1
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Suh D, Arattu Thodika AR, Kim S, Nam K, Im W. CHARMM-GUI QM/MM Interfacer for a Quantum Mechanical and Molecular Mechanical (QM/MM) Simulation Setup: 1. Semiempirical Methods. J Chem Theory Comput 2024. [PMID: 38856971 DOI: 10.1021/acs.jctc.4c00439] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2024]
Abstract
Quantum mechanical (QM) treatments, when combined with molecular mechanical (MM) force fields, can effectively handle enzyme-catalyzed reactions without significantly increasing the computational cost. In this context, we present CHARMM-GUI QM/MM Interfacer, a web-based cyberinfrastructure designed to streamline the preparation of various QM/MM simulation inputs with ligand modification. The development of QM/MM Interfacer has been achieved through integration with existing CHARMM-GUI modules, such as PDB Reader and Manipulator, Solution Builder, and Membrane Builder. In addition, new functionalities have been developed to facilitate the one-stop preparation of QM/MM systems and enable interactive and intuitive ligand modifications and QM atom selections. QM/MM Interfacer offers support for a range of semiempirical QM methods, including AM1(+/d), PM3(+/PDDG), MNDO(+/d, +/PDDG), PM6, RM1, and SCC-DFTB, tailored for both AMBER and CHARMM. A nontrivial setup related to ligand modification, link-atom insertion, and charge distribution is automatized through intuitive user interfaces. To illustrate the robustness of QM/MM Interfacer, we conducted QM/MM simulations of three enzyme-substrate systems: dihydrofolate reductase, insulin receptor kinase, and oligosaccharyltransferase. In addition, we have created three tutorial videos about building these systems, which can be found at https://www.charmm-gui.org/demo/qmi. QM/MM Interfacer is expected to be a valuable and accessible web-based tool that simplifies and accelerates the setup process for hybrid QM/MM simulations.
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Affiliation(s)
- Donghyuk Suh
- Department of Biological Sciences, Chemistry, Bioengineering, and Computer Science and Engineering, Lehigh University, Bethlehem, Pennsylvania 18015, United States
| | - Abdul Raafik Arattu Thodika
- Department of Chemistry and Biochemistry, The University of Texas at Arlington, Arlington, Texas 76019-9800, United States
| | - Seonghoon Kim
- Department of Biological Sciences, Chemistry, Bioengineering, and Computer Science and Engineering, Lehigh University, Bethlehem, Pennsylvania 18015, United States
| | - Kwangho Nam
- Department of Chemistry and Biochemistry, The University of Texas at Arlington, Arlington, Texas 76019-9800, United States
| | - Wonpil Im
- Department of Biological Sciences, Chemistry, Bioengineering, and Computer Science and Engineering, Lehigh University, Bethlehem, Pennsylvania 18015, United States
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2
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Xiong J, Xu D. Decarboxylation Mechanism of iso-Orotate Decarboxylase Revisited. J Chem Theory Comput 2024; 20:4218-4228. [PMID: 38720241 DOI: 10.1021/acs.jctc.4c00077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/29/2024]
Abstract
iso-Orotate decarboxylase (IDCase), which is involved in the thymidine salvage pathway, has attracted considerable interest owing to its chemical similarity to a hypothetical DNA decarboxylase in mammals. Although valuable insights into the active DNA demethylation of 5-methyl-cytosine can be obtained from the decarboxylation mechanism of 5-carboxyl-uracil (5caU) catalyzed by IDCase, this mechanism remains under debate. In this study, the catalytic mechanism of 5caU decarboxylation by IDCase was studied using hybrid quantum mechanics/molecular mechanics (QM/MM) methodologies and density functional theory (DFT) calculations with a truncated model. The calculations supported a mechanism involving three sequential stages: activation of the 5caU substrate via proton transfer from an arginine (R262') to the carboxyl group of 5caU, formation of a tetrahedral intermediate, and decarboxylation of the tetrahedral intermediate to generate uracil as the product. The reaction pathways and structures obtained using the QM/MM and DFT methods coincided with each other. These simulations provided detailed insights into the unique mechanism of IDCase, clarifying various unresolved issues, such as the critical role of R262'. In addition, aspartate D323 was found to act as a general base in the tetrahedral intermediate formation step and a general acid in the later C-C bond cleavage step.
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Affiliation(s)
- Jing Xiong
- School of Pharmacy, Chengdu Medical College, Chengdu, Sichuan 610500, P. R. China
| | - Dingguo Xu
- MOE Key Laboratory of Green Chemistry & Technology, College of Chemistry, Sichuan University, Chengdu, Sichuan 610064, P. R. China
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3
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Nam K, Shao Y, Major DT, Wolf-Watz M. Perspectives on Computational Enzyme Modeling: From Mechanisms to Design and Drug Development. ACS OMEGA 2024; 9:7393-7412. [PMID: 38405524 PMCID: PMC10883025 DOI: 10.1021/acsomega.3c09084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/14/2023] [Revised: 01/15/2024] [Accepted: 01/19/2024] [Indexed: 02/27/2024]
Abstract
Understanding enzyme mechanisms is essential for unraveling the complex molecular machinery of life. In this review, we survey the field of computational enzymology, highlighting key principles governing enzyme mechanisms and discussing ongoing challenges and promising advances. Over the years, computer simulations have become indispensable in the study of enzyme mechanisms, with the integration of experimental and computational exploration now established as a holistic approach to gain deep insights into enzymatic catalysis. Numerous studies have demonstrated the power of computer simulations in characterizing reaction pathways, transition states, substrate selectivity, product distribution, and dynamic conformational changes for various enzymes. Nevertheless, significant challenges remain in investigating the mechanisms of complex multistep reactions, large-scale conformational changes, and allosteric regulation. Beyond mechanistic studies, computational enzyme modeling has emerged as an essential tool for computer-aided enzyme design and the rational discovery of covalent drugs for targeted therapies. Overall, enzyme design/engineering and covalent drug development can greatly benefit from our understanding of the detailed mechanisms of enzymes, such as protein dynamics, entropy contributions, and allostery, as revealed by computational studies. Such a convergence of different research approaches is expected to continue, creating synergies in enzyme research. This review, by outlining the ever-expanding field of enzyme research, aims to provide guidance for future research directions and facilitate new developments in this important and evolving field.
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Affiliation(s)
- Kwangho Nam
- Department
of Chemistry and Biochemistry, University
of Texas at Arlington, Arlington, Texas 76019, United States
| | - Yihan Shao
- Department
of Chemistry and Biochemistry, University
of Oklahoma, Norman, Oklahoma 73019-5251, United States
| | - Dan T. Major
- Department
of Chemistry and Institute for Nanotechnology & Advanced Materials, Bar-Ilan University, Ramat-Gan 52900, Israel
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4
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Cai Y, Mu X, Li G, Xu D. Quantum Mechanical/Molecular Mechanical Elucidation of the Catalytic Mechanism of Leukotriene A4 Hydrolase as an Epoxidase. J Phys Chem B 2023; 127:10338-10350. [PMID: 38010510 DOI: 10.1021/acs.jpcb.3c05969] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2023]
Abstract
Leukotriene A4 hydrolase (LTA4H) functions as a mono-zinc bifunctional enzyme with aminopeptidase and epoxidase activities. While the aminopeptidase mechanism is well understood, the epoxidase mechanism remains less clear. In continuation of our prior research, we undertook an in-depth exploration of the LTA4H catalytic role as an epoxidase, employing a combined SCC-DFTB/CHARMM method. In the current work, we found that the conversion of LTA4 to leukotriene B4 (LTB4) involves three successive steps: epoxy ring opening (RO), nucleophilic attack (NA), and proton transfer (PT) reactions at the epoxy oxygen atom. Among these steps, the RO and NA stages constitute the potential rate-limiting step within the entire epoxidase mechanism. Notably, the NA step implicates D375 as the general base catalyst, while the PT step engages protonated E271 as the general acid catalyst. Additionally, we delved into the mechanism behind the formation of the isomer product, Δ6-trans-Δ8-cis-LTB4. Our findings debunked the feasibility of a direct LTB4 to iso-LTB4 conversion. Instead, we highlight the possibility of isomerization from LTA4 to its isomeric conjugate (iso-LTA4), showing comparable energy barriers of 5.1 and 5.5 kcal/mol in aqueous and enzymatic environments, respectively. The ensuing dynamics of iso-LTA4 hydrolysis subsequently yield iso-LTB4 via a mechanism akin to LTA4 hydrolysis, albeit with a heightened barrier. Our computations firmly support the notion that substrate isomerization exclusively takes place prior to or during the initial substrate-binding phase, while LTA4 remains the dominant conformer. Notably, our simulations suggest that irrespective of the active site's constrained L-shape, isomerization from LTA4 to its isomeric conjugate remains plausible. The mechanistic insights garnered from our simulations furnish a valuable understanding of LTA4H's role as an epoxidase, thereby facilitating potential advancements in inhibitor design.
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Affiliation(s)
- Yao Cai
- MOE Key Laboratory of Green Chemistry and Technology, College of Chemistry, Sichuan University, Chengdu, Sichuan 610064, P. R. China
| | - Xia Mu
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning 116000, P. R. China
| | - Guohui Li
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning 116000, P. R. China
| | - Dingguo Xu
- MOE Key Laboratory of Green Chemistry and Technology, College of Chemistry, Sichuan University, Chengdu, Sichuan 610064, P. R. China
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5
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Meelua W, Wanjai T, Thinkumrob N, Friedman R, Jitonnom J. Multiscale QM/MM Simulations Identify the Roles of Asp239 and 1-OH···Nucleophile in Transition State Stabilization in Arabidopsis thaliana Cell-Wall Invertase 1. J Chem Inf Model 2023; 63:4827-4838. [PMID: 37503869 DOI: 10.1021/acs.jcim.3c00796] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
Arabidopsis thaliana cell-wall invertase 1 (AtCWIN1), a key enzyme in sucrose metabolism in plants, catalyzes the hydrolysis of sucrose into fructose and glucose. AtCWIN1 belongs to the glycoside hydrolase GH-J clan, where two carboxylate residues (Asp23 and Glu203 in AtCWIN1) are well documented as a nucleophile and an acid/base catalyst. However, details at the atomic level about the role of neighboring residues and enzyme-substrate interactions during catalysis are not fully understood. Here, quantum mechanical/molecular mechanical (QM/MM) free-energy simulations were carried out to clarify the origin of the observed decreased rates in Asp239Ala, Asp239Asn, and Asp239Phe in AtCWIN1 compared to the wild type and delineate the role of Asp239 in catalysis. The glycosylation and deglycosylation steps were considered in both wild type and mutants. Deglycosylation is predicted to be the rate-determining step in the reaction, with a calculated overall free-energy barrier of 15.9 kcal/mol, consistent with the experimental barrier (15.3 kcal/mol). During the reaction, the -1 furanosyl ring underwent a conformational change corresponding to 3E ↔ [E2]⧧ ↔ 1E according to the nomenclature of saccharide structures along the full catalytic reaction. Asp239 was found to stabilize not only the transition state but also the fructosyl-enzyme intermediate, which explains findings from previous structural and mutagenesis experiments. The 1-OH···nucleophile interaction has been found to provide an important contribution to the transition state stabilization, with a contribution of ∼7 kcal/mol, and affected glycosylation more significantly than deglycosylation. This study provides molecular insights that improve the current understanding of sucrose binding and hydrolysis in members of clan GH-J, which may benefit protein engineering research. Finally, a rationale on the sucrose inhibitor configuration in chicory 1-FEH IIa, proposed a long time ago in the literature, is also provided based on the QM/MM calculations.
