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Soliman AM, Abd El-Wahab HAA, Akincioglu H, Gülçin İ, Omar FA. Piperazine-2-carboxylic acid derivatives as MTDLs anti-Alzheimer agents: Anticholinesterase activity, mechanistic aspect, and molecular modeling studies. Bioorg Chem 2024; 142:106916. [PMID: 37913584 DOI: 10.1016/j.bioorg.2023.106916] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Revised: 10/10/2023] [Accepted: 10/11/2023] [Indexed: 11/03/2023]
Abstract
Development of Multitarget-Directed Ligands (MTDLs) is a promising approach to combat the complex etiologies of Alzheimer's disease (AD). Herein we report the design, synthesis, and characterization of a new series of 1,4-bisbenzylpiperazine-2-carboxylic acid derivatives 3-5(a-g), 7a-f, 8a-s, and their piperazine-2-yl-1,3,4-oxadiazole analogs 6a-g. In vitro inhibitory effect against Electrophorus electricus acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) from Equine serum was evaluated using modified Ellman's method, considering donepezil and tacrine as reference drugs. Lineweaver-Burk plot analysis of the results proved competitive inhibition of AChE and BChE with Ki values, in low micromolar range. The free carboxylic acid series 4a-g showed enhanced selectivity for AChE. Hence, 4c, 1,4-bis (4-chlorobenzyl)-piperazinyl-2-carboxylic acid), was the most active member of this series (Ki (AChE) = 10.18 ± 1.00 µM) with clear selectivity for AChE (SI ∼ 17.90). However, the hydroxamic acids 7a-f and carboxamides 8a-s congeners were more potent and selective inhibitors of BChE (SI ∼ 5.38 - 21862.5). Extraordinarily, 1,4-bis (2-chlorobenzyl)-piperazinyl-2-hydroxamic acid 7b showed promising inhibitory activity against BChE enzyme (Ki = 1.6 ± 0.08 nM, SI = 21862.5), that was significantly superior to that elicited by donepezil (Ki = 12.5 ± 2.6 µM) and tacrine (Ki = 17.3 ± 2.3 nM). Cytotoxicity assessment of 4c and 7b, on human neuroblastoma (SH-SY5Y) cell lines, revealed lower toxicity than staurosporine and was nearly comparable to that of donepezil. Molecular docking and molecular dynamics simulation afforded unblemished insights into the structure-activity relationships for AChE and BChE inhibition. The results showed stable binding with fair H-bonding, hydrophobic and/or ionic interactions to the catalytic and peripheral anionic sites of the enzymes. In silico predicted ADME and physicochemical properties of conjugates showed good CNS bioavailability and safety parameters. In this regard, compound (7b) might be considered as a promising inhibitor of BChE with an innovative donepezil-based anti-Alzheimer activity. Further assessments of the most potent AChE and BChE inhibitors as potential MTDLs anti-Alzheimer's agents are under investigation with our research group and will be published later.
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Affiliation(s)
- Aya M Soliman
- Department of Medicinal Chemistry, Faculty of Pharmacy, Assiut University, 71526 Assiut, Egypt
| | - Hend A A Abd El-Wahab
- Department of Medicinal Chemistry, Faculty of Pharmacy, Assiut University, 71526 Assiut, Egypt
| | - Hulya Akincioglu
- Department of Chemistry, Faculty of Science and Arts, Agri-Ibrahim Cecen University, 04100 Agri, Turkey
| | - İlhami Gülçin
- Department of Chemistry, Faculty of Science, Ataturk University, 25240 Erzurum, Turkey.
| | - Farghaly A Omar
- Department of Medicinal Chemistry, Faculty of Pharmacy, Assiut University, 71526 Assiut, Egypt.
