bis-Naphthopyrones as Inhibitors of Botulinum Neurotoxin Serotype A. ACS Med Chem Lett 2012; 3:387-91. [PMID: 24900483 DOI: 10.1021/ml200312s] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2012] [Accepted: 04/02/2012] [Indexed: 11/30/2022] Open
Abstract
An in silico screen of the NIH Molecular Library Small Molecule Repository (MLSMR) of ∼350000 compounds and confirmatory bioassays led to identification of chaetochromin A (1) as an inhibitor of botulinum neurotoxin serotype A (BoNT A). Subsequent acquisition and testing of analogues of 1 uncovered two compounds, talaroderxines A (2) and B (3), with improved activity. These are the first fungal metabolites reported to exhibit BoNT/A inhibitory activity.
Collapse
Affiliation(s)
- John H. Cardellina
- Division of
Integrated Toxicology, U.S. Army Medical Research Institute of Infectious Diseases, Frederick, Maryland 21702-5011
| | - Virginia I. Roxas-Duncan
- Division of
Integrated Toxicology, U.S. Army Medical Research Institute of Infectious Diseases, Frederick, Maryland 21702-5011
| | - Vicki Montgomery
- Division of
Integrated Toxicology, U.S. Army Medical Research Institute of Infectious Diseases, Frederick, Maryland 21702-5011
| | - Vanessa Eccard
- Division of
Integrated Toxicology, U.S. Army Medical Research Institute of Infectious Diseases, Frederick, Maryland 21702-5011
| | - Yvette Campbell
- Division of
Integrated Toxicology, U.S. Army Medical Research Institute of Infectious Diseases, Frederick, Maryland 21702-5011
| | - Xin Hu
- Biotechnology High Performance
Computer Software Applications Institute, Telemedicine and Advanced
Technology Research Center, U.S. Army Medical Research and Materiel Command, Frederick, Maryland 21702
| | - Ilja Khavrutskii
- Biotechnology High Performance
Computer Software Applications Institute, Telemedicine and Advanced
Technology Research Center, U.S. Army Medical Research and Materiel Command, Frederick, Maryland 21702
| | - Gregory J. Tawa
- Biotechnology High Performance
Computer Software Applications Institute, Telemedicine and Advanced
Technology Research Center, U.S. Army Medical Research and Materiel Command, Frederick, Maryland 21702
| | - Anders Wallqvist
- Biotechnology High Performance
Computer Software Applications Institute, Telemedicine and Advanced
Technology Research Center, U.S. Army Medical Research and Materiel Command, Frederick, Maryland 21702
| | - James B. Gloer
- Department of Chemistry, University of Iowa, Iowa City, Iowa 52242-1294
| | - Nisarga L. Phatak
- Department of Chemistry, University of Iowa, Iowa City, Iowa 52242-1294
| | - Ulrich Höller
- Department of Chemistry, University of Iowa, Iowa City, Iowa 52242-1294
| | - Ashish G. Soman
- Department of Chemistry, University of Iowa, Iowa City, Iowa 52242-1294
| | - Biren K. Joshi
- Department of Chemistry, University of Iowa, Iowa City, Iowa 52242-1294
| | - Sara M. Hein
- Department of Chemistry, University of Iowa, Iowa City, Iowa 52242-1294
| | - Donald T. Wicklow
- Bacterial Foodborne Pathogens
and Mycology Research Unit, Agricultural Research Service, U.S. Department of Agriculture, Peoria, Illinois 61604
| | - Leonard A. Smith
- Senior Research Scientist for
Medical Countermeasures Technology, U.S. Army Medical Research Institute of Infectious Diseases, Frederick,
Maryland 21702-5011
| |
Collapse
|
35
|
Lapelosa M, Gallicchio E, Levy RM. Conformational Transitions and Convergence of Absolute Binding Free Energy Calculations. J Chem Theory Comput 2011; 8:47-60. [PMID: 22368530 DOI: 10.1021/ct200684b] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The Binding Energy Distribution Analysis Method (BEDAM) is employed to compute the standard binding free energies of a series of ligands to a FK506 binding protein (FKBP12) with implicit solvation. Binding free energy estimates are in reasonably good agreement with experimental affinities. The conformations of the complexes identified by the simulations are in good agreement with crystallographic data, which was not used to restrain ligand orientations. The BEDAM method is based on λ -hopping Hamiltonian parallel Replica Exchange (HREM) molecular dynamics conformational sampling, the OPLS-AA/AGBNP2 effective potential, and multi-state free energy estimators (MBAR). Achieving converged and accurate results depends on all of these elements of the calculation. Convergence of the binding free energy is tied to the level of convergence of binding energy distributions at critical intermediate states where bound and unbound states are at equilibrium, and where the rate of binding/unbinding conformational transitions is maximal. This finding mirrors similar observations in the context of order/disorder transitions as for example in protein folding. Insights concerning the physical mechanism of ligand binding and unbinding are obtained. Convergence for the largest FK506 ligand is achieved only after imposing strict conformational restraints, which however require accurate prior structural knowledge of the structure of the complex. The analytical AGBNP2 model is found to underestimate the magnitude of the hydrophobic driving force towards binding in these systems characterized by loosely packed protein-ligand binding interfaces. Rescoring of the binding energies using a numerical surface area model corrects this deficiency. This study illustrates the complex interplay between energy models, exploration of conformational space, and free energy estimators needed to obtain robust estimates from binding free energy calculations.
Collapse
Affiliation(s)
- Mauro Lapelosa
- BioMaPS Institute for Quantitative Biology and Department of Chemistry and Chemical Biology, Rutgers the State University of New Jersey, Piscataway, NJ 08854
| | | | | |
Collapse
|