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Affiliation(s)
- Wijitra Meelua
- Demonstration School, University of Phayao, Phayao 56000, Thailand
- Unit of Excellence in Computational Molecular Science and Catalysis, and Division of Chemistry, School of Science, University of Phayao, Phayao 56000, Thailand
| | - Tanchanok Wanjai
- Unit of Excellence in Computational Molecular Science and Catalysis, and Division of Chemistry, School of Science, University of Phayao, Phayao 56000, Thailand
| | - Natechanok Thinkumrob
- Unit of Excellence in Computational Molecular Science and Catalysis, and Division of Chemistry, School of Science, University of Phayao, Phayao 56000, Thailand
| | - Ran Friedman
- Department of Chemistry and Biomedical Sciences, Linnæus University, Kalmar SE-391 82, Sweden
| | - Jitrayut Jitonnom
- Unit of Excellence in Computational Molecular Science and Catalysis, and Division of Chemistry, School of Science, University of Phayao, Phayao 56000, Thailand
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6
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Bannwarth C, Martínez TJ. SQMBox: Interfacing a semiempirical integral library to modular ab initio electronic structure enables new semiempirical methods. J Chem Phys 2023; 158:074109. [PMID: 36813714 DOI: 10.1063/5.0132776] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Ab initio and semiempirical electronic structure methods are usually implemented in separate software packages or use entirely different code paths. As a result, it can be time-consuming to transfer an established ab initio electronic structure scheme to a semiempirical Hamiltonian. We present an approach to unify ab initio and semiempirical electronic structure code paths based on a separation of the wavefunction ansatz and the needed matrix representations of operators. With this separation, the Hamiltonian can refer to either an ab initio or semiempirical treatment of the resulting integrals. We built a semiempirical integral library and interfaced it to the GPU-accelerated electronic structure code TeraChem. Equivalency between ab initio and semiempirical tight-binding Hamiltonian terms is assigned according to their dependence on the one-electron density matrix. The new library provides semiempirical equivalents of the Hamiltonian matrix and gradient intermediates, corresponding to those provided by the ab initio integral library. This enables the straightforward combination of semiempirical Hamiltonians with the full pre-existing ground and excited state functionality of the ab initio electronic structure code. We demonstrate the capability of this approach by combining the extended tight-binding method GFN1-xTB with both spin-restricted ensemble-referenced Kohn-Sham and complete active space methods. We also present a highly efficient GPU implementation of the semiempirical Mulliken-approximated Fock exchange. The additional computational cost for this term becomes negligible even on consumer-grade GPUs, enabling Mulliken-approximated exchange in tight-binding methods for essentially no additional cost.
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Affiliation(s)
- Christoph Bannwarth
- Department of Chemistry and The PULSE Institute, Stanford University, Stanford, California 94305, USA and SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
| | - Todd J Martínez
- Department of Chemistry and The PULSE Institute, Stanford University, Stanford, California 94305, USA and SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
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7
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Csizi K, Reiher M. Universal
QM
/
MM
approaches for general nanoscale applications. WIRES COMPUTATIONAL MOLECULAR SCIENCE 2023. [DOI: 10.1002/wcms.1656] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
| | - Markus Reiher
- Laboratorium für Physikalische Chemie ETH Zürich Zürich Switzerland
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8
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Yin C, Song Z, Tian H, Palzkill T, Tao P. Unveiling the structural features that regulate carbapenem deacylation in KPC-2 through QM/MM and interpretable machine learning. Phys Chem Chem Phys 2023; 25:1349-1362. [PMID: 36537692 PMCID: PMC11162551 DOI: 10.1039/d2cp03724f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Resistance to carbapenem β-lactams presents major clinical and economical challenges for the treatment of pathogen infections. The fast hydrolysis of carbapenems by carbapenemase-producing bacterial strains enables the effective deactivation of carbapenem antibiotics. In this study, we aim to unravel the structural features that distinguish the notable deacylation activity of carbapenemases. The deacylation reactions between imipenem (IPM) and the KPC-2 class A serine-based β-lactamases (ASβLs) are modeled with combined quantum mechanical/molecular mechanical (QM/MM) minimum energy pathway (MEP) calculations and interpretable machine-learning (ML) methods. We first applied a dual-level computational protocol to achieve fast sampling of QM/MM MEPs. A tree-based ensemble ML model was employed to learn the MEP activation barriers from the conformational features of the KPC-2/IPM active site. The barrier-predicting model was then unboxed using the Shapley additive explanation (SHAP) importance attribution methods to derive mechanistic insights, which were also verified by additional QM/MM wavefunction analysis. Essentially, we show that potential hydrogen bonding interactions of the general base and the tautomerization states of the carbapenem pyrroline ring could concertedly regulate the activation barrier of KPC-2/IPM deacylation. Nonetheless, we demonstrate the efficacy of interpretable ML to assist the analysis of QM/MM simulation data for robust extraction of human-interpretable mechanistic insights.
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Affiliation(s)
- Chao Yin
- Department of Chemistry, Center for Research Computing, Center for Drug Discovery, Design, and Delivery (CD4), Southern Methodist University, Dallas, Texas, 75205, USA.
| | - Zilin Song
- Department of Chemistry, Center for Research Computing, Center for Drug Discovery, Design, and Delivery (CD4), Southern Methodist University, Dallas, Texas, 75205, USA.
| | - Hao Tian
- Department of Chemistry, Center for Research Computing, Center for Drug Discovery, Design, and Delivery (CD4), Southern Methodist University, Dallas, Texas, 75205, USA.
| | - Timothy Palzkill
- Department of Pharmacology and Chemical Biology, Baylor College of Medicine, Houston, Texas, 77030, USA
| | - Peng Tao
- Department of Chemistry, Center for Research Computing, Center for Drug Discovery, Design, and Delivery (CD4), Southern Methodist University, Dallas, Texas, 75205, USA.
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9
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Ogrizek M, Janežič M, Valjavec K, Perdih A. Catalytic Mechanism of ATP Hydrolysis in the ATPase Domain of Human DNA Topoisomerase IIα. J Chem Inf Model 2022; 62:3896-3909. [PMID: 35948041 PMCID: PMC9400105 DOI: 10.1021/acs.jcim.2c00303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
![]()
Human DNA topoisomerase IIα is a biological nanomachine
that
regulates the topological changes of the DNA molecule and is considered
a prime target for anticancer drugs. Despite intensive research, many
atomic details about its mechanism of action remain unknown. We investigated
the ATPase domain, a segment of the human DNA topoisomerase IIα,
using all-atom molecular simulations, multiscale quantum mechanics/molecular
mechanics (QM/MM) calculations, and a point mutation study. The results
suggested that the binding of ATP affects the overall dynamics of
the ATPase dimer. Reaction modeling revealed that ATP hydrolysis favors
the dissociative substrate-assisted reaction mechanism with the catalytic
Glu87 serving to properly position and polarize the lytic water molecule.
The point mutation study complemented our computational results, demonstrating
that Lys378, part of the important QTK loop, acts as a stabilizing
residue. The work aims to pave the way to a deeper understanding of
these important molecular motors and to advance the development of
new therapeutics.
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Affiliation(s)
- Mitja Ogrizek
- National Institute of Chemistry, Hajdrihova 19, SI-1001 Ljubljana, Slovenia
| | - Matej Janežič
- National Institute of Chemistry, Hajdrihova 19, SI-1001 Ljubljana, Slovenia
| | - Katja Valjavec
- National Institute of Chemistry, Hajdrihova 19, SI-1001 Ljubljana, Slovenia
| | - Andrej Perdih
- National Institute of Chemistry, Hajdrihova 19, SI-1001 Ljubljana, Slovenia.,Faculty of Pharmacy, University of Ljubljana, Aškerčeva 7, SI 1000 Ljubljana, Slovenia
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10
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Li P, Shi M, Wang X, Xu D. QM/MM investigation of the catalytic mechanism of processive endoglucanase Cel9G from Clostridium cellulovorans. Phys Chem Chem Phys 2022; 24:11919-11930. [PMID: 35514276 DOI: 10.1039/d2cp00593j] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Carbohydrate degradation catalyzed by glucoside hydrolases (GHs) is a major mechanism in biomass conversion. GH family 9 endoglucanase (Cel9G) from Clostridium cellulovorans, a typical multimodular enzyme, contains a catalytic domain closely linked to a family 3c carbohydrate-binding module (CBM3c). Unlike the conventional behavior proposed for other carbohydrate-binding modules, CBM3c has a direct impact on catalytic activity. In this work, extensive molecular dynamics (MD) simulations were employed to clarify the functional role of CBM3c. Furthermore, the detailed catalytic mechanism of Cel9G was investigated at the atomistic level using the combined quantum mechanical and molecular mechanical (QM/MM) method. Based on these simulations, owing to the rigidity of the peptide linker, CBM3c may affect the enzymatic activity via direct interactions with alpha helix 4 of GH9, especially with the K123 and H125 residues. In addition, using cellohexaose as a substrate, the QM/MM MD simulations confirmed that this enzyme can cleave the β-1,4-glycosidic linkage via an inverting mechanism. An oxocarbenium ion-like transition state was located with a barrier height of 19.6 kcal mol-1. Furthermore, the G(-1) pyranose unit preferentially adopted a distorted 1S5/4H5 conformer in the enzyme-substrate complex. For the cleavage of the glycosidic bond, we were able to identify a plausible route (1S5/4H5 → [4H5/4E]# → 4C1) from the reactant to the product at the G(-1) site.
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Affiliation(s)
- Penghui Li
- College of Chemistry, MOE Key Laboratory of Green Chemistry and Technology, Sichuan University, Chengdu, Sichuan, 610064, P. R. China.
| | - Mingsong Shi
- State Key Laboratory of Biotherapy, West China Hospital of Sichuan University, Chengdu, Sichuan, 610041, P. R. China
| | - Xin Wang
- College of Chemistry, MOE Key Laboratory of Green Chemistry and Technology, Sichuan University, Chengdu, Sichuan, 610064, P. R. China.
| | - Dingguo Xu
- College of Chemistry, MOE Key Laboratory of Green Chemistry and Technology, Sichuan University, Chengdu, Sichuan, 610064, P. R. China.
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11
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Piccini G, Lee MS, Yuk SF, Zhang D, Collinge G, Kollias L, Nguyen MT, Glezakou VA, Rousseau R. Ab initio molecular dynamics with enhanced sampling in heterogeneous catalysis. Catal Sci Technol 2022. [DOI: 10.1039/d1cy01329g] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Enhanced sampling ab initio simulations enable to study chemical phenomena in catalytic systems including thermal effects & anharmonicity, & collective dynamics describing enthalpic & entropic contributions, which can significantly impact on reaction free energy landscapes.
