1
|
Antalík A, Levy A, Kvedaravičiūtė S, Johnson SK, Carrasco-Busturia D, Raghavan B, Mouvet F, Acocella A, Das S, Gavini V, Mandelli D, Ippoliti E, Meloni S, Carloni P, Rothlisberger U, Olsen JMH. MiMiC: A high-performance framework for multiscale molecular dynamics simulations. J Chem Phys 2024; 161:022501. [PMID: 38990116 DOI: 10.1063/5.0211053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2024] [Accepted: 06/15/2024] [Indexed: 07/12/2024] Open
Abstract
MiMiC is a framework for performing multiscale simulations in which loosely coupled external programs describe individual subsystems at different resolutions and levels of theory. To make it highly efficient and flexible, we adopt an interoperable approach based on a multiple-program multiple-data (MPMD) paradigm, serving as an intermediary responsible for fast data exchange and interactions between the subsystems. The main goal of MiMiC is to avoid interfering with the underlying parallelization of the external programs, including the operability on hybrid architectures (e.g., CPU/GPU), and keep their setup and execution as close as possible to the original. At the moment, MiMiC offers an efficient implementation of electrostatic embedding quantum mechanics/molecular mechanics (QM/MM) that has demonstrated unprecedented parallel scaling in simulations of large biomolecules using CPMD and GROMACS as QM and MM engines, respectively. However, as it is designed for high flexibility with general multiscale models in mind, it can be straightforwardly extended beyond QM/MM. In this article, we illustrate the software design and the features of the framework, which make it a compelling choice for multiscale simulations in the upcoming era of exascale high-performance computing.
Collapse
Affiliation(s)
- Andrej Antalík
- Laboratory of Computational Chemistry and Biochemistry, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - Andrea Levy
- Laboratory of Computational Chemistry and Biochemistry, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - Sonata Kvedaravičiūtė
- DTU Chemistry, Technical University of Denmark (DTU), DK-2800 Kongens Lyngby, Denmark
| | - Sophia K Johnson
- Laboratory of Computational Chemistry and Biochemistry, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | | | - Bharath Raghavan
- Computational Biomedicine, Institute of Advanced Simulations IAS-5/Institute for Neuroscience and Medicine INM-9, Forschungszentrum Jülich GmbH, Jülich 52428, Germany
- Department of Physics, RWTH Aachen University, Aachen 52074, Germany
| | - François Mouvet
- Laboratory of Computational Chemistry and Biochemistry, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | | | - Sambit Das
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Vikram Gavini
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA
- Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Davide Mandelli
- Computational Biomedicine, Institute of Advanced Simulations IAS-5/Institute for Neuroscience and Medicine INM-9, Forschungszentrum Jülich GmbH, Jülich 52428, Germany
| | - Emiliano Ippoliti
- Computational Biomedicine, Institute of Advanced Simulations IAS-5/Institute for Neuroscience and Medicine INM-9, Forschungszentrum Jülich GmbH, Jülich 52428, Germany
| | - Simone Meloni
- Dipartimento di Scienze Chimiche, Farmaceutiche ed Agrarie (DOCPAS), Università degli Studi di Ferrara (Unife), I-44121 Ferrara, Italy
| | - Paolo Carloni
- Computational Biomedicine, Institute of Advanced Simulations IAS-5/Institute for Neuroscience and Medicine INM-9, Forschungszentrum Jülich GmbH, Jülich 52428, Germany
- Department of Physics, RWTH Aachen University, Aachen 52074, Germany
| | - Ursula Rothlisberger
- Laboratory of Computational Chemistry and Biochemistry, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | | |
Collapse
|
2
|
Carrasco-Busturia D, Ippoliti E, Meloni S, Rothlisberger U, Olsen JMH. Multiscale biomolecular simulations in the exascale era. Curr Opin Struct Biol 2024; 86:102821. [PMID: 38688076 DOI: 10.1016/j.sbi.2024.102821] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2024] [Revised: 04/03/2024] [Accepted: 04/04/2024] [Indexed: 05/02/2024]
Abstract
The complexity of biological systems and processes, spanning molecular to macroscopic scales, necessitates the use of multiscale simulations to get a comprehensive understanding. Quantum mechanics/molecular mechanics (QM/MM) molecular dynamics (MD) simulations are crucial for capturing processes beyond the reach of classical MD simulations. The advent of exascale computing offers unprecedented opportunities for scientific exploration, not least within life sciences, where simulations are essential to unravel intricate molecular mechanisms underlying biological processes. However, leveraging the immense computational power of exascale computing requires innovative algorithms and software designs. In this context, we discuss the current status and future prospects of multiscale biomolecular simulations on exascale supercomputers with a focus on QM/MM MD. We highlight our own efforts in developing a versatile and high-performance multiscale simulation framework with the aim of efficient utilization of state-of-the-art supercomputers. We showcase its application in uncovering complex biological mechanisms and its potential for leveraging exascale computing.
Collapse
Affiliation(s)
- David Carrasco-Busturia
- DTU Chemistry, Technical University of Denmark (DTU), Kongens Lyngby, DK-2800, Denmark. https://twitter.com/@DavidCdeB
| | - Emiliano Ippoliti
- Computational Biomedicine, Institute of Advanced Simulations IAS-5/Institute for Neuroscience and Medicine INM-9, Forschungszentrum Jülich GmbH, Jülich, DE-52428, Germany
| | - Simone Meloni
- Dipartimento di Scienze Chimiche, Farmaceutiche ed Agrarie (DOCPAS), Università degli Studi di Ferrara (Unife), Ferrara, I-44121, Italy. https://twitter.com/@smeloni99
| | - Ursula Rothlisberger
- Laboratory of Computational Chemistry and Biochemistry, Institute of Chemical Sciences and Engineering, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, CH-1015, Switzerland. https://twitter.com/@lcbc_epfl
| | | |
Collapse
|
3
|
Focke K, De Santis M, Wolter M, Martinez B JA, Vallet V, Pereira Gomes AS, Olejniczak M, Jacob CR. Interoperable workflows by exchanging grid-based data between quantum-chemical program packages. J Chem Phys 2024; 160:162503. [PMID: 38686818 DOI: 10.1063/5.0201701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2024] [Accepted: 04/02/2024] [Indexed: 05/02/2024] Open
Abstract
Quantum-chemical subsystem and embedding methods require complex workflows that may involve multiple quantum-chemical program packages. Moreover, such workflows require the exchange of voluminous data that go beyond simple quantities, such as molecular structures and energies. Here, we describe our approach for addressing this interoperability challenge by exchanging electron densities and embedding potentials as grid-based data. We describe the approach that we have implemented to this end in a dedicated code, PyEmbed, currently part of a Python scripting framework. We discuss how it has facilitated the development of quantum-chemical subsystem and embedding methods and highlight several applications that have been enabled by PyEmbed, including wave-function theory (WFT) in density-functional theory (DFT) embedding schemes mixing non-relativistic and relativistic electronic structure methods, real-time time-dependent DFT-in-DFT approaches, the density-based many-body expansion, and workflows including real-space data analysis and visualization. Our approach demonstrates, in particular, the merits of exchanging (complex) grid-based data and, in general, the potential of modular software development in quantum chemistry, which hinges upon libraries that facilitate interoperability.