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2
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Rani A, Singh A, Kaur J, Singh G, Bhatti R, Gumede N, Kisten P, Singh P, Sumanjit, Kumar V. 1H-1,2,3-triazole grafted tacrine-chalcone conjugates as potential cholinesterase inhibitors with the evaluation of their behavioral tests and oxidative stress in mice brain cells. Bioorg Chem 2021; 114:105053. [PMID: 34120027 DOI: 10.1016/j.bioorg.2021.105053] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 05/27/2021] [Accepted: 06/01/2021] [Indexed: 01/06/2023]
Abstract
The present paper explicates the synthesis of 1H-1,2,3-triazole tethered tacrine-chalcone conjugates and evaluation of their AChE and BuChE inhibitory activity. In-vitroAChE inhibition assay revealed three compounds, 9h, 9i, and 11f, being more potent than the standard drug tacrine and further evaluated against butyrylcholinesterase. The present study was extended to investigate the anti-amnestic effect of promising compoundson scopolamine-induced behavioral and neurochemical changes in mice. Inclined plane model and Elevated plus-maze model were performed to assess general limb motor activity and anxiety-like behavior, respectively, in mice pre-treated with scopolamine. Oxidative stress parameters reduced glutathione contents (GSH) and lipid peroxidation products (TBARS) in the brain homogenates as estimated using ex-vivo studies. Furthermore, molecular docking studies were performed for the potent compounds to decipher the mechanism of observed activities.
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Affiliation(s)
- Anu Rani
- Department of Chemistry, Guru Nanak Dev University, Amritsar 143005, Punjab, India
| | - Amandeep Singh
- Department of Chemistry, Guru Nanak Dev University, Amritsar 143005, Punjab, India
| | - Jashanpreet Kaur
- Department of Pharmaceutical Sciences, Guru Nanak Dev University, Amritsar 143005, India
| | - Gurjit Singh
- Department of Pharmaceutical Sciences, Guru Nanak Dev University, Amritsar 143005, India
| | - Rajbir Bhatti
- Department of Pharmaceutical Sciences, Guru Nanak Dev University, Amritsar 143005, India
| | - Njabulo Gumede
- Department of Chemistry, Mangosuthu University of Technology, P.O. Box 12363, Jacobs 4026, South Africa
| | - Prishani Kisten
- School of Chemistry and Physics, University of KwaZulu-Natal, P/Bag X54001, Westville, Durban, South Africa
| | - Parvesh Singh
- School of Chemistry and Physics, University of KwaZulu-Natal, P/Bag X54001, Westville, Durban, South Africa
| | - Sumanjit
- Department of Chemistry, Guru Nanak Dev University, Amritsar 143005, Punjab, India
| | - Vipan Kumar
- Department of Chemistry, Guru Nanak Dev University, Amritsar 143005, Punjab, India.
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3
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De Boer D, Nguyen N, Mao J, Moore J, Sorin EJ. A Comprehensive Review of Cholinesterase Modeling and Simulation. Biomolecules 2021; 11:580. [PMID: 33920972 PMCID: PMC8071298 DOI: 10.3390/biom11040580] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2021] [Revised: 04/08/2021] [Accepted: 04/11/2021] [Indexed: 01/18/2023] Open
Abstract
The present article reviews published efforts to study acetylcholinesterase and butyrylcholinesterase structure and function using computer-based modeling and simulation techniques. Structures and models of both enzymes from various organisms, including rays, mice, and humans, are discussed to highlight key structural similarities in the active site gorges of the two enzymes, such as flexibility, binding site location, and function, as well as differences, such as gorge volume and binding site residue composition. Catalytic studies are also described, with an emphasis on the mechanism of acetylcholine hydrolysis by each enzyme and novel mutants that increase catalytic efficiency. The inhibitory activities of myriad compounds have been computationally assessed, primarily through Monte Carlo-based docking calculations and molecular dynamics simulations. Pharmaceutical compounds examined herein include FDA-approved therapeutics and their derivatives, as well as several other prescription drug derivatives. Cholinesterase interactions with both narcotics and organophosphate compounds are discussed, with the latter focusing primarily on molecular recognition studies of potential therapeutic value and on improving our understanding of the reactivation of cholinesterases that are bound to toxins. This review also explores the inhibitory properties of several other organic and biological moieties, as well as advancements in virtual screening methodologies with respect to these enzymes.