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Affiliation(s)
- GiovanniMaria Piccini
- Basic & Applied Molecular Foundations, Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA 99352, USA
- Istituto Eulero, Università della Svizzera italiana, Via Giuseppe Buffi 13, Lugano, Ticino, Switzerland
| | - Mal-Soon Lee
- Basic & Applied Molecular Foundations, Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA 99352, USA
| | - Simuck F. Yuk
- Basic & Applied Molecular Foundations, Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA 99352, USA
- Department of Chemistry and Life Science, United States Military Academy, West Point, NY 10996, USA
| | - Difan Zhang
- Basic & Applied Molecular Foundations, Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA 99352, USA
| | - Greg Collinge
- Basic & Applied Molecular Foundations, Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA 99352, USA
| | - Loukas Kollias
- Basic & Applied Molecular Foundations, Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA 99352, USA
| | - Manh-Thuong Nguyen
- Basic & Applied Molecular Foundations, Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA 99352, USA
| | - Vassiliki-Alexandra Glezakou
- Basic & Applied Molecular Foundations, Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA 99352, USA
| | - Roger Rousseau
- Basic & Applied Molecular Foundations, Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA 99352, USA
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12
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Delle Piane M, Pesce L, Cioni M, Pavan GM. Reconstructing Reactivity in Dynamic Host-Guest Systems at Atomistic Resolution: Amide Hydrolysis Under Confinement in the Cavity of a Coordination Cage. Chem Sci 2022; 13:11232-11245. [PMID: 36320487 PMCID: PMC9517058 DOI: 10.1039/d2sc02000a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Accepted: 08/28/2022] [Indexed: 11/21/2022] Open
Abstract
Spatial confinement is widely employed by nature to attain unique efficiency in controlling chemical reactions. Notable examples are enzymes, which selectively bind reactants and exquisitely regulate their conversion into products. In an attempt to mimic natural catalytic systems, supramolecular metal–organic cages capable of encapsulating guests in their cavity and of controlling/accelerating chemical reactions under confinement are attracting increasing interest. However, the complex nature of these systems, where reactants/products continuously exchange in-and-out of the host, makes it often difficult to elucidate the factors controlling the reactivity in dynamic regimes. As a case study, here we focus on a coordination cage that can encapsulate amide guests and enhance their hydrolysis by favoring their mechanical twisting towards reactive molecular configurations under confinement. We designed an advanced multiscale simulation approach that allows us to reconstruct the reactivity in such host–guest systems in dynamic regimes. In this way, we can characterize amide encapsulation/expulsion in/out of the cage cavity (thermodynamics and kinetics), coupling such host–guest dynamic equilibrium with characteristic hydrolysis reaction constants. All computed kinetic/thermodynamic data are then combined, obtaining a statistical estimation of reaction acceleration in the host–guest system that is found in optimal agreement with the available experimental trends. This shows how, to understand the key factors controlling accelerations/variations in the reaction under confinement, it is necessary to take into account all dynamic processes that occur as intimately entangled in such host–guest systems. This also provides us with a flexible computational framework, useful to build structure–dynamics–property relationships for a variety of reactive host–guest systems. Encapsulation of guests in metal–organic cages allows control over chemical reactivity. Focusing on the hydrolysis of amides, here we show an effective molecular simulation approach to reconstruct reactivity in host–guest systems in dynamic regimes.![]()
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Affiliation(s)
- Massimo Delle Piane
- Department of Applied Science and Technology, Politecnico di Torino Corso Duca degli Abruzzi 24 10129 Torino Italy
| | - Luca Pesce
- Department of Innovative Technologies, University of Applied Sciences and Arts of Southern Switzerland, Polo Universitario Lugano Campus Est, Via la Santa 1 6962 Lugano-Viganello Switzerland
| | - Matteo Cioni
- Department of Applied Science and Technology, Politecnico di Torino Corso Duca degli Abruzzi 24 10129 Torino Italy
| | - Giovanni M Pavan
- Department of Applied Science and Technology, Politecnico di Torino Corso Duca degli Abruzzi 24 10129 Torino Italy
- Department of Innovative Technologies, University of Applied Sciences and Arts of Southern Switzerland, Polo Universitario Lugano Campus Est, Via la Santa 1 6962 Lugano-Viganello Switzerland
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13
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Meelua W, Wanjai T, Thinkumrob N, Oláh J, Mujika JI, Ketudat-Cairns JR, Hannongbua S, Jitonnom J. Active site dynamics and catalytic mechanism in arabinan hydrolysis catalyzed by GH43 endo-arabinanase from QM/MM molecular dynamics simulation and potential energy surface. J Biomol Struct Dyn 2021; 40:7439-7449. [PMID: 33715601 DOI: 10.1080/07391102.2021.1898469] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
The endo-1,5-α-L-arabinanases, belonging to glycoside hydrolase family 43 (GH43), catalyse the hydrolysis of α-1,5-arabinofuranosidic bonds in arabinose-containing polysaccharides. These enzymes are proposed targets for industrial and medical applications. Here, molecular dynamics (MD), potential energy surface and free energy (potential of mean force) simulations are undertaken using hybrid quantum mechanical/molecular mechanical (QM/MM) potentials to understand the active site dynamics, catalytic mechanism and the electrostatic influence of active site residues of the GH43 endo-arabinanase from G. stearothermophilus. The calculated results give support to the single-displacement mechanism proposed for the inverting GH43 enzymes: first a proton is transferred from the general acid E201 to the substrate, followed by a nucleophilic attack by water, activated by the general base D27, on the anomer carbon. A conformational change (2E ↔E3 ↔ 4E) in the -1 sugar ring is observed involving a transition state featuring an oxocarbenium ion character. Residues D87, K106, H271 are highlighted as potential targets for future mutation experiments in order to increase the efficiency of the reaction. To our knowledge, this is the first QM/MM study providing molecular insights into the glycosidic bond hydrolysis of a furanoside substrate by an inverting GH in solution.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Wijitra Meelua
- Demonstration School, University of Phayao, Phayao, Thailand.,Division of Chemistry, School of Science, University of Phayao, Phayao, Thailand
| | | | | | - Julianna Oláh
- Department of Inorganic and Analytical Chemistry, Budapest University of Technology and Economics, Budapest, Hungary
| | - Jon I Mujika
- Kimika Fakultatea, Euskal Herriko Unibertsitatea UPV/EHU, and Donostia International Physics Center (DIPC), Donostia, Euskadi, Spain
| | - James R Ketudat-Cairns
- Center for Biomolecular Structure, Function and Application, Suranaree University of Technology, Nakhon Ratchasima, Thailand
| | - Supa Hannongbua
- Department of Chemistry, Faculty of Science, Kasetsart University, Bangkok, Thailand
| | - Jitrayut Jitonnom
- Division of Chemistry, School of Science, University of Phayao, Phayao, Thailand
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14
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Xiong J, Xu D. Mechanistic Insights into the Hydrolysis of O-GlcNAcylation Catalyzed by Human O-GlcNAcase. J Phys Chem B 2020; 124:9310-9322. [PMID: 32970432 DOI: 10.1021/acs.jpcb.0c05755] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
O-GlcNAc glycosylation occurs on specific serine/threonine residues of intracellular proteins, which is widely related to various diseases, including type II diabetes, cancer, and Alzheimer's disease. Human O-GlcNAcase (hOGA) is responsible for the removal of O-GlcNAc modification and thus serves as the main target for inhibitor design. In this work, we systematically investigated the mechanism catalyzed by hOGA using the quantum mechanical/molecular mechanical method. Based on calculated free energy profiles, two essential steps named cyclization (Cyc) step and ring opening step are required to generate the final hemiacetal product. The Cyc of the 2-acetamido group, the rate-limiting step, leads to the generation of the intermediate of a bicyclic oxazolinium ion (EI1). Next, the oxazoline ring could be broken via the nucleophilic attack of a water molecule at the C1 position, which generates the final product. Along with this, our simulations clearly suggest the existence of an oxazoline intermediate (EI2), which is produced via proton transfer (PT) from the 2-acetamido group (EI1) to D174. This PT step features a reversible process with a low energy barrier, which could be attributed to a low barrier hydrogen bond between the donor and acceptor. The stabilizing effect of the low barrier hydrogen bond on EI1 is proposed to be very important for accelerating the overall reaction. In fact, the site-directed mutagenesis simulations of D174A and D175A strongly indicate that the catalytic residues mainly affect the observed reaction rate by affecting the stability of the intermediate.
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Affiliation(s)
- Jing Xiong
- School of Pharmacy, Chengdu Medical College, Chengdu, Sichuan 610500, P. R. China
| | - Dingguo Xu
- MOE Key Laboratory of Green Chemistry & Technology, College of Chemistry, Sichuan University, Chengdu, Sichuan 610064, P. R. China
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15
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Sanusi ZK, Lawal MM, Gupta PL, Govender T, Baijnath S, Naicker T, Maguire GEM, Honarparvar B, Roitberg AE, Kruger HG. Exploring the concerted mechanistic pathway for HIV-1 PR-substrate revealed by umbrella sampling simulation. J Biomol Struct Dyn 2020; 40:1736-1747. [PMID: 33073714 DOI: 10.1080/07391102.2020.1832578] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
HIV-1 protease (HIV-1 PR) is an essential enzyme for the replication process of its virus, and therefore considered an important target for the development of drugs against the acquired immunodeficiency syndrome (AIDS). Our previous study shows that the catalytic mechanism of subtype B/C-SA HIV-1 PR follows a one-step concerted acyclic hydrolysis reaction process using a two-layered ONIOM B3LYP/6-31++G(d,p) method. This present work is aimed at exploring the proposed mechanism of the proteolysis catalyzed by HIV-1 PR and to ensure our proposed mechanism is not an artefact of a single theoretical technique. Hence, we present umbrella sampling method that is suitable for calculating potential mean force (PMF) for non-covalent ligand/substrate-enzyme association/dissociation interactions which provide thermodynamic details for molecular recognition. The free activation energy results were computed in terms of PMF analysis within the hybrid QM(DFTB)/MM approach. The theoretical findings suggest that the proposed mechanism corresponds in principle with experimental data. Given our observations, we suggest that the QM/MM MD method can be used as a reliable computational technique to rationalize lead compounds against specific targets such as the HIV-1 protease.
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Affiliation(s)
- Zainab K Sanusi
- Catalysis and Peptide Research Unit, School of Health Sciences, University of KwaZulu-Natal, Durban, South Africa
| | - Monsurat M Lawal
- Catalysis and Peptide Research Unit, School of Health Sciences, University of KwaZulu-Natal, Durban, South Africa
| | - Pancham Lal Gupta
- Department of Chemistry, University of Florida, Gainesville, Florida, USA
| | | | - Sooraj Baijnath
- Catalysis and Peptide Research Unit, School of Health Sciences, University of KwaZulu-Natal, Durban, South Africa
| | - Tricia Naicker
- Catalysis and Peptide Research Unit, School of Health Sciences, University of KwaZulu-Natal, Durban, South Africa
| | - Glenn E M Maguire
- Catalysis and Peptide Research Unit, School of Health Sciences, University of KwaZulu-Natal, Durban, South Africa.,School of Chemistry and Physics, University of KwaZulu-Natal, Durban, South Africa
| | - Bahareh Honarparvar
- Catalysis and Peptide Research Unit, School of Health Sciences, University of KwaZulu-Natal, Durban, South Africa
| | - Adrian E Roitberg
- Department of Chemistry, University of Florida, Gainesville, Florida, USA
| | - Hendrik G Kruger
- Catalysis and Peptide Research Unit, School of Health Sciences, University of KwaZulu-Natal, Durban, South Africa
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16
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Song Z, Zhou H, Tian H, Wang X, Tao P. Unraveling the energetic significance of chemical events in enzyme catalysis via machine-learning based regression approach. Commun Chem 2020; 3:134. [PMID: 36703376 PMCID: PMC9814854 DOI: 10.1038/s42004-020-00379-w] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Accepted: 09/11/2020] [Indexed: 01/29/2023] Open
Abstract
The bacterial enzyme class of β-lactamases are involved in benzylpenicillin acylation reactions, which are currently being revisited using hybrid quantum mechanical molecular mechanical (QM/MM) chain-of-states pathway optimizations. Minimum energy pathways are sampled by reoptimizing pathway geometry under different representative protein environments obtained through constrained molecular dynamics simulations. Predictive potential energy surface models in the reaction space are trained with machine-learning regression techniques. Herein, using TEM-1/benzylpenicillin acylation reaction as the model system, we introduce two model-independent criteria for delineating the energetic contributions and correlations in the predicted reaction space. Both methods are demonstrated to effectively quantify the energetic contribution of each chemical process and identify the rate limiting step of enzymatic reaction with high degrees of freedom. The consistency of the current workflow is tested under seven levels of quantum chemistry theory and three non-linear machine-learning regression models. The proposed approaches are validated to provide qualitative compliance with experimental mutagenesis studies.