Collapse
Affiliation(s)
- Kevin Focke
- Institute of Physical and Theoretical Chemistry, Technische Universität Braunschweig, Gaußstraße 17, 38106 Braunschweig, Germany
| | - Matteo De Santis
- CNRS, UMR 8523-PhLAM-Physique des Lasers Atomes et Molécules, Univ. Lille, F-59000 Lille, France
| | - Mario Wolter
- Institute of Physical and Theoretical Chemistry, Technische Universität Braunschweig, Gaußstraße 17, 38106 Braunschweig, Germany
| | - Jessica A Martinez B
- CNRS, UMR 8523-PhLAM-Physique des Lasers Atomes et Molécules, Univ. Lille, F-59000 Lille, France
- Department of Chemistry, Rutgers University, Newark, New Jersey 07102, USA
| | - Valérie Vallet
- CNRS, UMR 8523-PhLAM-Physique des Lasers Atomes et Molécules, Univ. Lille, F-59000 Lille, France
| | | | - Małgorzata Olejniczak
- Centre of New Technologies, University of Warsaw, S. Banacha 2c, 02-097 Warsaw, Poland
| | - Christoph R Jacob
- Institute of Physical and Theoretical Chemistry, Technische Universität Braunschweig, Gaußstraße 17, 38106 Braunschweig, Germany
| |
Collapse
|
4
|
Schöller A, Woodcock HL, Boresch S. Exploring Routes to Enhance the Calculation of Free Energy Differences via Non-Equilibrium Work SQM/MM Switching Simulations Using Hybrid Charge Intermediates between MM and SQM Levels of Theory or Non-Linear Switching Schemes. Molecules 2023; 28:4006. [PMID: 37241747 PMCID: PMC10222338 DOI: 10.3390/molecules28104006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Revised: 04/25/2023] [Accepted: 04/26/2023] [Indexed: 05/28/2023] Open
Abstract
Non-equilibrium work switching simulations and Jarzynski's equation are a reliable method for computing free energy differences, ΔAlow→high, between two levels of theory, such as a pure molecular mechanical (MM) and a quantum mechanical/molecular mechanical (QM/MM) description of a system of interest. Despite the inherent parallelism, the computational cost of this approach can quickly become very high. This is particularly true for systems where the core region, the part of the system to be described at different levels of theory, is embedded in an environment such as explicit solvent water. We find that even for relatively simple solute-water systems, switching lengths of at least 5 ps are necessary to compute ΔAlow→high reliably. In this study, we investigate two approaches towards an affordable protocol, with an emphasis on keeping the switching length well below 5 ps. Inserting a hybrid charge intermediate state with modified partial charges, which resembles the charge distribution of the desired high level, makes it possible to obtain reliable calculations with 2 ps switches. Attempts using step-wise linear switching paths, on the other hand, did not lead to improvement, i.e., a faster convergence for all systems. To understand these findings, we analyzed the solutes' properties as a function of the partial charges used and the number of water molecules in direct contact with the solute, and studied the time needed for water molecules to reorient themselves upon a change in the solute's charge distribution.
Collapse
Affiliation(s)
- Andreas Schöller
- Faculty of Chemistry, Department of Computational Biological Chemistry, University of Vienna, Währingerstr. 17, A-1090 Vienna, Austria
- Vienna Doctoral School in Chemistry (DoSChem), University of Vienna, Währingerstr. 42, A-1090 Vienna, Austria
| | - H. Lee Woodcock
- Department of Chemistry, University of South Florida, 4202 E. Fowler Ave., CHE205, Tampa, FL 33620-5250, USA;
| | - Stefan Boresch
- Faculty of Chemistry, Department of Computational Biological Chemistry, University of Vienna, Währingerstr. 17, A-1090 Vienna, Austria
| |
Collapse
|
5
|
Schöller A, Kearns F, Woodcock HL, Boresch S. Optimizing the Calculation of Free Energy Differences in Nonequilibrium Work SQM/MM Switching Simulations. J Phys Chem B 2022; 126:2798-2811. [PMID: 35404610 PMCID: PMC9036525 DOI: 10.1021/acs.jpcb.2c00696] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Revised: 03/24/2022] [Indexed: 11/27/2022]
Abstract
A key step during indirect alchemical free energy simulations using quantum mechanical/molecular mechanical (QM/MM) hybrid potential energy functions is the calculation of the free energy difference ΔAlow→high between the low level (e.g., pure MM) and the high level of theory (QM/MM). A reliable approach uses nonequilibrium work (NEW) switching simulations in combination with Jarzynski's equation; however, it is computationally expensive. In this study, we investigate whether it is more efficient to use more shorter switches or fewer but longer switches. We compare results obtained with various protocols to reference free energy differences calculated with Crooks' equation. The central finding is that fewer longer switches give better converged results. As few as 200 sufficiently long switches lead to ΔAlow→high values in good agreement with the reference results. This optimized protocol reduces the computational cost by a factor of 40 compared to earlier work. We also describe two tools/ways of analyzing the raw data to detect sources of poor convergence. Specifically, we find it helpful to analyze the raw data (work values from the NEW switching simulations) in a quasi-time series-like manner. Principal component analysis helps to detect cases where one or more conformational degrees of freedom are different at the low and high level of theory.
Collapse
Affiliation(s)
- Andreas Schöller
- Faculty
of Chemistry, Department of Computational Biological Chemistry, University of Vienna, Währingerstrasse 17, A-1090 Vienna, Austria
- Vienna
Doctoral School in Chemistry (DoSChem), University of Vienna, Währingerstrasse 42, A-1090 Vienna, Austria
| | - Fiona Kearns
- Department
of Chemistry, University of South Florida, 4202 E. Fowler Avenue, CHE205, Tampa, Florida 33620-5250, United States
| | - H. Lee Woodcock
- Department
of Chemistry, University of South Florida, 4202 E. Fowler Avenue, CHE205, Tampa, Florida 33620-5250, United States
| | - Stefan Boresch
- Faculty
of Chemistry, Department of Computational Biological Chemistry, University of Vienna, Währingerstrasse 17, A-1090 Vienna, Austria
| |
Collapse
|
6
|
König G, Ries B, Hünenberger PH, Riniker S. Efficient Alchemical Intermediate States in Free Energy Calculations Using λ-Enveloping Distribution Sampling. J Chem Theory Comput 2021; 17:5805-5815. [PMID: 34476947 DOI: 10.1021/acs.jctc.1c00418] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Alchemical free energy calculations generally require intermediate states along a coupling parameter λ to establish sufficient phase space overlap for obtaining converged results. Such intermediate states can also be engineered to lower the energy barriers and, consequently, reduce the required sampling time. The recently introduced λ-enveloping distribution sampling (λ-EDS) scheme combines the properties of the minimum variance pathway and the EDS methods to improve sampling and allow for larger steps along the alchemical pathway compared to conventional approaches. This scheme also eliminates the need for soft-core potentials and retains the behavior of conventional λ-intermediate states as a limiting case. In this study, an automated procedure is developed to select the parameters of λ-EDS for optimal performance. The underlying theory is illustrated based on simulations of simple test systems (bond length changes in harmonic oscillators, mutations of dihedral angles, and charge creation in water), as well as on the calculation of the absolute hydration free energies of 12 small organic molecules.
Collapse
Affiliation(s)
- Gerhard König
- Laboratory of Physical Chemistry, ETH Zürich, Vladimir-Prelog-Weg 2, 8093 Zürich, Switzerland.,Centre for Enzyme Innovation, University of Portsmouth, St. Michael's Building, PO1 2DT Portsmouth, U.K
| | - Benjamin Ries
- Laboratory of Physical Chemistry, ETH Zürich, Vladimir-Prelog-Weg 2, 8093 Zürich, Switzerland
| | - Philippe H Hünenberger
- Laboratory of Physical Chemistry, ETH Zürich, Vladimir-Prelog-Weg 2, 8093 Zürich, Switzerland
| | - Sereina Riniker
- Laboratory of Physical Chemistry, ETH Zürich, Vladimir-Prelog-Weg 2, 8093 Zürich, Switzerland
| |
Collapse
|
7
|
König G, Glaser N, Schroeder B, Kubincová A, Hünenberger PH, Riniker S. An Alternative to Conventional λ-Intermediate States in Alchemical Free Energy Calculations: λ-Enveloping Distribution Sampling. J Chem Inf Model 2020; 60:5407-5423. [PMID: 32794763 DOI: 10.1021/acs.jcim.0c00520] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Alchemical free energy calculations typically rely on intermediate states to bridge between the relevant phase spaces of the two end states. These intermediate states are usually created by mixing the energies or parameters of the end states according to a coupling parameter λ. The choice of the procedure has a strong impact on the efficiency of the calculation, as it affects both the encountered energy barriers and the phase space overlap between the states. The present work builds on the connection between the minimum variance pathway (MVP) and enveloping distribution sampling (EDS). It is shown that both methods can be regarded as special cases of a common scheme referred to as λ-EDS, which can also reproduce the behavior of conventional λ-intermediate states. A particularly attractive feature of λ-EDS is its ability to emulate the use of soft core potentials (SCP) while avoiding the associated computational overhead when applying efficient free energy estimators such as the multistate Bennett's acceptance ratio (MBAR). The method is illustrated for both relative and absolute free energy calculations considering five benchmark systems. The first two systems (charge inversion and cavity creation in a dipolar solvent) demonstrate the use of λ-EDS as an alternative coupling scheme in the context of thermodynamic integration (TI). The three other systems (change of bond length, change of dihedral angles, and cavity creation in water) investigate the efficiency and optimal choice of parameters in the context of free energy perturbation (FEP) and Bennett's acceptance ratio (BAR). It is shown that λ-EDS allows larger steps along the alchemical pathway than conventional intermediate states.