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Affiliation(s)
- Danna De Boer
- Department of Chemistry & Biochemistry, California State University, Long Beach, CA 90840, USA;
| | - Nguyet Nguyen
- Department of Chemical Engineering, California State University, Long Beach, CA 90840, USA; (N.N.); (J.M.)
| | - Jia Mao
- Department of Chemical Engineering, California State University, Long Beach, CA 90840, USA; (N.N.); (J.M.)
| | - Jessica Moore
- Department of Biomedical Engineering, California State University, Long Beach, CA 90840, USA;
| | - Eric J. Sorin
- Department of Chemistry & Biochemistry, California State University, Long Beach, CA 90840, USA;
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4
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El-Sayed NAE, Farag AES, Ezzat MAF, Akincioglu H, Gülçin İ, Abou-Seri SM. Design, synthesis, in vitro and in vivo evaluation of novel pyrrolizine-based compounds with potential activity as cholinesterase inhibitors and anti-Alzheimer's agents. Bioorg Chem 2019; 93:103312. [DOI: 10.1016/j.bioorg.2019.103312] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Revised: 09/09/2019] [Accepted: 09/23/2019] [Indexed: 01/17/2023]
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5
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Novel tacrine-tryptophan hybrids: Multi-target directed ligands as potential treatment for Alzheimer's disease. Eur J Med Chem 2019; 168:491-514. [DOI: 10.1016/j.ejmech.2019.02.021] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2018] [Revised: 02/07/2019] [Accepted: 02/07/2019] [Indexed: 12/28/2022]
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6
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Sun H, Jiang J, Sun Y, Zhang Q, Liu M. Self-assembled organic nanotube promoted allylation of ketones in aqueous phase. Chem Commun (Camb) 2019; 55:3254-3257. [PMID: 30810138 DOI: 10.1039/c9cc00941h] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
A self-assembled organic nanotube was found to promote the allylation of ketones in the aqueous phase.
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Affiliation(s)
- Hui Sun
- School of Chemical & Environmental Engineering, China University of Mining & Technology, Beijing, 100083, P. R. China. and CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience, Nanophotonics Research Division, National Center for Nanoscience and Technology (NCNST), No. 11 ZhongGuanCun BeiYiTiao, 100190 Beijing, P. R. China.
| | - Jian Jiang
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience, Nanophotonics Research Division, National Center for Nanoscience and Technology (NCNST), No. 11 ZhongGuanCun BeiYiTiao, 100190 Beijing, P. R. China.
| | - Yimeng Sun
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience, Nanophotonics Research Division, National Center for Nanoscience and Technology (NCNST), No. 11 ZhongGuanCun BeiYiTiao, 100190 Beijing, P. R. China.
| | - Qingwu Zhang
- School of Chemical & Environmental Engineering, China University of Mining & Technology, Beijing, 100083, P. R. China.
| | - Minghua Liu
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience, Nanophotonics Research Division, National Center for Nanoscience and Technology (NCNST), No. 11 ZhongGuanCun BeiYiTiao, 100190 Beijing, P. R. China. and Beijing National Laboratory for Molecular Science, CAS Key Laboratory of Colloid, Interface and Chemical Thermodynamics, Institute of Chemistry, Chinese Academy of Sciences, No. 2 ZhongGuanCun BeiYiJie, 100190, Beijing, P. R. China
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7
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Zlobin AS, Zalevsky AO, Mokrushina YA, Kartseva OV, Golovin AV, Smirnov IV. The Preferable Binding Pose of Canonical Butyrylcholinesterase Substrates Is Unproductive for Echothiophate. Acta Naturae 2018; 10:121-124. [PMID: 30713771 PMCID: PMC6351040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Indexed: 10/25/2022] Open
Abstract
In this paper, we, for the first time, describe the interaction between the butyrylcholinesterase enzyme and echothiophate, a popular model compound and an analogue of the chemical warfare agents VX and VR, at the atomistic level. Competition between the two echothiophate conformations in the active site was found using molecular modeling techniques. The first one is close to the mode of binding of the substrates of choline series (butyrylcholine and butyrylthiocholine) and is inhibitory, since it is unable to react with the enzyme. The second one is characterized by a significantly worse estimated binding affinity and is reactive. Thus, echothiophate combines the features of two types of inhibitors: competitive and suicidal. This observation will help clarify the kinetic reaction scheme in order to accurately assess the kinetic constants, which is especially important when designing new butyrylcholinesterase variants capable of full-cycle hydrolysis of organophosphorus compounds.