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Affiliation(s)
- Zilin Song
- grid.263864.d0000 0004 1936 7929Department of Chemistry, Center for Research Computing, Center for Drug Discovery, Design, and Delivery (CD4), Southern Methodist University, Dallas, TX 75275 USA
| | - Hongyu Zhou
- grid.263864.d0000 0004 1936 7929Department of Chemistry, Center for Research Computing, Center for Drug Discovery, Design, and Delivery (CD4), Southern Methodist University, Dallas, TX 75275 USA
| | - Hao Tian
- grid.263864.d0000 0004 1936 7929Department of Chemistry, Center for Research Computing, Center for Drug Discovery, Design, and Delivery (CD4), Southern Methodist University, Dallas, TX 75275 USA
| | - Xinlei Wang
- grid.263864.d0000 0004 1936 7929Department of Statistical Science, Southern Methodist University, Dallas, TX 75275 USA
| | - Peng Tao
- grid.263864.d0000 0004 1936 7929Department of Chemistry, Center for Research Computing, Center for Drug Discovery, Design, and Delivery (CD4), Southern Methodist University, Dallas, TX 75275 USA
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17
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Can multiscale simulations unravel the function of metallo-enzymes to improve knowledge-based drug discovery? Future Med Chem 2019; 11:771-791. [DOI: 10.4155/fmc-2018-0495] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Metallo-enzymes are a large class of biomolecules promoting specialized chemical reactions. Quantum-classical quantum mechanics/molecular mechanics molecular dynamics, describing the metal site at quantum mechanics level, while accounting for the rest of system at molecular mechanics level, has an accessible time-scale limited by its computational cost. Hence, it must be integrated with classical molecular dynamics and enhanced sampling simulations to disentangle the functions of metallo-enzymes. In this review, we provide an overview of these computational methods and their capabilities. In particular, we will focus on some systems such as CYP19A1 a Fe-dependent enzyme involved in estrogen biosynthesis, and on Mg2+-dependent DNA/RNA processing enzymes/ribozymes and the spliceosome, a protein-directed ribozyme. This information may guide the discovery of drug-like molecules and genetic manipulation tools.
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18
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Catalysis mechanism of oxidized polyvinyl alcohol by pseudomonas hydrolase: Insights from molecular dynamics and QM/MM analysis. Chem Phys Lett 2019. [DOI: 10.1016/j.cplett.2019.02.023] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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19
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Reinhardt CR, Hu QH, Bresnahan CG, Hati S, Bhattacharyya S. Cyclic Changes in Active Site Polarization and Dynamics Drive the 'Ping-pong' Kinetics in NRH:Quinone Oxidoreductase 2: An Insight from QM/MM Simulations. ACS Catal 2018; 8:12015-12029. [PMID: 31583178 DOI: 10.1021/acscatal.8b04193] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Quinone reductases belong to the family of flavin-dependent oxidoreductases. With the redox active cofactor, flavin adenine dinucleotide, quinone reductases are known to utilize a 'ping-pong' kinetic mechanism during catalysis in which a hydride is bounced back and forth between flavin and its two substrates. However, the continuation of this catalytic cycle requires product displacement steps, where the product of one redox half-cycle is displaced by the substrate of the next half-cycle. Using improved hybrid quantum mechanical/molecular mechanical simulations, both the catalytic hydride transfer and the product displacement reactions were studied in NRH:quinone oxidoreductase 2. Initially, the self-consistent charge-density functional tight binding theory was used to describe flavin ring and the substrate atoms, while embedded in the molecular mechanically-treated solvated active site. Then, for each step of the catalytic cycle, a further improvement of energetics was made using density functional theory-based corrections. The present study showcases an integrated interplay of solvation, protonation, and protein matrix-induced polarization as the driving force behind the thermodynamic wheel of the 'ping-pong' kinetics. Reported here is the first-principles model of the 'ping-pong' kinetics that portrays how cyclic changes in the active site polarization and dynamics govern the oscillatory hydride transfer and product displacement in this enzyme.
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Affiliation(s)
- Clorice R. Reinhardt
- Department of Chemistry, University of Wisconsin-Eau Claire, Eau Claire, Wisconsin 54702, United States
| | - Quin H. Hu
- Department of Chemistry, University of Wisconsin-Eau Claire, Eau Claire, Wisconsin 54702, United States
| | - Caitlin G. Bresnahan
- Department of Chemistry, University of Wisconsin-Eau Claire, Eau Claire, Wisconsin 54702, United States
| | - Sanchita Hati
- Department of Chemistry, University of Wisconsin-Eau Claire, Eau Claire, Wisconsin 54702, United States
| | - Sudeep Bhattacharyya
- Department of Chemistry, University of Wisconsin-Eau Claire, Eau Claire, Wisconsin 54702, United States
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20
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Mu X, Xu D. QM/MM Molecular Dynamics Investigations of the Substrate Binding of Leucotriene A4 Hydrolase: Implication for the Catalytic Mechanism. J Phys Chem B 2018; 122:7253-7263. [PMID: 29965770 DOI: 10.1021/acs.jpcb.8b04203] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
LTA4H is a monozinc bifunctional enzyme which exhibits both aminopeptidase and epoxide hydrolase activities. Its dual functions in anti- and pro-inflammatory roles have attracted wide attention to the inhibitor design. In this work, we tried to construct Michaelis complexes of LTA4H with both a native peptide substrate and LTA4 molecule using combined quantum mechanics and molecular mechanics molecular dynamics simulations. First of all, the zinc ion is coordinated by H295, H299, and E318. For its aminopeptidase activity, similar to conventional peptidases, the fourth ligand to the zinc ion is suggested to be an active site water, which is further hydrogen bonded with a downstream glutamic acid, E296. For the epoxide hydrolase activity, the fourth ligand to the zinc ion is found to be an epoxy oxygen atom. The potential of mean force calculation indicates about an 8.5 kcal/mol activation barrier height for the ring-opening reaction, which will generate a metastable carbenium intermediate. Subsequent frontier molecular orbital analyses suggest that the next step would be the nucleophilic attacking reaction at the C12 atom by a water molecule activated by D375. Our simulations also analyzed functions of several important residues like R563, K565, E271, Y383, and Y378 in the binding of peptide and LTA4.
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Affiliation(s)
- Xia Mu
- MOE Key Laboratory of Green Chemistry and Technology, College of Chemistry , Sichuan University , Chengdu , Sichuan , People's Republic of China 610064
| | - Dingguo Xu
- MOE Key Laboratory of Green Chemistry and Technology, College of Chemistry , Sichuan University , Chengdu , Sichuan , People's Republic of China 610064
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21
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Pierdominici-Sottile G, Cossio-Pérez R, Da Fonseca I, Kizjakina K, Tanner JJ, Sobrado P. Steric Control of the Rate-Limiting Step of UDP-Galactopyranose Mutase. Biochemistry 2018; 57:3713-3721. [PMID: 29757624 DOI: 10.1021/acs.biochem.8b00323] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Galactose is an abundant monosaccharide found exclusively in mammals as galactopyranose (Gal p), the six-membered ring form of this sugar. In contrast, galactose appears in many pathogenic microorganisms as the five-membered ring form, galactofuranose (Gal f). Gal f biosynthesis begins with the conversion of UDP-Gal p to UDP-Gal f catalyzed by the flavoenzyme UDP-galactopyranose mutase (UGM). Because UGM is essential for the survival and proliferation of several pathogens, there is interest in understanding the catalytic mechanism to aid inhibitor development. Herein, we have used kinetic measurements and molecular dynamics simulations to explore the features of UGM that control the rate-limiting step (RLS). We show that UGM from the pathogenic fungus Aspergillus fumigatus also catalyzes the isomerization of UDP-arabinopyranose (UDP-Ara p), which differs from UDP-Gal p by lacking a -CH2-OH substituent at the C5 position of the hexose ring. Unexpectedly, the RLS changed from a chemical step for the natural substrate to product release with UDP-Ara p. This result implicated residues that contact the -CH2-OH of UDP-Gal p in controlling the mechanistic path. The mutation of one of these residues, Trp315, to Ala changed the RLS of the natural substrate to product release, similar to the wild-type enzyme with UDP-Ara p. Molecular dynamics simulations suggest that steric complementarity in the Michaelis complex is responsible for this distinct behavior. These results provide new insight into the UGM mechanism and, more generally, how steric factors in the enzyme active site control the free energy barriers along the reaction path.
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Affiliation(s)
| | - Rodrigo Cossio-Pérez
- Sci-prot. Departamento de Ciencia y Tecnología , Universidad Nacional de Quilmes , Bernal B1876BXD , Argentina
| | - Isabel Da Fonseca
- Department of Biochemistry , Virginia Tech , Blacksburg , Virginia 24061 , United States
| | - Karina Kizjakina
- Department of Biochemistry , Virginia Tech , Blacksburg , Virginia 24061 , United States
| | - John J Tanner
- Departments of Biochemistry and Chemistry , University of Missouri-Columbia , Columbia , Missouri 65211 , United States
| | - Pablo Sobrado
- Department of Biochemistry , Virginia Tech , Blacksburg , Virginia 24061 , United States
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22
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Borišek J, Pintar S, Ogrizek M, Turk D, Perdih A, Novič M. A Water-Assisted Catalytic Mechanism in Glycoside Hydrolases Demonstrated on the Staphylococcus aureus Autolysin E. ACS Catal 2018. [DOI: 10.1021/acscatal.8b01064] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Jure Borišek
- National Institute of Chemistry, Hajdrihova 19, SI-1001 Ljubljana, Slovenia
| | - Sara Pintar
- Department of Biochemistry, Molecular and Structural Biology, Jozef Stefan Institute, Jamova cesta 39, SI-1000 Ljubljana, Slovenia
- Jozef Stefan International Postgraduate School, Jamova cesta 39, SI-1000 Ljubljana, Slovenia
| | - Mitja Ogrizek
- National Institute of Chemistry, Hajdrihova 19, SI-1001 Ljubljana, Slovenia
| | - Dušan Turk
- Department of Biochemistry, Molecular and Structural Biology, Jozef Stefan Institute, Jamova cesta 39, SI-1000 Ljubljana, Slovenia
- Centre of Excellence for Integrated Approaches in Chemistry and Biology of Proteins, Jamova cesta 39, SI-1000 Ljubljana, Slovenia
| | - Andrej Perdih
- National Institute of Chemistry, Hajdrihova 19, SI-1001 Ljubljana, Slovenia
| | - Marjana Novič
- National Institute of Chemistry, Hajdrihova 19, SI-1001 Ljubljana, Slovenia
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23
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Ainsley J, Lodola A, Mulholland AJ, Christov CZ, Karabencheva-Christova TG. Combined Quantum Mechanics and Molecular Mechanics Studies of Enzymatic Reaction Mechanisms. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2018; 113:1-32. [PMID: 30149903 DOI: 10.1016/bs.apcsb.2018.07.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The combined quantum mechanics/molecular mechanics (QM/MM) methods have become a valuable tool in computational biochemistry and received versatile applications for studying the reaction mechanisms of enzymes. The approach combines the calculations of the electronic structure of the active site by QM, with modeling of the protein environment using MM force field, which allows the long-range electrostatics and steric effects on the enzyme reactivity to be accounted for. In this review, we review some key theoretical and computational aspects of the method and we also present some applications to particular enzymatic reactions such as tryptophan-7-halogenase, cyclooxygenase-1, and the epidermal growth factor receptor.
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Affiliation(s)
- Jon Ainsley
- Department of Applied Sciences, Faculty of Health and Life Sciences, Northumbria University, Newcastle upon Tyne, United Kingdom
| | | | - Adrian J Mulholland
- Centre for Computational Chemistry, School of Chemistry, University of Bristol, Bristol, United Kingdom
| | - Christo Z Christov
- Department of Chemistry, Michigan Technological University, Houghton, MI, United States.