Collapse
Affiliation(s)
- Gerhard König
- Laboratory of Physical Chemistry, Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir-Prelog-Weg 2, 8093 Zürich, Switzerland
| | - Nina Glaser
- Laboratory of Physical Chemistry, Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir-Prelog-Weg 2, 8093 Zürich, Switzerland
| | - Benjamin Schroeder
- Laboratory of Physical Chemistry, Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir-Prelog-Weg 2, 8093 Zürich, Switzerland
| | - Alžbeta Kubincová
- 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
| | - Sereina Riniker
- Laboratory of Physical Chemistry, Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir-Prelog-Weg 2, 8093 Zürich, Switzerland
| |
Collapse
|
8
|
Hudson PS, Woodcock HL, Boresch S. Use of Interaction Energies in QM/MM Free Energy Simulations. J Chem Theory Comput 2019; 15:4632-4645. [PMID: 31142113 DOI: 10.1021/acs.jctc.9b00084] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The use of the most accurate (i.e., QM or QM/MM) levels of theory for free energy simulations (FES) is typically not possible. Primarily, this is because the computational cost associated with the extensive configurational sampling needed for converging FES is prohibitive. To ensure the feasibility of QM-based FES, the "indirect" approach is generally taken, necessitating a free energy calculation between the MM and QM/MM potential energy surfaces. Ideally, this step is performed with standard free energy perturbation (Zwanzig's equation) as it only requires simulations be carried out at the low level of theory; however, work from several groups over the past few years has conclusively shown that Zwanzig's equation is ill-suited to this task. As such, many approximations have arisen to mitigate difficulties with Zwanzig's equation. One particularly popular notion is that the convergence of Zwanzig's equation can be improved by using interaction energy differences instead of total energy differences. Although problematic numerical fluctuations (a major problem when using Zwanzig's equation) are indeed reduced, our results and analysis demonstrate that this "interaction energy approximation" (IEA) is theoretically incorrect, and the implicit approximation invoked is spurious at best. Herein, we demonstrate this via solvation free energy calculations using IEA from two different low levels of theory to the same target high level. Results from this proof-of-concept consistently yield the wrong results, deviating by ∼1.5 kcal/mol from the rigorously obtained value.
Collapse
Affiliation(s)
- Phillip S Hudson
- Department of Chemistry , University of South Florida , 4202 East Fowler Avenue, CHE205 , Tampa , Florida 33620-5250 , United States.,Laboratory of Computational Biology , National Institutes of Health, National Heart, Lung and Blood Institute , 12 South Drive, Rm 3053 , Bethesda , Maryland 20892-5690 , United States
| | - H Lee Woodcock
- Department of Chemistry , University of South Florida , 4202 East Fowler Avenue, CHE205 , Tampa , Florida 33620-5250 , United States
| | - Stefan Boresch
- Faculty of Chemistry, Department of Computational Biological Chemistry , University of Vienna , Währingerstraße 17 , Vienna A-1090 , Austria
| |
Collapse
|
9
|
Kearns FL, Warrensford L, Boresch S, Woodcock HL. The Good, the Bad, and the Ugly: "HiPen", a New Dataset for Validating (S)QM/MM Free Energy Simulations. Molecules 2019; 24:E681. [PMID: 30769826 PMCID: PMC6413162 DOI: 10.3390/molecules24040681] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2018] [Revised: 01/28/2019] [Accepted: 01/29/2019] [Indexed: 11/25/2022] Open
Abstract
Indirect (S)QM/MM free energy simulations (FES) are vital to efficiently incorporating sufficient sampling and accurate (QM) energetic evaluations when estimating free energies of practical/experimental interest. Connecting between levels of theory, i.e., calculating Δ A l o w → h i g h , remains to be the most challenging step within an indirect FES protocol. To improve calculations of Δ A l o w → h i g h , we must: (1) compare the performance of all FES methods currently available; and (2) compile and maintain datasets of Δ A l o w → h i g h calculated for a wide-variety of molecules so that future practitioners may replicate or improve upon the current state-of-the-art. Towards these two aims, we introduce a new dataset, "HiPen", which tabulates Δ A g a s M M → 3 o b (the free energy associated with switching from an M M to an S C C - D F T B molecular description using the 3ob parameter set in gas phase), calculated for 22 drug-like small molecules. We compare the calculation of this value using free energy perturbation, Bennett's acceptance ratio, Jarzynski's equation, and Crooks' equation. We also predict the reliability of each calculated Δ A g a s M M → 3 o b by evaluating several convergence criteria including sample size hysteresis, overlap statistics, and bias metric ( Π ). Within the total dataset, three distinct categories of molecules emerge: the "good" molecules, for which we can obtain converged Δ A g a s M M → 3 o b using Jarzynski's equation; "bad" molecules which require Crooks' equation to obtain a converged Δ A g a s M M → 3 o b ; and "ugly" molecules for which we cannot obtain reliably converged Δ A g a s M M → 3 o b with either Jarzynski's or Crooks' equations. We discuss, in depth, results from several example molecules in each of these categories and describe how dihedral discrepancies between levels of theory cause convergence failures even for these gas phase free energy simulations.
Collapse
Affiliation(s)
- Fiona L Kearns
- Department of Chemistry, University of South Florida, 4202 E. Fowler Avenue, Tampa, FL 33620, USA.
| | - Luke Warrensford
- Department of Chemistry, University of South Florida, 4202 E. Fowler Avenue, Tampa, FL 33620, USA.
| | - Stefan Boresch
- Department of Computational Biological Chemistry, Faculty of Chemistry, University of Vienna, Waehringerstrasse 17, A-1090 Vienna, Austria.
| | - H Lee Woodcock
- Department of Chemistry, University of South Florida, 4202 E. Fowler Avenue, Tampa, FL 33620, USA.
| |
Collapse
|
10
|
Duster AW, Garza CM, Aydintug BO, Negussie MB, Lin H. Adaptive Partitioning QM/MM for Molecular Dynamics Simulations: 6. Proton Transport through a Biological Channel. J Chem Theory Comput 2019; 15:892-905. [DOI: 10.1021/acs.jctc.8b01128] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Adam W. Duster
- Chemistry Department, CB 194, University of Colorado, Denver, Colorado 80217, United States
| | - Christina M. Garza
- Chemistry Department, CB 194, University of Colorado, Denver, Colorado 80217, United States
| | - Baris O. Aydintug
- Chemistry Department, CB 194, University of Colorado, Denver, Colorado 80217, United States
| | - Mikias B. Negussie
- Chemistry Department, CB 194, University of Colorado, Denver, Colorado 80217, United States
| | - Hai Lin
- Chemistry Department, CB 194, University of Colorado, Denver, Colorado 80217, United States
| |
Collapse
|
11
|
Hudson PS, Boresch S, Rogers DM, Woodcock HL. Accelerating QM/MM Free Energy Computations via Intramolecular Force Matching. J Chem Theory Comput 2018; 14:6327-6335. [PMID: 30300543 PMCID: PMC6314469 DOI: 10.1021/acs.jctc.8b00517] [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: 11/30/2022]
Abstract
The calculation of free energy differences between levels of theory has numerous potential pitfalls. Chief among them is the lack of overlap, i.e., ensembles generated at one level of theory (e.g., "low") not being good approximations of ensembles at the other (e.g., "high"). Numerous strategies have been devised to mitigate this issue. However, the most straightforward approach is to ensure that the "low" level ensemble more closely resembles that of the "high". Ideally, this is done without increasing computational cost. Herein, we demonstrate that by reparametrizing classical intramolecular potentials to reproduce high level forces (i.e., force matching) configurational overlap between a "low" (i.e., classical) and "high" (i.e., quantum) level can be significantly improved. This procedure is validated on two test cases and results in vastly improved convergence of free energy simulations.
Collapse
Affiliation(s)
- Phillip S Hudson
- Department of Chemistry , University of South Florida , 4202 East Fowler Avenue, CHE205 , Tampa , Florida 33620-5250 , United States
- Laboratory of Computational Biology , National Institutes of Health, National Heart, Lung and Blood Institute , 12 South Drive Rm 3053 , Bethesda , Maryland 20892-5690 , United States
| | - Stefan Boresch
- Faculty of Chemistry, Department of Computational Biological Chemistry , University of Vienna , Währingerstraße 17 , A-1090 Vienna , Austria
| | - David M Rogers
- Department of Chemistry , University of South Florida , 4202 East Fowler Avenue, CHE205 , Tampa , Florida 33620-5250 , United States
| | - H Lee Woodcock
- Department of Chemistry , University of South Florida , 4202 East Fowler Avenue, CHE205 , Tampa , Florida 33620-5250 , United States
| |
Collapse
|
12
|
Rackers JA, Wang Z, Lu C, Laury ML, Lagardère L, Schnieders MJ, Piquemal JP, Ren P, Ponder JW. Tinker 8: Software Tools for Molecular Design. J Chem Theory Comput 2018; 14:5273-5289. [PMID: 30176213 PMCID: PMC6335969 DOI: 10.1021/acs.jctc.8b00529] [Citation(s) in RCA: 290] [Impact Index Per Article: 48.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The Tinker software, currently released as version 8, is a modular molecular mechanics and dynamics package written primarily in a standard, easily portable dialect of Fortran 95 with OpenMP extensions. It supports a wide variety of force fields, including polarizable models such as the Atomic Multipole Optimized Energetics for Biomolecular Applications (AMOEBA) force field. The package runs on Linux, macOS, and Windows systems. In addition to canonical Tinker, there are branches, Tinker-HP and Tinker-OpenMM, designed for use on message passing interface (MPI) parallel distributed memory supercomputers and state-of-the-art graphical processing units (GPUs), respectively. The Tinker suite also includes a tightly integrated Java-based graphical user interface called Force Field Explorer (FFE), which provides molecular visualization capabilities as well as the ability to launch and control Tinker calculations.