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Affiliation(s)
- A. S. Zlobin
- Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Leninskie gori, 1 , bldg. 73, Moscow, 119991, Russia
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry RAS, Miklukho-Maklaya Str., 16/10, Moscow, 117997, Russia
| | - A. O. Zalevsky
- Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Leninskie gori, 1 , bldg. 73, Moscow, 119991, Russia
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry RAS, Miklukho-Maklaya Str., 16/10, Moscow, 117997, Russia
- Institute of Molecular Medicine, I.M. Sechenov First Moscow State Medical University, Trubetskaya Str., 8, bldg. 2, Moscow, 119992, Russia
| | - Yu. A. Mokrushina
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry RAS, Miklukho-Maklaya Str., 16/10, Moscow, 117997, Russia
| | - O. V. Kartseva
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry RAS, Miklukho-Maklaya Str., 16/10, Moscow, 117997, Russia
| | - A. V. Golovin
- Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Leninskie gori, 1 , bldg. 73, Moscow, 119991, Russia
- Institute of Molecular Medicine, I.M. Sechenov First Moscow State Medical University, Trubetskaya Str., 8, bldg. 2, Moscow, 119992, Russia
- National Research University HSE, Myasnitskaya Str., 20, Moscow, 101000, Russia
| | - I. V. Smirnov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry RAS, Miklukho-Maklaya Str., 16/10, Moscow, 117997, Russia
- Chemical Faculty of Lomonosov Moscow State University, Leninskie gori, 1, bldg. 3, Moscow, 119991 , Russia
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8
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Wan X, Yao Y, Fang L, Liu J. Unexpected protonation state of Glu197 discovered from simulations of tacrine in butyrylcholinesterase. Phys Chem Chem Phys 2018; 20:14938-14946. [PMID: 29786716 DOI: 10.1039/c8cp01566j] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Butyrylcholinesterase (BChE) has been actively involved in drug discoveries from many fields for decades. In the crystal structure of the BChE-tacrine complex, there is an unanticipated formyl-proline molecule resolved very close to tacrine, raising an essential question on how reliable it is to apply the binding pose in a crystal structure to analyze related experimental observations, in which no formyl-proline is actually involved. In this study, by performing a series of 100 ns molecular dynamics simulations, we demonstrate that it is safe to employ the structural information from this crystal structure to analyze related experimental observations. Surprisingly, Glu197 needs to be protonated to have the structures simulated appropriately. It should be noted that Glu197 has been commonly considered as deprotonated in diverse analyses due to its low pKa in aqueous solution, for which some interpretations are inconsistent or unclear. Our further investigation shows that the protonated Glu197 plays a very important role in preserving His438 within the catalytic triad through stabilizing a highly conserved water molecule. Interestingly, the catalytic triad and Glu197 have been long recognized for possibly deviating largely from the crystal structure, which might be catalytically deficient and is generally considered to result from the difference between the crystal and aqueous environment. Herein, our results suggest that the large deviations of the catalytic triad and Glu197 from the crystal structure are caused by the inappropriate protonation state of Glu197. This finding shall provide an important clue that has been long missing for a better understanding of BChE-related puzzles or even reconsideration of some BChE-catalyzed reaction mechanisms.