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24
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Jitonnom J, Mujika JI, van der Kamp MW, Mulholland AJ. Quantum Mechanics/Molecular Mechanics Simulations Identify the Ring-Opening Mechanism of Creatininase. Biochemistry 2017; 56:6377-6388. [PMID: 29140090 DOI: 10.1021/acs.biochem.7b01032] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Creatininase catalyzes the conversion of creatinine (a biosensor for kidney function) to creatine via a two-step mechanism: water addition followed by ring opening. Water addition is common to other known cyclic amidohydrolases, but the precise mechanism for ring opening is still under debate. The proton donor in this step is either His178 or a water molecule bound to one of the metal ions, and the roles of His178 and Glu122 are unclear. Here, the two possible reaction pathways have been fully examined by means of combined quantum mechanics/molecular mechanics simulations at the SCC-DFTB/CHARMM22 level of theory. The results indicate that His178 is the main catalytic residue for the whole reaction and explain its role as proton shuttle during the ring-opening step. In the first step, His178 provides electrostatic stabilization to the gem-diolate tetrahedral intermediate. In the second step, His178 abstracts the hydroxyl proton of the intermediate and delivers it to the cyclic amide nitrogen, leading to ring opening. The latter is the rate-limiting step with a free energy barrier of 18.5 kcal/mol, in agreement with the experiment. We find that Glu122 must be protonated during the enzyme reaction, so that it can form a stable hydrogen bond with its neighboring water molecule. Simulations of the E122Q mutant showed that this replacement disrupts the H-bond network formed by three conserved residues (Glu34, Ser78, and Glu122) and water, increasing the energy barrier. Our computational studies provide a comprehensive explanation for previous structural and kinetic observations, including why the H178A mutation causes a complete loss of activity but the E122Q mutation does not.
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Affiliation(s)
- Jitrayut Jitonnom
- Division of Chemistry, School of Science, University of Phayao , Phayao 56000, Thailand
| | - Jon I Mujika
- Kimika Fakultatea, Euskal Herriko Unibertsitatea UPV/EHU, and Donostia International Physics Center (DIPC) , P.K. 1072, 20080 Donostia, Euskadi, Spain
| | - Marc W van der Kamp
- School of Biochemistry, University of Bristol , Biomedical Sciences Building, University Walk, Bristol BS8 1TD, U.K
- Centre for Computational Chemistry, School of Chemistry, University of Bristol , Bristol BS8 1TS, U.K
| | - Adrian J Mulholland
- Centre for Computational Chemistry, School of Chemistry, University of Bristol , Bristol BS8 1TS, U.K
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25
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Ojeda-May P, Nam K. Acceleration of Semiempirical QM/MM Methods through Message Passage Interface (MPI), Hybrid MPI/Open Multiprocessing, and Self-Consistent Field Accelerator Implementations. J Chem Theory Comput 2017. [PMID: 28628742 DOI: 10.1021/acs.jctc.7b00322] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The strategy and implementation of scalable and efficient semiempirical (SE) QM/MM methods in CHARMM are described. The serial version of the code was first profiled to identify routines that required parallelization. Afterward, the code was parallelized and accelerated with three approaches. The first approach was the parallelization of the entire QM/MM routines, including the Fock matrix diagonalization routines, using the CHARMM message passage interface (MPI) machinery. In the second approach, two different self-consistent field (SCF) energy convergence accelerators were implemented using density and Fock matrices as targets for their extrapolations in the SCF procedure. In the third approach, the entire QM/MM and MM energy routines were accelerated by implementing the hybrid MPI/open multiprocessing (OpenMP) model in which both the task- and loop-level parallelization strategies were adopted to balance loads between different OpenMP threads. The present implementation was tested on two solvated enzyme systems (including <100 QM atoms) and an SN2 symmetric reaction in water. The MPI version exceeded existing SE QM methods in CHARMM, which include the SCC-DFTB and SQUANTUM methods, by at least 4-fold. The use of SCF convergence accelerators further accelerated the code by ∼12-35% depending on the size of the QM region and the number of CPU cores used. Although the MPI version displayed good scalability, the performance was diminished for large numbers of MPI processes due to the overhead associated with MPI communications between nodes. This issue was partially overcome by the hybrid MPI/OpenMP approach which displayed a better scalability for a larger number of CPU cores (up to 64 CPUs in the tested systems).
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Affiliation(s)
| | - Kwangho Nam
- Department of Chemistry and Biochemistry, University of Texas at Arlington , Arlington, Texas 76019-0065, United States
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26
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White JK, Handa S, Vankayala SL, Merkler DJ, Woodcock HL. Thiamin Diphosphate Activation in 1-Deoxy-d-xylulose 5-Phosphate Synthase: Insights into the Mechanism and Underlying Intermolecular Interactions. J Phys Chem B 2016; 120:9922-34. [PMID: 27537621 PMCID: PMC5379999 DOI: 10.1021/acs.jpcb.6b07248] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
1-Deoxy-d-xylulose 5-phosphate synthase (DXS) is a thiamin diphosphate (TDP) dependent enzyme that marks the beginning of the methylerythritol 4-phosphate isoprenoid biosynthesis pathway. The mechanism of action for DXS is still poorly understood and begins with the formation of a thiazolium ylide. This TDP activation step is thought to proceed through an intramolecular deprotonation by the 4'-aminopyrimidine ring of TDP; however, this step would occur only after an initial deprotonation of its own 4'-amino group. The mechanism of the initial deprotonation has been hypothesized, by analogy to transketolases, to occur via a histidine or an active site water molecule. Results from hybrid quantum mechanical/molecular mechanical (QM/MM) reaction path calculations reveal an ∼10 kcal/mol difference in transition state energies, favoring a water mediated mechanism over direct deprotonation by histidine. This difference was determined to be largely governed by electrostatic changes induced by conformational variations in the active site. Additionally, mutagenesis studies reveal DXS to be an evolutionarily resilient enzyme. Particularly, we hypothesize that residues H82 and H304 may act in a compensatory fashion if the other is lost due to mutation. Further, nucleus-independent chemical shifts (NICSs) and aromatic stabilization energy (ASE) calculations suggest that reduction in TDP aromaticity also serves as a factor for regulating ylide formation and controlling reactivity.
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Affiliation(s)
- Justin K. White
- Department of Chemistry, University of South Florida, 4202 E. Fowler Avenue, CHE205, Tampa, Florida 33620-5250, United States
| | - Sumit Handa
- Department of Chemistry, University of South Florida, 4202 E. Fowler Avenue, CHE205, Tampa, Florida 33620-5250, United States
- Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0332, United States
| | - Sai Lakshmana Vankayala
- Department of Chemistry, University of South Florida, 4202 E. Fowler Avenue, CHE205, Tampa, Florida 33620-5250, United States
| | - David J. Merkler
- 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
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Ogrizek M, Konc J, Bren U, Hodošček M, Janežič D. Role of magnesium ions in the reaction mechanism at the interface between Tm1631 protein and its DNA ligand. Chem Cent J 2016; 10:41. [PMID: 27398092 PMCID: PMC4939058 DOI: 10.1186/s13065-016-0188-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2016] [Accepted: 06/27/2016] [Indexed: 12/24/2022] Open
Abstract
A protein, Tm1631 from the hyperthermophilic organism Thermotoga maritima belongs to a domain of unknown function protein family. It was predicted that Tm1631 binds with the DNA and that the Tm1631–DNA complex is an endonuclease repair system with a DNA repair function (Konc et al. PLoS Comput Biol 9(11): e1003341, 2013). We observed that the severely bent, strained DNA binds to the protein for the entire 90 ns of classical molecular dynamics (MD) performed; we could observe no significant changes in the most distorted region of the DNA, where the cleavage of phosphodiester bond occurs. In this article, we modeled the reaction mechanism at the interface between Tm1631 and its proposed ligand, the DNA molecule, focusing on cleavage of the phosphodiester bond. After addition of two Mg2+ ions to the reaction center and extension of classical MD by 50 ns (totaling 140 ns), the DNA ligand stayed bolted to the protein. Results from density functional theory quantum mechanics/molecular mechanics (QM/MM) calculations suggest that the reaction is analogous to known endonuclease mechanisms: an enzyme reaction mechanism with two Mg2+ ions in the reaction center and a pentacovalent intermediate. The minimum energy pathway profile shows that the phosphodiester bond cleavage step of the reaction is kinetically controlled and not thermodynamically because of a lack of any energy barrier above the accuracy of the energy profile calculation. The role of ions is shown by comparing the results with the reaction mechanisms in the absence of the Mg2+ ions where there is a significantly higher reaction barrier than in the presence of the Mg2+ ions.A protein, Tm1631 from the hyperthermophilic organism Thermotoga maritima belongs to a domain of unknown function protein family. We modeled the reaction mechanism at the interface between Tm1631 and its proposed ligand, the DNA molecule, focusing on cleavage of the phosphodiester bond ![]()
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Affiliation(s)
- Mitja Ogrizek
- National Institute of Chemistry, Hajdrihova 19, 1000 Ljubljana, Slovenia
| | - Janez Konc
- National Institute of Chemistry, Hajdrihova 19, 1000 Ljubljana, Slovenia ; Laboratory for Physical Chemistry and Thermodynamics, Faculty of Chemistry and Chemical Technology, University of Maribor, Smetanova ulica 17, 2000 Maribor, Slovenia ; Faculty of Mathematics, Natural Sciences and Information Technologies, University of Primorska, Glagoljaška 8, 6000 Koper, Slovenia
| | - Urban Bren
- National Institute of Chemistry, Hajdrihova 19, 1000 Ljubljana, Slovenia ; Laboratory for Physical Chemistry and Thermodynamics, Faculty of Chemistry and Chemical Technology, University of Maribor, Smetanova ulica 17, 2000 Maribor, Slovenia ; Faculty of Mathematics, Natural Sciences and Information Technologies, University of Primorska, Glagoljaška 8, 6000 Koper, Slovenia
| | - Milan Hodošček
- National Institute of Chemistry, Hajdrihova 19, 1000 Ljubljana, Slovenia
| | - Dušanka Janežič
- Faculty of Mathematics, Natural Sciences and Information Technologies, University of Primorska, Glagoljaška 8, 6000 Koper, Slovenia
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28
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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.
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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.
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29
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Mu X, Zhang C, Xu D. QM/MM investigation of the catalytic mechanism of angiotensin-converting enzyme. J Mol Model 2016; 22:132. [PMID: 27184002 DOI: 10.1007/s00894-016-3004-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2016] [Accepted: 05/02/2016] [Indexed: 10/21/2022]
Abstract
Angiotensin-converting enzyme (ACE) converts angiotensin I to angiotensin II and degrades bradykinin and other vasoactive peptides. ACE inhibitors are used to treat diseases such as hypertension and heart failure. It is thus highly desirable to understand the catalytic mechanism of ACE, as this should facilitate the design of more powerful and selective ACE inhibitors. ACE exhibits two different active domains, the C-domain and the N-domain. In this work, we systematically investigated the inhibitor- and substrate-binding patterns in the N-domain of human ACE using a combined quantum mechanical and molecular mechanical approach. The hydrolysis of hippuryl-histidyl-leucine (HHL) as catalyzed by the N-domain of human somatic ACE was explored, and the effects of chloride ion on the overall reaction were also investigated. Two models, one with and one without a chloride ion at the first binding position, were then designed to examine the chloride dependence of inhibitor-substrate binding and the catalytic mechanism. Our calculations indicate that the hydrolysis reaction follows a stepwise general base/general acid catalysis path. The estimated mean free energy barrier height in the two models is about 15.6 kcal/mol, which agrees very well with the experimentally estimated value of 15.8 kcal/mol. Our simulations thus suggest that the N-domain is in a mixed form during ACE-catalyzed hydrolysis, with the single-chloride-ion and the double-chloride-ion forms existing simultaneously. Graphical Abstract Superposition of ACE C- and N- domains.