Collapse
Affiliation(s)
- Joshua A. Rackers
- Program in Computational & Molecular Biophysics, Washington University School of Medicine, Saint Louis, Missouri 63110, United States
| | - Zhi Wang
- Department of Chemistry, Washington University in Saint Louis, Saint Louis, Missouri 63130, United States
| | - Chao Lu
- Department of Chemistry, Washington University in Saint Louis, Saint Louis, Missouri 63130, United States
| | - Marie L. Laury
- Department of Chemistry, Washington University in Saint Louis, Saint Louis, Missouri 63130, United States
| | - Louis Lagardère
- Laboratoire de Chimie Théorique, Sorbonne Universités, UPMC Paris 06, UMR 7616, case courrier 137, 4 place Jussieu, F-75005, Paris, France
| | - Michael J. Schnieders
- Department of Biomedical Engineering, The University of Iowa, Iowa City, IA 52242, United States
| | - Jean-Philip Piquemal
- Laboratoire de Chimie Théorique, Sorbonne Universités, UPMC Paris 06, UMR 7616, case courrier 137, 4 place Jussieu, F-75005, Paris, France
| | - Pengyu Ren
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Jay W. Ponder
- Program in Computational & Molecular Biophysics, Washington University School of Medicine, Saint Louis, Missouri 63110, United States
- Department of Chemistry, Washington University in Saint Louis, Saint Louis, Missouri 63130, United States
| |
Collapse
|
13
|
Duster AW, Wang CH, Lin H. Adaptive QM/MM for Molecular Dynamics Simulations: 5. On the Energy-Conserved Permuted Adaptive-Partitioning Schemes. Molecules 2018; 23:E2170. [PMID: 30154373 PMCID: PMC6225285 DOI: 10.3390/molecules23092170] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Revised: 08/23/2018] [Accepted: 08/24/2018] [Indexed: 11/16/2022] Open
Abstract
In combined quantum-mechanical/molecular-mechanical (QM/MM) dynamics simulations, the adaptive-partitioning (AP) schemes reclassify atoms on-the-fly as QM or MM in a smooth manner. This yields a mobile QM subsystem with contents that are continuously updated as needed. Here, we tailor the Hamiltonian adaptive many-body correction (HAMBC) proposed by Boreboom et al. [J. Chem. Theory Comput.2016, 12, 3441] to the permuted AP (PAP) scheme. The treatments lead to the HAMBC-PAP method (HPAP), which both conserves energy and produces accurate solvation structures in the test of "water-in-water" model system.
Collapse
Affiliation(s)
- Adam W Duster
- Department of Chemistry, University of Colorado Denver, Denver, CO 80217, USA.
| | - Chun-Hung Wang
- Department of Chemistry, University of Colorado Denver, Denver, CO 80217, USA.
| | - Hai Lin
- Department of Chemistry, University of Colorado Denver, Denver, CO 80217, USA.
| |
Collapse
|
14
|
Multiscale simulation on shearing transitions of thin-film lubrication with multi-layer molecules. Chem Phys Lett 2017. [DOI: 10.1016/j.cplett.2017.04.079] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
|
15
|
Duster AW, Wang C, Garza CM, Miller DE, Lin H. Adaptive quantum/molecular mechanics: what have we learned, where are we, and where do we go from here? WILEY INTERDISCIPLINARY REVIEWS-COMPUTATIONAL MOLECULAR SCIENCE 2017. [DOI: 10.1002/wcms.1310] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Affiliation(s)
- Adam W. Duster
- Chemistry Department University of Colorado Denver Denver CO USA
| | - Chun‐Hung Wang
- Chemistry Department University of Colorado Denver Denver CO USA
| | | | | | - Hai Lin
- Chemistry Department University of Colorado Denver Denver CO USA
| |
Collapse
|
16
|
Kearns FL, Hudson PS, Woodcock HL, Boresch S. Computing converged free energy differences between levels of theory via nonequilibrium work methods: Challenges and opportunities. J Comput Chem 2017; 38:1376-1388. [PMID: 28272811 DOI: 10.1002/jcc.24706] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Accepted: 10/29/2016] [Indexed: 01/09/2023]
Abstract
We demonstrate that Jarzynski's equation can be used to reliably compute free energy differences between low and high level representations of systems. The need for such a calculation arises when employing the so-called "indirect" approach to free energy simulations with mixed quantum mechanical/molecular mechanical (QM/MM) Hamiltonians; a popular technique for circumventing extensive simulations involving quantum chemical computations. We have applied this methodology to several small and medium sized organic molecules, both in the gas phase and explicit solvent. Test cases include several systems for which the standard approach; that is, free energy perturbation between low and high level description, fails to converge. Finally, we identify three major areas in which the difference between low and high level representations make the calculation of ΔAlow→high difficult: bond stretching and angle bending, different preferred conformations, and the response of the MM region to the charge distribution of the QM region. © 2016 Wiley Periodicals, Inc.
Collapse
Affiliation(s)
- Fiona L Kearns
- Department of Chemistry, University of South Florida, 4202 E. Fowler Ave, CHE205, Tampa, Florida, 33620-5250
| | - Phillip S Hudson
- Department of Chemistry, University of South Florida, 4202 E. Fowler Ave, CHE205, Tampa, Florida, 33620-5250
| | - Henry L Woodcock
- Department of Chemistry, University of South Florida, 4202 E. Fowler Ave, CHE205, Tampa, Florida, 33620-5250
| | - Stefan Boresch
- Faculty of Chemistry, Department of Computational Biological Chemistry, University of Vienna, Währingerstraße 17, Vienna, A-1090, Austria
| |
Collapse
|
17
|
Xu Y, Villa A, Nilsson L. The free energy of locking a ring: Changing a deoxyribonucleoside to a locked nucleic acid. J Comput Chem 2017; 38:1147-1157. [PMID: 28101966 PMCID: PMC5434909 DOI: 10.1002/jcc.24692] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Revised: 11/01/2016] [Accepted: 11/08/2016] [Indexed: 01/09/2023]
Abstract
Locked nucleic acid (LNA), a modified nucleoside which contains a bridging group across the ribose ring, improves the stability of DNA/RNA duplexes significantly, and therefore is of interest in biotechnology and gene therapy applications. In this study, we investigate the free energy change between LNA and DNA nucleosides. The transformation requires the breaking of the bridging group across the ribose ring, a problematic transformation in free energy calculations. To address this, we have developed a 3-step (easy to implement) and a 1-step protocol (more efficient, but more complicated to setup), for single and dual topologies in classical molecular dynamics simulations, using the Bennett Acceptance Ratio method to calculate the free energy. We validate the approach on the solvation free energy difference for the nucleosides thymidine, cytosine, and 5-methyl-cytosine. © 2017 The Authors. Journal of Computational Chemistry Published by Wiley Periodicals, Inc.
Collapse
Affiliation(s)
- You Xu
- Department of Biosciences and Nutrition, Karolinska Institutet, Huddinge, SE-141 83, Sweden
| | - Alessandra Villa
- Department of Biosciences and Nutrition, Karolinska Institutet, Huddinge, SE-141 83, Sweden
| | - Lennart Nilsson
- Department of Biosciences and Nutrition, Karolinska Institutet, Huddinge, SE-141 83, Sweden
| |
Collapse
|
18
|
Kearns FL, Hudson PS, Boresch S, Woodcock HL. Methods for Efficiently and Accurately Computing Quantum Mechanical Free Energies for Enzyme Catalysis. Methods Enzymol 2016; 577:75-104. [PMID: 27498635 DOI: 10.1016/bs.mie.2016.05.053] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Enzyme activity is inherently linked to free energies of transition states, ligand binding, protonation/deprotonation, etc.; these free energies, and thus enzyme function, can be affected by residue mutations, allosterically induced conformational changes, and much more. Therefore, being able to predict free energies associated with enzymatic processes is critical to understanding and predicting their function. Free energy simulation (FES) has historically been a computational challenge as it requires both the accurate description of inter- and intramolecular interactions and adequate sampling of all relevant conformational degrees of freedom. The hybrid quantum mechanical molecular mechanical (QM/MM) framework is the current tool of choice when accurate computations of macromolecular systems are essential. Unfortunately, robust and efficient approaches that employ the high levels of computational theory needed to accurately describe many reactive processes (ie, ab initio, DFT), while also including explicit solvation effects and accounting for extensive conformational sampling are essentially nonexistent. In this chapter, we will give a brief overview of two recently developed methods that mitigate several major challenges associated with QM/MM FES: the QM non-Boltzmann Bennett's acceptance ratio method and the QM nonequilibrium work method. We will also describe usage of these methods to calculate free energies associated with (1) relative properties and (2) along reaction paths, using simple test cases with relevance to enzymes examples.