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Affiliation(s)
- Xiao Wan
- School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, 13 Hangkong Road, Wuhan, Hubei 430030, P. R. China.
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9
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Yao J, Chen X, Zheng F, Zhan CG. Catalytic Reaction Mechanism for Drug Metabolism in Human Carboxylesterase-1: Cocaine Hydrolysis Pathway. Mol Pharm 2018; 15:3871-3880. [PMID: 30095924 DOI: 10.1021/acs.molpharmaceut.8b00354] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Carboxylesterase-1 (CE-1) is a crucial enzyme responsible for metabolism/activation/inactivation of xenobiotics (therapeutic agents, prodrugs, abused drugs, and organophosphorus nerve agents etc.) and also involved in many other biological processes. In this study, we performed extensive computational modeling and simulations to understand the fundamental reaction mechanism of cocaine hydrolysis catalyzed by CE-1, revealing that CE-1-catalyzed cocaine hydrolysis follows a novel reaction pathway with only two reaction steps: a single-step acylation process and a single-step deacylation process. In the transition states of both single-step processes, the cocaine NH group joins the oxyanion hole to form an additional hydrogen bond with the negatively charged carbonyl oxygen atom of the cocaine. Thus, the transition states are stabilized by both intermolecular and intramolecular hydrogen bonds with the methyl ester of cocaine, specifically the carbonyl oxygen atom. The rate-limiting transition state is associated with the acylation process, and the activation free energy barrier was predicted to be 20.1 kcal/mol. Further, in vitro experimental kinetic analysis was performed for human CE-1-catalyzed cocaine hydrolysis. For CE-1-catalyzed cocaine hydrolysis, the computationally predicted free energy barrier (20.1 kcal/mol) is reasonably close to the experimentally derived turnover number ( kcat = 0.058 min-1), indicating the reasonability of the computational results. The obtained novel mechanistic insights are expected to benefit not only CE-1 related rational drug discovery but also future research on the catalytic mechanism of other esterases.
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Affiliation(s)
- Jianzhuang Yao
- School of Biological Science and Techonology , University of Jinan , Jinan 250022 , China
| | - Xiabin Chen
- School of Medicine , Hangzhou Normal University , Hangzhou 311121 , China
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10
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Plant-expressed cocaine hydrolase variants of butyrylcholinesterase exhibit altered allosteric effects of cholinesterase activity and increased inhibitor sensitivity. Sci Rep 2017; 7:10419. [PMID: 28874829 PMCID: PMC5585256 DOI: 10.1038/s41598-017-10571-z] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Accepted: 08/10/2017] [Indexed: 12/04/2022] Open
Abstract
Butyrylcholinesterase (BChE) is an enzyme with broad substrate and ligand specificities and may function as a generalized bioscavenger by binding and/or hydrolyzing various xenobiotic agents and toxicants, many of which target the central and peripheral nervous systems. Variants of BChE were rationally designed to increase the enzyme’s ability to hydrolyze the psychoactive enantiomer of cocaine. These variants were cloned, and then expressed using the magnICON transient expression system in plants and their enzymatic properties were investigated. In particular, we explored the effects that these site-directed mutations have over the enzyme kinetics with various substrates of BChE. We further compared the affinity of various anticholinesterases including organophosphorous nerve agents and pesticides toward these BChE variants relative to the wild type enzyme. In addition to serving as a therapy for cocaine addiction-related diseases, enhanced bioscavenging against other harmful agents could add to the practicality and versatility of the plant-derived recombinant enzyme as a multivalent therapeutic.