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Affiliation(s)
- Xia Mu
- MOE Key Laboratory of Green Chemistry, College of Chemistry, Sichuan University, Chengdu, Sichuan, 610064, People's Republic of China
| | - Chunchun Zhang
- Analytical & Testing Center, Sichuan University, Chengdu, Sichuan, 610064, People's Republic of China
| | - Dingguo Xu
- MOE Key Laboratory of Green Chemistry, College of Chemistry, Sichuan University, Chengdu, Sichuan, 610064, People's Republic of China. .,Geonome Research Center for Biomaterials, Sichuan University, Chengdu, Sichuan, 610064, People's Republic of China.
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30
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Ramírez C, Martí M, Roitberg A. Steered Molecular Dynamics Methods Applied to Enzyme Mechanism and Energetics. Methods Enzymol 2016; 578:123-43. [DOI: 10.1016/bs.mie.2016.05.029] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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31
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Chou CP, Nishimura Y, Fan CC, Mazur G, Irle S, Witek HA. Automatized Parameterization of DFTB Using Particle Swarm Optimization. J Chem Theory Comput 2015; 12:53-64. [DOI: 10.1021/acs.jctc.5b00673] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Chien-Pin Chou
- Department
of Applied Chemistry and Institute of Molecular Science, National Chiao Tung University, Hsinchu 30010, Taiwan
| | - Yoshifumi Nishimura
- Department
of Applied Chemistry and Institute of Molecular Science, National Chiao Tung University, Hsinchu 30010, Taiwan
| | - Chin-Chai Fan
- Department
of Applied Chemistry and Institute of Molecular Science, National Chiao Tung University, Hsinchu 30010, Taiwan
| | - Grzegorz Mazur
- K. Gumiński
Department of Theoretical Chemistry, Jagiellonian University, Ingardena
3, 30-060 Cracow, Poland
| | | | - Henryk A. Witek
- Department
of Applied Chemistry and Institute of Molecular Science, National Chiao Tung University, Hsinchu 30010, Taiwan
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32
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Nichols DA, Hargis JC, Sanishvili R, Jaishankar P, Defrees K, Smith E, Wang KK, Prati F, Renslo AR, Woodcock HL, Chen Y. Ligand-Induced Proton Transfer and Low-Barrier Hydrogen Bond Revealed by X-ray Crystallography. J Am Chem Soc 2015; 137:8086-95. [PMID: 26057252 PMCID: PMC4530788 DOI: 10.1021/jacs.5b00749] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Ligand binding can change the pKa of protein residues and influence enzyme catalysis. Herein, we report three ultrahigh resolution X-ray crystal structures of CTX-M β-lactamase, directly visualizing protonation state changes along the enzymatic pathway: apo protein at 0.79 Å, precovalent complex with nonelectrophilic ligand at 0.89 Å, and acylation transition state (TS) analogue at 0.84 Å. Binding of the noncovalent ligand induces a proton transfer from the catalytic Ser70 to the negatively charged Glu166, and the formation of a low-barrier hydrogen bond (LBHB) between Ser70 and Lys73, with a length of 2.53 Å and the shared hydrogen equidistant from the heteroatoms. QM/MM reaction path calculations determined the proton transfer barrier to be 1.53 kcal/mol. The LBHB is absent in the other two structures although Glu166 remains neutral in the covalent complex. Our data represents the first X-ray crystallographic example of a hydrogen engaged in an enzymatic LBHB, and demonstrates that desolvation of the active site by ligand binding can provide a protein microenvironment conducive to LBHB formation. It also suggests that LBHBs may contribute to stabilization of the TS in general acid/base catalysis together with other preorganized features of enzyme active sites. These structures reconcile previous experimental results suggesting alternatively Glu166 or Lys73 as the general base for acylation, and underline the importance of considering residue protonation state change when modeling protein-ligand interactions. Additionally, the observation of another LBHB (2.47 Å) between two conserved residues, Asp233 and Asp246, suggests that LBHBs may potentially play a special structural role in proteins.
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Affiliation(s)
- Derek A. Nichols
- University of South Florida College of Medicine, Dept of Molecular Medicine, 12901 Bruce B. Downs Blvd, MDC 3522, Tampa, FL 33612
| | | | - Ruslan Sanishvili
- GMCA@APS, X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439
| | - Priyadarshini Jaishankar
- Department of Pharmaceutical Chemistry and Small Molecule Discovery Center, University of California San Francisco, 1700 4 Street, Byers Hall S504, San Francisco, CA 94158
| | - Kyle Defrees
- Department of Pharmaceutical Chemistry and Small Molecule Discovery Center, University of California San Francisco, 1700 4 Street, Byers Hall S504, San Francisco, CA 94158
| | - Emmanuel Smith
- University of South Florida College of Medicine, Dept of Molecular Medicine, 12901 Bruce B. Downs Blvd, MDC 3522, Tampa, FL 33612
| | - Kenneth K. Wang
- Department of Chemistry, University of South Florida, Tampa, Florida 33620
| | - Fabio Prati
- Department of Life Sciences, University of Modena and Reggio Emilia, Italy
| | - Adam R. Renslo
- Department of Pharmaceutical Chemistry and Small Molecule Discovery Center, University of California San Francisco, 1700 4 Street, Byers Hall S504, San Francisco, CA 94158
| | - H. Lee Woodcock
- Department of Chemistry, University of South Florida, Tampa, Florida 33620
| | - Yu Chen
- University of South Florida College of Medicine, Dept of Molecular Medicine, 12901 Bruce B. Downs Blvd, MDC 3522, Tampa, FL 33612
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Alves CN, Silva JRA, Roitberg AE. Insights into the mechanism of oxidation of dihydroorotate to orotate catalysed by human class 2 dihydroorotate dehydrogenase: a QM/MM free energy study. Phys Chem Chem Phys 2015; 17:17790-6. [PMID: 26087682 DOI: 10.1039/c5cp02016f] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The dihydroorotate dehydrogenase (DHOD) enzyme catalyzes the unique redox reaction in the de novo pyrimidine biosynthesis pathway. In this reaction, the oxidation of dihydroorotate (DHO) to orotate (OA) and reduction of the flavin mononucleotide (FMN) cofactor is catalysed by DHOD. The class 2 DHOD, to which the human enzyme belongs, was experimentally shown to follow a stepwise mechanism but the data did not allow the determination of the order of bond-breaking in a stepwise oxidation of DHO. The goal of this study is to understand the reaction mechanism at the molecular level of class 2 DHOD, which may aid in the design of inhibitors that selectively impact the activity of only certain members of the enzyme family. In this paper, the catalytic mechanism of oxidation of DHO to OA in human DHOD was studied using a hybrid Quantum Mechanical/Molecular Mechanical (QM/MM) approach and Molecular Dynamics (MD) simulations. The free energy barriers calculated reveal that the mechanism in human DHOD occurs via a stepwise reaction pathway. In the first step, a proton is abstracted from the C5 of DHO to the deprotonated Ser215 side chain. Whereas, in the second step, the transfer of the hydride or hydride equivalent from the C6 of DHO to the N5 of FMN, where free energy barrier calculated by the DFT/MM level is 10.84 kcal mol(-1). Finally, a residual decomposition analysis was carried out in order to elucidate the influence of the catalytic region residues during DHO oxidation.
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Affiliation(s)
- Cláudio Nahum Alves
- Laboratório de Planejamento e Desenvolvimento de Fármacos, Instituto de Ciências Exatas e Naturais, Universidade Federal do Pará, Belém, Brazil. mail:
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Domínguez A, Niehaus TA, Frauenheim T. Accurate hydrogen bond energies within the density functional tight binding method. J Phys Chem A 2015; 119:3535-44. [PMID: 25763597 DOI: 10.1021/acs.jpca.5b01732] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The density-functional-based tight-binding (DFTB) approach has been recently extended by incorporating one-center exchange-like terms in the expansion of the multicenter integrals. This goes beyond the Mulliken approximation and leads to a scheme which treats in a self-consistent way the fluctuations of the whole dual density matrix and not only its diagonal elements (Mulliken charges). To date, only the performance of this new formalism to reproduce excited-state properties has been assessed (Domínguez et al. J. Chem. Theory Comput., 2013, 9, 4901-4914). Here we study the effect of our corrections on the computation of hydrogen bond energies for water clusters and water-containing systems. The limitations of traditional DFTB to reproduce hydrogen bonds has been acknowledged often. We compare our results for a set of 22 small water clusters and water-containing systems as well as for five water hexadecamers to those obtained with the DFTB3 method. Additionally, we combine our extension with a third-order energy expansion in the charge fluctuations. Our results show that the new formalisms significantly improve upon original DFTB.
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Affiliation(s)
- A Domínguez
- †Bremen Center for Computational Materials Science, Universität Bremen, Am Fallturm 1, 28359 Bremen, Germany
| | - T A Niehaus
- ‡Department of Theoretical Physics, University of Regensburg, 93040 Regensburg, Germany
| | - T Frauenheim
- †Bremen Center for Computational Materials Science, Universität Bremen, Am Fallturm 1, 28359 Bremen, Germany
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35
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Capoferri L, Lodola A, Rivara S, Mor M. Quantum mechanics/molecular mechanics modeling of covalent addition between EGFR-cysteine 797 and N-(4-anilinoquinazolin-6-yl) acrylamide. J Chem Inf Model 2015; 55:589-99. [PMID: 25658136 DOI: 10.1021/ci500720e] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Irreversible epidermal growth factor receptor (EGFR) inhibitors can circumvent resistance to first-generation ATP-competitive inhibitors in the treatment of nonsmall-cell lung cancer. They covalently bind a noncatalytic cysteine (Cys797) at the surface of EGFR active site by an acrylamide warhead. Herein, we used a hybrid quantum mechanics/molecular mechanics (QM/MM) potential in combination with umbrella sampling in the path-collective variable space to investigate the mechanism of alkylation of Cys797 by the prototypical covalent inhibitor N-(4-anilinoquinazolin-6-yl) acrylamide. Calculations show that Cys797 reacts with the acrylamide group of the inhibitor through a direct addition mechanism, with Asp800 acting as a general base/general acid in distinct steps of the reaction. The obtained reaction free energy is negative (ΔA = -12 kcal/mol) consistent with the spontaneous and irreversible alkylation of Cys797 by N-(4-anilinoquinazolin-6-yl) acrylamide. Our calculations identify desolvation of Cys797 thiolate anion as a key step of the alkylation process, indicating that changes in the intrinsic reactivity of the acrylamide would have only a minor impact on the inhibitor potency.