Collapse
Affiliation(s)
- F L Kearns
- University of South Florida, Tampa, FL, United States
| | - P S Hudson
- University of South Florida, Tampa, FL, United States
| | - S Boresch
- Faculty of Chemistry, University of Vienna, Vienna, Austria.
| | - H L Woodcock
- University of South Florida, Tampa, FL, United States.
| |
Collapse
|
19
|
Kratz EG, Walker AR, Lagardère L, Lipparini F, Piquemal JP, Cisneros GA. LICHEM: A QM/MM program for simulations with multipolar and polarizable force fields. J Comput Chem 2016; 37:1019-29. [PMID: 26781073 PMCID: PMC4808410 DOI: 10.1002/jcc.24295] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2015] [Revised: 09/21/2015] [Accepted: 12/17/2015] [Indexed: 12/23/2022]
Abstract
We introduce an initial implementation of the LICHEM software package. LICHEM can interface with Gaussian, PSI4, NWChem, TINKER, and TINKER-HP to enable QM/MM calculations using multipolar/polarizable force fields. LICHEM extracts forces and energies from unmodified QM and MM software packages to perform geometry optimizations, single-point energy calculations, or Monte Carlo simulations. When the QM and MM regions are connected by covalent bonds, the pseudo-bond approach is employed to smoothly transition between the QM region and the polarizable force field. A series of water clusters and small peptides have been employed to test our initial implementation. The results obtained from these test systems show the capabilities of the new software and highlight the importance of including explicit polarization. © 2016 Wiley Periodicals, Inc.
Collapse
|
20
|
Dybeck EC, König G, Brooks BR, Shirts MR. Comparison of Methods To Reweight from Classical Molecular Simulations to QM/MM Potentials. J Chem Theory Comput 2016; 12:1466-80. [PMID: 26928941 PMCID: PMC6497519 DOI: 10.1021/acs.jctc.5b01188] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
We examine methods to reweight classical molecular mechanics solvation calculations to more expensive QM/MM energy functions. We first consider the solvation free energy difference between ethane and methanol in a QM/MM Hamiltonian from configurations generated in a cheaper MM potential. The solute molecules in the QM/MM Hamiltonian are treated with B3LYP/6-31G*, and the solvent water molecules are treated classically. The free energy difference in the QM/MM Hamiltonian is estimated using Boltzmann reweighting with both the non-Boltzmann Bennett method (NBB) and the multistate Bennett acceptance ratio (MBAR), and the variance of each method is directly compared for an identical data set. For this system, MBAR-derived methods are found to produce smaller overall uncertainties than NBB-based methods. Additionally, we show that to reduce the variance in the overall free energy difference estimate in this system for a fixed amount of QM/MM calculations, the energy re-evaluations in the Boltzmann reweighting step should be concentrated on the physical MM states with the highest overlap to the QM/MM states, rather than allocated equally over all sampled MM states. We also show that reallocating the QM/MM re-evaluations can be used to diagnose poor overlap between the sampled and target state. The solvation free energies for molecules in the SAMPL4 solvation data set are also calculated in the QM/MM Hamiltonian with NBB and MBAR, and the variances are marginally smaller for MBAR. Overall, NBB and MBAR produce similar variances for systems with poor sampling efficiency, and MBAR provides smaller variances than NBB in systems with high sampling efficiency. Both NBB and MBAR converge to identical solvation free energy estimates in the QM/MM Hamiltonian, and the RMSD to experimental values for molecules in the SAMPL4 solvation data set decreases by approximately 28% when switching from the MM Hamiltonian to the QM/MM Hamiltonian.
Collapse
Affiliation(s)
- Eric C Dybeck
- Department of Chemical Engineering, University of Virginia , Charlottesville, Virginia 22904, United States
| | - Gerhard König
- Laboratory of Computational Biology, National Heart, Lung and Blood Institute, National Institutes of Health , 5635 Fishers Lane, T-900 Suite, Rockville, Maryland 20852, United States
| | - Bernard R Brooks
- Laboratory of Computational Biology, National Heart, Lung and Blood Institute, National Institutes of Health , 5635 Fishers Lane, T-900 Suite, Rockville, Maryland 20852, United States
| | - Michael R Shirts
- Department of Chemical Engineering, University of Virginia , Charlottesville, Virginia 22904, United States
- Department of Chemical and Biological Engineering, University of Colorado Boulder , Boulder, Colorado 80309, United States
| |
Collapse
|
21
|
Hudson PS, Woodcock HL, Boresch S. Use of Nonequilibrium Work Methods to Compute Free Energy Differences Between Molecular Mechanical and Quantum Mechanical Representations of Molecular Systems. J Phys Chem Lett 2015; 6:4850-4856. [PMID: 26539729 DOI: 10.1021/acs.jpclett.5b02164] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Carrying out free energy simulations (FES) using quantum mechanical (QM) Hamiltonians remains an attractive, albeit elusive goal. Renewed efforts in this area have focused on using "indirect" thermodynamic cycles to connect "low level" simulation results to "high level" free energies. The main obstacle to computing converged free energy results between molecular mechanical (MM) and QM (ΔA(MM→QM)), as recently demonstrated by us and others, is differences in the so-called "stiff" degrees of freedom (e.g., bond stretching) between the respective energy surfaces. Herein, we demonstrate that this problem can be efficiently circumvented using nonequilibrium work (NEW) techniques, i.e., Jarzynski's and Crooks' equations. Initial applications of computing ΔA(NEW)(MM→QM), for blocked amino acids alanine and serine as well as to generate butane's potentials of mean force via the indirect QM/MM FES method, showed marked improvement over traditional FES approaches.
Collapse
Affiliation(s)
- Phillip S Hudson
- Department of Chemistry, University of South Florida , 4202 East Fowler Avenue, CHE205, Tampa, Florida 33620-5250, United States
| | - H Lee Woodcock
- Department of Chemistry, University of South Florida , 4202 East Fowler Avenue, CHE205, Tampa, Florida 33620-5250, United States
| | - Stefan Boresch
- Department of Computational Biological Chemistry, Faculty of Chemistry, University of Vienna , Währingerstraße 17, A-1090 Vienna, Austria
| |
Collapse
|
22
|
Konc J, Miller BT, Štular T, Lešnik S, Woodcock HL, Brooks BR, Janežič D. ProBiS-CHARMMing: Web Interface for Prediction and Optimization of Ligands in Protein Binding Sites. J Chem Inf Model 2015; 55:2308-14. [DOI: 10.1021/acs.jcim.5b00534] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Janez Konc
- Laboratory
for Molecular Modeling, National Institute of Chemistry, Hajdrihova
19, SI-1000, Ljubljana, Slovenia
- Faculty
of Mathematics, Natural Sciences and Information Technologies, University of Primorska, Glagoljaška 8, SI-6000, Koper, Slovenia
| | - Benjamin T. Miller
- Laboratory
of Computational Biology, Biochemistry and Biophysics Center, National
Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Tanja Štular
- Faculty
of Mathematics, Natural Sciences and Information Technologies, University of Primorska, Glagoljaška 8, SI-6000, Koper, Slovenia
| | - Samo Lešnik
- Laboratory
for Molecular Modeling, National Institute of Chemistry, Hajdrihova
19, SI-1000, Ljubljana, Slovenia
| | - H. Lee Woodcock
- Department
of Chemistry, University of South Florida, 4202 East Fowler Ave., Tampa, Florida 33620, United States
| | - Bernard R. Brooks
- Laboratory
of Computational Biology, Biochemistry and Biophysics Center, National
Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Dušanka Janežič
- Faculty
of Mathematics, Natural Sciences and Information Technologies, University of Primorska, Glagoljaška 8, SI-6000, Koper, Slovenia
| |
Collapse
|
23
|
Lee J, Miller BT, Brooks BR. Computational scheme for pH-dependent binding free energy calculation with explicit solvent. Protein Sci 2015; 25:231-43. [PMID: 26189656 PMCID: PMC4815317 DOI: 10.1002/pro.2755] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Accepted: 07/16/2015] [Indexed: 01/25/2023]
Abstract
We present a computational scheme to compute the pH‐dependence of binding free energy with explicit solvent. Despite the importance of pH, the effect of pH has been generally neglected in binding free energy calculations because of a lack of accurate methods to model it. To address this limitation, we use a constant‐pH methodology to obtain a true ensemble of multiple protonation states of a titratable system at a given pH and analyze the ensemble using the Bennett acceptance ratio (BAR) method. The constant pH method is based on the combination of enveloping distribution sampling (EDS) with the Hamiltonian replica exchange method (HREM), which yields an accurate semi‐grand canonical ensemble of a titratable system. By considering the free energy change of constraining multiple protonation states to a single state or releasing a single protonation state to multiple states, the pH dependent binding free energy profile can be obtained. We perform benchmark simulations of a host‐guest system: cucurbit[7]uril (CB[7]) and benzimidazole (BZ). BZ experiences a large pKa shift upon complex formation. The pH‐dependent binding free energy profiles of the benchmark system are obtained with three different long‐range interaction calculation schemes: a cutoff, the particle mesh Ewald (PME), and the isotropic periodic sum (IPS) method. Our scheme captures the pH‐dependent behavior of binding free energy successfully. Absolute binding free energy values obtained with the PME and IPS methods are consistent, while cutoff method results are off by 2 kcal mol−1. We also discuss the characteristics of three long‐range interaction calculation methods for constant‐pH simulations.