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11
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Zhao X, Lu J, Wu L, Chen X. Efficient construction of 3-substituted-quinazolin-4(3H)-ones and theoretical investigation on the reaction pathways. PHOSPHORUS SULFUR 2017. [DOI: 10.1080/10426507.2017.1322085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
- Xinyun Zhao
- College of Chemistry and Materials Science, South-Central University for Nationalities, Wuhan, P. R. China
| | - Juanfeng Lu
- College of Chemistry and Materials Science, South-Central University for Nationalities, Wuhan, P. R. China
| | - Lamei Wu
- College of Chemistry and Materials Science, South-Central University for Nationalities, Wuhan, P. R. China
| | - Xi Chen
- College of Chemistry and Materials Science, South-Central University for Nationalities, Wuhan, P. R. China
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12
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Arodola OA, Soliman MES. Quantum mechanics implementation in drug-design workflows: does it really help? Drug Des Devel Ther 2017; 11:2551-2564. [PMID: 28919707 PMCID: PMC5587087 DOI: 10.2147/dddt.s126344] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
The pharmaceutical industry is progressively operating in an era where development costs are constantly under pressure, higher percentages of drugs are demanded, and the drug-discovery process is a trial-and-error run. The profit that flows in with the discovery of new drugs has always been the motivation for the industry to keep up the pace and keep abreast with the endless demand for medicines. The process of finding a molecule that binds to the target protein using in silico tools has made computational chemistry a valuable tool in drug discovery in both academic research and pharmaceutical industry. However, the complexity of many protein-ligand interactions challenges the accuracy and efficiency of the commonly used empirical methods. The usefulness of quantum mechanics (QM) in drug-protein interaction cannot be overemphasized; however, this approach has little significance in some empirical methods. In this review, we discuss recent developments in, and application of, QM to medically relevant biomolecules. We critically discuss the different types of QM-based methods and their proposed application to incorporating them into drug-design and -discovery workflows while trying to answer a critical question: are QM-based methods of real help in drug-design and -discovery research and industry?
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Affiliation(s)
- Olayide A Arodola
- Department of Pharmaceutical Chemistry, University of KwaZulu-Natal, Durban, South Africa
| | - Mahmoud ES Soliman
- Department of Pharmaceutical Chemistry, University of KwaZulu-Natal, Durban, South Africa
- Department of Pharmaceutical Organic Chemistry, Faculty of Pharmacy, Zagazig University, Egypt
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13
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Wei D, Huang X, Qiao Y, Rao J, Wang L, Liao F, Zhan CG. Catalytic Mechanisms for Cofactor-Free Oxidase-Catalyzed Reactions: Reaction Pathways of Uricase-Catalyzed Oxidation and Hydration of Uric Acid. ACS Catal 2017; 7:4623-4636. [PMID: 28890842 DOI: 10.1021/acscatal.7b00901] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
First-principles quantum mechanical/molecular mechanical (QM/MM)-free energy calculations have been performed to uncover how uricase catalyzes metabolic reactions of uric acid (UA), demonstrating that the entire reaction process of UA in uricase consists of two stages-oxidation followed by hydration. The oxidation consists of four steps: (1) chemical transformation from 8-hydroxyxythine to an anionic radical via a proton transfer along with an electron transfer, which is different from the previously proposed electron-transfer mechanism that involves a dianion intermediate (UA2-) during the catalytic reaction process; (2) proton transfer to the O2- anion (radical); (3) diradical recombination to form a peroxo intermediate; (4) dissociation of H2O2 to generate the dehydrourate. Hydration, for the most favorable pathway, is initiated by the nucleophilic attack of a water molecule on dehydrourate, along with a concerted proton transfer through residue Thr69 in the catalytic site. According to the calculated free energy profile, the hydration is the rate-determining step, and the corresponding free energy barrier of 16.2 kcal/mol is consistent with that derived from experimental kinetic data, suggesting that the computational insights into the catalytic mechanisms are reasonable. The mechanistic insights not only provide a mechanistic base for future rational design of uricase mutants with improved catalytic activity against uric acid as an improved enzyme therapy, but also are valuable for understanding a variety of other cofactor-free oxidase-catalyzed reactions involving an oxygen molecule.