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Affiliation(s)
- Luigi Capoferri
- Dipartimento di Farmacia, Università degli Studi di Parma, Viale delle Scienze 27/A, I-43124, Parma, Italy
| | - Alessio Lodola
- Dipartimento di Farmacia, Università degli Studi di Parma, Viale delle Scienze 27/A, I-43124, Parma, Italy
| | - Silvia Rivara
- Dipartimento di Farmacia, Università degli Studi di Parma, Viale delle Scienze 27/A, I-43124, Parma, Italy
| | - Marco Mor
- Dipartimento di Farmacia, Università degli Studi di Parma, Viale delle Scienze 27/A, I-43124, Parma, Italy
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36
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Kaiyawet N, Lonsdale R, Rungrotmongkol T, Mulholland AJ, Hannongbua S. High-level QM/MM calculations support the concerted mechanism for Michael addition and covalent complex formation in thymidylate synthase. J Chem Theory Comput 2015; 11:713-22. [PMID: 26579604 DOI: 10.1021/ct5005033] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Thymidylate synthase (TS) is a promising cancer target, due to its crucial function in thymine synthesis. It performs the reductive methylation of 2'-deoxyuridine-5'-phosphate (dUMP) to thymidine-5'-phosphate (dTMP), using N-5,10-methylene-5,6,7,8-tetrahydrofolate (mTHF) as a cofactor. After the formation of the dUMP/mTHF/TS noncovalent complex, and subsequent conformational activation, this complex has been proposed to react via nucleophilic attack (Michael addition) by Cys146, followed by methylene-bridge formation to generate the ternary covalent intermediate. Herein, QM/MM (B3LYP-D/6-31+G(d)-CHARMM27) methods are used to model the formation of the ternary covalent intermediate. A two-dimensional potential energy surface reveals that the methylene-bridged intermediate is formed via a concerted mechanism, as indicated by a single transition state on the minimum energy pathway and the absence of a stable enolate intermediate. A range of different QM methods (B3LYP, MP2 and SCS-MP2, and different basis sets) are tested for the calculation of the activation energy barrier for the formation of the methylene-bridged intermediate. We test convergence of the QM/MM results with respect to size of the QM region. Inclusion of Arg166, which interacts with the nucleophilic thiolate, in the QM region is important for reliable results; the MM model apparently does not reproduce energies for distortion of the guanidinium side chain correctly. The spin component scaled-Møller-Plessett perturbation theory (SCS-MP2) approach was shown to be in best agreement (within 1.1 kcal/mol) while the results obtained with MP2 and B3LYP also yielded acceptable values (deviating by less than 3 kcal/mol) compared with the barrier derived from experiment. Our results indicate that using a dispersion-corrected DFT method, or a QM method with an accurate treatment of electron correlation, increases the agreement between the calculated and experimental activation energy barriers, compared with the semiempirical AM1 method. These calculations provide important insight into the reaction mechanism of TS and may be useful in the design of new TS inhibitors.
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Affiliation(s)
| | - Richard Lonsdale
- Centre for Computational Chemistry, School of Chemistry, University of Bristol , Bristol, BS8 1TS, United Kingdom
| | | | - Adrian J Mulholland
- Centre for Computational Chemistry, School of Chemistry, University of Bristol , Bristol, BS8 1TS, United Kingdom
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37
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Silva JRA, Roitberg AE, Alves CN. A QM/MM free energy study of the oxidation mechanism of dihydroorotate dehydrogenase (class 1A) from Lactococcus lactis. J Phys Chem B 2015; 119:1468-73. [PMID: 25564307 DOI: 10.1021/jp512860r] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The dihydroorotate dehydrogenase (DHOD) class 1A enzyme catalyzes is the only redox enzyme in the biosynthetic pathway (de novo) of pyrimidines where dihydroorotate (DHO) is oxidized to orotate (OA) coupled to reduction of a flavin mononucleotide (FMN) cofactor. The rupture of two DHO C-H bonds can proceed in a concerted or stepwise way. Herein, the catalytic mechanism of DHOD from Lactococcus lactis involving DHO oxidation (first half-reaction) was described using a hybrid quantum mechanics/molecular mechanics (QM/MM) approach and molecular dynamics simulations. The free energy profile obtained from self-consistent charge-density functional tight binding/molecular mechanics calculations (corrected by DFT/MM) reveals that this occurs with the proton abstraction from DHO C5 to Cys130 deprotonated and DHO H6 is transferred to FMN N5 in a concerted mechanism with a very low barrier of 5.64 kcal/mol. Finally, through a residual decomposition analysis, the residues that have the main influence on the redox reaction were identified.
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Affiliation(s)
- José Rogério A Silva
- Laboratório de Planejamento e Desenvolvimento de Fármacos, Instituto de Ciências Exatas e Naturais, Universidade Federal do Pará , Belém, PA 66075-110, Brazil
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38
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Wang J, Wang W, Liu C, Zhao Y, Cao H, Liu Y, Liu R. Theoretical identification on the role of Lys15 for Sulfolobus tokodaii hexokinase. RSC Adv 2015. [DOI: 10.1039/c4ra16652c] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
QM/MM studies indicate that the phosphate transfer process is rate-determining, while the existence of K15 facilitates the reaction to proceed.
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Affiliation(s)
- Jinhu Wang
- School of Environmental Science and Engineering
- Shandong University
- Jinan 250100
- China
- College of Chemistry Chemical Engineering and Material Science
| | - Wen Wang
- College of Chemistry Chemical Engineering and Material Science
- Zaozhuang University
- Zaozhuang
- China
| | - Chunli Liu
- College of Chemistry Chemical Engineering and Material Science
- Zaozhuang University
- Zaozhuang
- China
| | - Yuliang Zhao
- College of Chemistry Chemical Engineering and Material Science
- Zaozhuang University
- Zaozhuang
- China
| | - Han Cao
- College of Chemistry Chemical Engineering and Material Science
- Zaozhuang University
- Zaozhuang
- China
| | - Yongjun Liu
- Key Lab of Theoretical and Computational Chemistry in University of Shandong
- School of Chemistry and Chemical Engineering
- Shandong University
- Jinan
- China
| | - Rutao Liu
- School of Environmental Science and Engineering
- Shandong University
- Jinan 250100
- China
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39
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Chudyk EI, Limb MAL, Jones C, Spencer J, van der Kamp MW, Mulholland AJ. QM/MM simulations as an assay for carbapenemase activity in class A β-lactamases. Chem Commun (Camb) 2014; 50:14736-9. [PMID: 25321894 DOI: 10.1039/c4cc06495j] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Carbapenems, 'last resort' antibiotics for many bacterial infections, can now be broken down by several class A β-lactamases (i.e. carbapenemases). Here, carbapenemase activity is predicted through QM/MM dynamics simulations of acyl-enzyme deacylation, requiring only the 3D structure of the apo-enzyme. This may assist in anticipating resistance and future antibiotic design.
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Affiliation(s)
- Ewa I Chudyk
- Centre for Computational Chemistry, School of Chemistry, University of Bristol, Cantock's Close, Bristol, BS8 1TS, UK.
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40
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Investigation of the rescue mechanism catalyzed by a nucleophile mutant of rice BGlu1. J Mol Graph Model 2014; 54:100-6. [PMID: 25459761 DOI: 10.1016/j.jmgm.2014.10.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2014] [Revised: 09/30/2014] [Accepted: 10/08/2014] [Indexed: 11/22/2022]
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41
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Pierdominici-Sottile G, Cossio Pérez R, Galindo JF, Palma J. QM/MM molecular dynamics study of the galactopyranose → galactofuranose reaction catalysed by Trypanosoma cruzi UDP-galactopyranose mutase. PLoS One 2014; 9:e109559. [PMID: 25299056 PMCID: PMC4192007 DOI: 10.1371/journal.pone.0109559] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2014] [Accepted: 08/25/2014] [Indexed: 12/18/2022] Open
Abstract
The enzyme UDP-Galactopyranose Mutase (UGM) catalyses the conversion of galactopyranose into galactofuranose. It is known to be critical for the survival and proliferation of several pathogenic agents, both prokaryotic and eukaryotic. Among them is Trypanosoma cruzi, the parasite responsible for Chagas' disease. Since the enzyme is not present in mammals, it appears as a promising target for the design of drugs to treat this illness. A precise knowledge of the mechanism of the catalysed reaction would be crucial to assist in such design. In this article we present a detailed study of all the putative steps of the mechanism. The study is based on QM/MM free energy calculations along properly selected reaction coordinates, and on the analysis of the main structural changes and interactions taking place at every step. The results are discussed in connection with the experimental evidence and previous theoretical studies.
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Affiliation(s)
| | - Rodrigo Cossio Pérez
- Departamento de Ciencia y Tecnología, Universidad Nacional de Quilmes, Bernal, Argentina
| | - Johan F. Galindo
- Quantum and Computational Chemistry Group, Departamento de Química, Universidad Nacional de Colombia, Bogotá, Colombia
| | - Juliana Palma
- Departamento de Ciencia y Tecnología, Universidad Nacional de Quilmes, Bernal, Argentina
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Hudson PS, White JK, Kearns FL, Hodoscek M, Boresch S, Lee Woodcock H. Efficiently computing pathway free energies: New approaches based on chain-of-replica and Non-Boltzmann Bennett reweighting schemes. Biochim Biophys Acta Gen Subj 2014; 1850:944-953. [PMID: 25239198 DOI: 10.1016/j.bbagen.2014.09.016] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2014] [Revised: 09/09/2014] [Accepted: 09/10/2014] [Indexed: 11/25/2022]
Abstract
BACKGROUND Accurately modeling condensed phase processes is one of computation's most difficult challenges. Include the possibility that conformational dynamics may be coupled to chemical reactions, where multiscale (i.e., QM/MM) methods are needed, and this task becomes even more daunting. METHODS Free energy simulations (i.e., molecular dynamics), multiscale modeling, and reweighting schemes. RESULTS Herein, we present two new approaches for mitigating the aforementioned challenges. The first is a new chain-of-replica method (off-path simulations, OPS) for computing potentials of mean force (PMFs) along an easily defined reaction coordinate. This development is coupled with a new distributed, highly-parallel replica framework (REPDstr) within the CHARMM package. Validation of these new schemes is carried out on two processes that undergo conformational changes. First is the simple torsional rotation of butane, while a much more challenging glycosidic rotation (in vacuo and solvated) is the second. Additionally, a new approach that greatly improves (i.e., possibly an order of magnitude) the efficiency of computing QM/MM PMFs is introduced and compared to standard schemes. Our efforts are grounded in the recently developed method for efficiently computing QM-based free energies (i.e., QM-Non-Boltzmann Bennett, QM-NBB). Again, we validate this new technique by computing the QM/MM PMF of butane's torsional rotation. CONCLUSIONS The OPS-REPDstr method is a promising new approach that overcomes many limitations of standard pathway simulations in CHARMM. The combination of QM-NBB with pathway techniques is very promising as it offers significant advantages over current procedures. GENERAL SIGNIFICANCE Efficiently computing potentials of mean force is a major, unresolved, area of interest. This article is part of a Special Issue entitled Recent developments of molecular dynamics.
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Affiliation(s)
- Phillip S Hudson
- Department of Chemistry, University of South Florida, 4202 E. Fowler Ave., CHE205, Tampa, FL 33620-5250, USA
| | - Justin K White
- Department of Chemistry, University of South Florida, 4202 E. Fowler Ave., CHE205, Tampa, FL 33620-5250, USA
| | - Fiona L Kearns
- Department of Chemistry, University of South Florida, 4202 E. Fowler Ave., CHE205, Tampa, FL 33620-5250, USA
| | - Milan Hodoscek
- Center for Molecular Modeling, National Institute of Chemistry, Hajdrihova 19, SI-1000 Ljubljana, Slovenia
| | - 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 Ave., CHE205, Tampa, FL 33620-5250, USA.