Collapse
Affiliation(s)
- Juyong Lee
- Laboratory of Computational Biology, National Heart, Lung, and Blood Institute (NHLBI), National Institutes of Health (NIH), Bethesda, Maryland, 20892
| | - Benjamin T Miller
- Laboratory of Computational Biology, National Heart, Lung, and Blood Institute (NHLBI), National Institutes of Health (NIH), Bethesda, Maryland, 20892
| | - Bernard R Brooks
- Laboratory of Computational Biology, National Heart, Lung, and Blood Institute (NHLBI), National Institutes of Health (NIH), Bethesda, Maryland, 20892
| |
Collapse
|
24
|
Tan ML, Miller BT, Te J, Cendagorta JR, Brooks BR, Ichiye T. Hydrophobic hydration and the anomalous partial molar volumes in ethanol-water mixtures. J Chem Phys 2015; 142:064501. [PMID: 25681917 DOI: 10.1063/1.4906750] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The anomalous behavior in the partial molar volumes of ethanol-water mixtures at low concentrations of ethanol is studied using molecular dynamics simulations. Previous work indicates that the striking minimum in the partial molar volume of ethanol VE as a function of ethanol mole fraction XE is determined mainly by water-water interactions. These results were based on simulations that used one water model for the solute-water interactions but two different water models for the water-water interactions. This is confirmed here by using two more water models for the water-water interactions. Furthermore, the previous work indicates that the initial decrease is caused by association of the hydration shells of the hydrocarbon tails, and the minimum occurs at the concentration where all of the hydration shells are touching each other. Thus, the characteristics of the hydration of the tail that cause the decrease and the features of the water models that reproduce this type of hydration are also examined here. The results show that a single-site multipole water model with a charge distribution that mimics the large quadrupole and the p-orbital type electron density out of the molecular plane has "brittle" hydration with hydrogen bonds that break as the tails touch, which reproduces the deep minimum. However, water models with more typical site representations with partial charges lead to flexible hydration that tends to stay intact, which produces a shallow minimum. Thus, brittle hydration may play an essential role in hydrophobic association in water.
Collapse
Affiliation(s)
- Ming-Liang Tan
- Department of Chemistry, Georgetown University, Washington, District of Columbia 20057, USA
| | - Benjamin T Miller
- Laboratory of Computational Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Rockville, Maryland 20892, USA
| | - Jerez Te
- Department of Chemistry, Georgetown University, Washington, District of Columbia 20057, USA
| | - Joseph R Cendagorta
- Department of Chemistry, Georgetown University, Washington, District of Columbia 20057, USA
| | - Bernard R Brooks
- Laboratory of Computational Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Rockville, Maryland 20892, USA
| | - Toshiko Ichiye
- Department of Chemistry, Georgetown University, Washington, District of Columbia 20057, USA
| |
Collapse
|
25
|
Lee J, Miller BT, Damjanović A, Brooks BR. Enhancing constant-pH simulation in explicit solvent with a two-dimensional replica exchange method. J Chem Theory Comput 2015; 11:2560-74. [PMID: 26575555 DOI: 10.1021/ct501101f] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
We present a new method for enhanced sampling for constant-pH simulations in explicit water based on a two-dimensional (2D) replica exchange scheme. The new method is a significant extension of our previously developed constant-pH simulation method, which is based on enveloping distribution sampling (EDS) coupled with a one-dimensional (1D) Hamiltonian exchange method (HREM). EDS constructs a hybrid Hamiltonian from multiple discrete end state Hamiltonians that, in this case, represent different protonation states of the system. The ruggedness and heights of the hybrid Hamiltonian's energy barriers can be tuned by the smoothness parameter. Within the context of the 1D EDS-HREM method, exchanges are performed between replicas with different smoothness parameters, allowing frequent protonation-state transitions and sampling of conformations that are favored by the end-state Hamiltonians. In this work, the 1D method is extended to 2D with an additional dimension, external pH. Within the context of the 2D method (2D EDS-HREM), exchanges are performed on a lattice of Hamiltonians with different pH conditions and smoothness parameters. We demonstrate that both the 1D and 2D methods exactly reproduce the thermodynamic properties of the semigrand canonical (SGC) ensemble of a system at a given pH. We have tested our new 2D method on aspartic acid, glutamic acid, lysine, a four residue peptide (sequence KAAE), and snake cardiotoxin. In all cases, the 2D method converges faster and without loss of precision; the only limitation is a loss of flexibility in how CPU time is employed. The results for snake cardiotoxin demonstrate that the 2D method enhances protonation-state transitions, samples a wider conformational space with the same amount of computational resources, and converges significantly faster overall than the original 1D method.