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Affiliation(s)
- Donghui Wei
- College
of Chemistry and Molecular Engineering, Zhengzhou University, 100 Science Avenue, Zhengzhou, Henan 450001, P. R. China
- Department
of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, 789 South Limestone Street, Lexington, Kentucky 40536, United States,
| | - Xiaoqin Huang
- Department
of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, 789 South Limestone Street, Lexington, Kentucky 40536, United States,
- Center
for Theoretical Biological Physics, and Center for Research Computing, Rice University, Houston, Texas 77030, United States,
| | - Yan Qiao
- College
of Chemistry and Molecular Engineering, Zhengzhou University, 100 Science Avenue, Zhengzhou, Henan 450001, P. R. China
- Department
of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, 789 South Limestone Street, Lexington, Kentucky 40536, United States,
| | - Jingjing Rao
- Key
Laboratory of Medical Laboratory Diagnostics of the Education Ministry,
College of Laboratory Medicine, Chongqing Medical University, No.1, Yixueyuan Road, Chongqing 400016, China
| | - Lu Wang
- Key
Laboratory of Medical Laboratory Diagnostics of the Education Ministry,
College of Laboratory Medicine, Chongqing Medical University, No.1, Yixueyuan Road, Chongqing 400016, China
| | - Fei Liao
- Key
Laboratory of Medical Laboratory Diagnostics of the Education Ministry,
College of Laboratory Medicine, Chongqing Medical University, No.1, Yixueyuan Road, Chongqing 400016, China
| | - Chang-Guo Zhan
- Department
of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, 789 South Limestone Street, Lexington, Kentucky 40536, United States,
- Molecular
Modeling and Biopharmaceutical Center, College of Pharmacy, University of Kentucky, 789 South Limestone Street, Lexington, Kentucky 40536, United States
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14
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Sorin EJ, Alvarado W, Cao S, Radcliffe A, La P, An Y. Ensemble Molecular Dynamics of a Protein-Ligand Complex: Residual Inhibitor Entropy Enhances Drug Potency in Butyrylcholinesterase. ACTA ACUST UNITED AC 2017; 6. [PMID: 28944107 DOI: 10.4172/2167-7662.1000145] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Butyrylcholinesterase is a key enzyme that catalyzes the hydrolysis of the neurotransmitter acetylcholine and shows an increased activity in patients suffering from Alzheimer's disease (AD), making this enzyme a primary target in treating AD. Central to this problem, and to similar scenarios involving biomolecular recognition, is our understanding of the nature of the protein-ligand complex. The butyrylcholinesterase enzyme was studied via all-atom, explicit solvent, ensemble molecular dynamics simulations sans inhibitor and in the presence of three dialkyl phenyl phosphate inhibitors of known potency to a cumulative sampling of over 40 μs. Following the relaxation of these ensembles to conformational equilibria, binding modes for each inhibitor were identified. While classical models, which assume significant reduction in protein and ligand conformational entropies, continue to be favored in contemporary studies, our observations contradict those assumptions: bound ligands occupy many conformational states, thereby stabilizing the complex, while also promoting protein flexibility.