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43
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Silva JRA, Roitberg AE, Alves CN. Catalytic mechanism of L,D-transpeptidase 2 from Mycobacterium tuberculosis described by a computational approach: insights for the design of new antibiotics drugs. J Chem Inf Model 2014; 54:2402-10. [PMID: 25149147 DOI: 10.1021/ci5003069] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Tuberculosis is perhaps the most persistent human disease caused by an infections bacterium, Mycobacterium tuberculosis. The L,D-transpeptidase enzyme catalyzes the formation of 3 → 3 peptidoglycan cross-links of the Mtb cell wall and facilitates resistance against classical β-lactams. Herein, the experimentally proposed mechanism for LdtMt2 was studied by performing QM/MM MD simulations. The whole mechanistic process includes two stages: acylation and deacylation. During the acylation step, two steps were observed: the first step is a thiolate/imidazole ion-pair in the zwitterionic form, and the second step is the nucleophilic attack on the carboxyl carbon of the natural substrate accompanied by the breaking of the peptide bond on substrate. In the deacylation step the acyl-enzyme suffers a nucleophilic attack on the carboxyl carbon by the amine group of the second substrate. Our free energy results obtained by PMF analysis reveal that the first step (acylation) is the rate-limiting step in the whole catalytic mechanism in accordance with the experimental proposal. Also, the residues responsible for binding of the substrate and transition state stabilization were identified by energy decomposition methods.
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Affiliation(s)
- José Rogério A Silva
- Laboratório de Planejamento e Desenvolvimento de Fármacos, Instituto de Ciências Exatas e Naturais, Universidade Federal do Pará , Belém, PA 66075-110, Brazil
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Bueren-Calabuig JA, Pierdominici-Sottile G, Roitberg AE. Unraveling the differences of the hydrolytic activity of Trypanosoma cruzi trans-sialidase and Trypanosoma rangeli sialidase: a quantum mechanics-molecular mechanics modeling study. J Phys Chem B 2014; 118:5807-16. [PMID: 24814976 PMCID: PMC4051249 DOI: 10.1021/jp412294r] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Revised: 05/08/2014] [Indexed: 12/02/2022]
Abstract
Chagas' disease, also known as American trypanosomiasis, is a lethal, chronic disease that currently affects more than 10 million people in Central and South America. The trans-sialidase from Trypanosoma cruzi (T. cruzi, TcTS) is a crucial enzyme for the survival of this parasite: sialic acids from the host are transferred to the cell surface glycoproteins of the trypanosome, thereby evading the host's immune system. On the other hand, the sialidase of T. rangeli (TrSA), which shares 70% sequence identity with TcTS, is a strict hydrolase and shows no trans-sialidase activity. Therefore, TcTS and TrSA represent an excellent framework to understand how different catalytic activities can be achieved with extremely similar structures. By means of combined quantum mechanics-molecular mechanics (QM/MM, SCC-DFTB/Amberff99SB) calculations and umbrella sampling simulations, we investigated the hydrolysis mechanisms of TcTS and TrSA and computed the free energy profiles of these reactions. The results, together with our previous computational investigations, are able to explain the catalytic mechanism of sialidases and describe how subtle differences in the active site make TrSA a strict hydrolase and TcTS a more efficient trans-sialidase.
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Affiliation(s)
- Juan A. Bueren-Calabuig
- Department
of Chemistry, Quantum Theory Project, University
of Florida, Gainesville, Florida 32611, United
States
| | | | - Adrian E. Roitberg
- Department
of Chemistry, Quantum Theory Project, University
of Florida, Gainesville, Florida 32611, United
States
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45
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Jitonnom J, Limb MAL, Mulholland AJ. QM/MM free-energy simulations of reaction in Serratia marcescens Chitinase B reveal the protonation state of Asp142 and the critical role of Tyr214. J Phys Chem B 2014; 118:4771-83. [PMID: 24730355 DOI: 10.1021/jp500652x] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Serratia marcescens Chitinase B (ChiB), belonging to the glycosidase family 18 (GH18), catalyzes the hydrolysis of β-1,4-glycosidic bond, with retention of configuration, via an unusual substrate-assisted mechanism, in which the substrate itself acts as an intramolecular nucleophile. Here, both elementary steps (glycosylation and deglycosylation) of the ChiB-catalyzed reaction are investigated by means of combined quantum mechanics/molecular mechanics (QM/MM) umbrella sampling molecular dynamics (MD) simulations at the SCC-DFTB/CHARMM22 level of theory. We examine the influence of the Asp142 protonation state on the reaction and the role that this residue performs in the reaction. Our simulations show that reaction with a neutral Asp142 is preferred and demonstrate that this residue provides electrostatic stabilization of the oxazolinium ion intermediate formed in the reaction. Insight into the conformational itinerary ((1,4)B↔(4)H5↔(4)C1) adopted by the substrate (bound in subsite -1) along the preferred reaction pathway is also provided by the simulations. The relative energies of the stationary points found along the reaction pathway calculated with SCC-DFTB and B3LYP were compared. The results suggest that SCC-DFTB is an accurate method for estimating the relative barriers for both steps of the reaction; however, it was found to overestimate the relative energy of an intermediate formed in the reaction when compared with the higher level of theory. Glycosylation is suggested to be a rate-determining step in the reaction with calculated overall reaction free-energy barrier of 20.5 kcal/mol, in a reasonable agreement with the 16.1 kcal/mol barrier derived from the experiment. The role of Tyr214 in catalysis was also investigated with the results, indicating that the residue plays a critical role in the deglycosylation step of the reaction. Simulations of the enzyme-product complex were also performed with an unbinding event suggested to have been observed, affording potential new mechanistic insight into the release of the product of ChiB.
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Affiliation(s)
- Jitrayut Jitonnom
- Division of Chemistry, School of Science, University of Phayao , Phayao 56000, Thailand
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Pierdominici-Sottile G, Palma J, Roitberg AE. Free-energy computations identify the mutations required to confer trans-sialidase activity into Trypanosoma rangeli sialidase. Proteins 2013; 82:424-35. [PMID: 23999862 DOI: 10.1002/prot.24408] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2013] [Revised: 07/26/2013] [Accepted: 08/14/2013] [Indexed: 11/09/2022]
Abstract
Trypanosoma rangeli's sialidase (TrSA) and Trypanosoma cruzi's trans-sialidase (TcTS) are members of the glycoside hydrolase family 33 (GH-33). They share 70% of sequence identity and their crystallographic Cα RMSD is 0.59 Å. Despite these similarities they catalyze different reactions. TcTS transfers sialic acid between glycoconjugates while TrSA can only cleave sialic acid from sialyl-glyconjugates. Significant effort has been invested into unraveling the differences between TrSA and TcTS, and into conferring TrSA with trans-sialidase activity through appropriate point mutations. Recently, we calculated the free-energy change for the formation of the covalent intermediate (CI) in TcTS and performed an energy decomposition analysis of that process. In this article we present a similar study for the formation of the CI in TrSA, as well as in a quintuple mutant (TrSA5mut), which has faint trans-sialidase activity. The comparison of these new results with those previously obtained for TcTS allowed identifying five extra mutations to be introduced in TrSA5mut that should create a mutant (TrSA10mut ) with high trans-sialidase activity.
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Affiliation(s)
- Gustavo Pierdominici-Sottile
- Departamento de Ciencia y Tecnología, Universidad Nacional de Quilmes, Saenz Peña 352, Bernal, B1876BXD, Argentina
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Zheng M, Xu D. Catalytic Mechanism of Hyaluronate Lyase from Spectrococcus pneumonia: Quantum Mechanical/Molecular Mechanical and Density Functional Theory Studies. J Phys Chem B 2013; 117:10161-72. [DOI: 10.1021/jp406206s] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Min Zheng
- MOE Key Laboratory of Green
Chemistry and Technology, College of Chemistry, Sichuan University, Chengdu, Sichuan, 610064, P. R. China
| | - Dingguo Xu
- MOE Key Laboratory of Green
Chemistry and Technology, College of Chemistry, Sichuan University, Chengdu, Sichuan, 610064, P. R. China
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48
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D'Cunha C, Morozov AN, Chatfield DC. Theoretical study of HOCl-catalyzed keto-enol tautomerization of β-cyclopentanedione in an explicit water environment. J Phys Chem A 2013; 117:8437-48. [PMID: 23902476 DOI: 10.1021/jp401409y] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The mechanism of acid-catalyzed keto-enol tautomerization of β-cyclopentanedione (CPD) in solution is studied computationally. Reaction profiles are first calculated for a limited solvation environment using ab initio and density functional methods. Barrier heights for systems including up to one hydration shell of explicit water molecules depend strongly on the number of waters involved in proton transfer and to a lesser but significant extent on the number of waters forming hydrogen bonds with waters in the proton-transfer chain (each such water reduces the barrier by 4.4 kcal/mol on average). Barriers of 8-13 kcal/mol were obtained when a full or nearly full hydration shell was present, consistent with calculations for nonacid-catalyzed keto-enol tautomerization of related molecules. The presence of HOCl reduced the barrier by 4.5 kcal/mol in relation to the gas phase, consistent with the well-known principle that keto-enol tautomerization can be acid- or base-catalyzed. The reaction was also modeled beginning with snapshots of reactant conformations taken from a 300 K molecular dynamics simulation of CPD, HOCl, and 324 explicit waters. Reaction profiles were calculated at a QM/MM level with waters in the first hydration shell either fixed or energy-minimized at each step along the reaction coordinate. A substantial variation in barrier height was observed in both cases, depending primarily on electrostatic interactions (hydrogen bonding) with first-hydration-shell waters and, to a lesser extent, on electrostatic interactions with more distant waters and geometric distortion effects. For the lowest barriers, the extent of barrier reduction by waters involved in proton transfer is consistent with the limited solvation results, but further barrier reduction due to hydrogen bonding to waters involved in proton transfer is not observed. It is postulated that this is because highly flexible structures such as extensive hydrogen bonding networks optimal for reaction are entropically disfavored and so may not contribute significantly to the observed reaction rate.
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Affiliation(s)
- Cassian D'Cunha
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, USA
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49
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Zhang C, Wu S, Xu D. Catalytic Mechanism of Angiotensin-Converting Enzyme and Effects of the Chloride Ion. J Phys Chem B 2013; 117:6635-45. [DOI: 10.1021/jp400974n] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Chunchun Zhang
- Analytical&Testing Center and ‡MOE Key Laboratory of Green Chemistry and Technology, College of Chemistry, Sichuan University, Chengdu, Sichuan, 610064, P. R. China
| | - Shanshan Wu
- Analytical&Testing Center and ‡MOE Key Laboratory of Green Chemistry and Technology, College of Chemistry, Sichuan University, Chengdu, Sichuan, 610064, P. R. China
| | - Dingguo Xu
- Analytical&Testing Center and ‡MOE Key Laboratory of Green Chemistry and Technology, College of Chemistry, Sichuan University, Chengdu, Sichuan, 610064, P. R. China
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50
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Lodola A, Capoferri L, Rivara S, Tarzia G, Piomelli D, Mulholland A, Mor M. Quantum mechanics/molecular mechanics modeling of fatty acid amide hydrolase reactivation distinguishes substrate from irreversible covalent inhibitors. J Med Chem 2013; 56:2500-12. [PMID: 23425199 DOI: 10.1021/jm301867x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Carbamate and urea derivatives are important classes of fatty acid amide hydrolase (FAAH) inhibitors that carbamoylate the active-site nucleophile Ser241. In the present work, the reactivation mechanism of carbamoylated FAAH is investigated by means of a quantum mechanics/molecular mechanics (QM/MM) approach. The potential energy surfaces for decarbamoylation of FAAH covalent adducts, derived from the O-aryl carbamate URB597 and from the N-piperazinylurea JNJ1661610, were calculated and compared to that for deacylation of FAAH acylated by the substrate oleamide. Calculations show that a carbamic group bound to Ser241 prevents efficient stabilization of transition states of hydrolysis, leading to large increments in the activation barrier. Moreover, the energy barrier for the piperazine carboxylate was significantly lower than that for the cyclohexyl carbamate derived from URB597. This is consistent with experimental data showing slowly reversible FAAH inhibition for the N-piperazinylurea inhibitor and irreversible inhibition for URB597.
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Affiliation(s)
- Alessio Lodola
- Dipartimento di Farmacia, Università degli Studi di Parma, I-43124 Parma, Italy
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