Collapse
Affiliation(s)
- Juyong Lee
- Laboratory of Computational Biology, National Heart, Lung, and Blood Institute, National Institutes of Health , Bethesda, Maryland 20892, United States
| | - Benjamin T Miller
- Laboratory of Computational Biology, National Heart, Lung, and Blood Institute, National Institutes of Health , Bethesda, Maryland 20892, United States
| | - Ana Damjanović
- Laboratory of Computational Biology, National Heart, Lung, and Blood Institute, National Institutes of Health , Bethesda, Maryland 20892, United States.,Department of Biophysics, Johns Hopkins University , Baltimore, Maryland 21218, United States
| | - Bernard R Brooks
- Laboratory of Computational Biology, National Heart, Lung, and Blood Institute, National Institutes of Health , Bethesda, Maryland 20892, United States
| |
Collapse
|
26
|
Pezeshki S, Lin H. Adaptive-Partitioning QM/MM for Molecular Dynamics Simulations: 4. Proton Hopping in Bulk Water. J Chem Theory Comput 2015; 11:2398-411. [DOI: 10.1021/ct501019y] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Soroosh Pezeshki
- Chemistry Department, University of Colorado Denver, Denver, Colorado 80217-3364, United States
| | - Hai Lin
- Chemistry Department, University of Colorado Denver, Denver, Colorado 80217-3364, United States
| |
Collapse
|
27
|
Shi Y, Ren P, Schnieders M, Piquemal JP. Polarizable Force Fields for Biomolecular Modeling. REVIEWS IN COMPUTATIONAL CHEMISTRY 2015. [DOI: 10.1002/9781118889886.ch2] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
|
28
|
Chung LW, Sameera WMC, Ramozzi R, Page AJ, Hatanaka M, Petrova GP, Harris TV, Li X, Ke Z, Liu F, Li HB, Ding L, Morokuma K. The ONIOM Method and Its Applications. Chem Rev 2015; 115:5678-796. [PMID: 25853797 DOI: 10.1021/cr5004419] [Citation(s) in RCA: 743] [Impact Index Per Article: 82.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Lung Wa Chung
- †Department of Chemistry, South University of Science and Technology of China, Shenzhen 518055, China
| | - W M C Sameera
- ‡Fukui Institute for Fundamental Chemistry, Kyoto University, 34-4 Takano Nishihiraki-cho, Sakyo, Kyoto 606-8103, Japan
| | - Romain Ramozzi
- ‡Fukui Institute for Fundamental Chemistry, Kyoto University, 34-4 Takano Nishihiraki-cho, Sakyo, Kyoto 606-8103, Japan
| | - Alister J Page
- §Newcastle Institute for Energy and Resources, The University of Newcastle, Callaghan 2308, Australia
| | - Miho Hatanaka
- ‡Fukui Institute for Fundamental Chemistry, Kyoto University, 34-4 Takano Nishihiraki-cho, Sakyo, Kyoto 606-8103, Japan
| | - Galina P Petrova
- ∥Faculty of Chemistry and Pharmacy, University of Sofia, Bulgaria Boulevard James Bourchier 1, 1164 Sofia, Bulgaria
| | - Travis V Harris
- ‡Fukui Institute for Fundamental Chemistry, Kyoto University, 34-4 Takano Nishihiraki-cho, Sakyo, Kyoto 606-8103, Japan.,⊥Department of Chemistry, State University of New York at Oswego, Oswego, New York 13126, United States
| | - Xin Li
- #State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Zhuofeng Ke
- ∇School of Chemistry and Chemical Engineering, Sun Yat-sen University, Guangzhou 510275, China
| | - Fengyi Liu
- ○Key Laboratory of Macromolecular Science of Shaanxi Province, School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi'an, Shaanxi 710119, China
| | - Hai-Bei Li
- ■School of Ocean, Shandong University, Weihai 264209, China
| | - Lina Ding
- ▲School of Pharmaceutical Sciences, Zhengzhou University, 100 Kexue Avenue, Zhengzhou, Henan 450001, China
| | - Keiji Morokuma
- ‡Fukui Institute for Fundamental Chemistry, Kyoto University, 34-4 Takano Nishihiraki-cho, Sakyo, Kyoto 606-8103, Japan
| |
Collapse
|
29
|
Cendagorta JR, Ichiye T. The Surface Potential of the Water–Vapor Interface from Classical Simulations. J Phys Chem B 2015; 119:9114-22. [DOI: 10.1021/jp508878v] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Joseph R. Cendagorta
- Department
of Chemistry, Georgetown University, Washington, DC 20057, United States
| | - Toshiko Ichiye
- Department
of Chemistry, Georgetown University, Washington, DC 20057, United States
| |
Collapse
|
30
|
Recent Progress in Adaptive-Partitioning QM/MM Methods for Born-Oppenheimer Molecular Dynamics. CHALLENGES AND ADVANCES IN COMPUTATIONAL CHEMISTRY AND PHYSICS 2015. [DOI: 10.1007/978-3-319-21626-3_3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
|
31
|
Tan ML, Cendagorta JR, Ichiye T. The molecular charge distribution, the hydration shell, and the unique properties of liquid water. J Chem Phys 2014; 141:244504. [DOI: 10.1063/1.4904263] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Ming-Liang Tan
- Department of Chemistry, Georgetown University, Washington DC 20057, USA
| | | | - Toshiko Ichiye
- Department of Chemistry, Georgetown University, Washington DC 20057, USA
| |
Collapse
|
32
|
Correcting for the free energy costs of bond or angle constraints in molecular dynamics simulations. Biochim Biophys Acta Gen Subj 2014; 1850:932-943. [PMID: 25218695 DOI: 10.1016/j.bbagen.2014.09.001] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Revised: 08/28/2014] [Accepted: 09/01/2014] [Indexed: 11/22/2022]
Abstract
BACKGROUND Free energy simulations are an important tool in the arsenal of computational biophysics, allowing the calculation of thermodynamic properties of binding or enzymatic reactions. This paper introduces methods to increase the accuracy and precision of free energy calculations by calculating the free energy costs of constraints during post-processing. The primary purpose of employing constraints for these free energy methods is to increase the phase space overlap between ensembles, which is required for accuracy and convergence. METHODS The free energy costs of applying or removing constraints are calculated as additional explicit steps in the free energy cycle. The new techniques focus on hard degrees of freedom and use both gradients and Hessian estimation. Enthalpy, vibrational entropy, and Jacobian free energy terms are considered. RESULTS We demonstrate the utility of this method with simple classical systems involving harmonic and anharmonic oscillators, four-atomic benchmark systems, an alchemical mutation of ethane to methanol, and free energy simulations between alanine and serine. The errors for the analytical test cases are all below 0.0007kcal/mol, and the accuracy of the free energy results of ethane to methanol is improved from 0.15 to 0.04kcal/mol. For the alanine to serine case, the phase space overlaps of the unconstrained simulations range between 0.15 and 0.9%. The introduction of constraints increases the overlap up to 2.05%. On average, the overlap increases by 94% relative to the unconstrained value and precision is doubled. CONCLUSIONS The approach reduces errors arising from constraints by about an order of magnitude. Free energy simulations benefit from the use of constraints through enhanced convergence and higher precision. GENERAL SIGNIFICANCE The primary utility of this approach is to calculate free energies for systems with disparate energy surfaces and bonded terms, especially in multi-scale molecular mechanics/quantum mechanics simulations. This article is part of a Special Issue entitled Recent developments of molecular dynamics.
Collapse
|
33
|
Lee J, Miller BT, Damjanović A, Brooks BR. Constant pH Molecular Dynamics in Explicit Solvent with Enveloping Distribution Sampling and Hamiltonian Exchange. J Chem Theory Comput 2014; 10:2738-2750. [PMID: 25061443 PMCID: PMC4095908 DOI: 10.1021/ct500175m] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2014] [Indexed: 12/21/2022]
Abstract
We present a new computational approach for constant pH simulations in explicit solvent based on the combination of the enveloping distribution sampling (EDS) and Hamiltonian replica exchange (HREX) methods. Unlike constant pH methods based on variable and continuous charge models, our method is based on discrete protonation states. EDS generates a hybrid Hamiltonian of different protonation states. A smoothness parameter s is used to control the heights of energy barriers of the hybrid-state energy landscape. A small s value facilitates state transitions by lowering energy barriers. Replica exchange between EDS potentials with different s values allows us to readily obtain a thermodynamically accurate ensemble of multiple protonation states with frequent state transitions. The analysis is performed with an ensemble obtained from an EDS Hamiltonian without smoothing, s = ∞, which strictly follows the minimum energy surface of the end states. The accuracy and efficiency of this method is tested on aspartic acid, lysine, and glutamic acid, which have two protonation states, a histidine with three states, a four-residue peptide with four states, and snake cardiotoxin with eight states. The pKa values estimated with the EDS-HREX method agree well with the experimental pKa values. The mean absolute errors of small benchmark systems range from 0.03 to 0.17 pKa units, and those of three titratable groups of snake cardiotoxin range from 0.2 to 1.6 pKa units. This study demonstrates that EDS-HREX is a potent theoretical framework, which gives the correct description of multiple protonation states and good calculated pKa values.
Collapse
Affiliation(s)
- Juyong Lee
- Laboratory of Computational Biology, National Heart, Lung, and Blood Institute, National Institutes of Health , Bethesda, Maryland 20892, United States
| | - Benjamin T Miller
- Laboratory of Computational Biology, National Heart, Lung, and Blood Institute, National Institutes of Health , Bethesda, Maryland 20892, United States
| | - Ana Damjanović
- Laboratory of Computational Biology, National Heart, Lung, and Blood Institute, National Institutes of Health , Bethesda, Maryland 20892, United States ; Department of Biophysics, Johns Hopkins University , Baltimore, Maryland, United States
| | - Bernard R Brooks
- Laboratory of Computational Biology, National Heart, Lung, and Blood Institute, National Institutes of Health , Bethesda, Maryland 20892, United States
| |
Collapse
|
34
|
Pezeshki S, Lin H. Recent developments in QM/MM methods towards open-boundary multi-scale simulations. MOLECULAR SIMULATION 2014. [DOI: 10.1080/08927022.2014.911870] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
|
35
|
König G, Hudson PS, Boresch S, Woodcock HL. Multiscale Free Energy Simulations: An Efficient Method for Connecting Classical MD Simulations to QM or QM/MM Free Energies Using Non-Boltzmann Bennett Reweighting Schemes. J Chem Theory Comput 2014; 10:1406-1419. [PMID: 24803863 PMCID: PMC3985817 DOI: 10.1021/ct401118k] [Citation(s) in RCA: 104] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2013] [Indexed: 11/28/2022]
Abstract
![]()
The reliability of free energy simulations
(FES) is limited by
two factors: (a) the need for correct sampling and (b) the accuracy
of the computational method employed. Classical methods (e.g., force
fields) are typically used for FES and present a myriad of challenges,
with parametrization being a principle one. On the other hand, parameter-free
quantum mechanical (QM) methods tend to be too computationally expensive
for adequate sampling. One widely used approach is a combination of
methods, where the free energy difference between the two end states
is computed by, e.g., molecular mechanics (MM), and the end states
are corrected by more accurate methods, such as QM or hybrid QM/MM
techniques. Here we report two new approaches that significantly improve
the aforementioned scheme; with a focus on how to compute corrections
between, e.g., the MM and the more accurate QM calculations. First,
a molecular dynamics trajectory that properly samples relevant conformational
degrees of freedom is generated. Next, potential energies of each
trajectory frame are generated with a QM or QM/MM Hamiltonian. Free
energy differences are then calculated based on the QM or QM/MM energies
using either a non-Boltzmann Bennett approach (QM-NBB) or non-Boltzmann
free energy perturbation (NB-FEP). Both approaches are applied to
calculate relative and absolute solvation free energies in explicit
and implicit solvent environments. Solvation free energy differences
(relative and absolute) between ethane and methanol in explicit solvent
are used as the initial test case for QM-NBB. Next, implicit solvent
methods are employed in conjunction with both QM-NBB and NB-FEP to
compute absolute solvation free energies for 21 compounds. These compounds
range from small molecules such as ethane and methanol to fairly large,
flexible solutes, such as triacetyl glycerol. Several technical aspects
were investigated. Ultimately some best practices are suggested for
improving methods that seek to connect MM to QM (or QM/MM) levels
of theory in FES.
Collapse
Affiliation(s)
- Gerhard König
- Laboratory of Computational Biology, National Heart Lung and Blood Institute, National Institutes of Health , Bethesda, Maryland 20892, United States
| | - Phillip S Hudson
- Department of Chemistry, University of South Florida , 4202 E. Fowler Avenue, CHE205, Tampa, Florida 33620-5250, United States
| | - Stefan Boresch
- Department of Computational Biological Chemistry, Faculty of Chemistry, University of Vienna , Währingerstraße 17, A-1090 Vienna, Austria
| | - H Lee Woodcock
- Department of Chemistry, University of South Florida , 4202 E. Fowler Avenue, CHE205, Tampa, Florida 33620-5250, United States
| |
Collapse
|
36
|
Ghysels A, Miller BT, Pickard FC, Brooks BR. Comparing normal modes across different models and scales: Hessian reductionversuscoarse-graining. J Comput Chem 2012; 33:2250-75. [DOI: 10.1002/jcc.23076] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2011] [Revised: 05/09/2012] [Accepted: 06/24/2012] [Indexed: 12/24/2022]
|
37
|
König G, Miller BT, Boresch S, Wu X, Brooks BR. Enhanced Sampling in Free Energy Calculations: Combining SGLD with the Bennett's Acceptance Ratio and Enveloping Distribution Sampling Methods. J Chem Theory Comput 2012; 8:3650-62. [PMID: 26593010 DOI: 10.1021/ct300116r] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
One of the key requirements for the accurate calculation of free energy differences is proper sampling of conformational space. Especially in biological applications, molecular dynamics simulations are often confronted with rugged energy surfaces and high energy barriers, leading to insufficient sampling and, in turn, poor convergence of the free energy results. In this work, we address this problem by employing enhanced sampling methods. We explore the possibility of using self-guided Langevin dynamics (SGLD) to speed up the exploration process in free energy simulations. To obtain improved free energy differences from such simulations, it is necessary to account for the effects of the bias due to the guiding forces. We demonstrate how this can be accomplished for the Bennett's acceptance ratio (BAR) and the enveloping distribution sampling (EDS) methods. While BAR is considered among the most efficient methods available for free energy calculations, the EDS method developed by Christ and van Gunsteren is a promising development that reduces the computational costs of free energy calculations by simulating a single reference state. To evaluate the accuracy of both approaches in connection with enhanced sampling, EDS was implemented in CHARMM. For testing, we employ benchmark systems with analytical reference results and the mutation of alanine to serine. We find that SGLD with reweighting can provide accurate results for BAR and EDS where conventional molecular dynamics simulations fail. In addition, we compare the performance of EDS with other free energy methods. We briefly discuss the implications of our results and provide practical guidelines for conducting free energy simulations with SGLD.
Collapse
Affiliation(s)
- Gerhard König
- Laboratory of Computational Biology, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Benjamin T Miller
- Laboratory of Computational Biology, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Stefan Boresch
- Department of Computational Biological Chemistry, Faculty of Chemistry, University of Vienna, Währingerstraße 17, A-1090 Vienna, Austria
| | - Xiongwu Wu
- Laboratory of Computational Biology, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Bernard R Brooks
- Laboratory of Computational Biology, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892, United States
| |
Collapse
|
38
|
Structural features of aquaporin 4 supporting the formation of arrays and junctions in biomembranes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2012; 1818:2234-43. [PMID: 22554469 DOI: 10.1016/j.bbamem.2012.04.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2012] [Revised: 04/11/2012] [Accepted: 04/12/2012] [Indexed: 01/08/2023]
Abstract
A limited class of aquaporins has been described to form regular arrays and junctions in membranes. The biological significance of these structures, however, remains uncertain. Here we analyze the underlying physical principles with the help of a computational procedure that takes into account protein-protein as well as protein-membrane interactions. Experimentally observed array/junction structures are systematically (dis)assembled and major driving forces identified. Aquaporin 4 was found to be markedly different from the non-junction forming aquaporin 1. The environmental stabilization resulting from embedding into the biomembrane was identified as the main driving force. This highlights the role of protein-membrane interactions in aquaporin 4. Analysis of the type presented here can help to decipher the biological role of membrane arrays and junctions formed by aquaporin.
Collapse
|
39
|
Biswas PK, Vellore NA, Yancey JA, Kucukkal TG, Collier G, Brooks BR, Stuart SJ, Latour RA. Simulation of multiphase systems utilizing independent force fields to control intraphase and interphase behavior. J Comput Chem 2012; 33:1458-66. [PMID: 22488548 DOI: 10.1002/jcc.22979] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2011] [Revised: 01/24/2012] [Accepted: 03/02/2012] [Indexed: 11/05/2022]
Abstract
Fixed-charge empirical force fields have been developed and widely used over the past three decades for all-atom molecular simulations. Most simulation programs providing these methods enable only one set of force field parameters to be used for the entire system. Whereas this is generally suitable for single-phase systems, the molecular environment at the interface between two phases may be sufficiently different from the individual phases to require a different set of parameters to be used to accurately represent the system. Recently published simulations of peptide adsorption to material surfaces using the CHARMM force field have clearly demonstrated this issue by revealing that calculated values of adsorption free energy substantially differ from experimental results. Whereas nonbonded parameters could be adjusted to correct this problem, this cannot be done without also altering the conformational behavior of the peptide in solution, for which CHARMM has been carefully tuned. We have developed a dual-force-field approach (Dual-FF) to address this problem and implemented it in the CHARMM simulation package. This Dual-FF method provides the capability to use two separate sets of nonbonded force field parameters within the same simulation: one set to represent intraphase interactions and a separate set to represent interphase interactions. Using this approach, we show that interfacial parameters can be adjusted to correct errors in peptide adsorption free energy without altering peptide conformational behavior in solution. This program thus provides the capability to enable both intraphase and interphase molecular behavior to be accurately and efficiently modeled in the same simulation.
Collapse
|
40
|
In Silico Strategies Toward Enzyme Function and Dynamics. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2012. [DOI: 10.1016/b978-0-12-398312-1.00009-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register]
|
41
|
Machado MR, Dans PD, Pantano S. A hybrid all-atom/coarse grain model for multiscale simulations of DNA. Phys Chem Chem Phys 2011; 13:18134-44. [PMID: 21927740 DOI: 10.1039/c1cp21248f] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Hybrid simulations of molecular systems, which combine all-atom (AA) with simplified (or coarse grain, CG) representations, propose an advantageous alternative to gain atomistic details on relevant regions while getting profit from the speedup of treating a bigger part of the system at the CG level. Here we present a reduced set of parameters derived to treat a hybrid interface in DNA simulations. Our method allows us to forthrightly link a state-of-the-art force field for AA simulations of DNA with a CG representation developed by our group. We show that no modification is needed for any of the existing residues (neither AA nor CG). Only the bonding parameters at the hybrid interface are enough to produce a smooth transition of electrostatic, mechanic and dynamic features in different AA/CG systems, which are studied by molecular dynamics simulations using an implicit solvent. The simplicity of the approach potentially permits us to study the effect of mutations/modifications as well as DNA binding molecules at the atomistic level within a significantly larger DNA scaffold considered at the CG level. Since all the interactions are computed within the same classical Hamiltonian, the extension to a quantum/classical/coarse-grain multilayer approach using QM/MM modules implemented in widely used simulation packages is straightforward.
Collapse
|