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Affiliation(s)
- Eric J Sorin
- Department of Chemistry and Biochemistry, California State University Long Beach, California, USA
| | - Walter Alvarado
- Department of Physics and Astronomy, California State University Long Beach, California, USA
| | - Samantha Cao
- Department of Chemistry and Biochemistry, California State University Long Beach, California, USA
| | - Amethyst Radcliffe
- Department of Physics and Astronomy, California State University Long Beach, California, USA
| | - Phuc La
- Department of Chemistry and Biochemistry, California State University Long Beach, California, USA
| | - Yi An
- Department of Chemistry and Biochemistry, California State University Long Beach, California, USA
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15
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Wei D, Tang M, Zhan CG. Fundamental reaction pathway and free energy profile of proteasome inhibition by syringolin A (SylA). Org Biomol Chem 2016; 13:6857-65. [PMID: 26018983 DOI: 10.1039/c5ob00737b] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In this study, molecular dynamics (MD) simulations and first-principles quantum mechanical/molecular mechanical free energy (QM/MM-FE) calculations have been performed to uncover the fundamental reaction pathway of proteasome with a representative inhibitor syringolin A (SylA). The calculated results reveal that the reaction process consists of three steps. The first step is a proton transfer process, activating Thr1-O(γ) directly by Thr1-N(z) to form a zwitterionic intermediate. The next step is a nucleophilic attack on the olefin carbon of SylA by the negatively charged Thr1-O(γ) atom. The last step is a proton transfer from Thr1-N(z) to another olefin carbon of SylA to complete the inhibition reaction process. The calculated free energy profile demonstrates that the second step should be the rate-determining step and has the highest free energy barrier of 24.6 kcal mol(-1), which is reasonably close to the activation free energy (∼22.4-23.0 kcal mol(-1)) derived from the available experimental kinetic data. In addition, our computational results indicate that no water molecule can assist the rate-determining step, since the second step is not involved in a proton transfer process. The obtained mechanistic insights should be valuable for understanding the inhibition process of proteasome by SylA and structurally related inhibitors at a molecular level, and thus provide a solid mechanistic base and valuable clues for future rational design of novel, more potent inhibitors of proteasome.
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Affiliation(s)
- Donghui Wei
- Department of Chemistry, Zhengzhou University, Daxue Road, Zhengzhou, Henan 450052, China
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16
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Yao J, Yuan Y, Zheng F, Zhan CG. Unexpected Reaction Pathway for butyrylcholinesterase-catalyzed inactivation of "hunger hormone" ghrelin. Sci Rep 2016; 6:22322. [PMID: 26922910 PMCID: PMC4770301 DOI: 10.1038/srep22322] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Accepted: 02/12/2016] [Indexed: 11/16/2022] Open
Abstract
Extensive computational modeling and simulations have been carried out, in the present study, to uncover the fundamental reaction pathway for butyrylcholinesterase (BChE)-catalyzed hydrolysis of ghrelin, demonstrating that the acylation process of BChE-catalyzed hydrolysis of ghrelin follows an unprecedented single-step reaction pathway and the single-step acylation process is rate-determining. The free energy barrier (18.8 kcal/mol) calculated for the rate-determining step is reasonably close to the experimentally-derived free energy barrier (~19.4 kcal/mol), suggesting that the obtained mechanistic insights are reasonable. The single-step reaction pathway for the acylation is remarkably different from the well-known two-step acylation reaction pathway for numerous ester hydrolysis reactions catalyzed by a serine esterase. This is the first time demonstrating that a single-step reaction pathway is possible for an ester hydrolysis reaction catalyzed by a serine esterase and, therefore, one no longer can simply assume that the acylation process must follow the well-known two-step reaction pathway.
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Affiliation(s)
- Jianzhuang Yao
- Molecular Modeling and Biopharmaceutical Center and College of Pharmacy, University of Kentucky, 789 South Limestone Street, Lexington, KY 40536, USA.,Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, 789 South Limestone Street, Lexington, KY 40536, USA
| | - Yaxia Yuan
- Molecular Modeling and Biopharmaceutical Center and College of Pharmacy, University of Kentucky, 789 South Limestone Street, Lexington, KY 40536, USA.,Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, 789 South Limestone Street, Lexington, KY 40536, USA
| | - Fang Zheng
- Molecular Modeling and Biopharmaceutical Center and College of Pharmacy, University of Kentucky, 789 South Limestone Street, Lexington, KY 40536, USA.,Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, 789 South Limestone Street, Lexington, KY 40536, USA
| | - Chang-Guo Zhan
- Molecular Modeling and Biopharmaceutical Center and College of Pharmacy, University of Kentucky, 789 South Limestone Street, Lexington, KY 40536, USA.,Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, 789 South Limestone Street, Lexington, KY 40536, USA
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17
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Yao Y, Liu J, Zheng F, Zhan CG. Reaction Pathway for Cocaine Hydrolase-Catalyzed Hydrolysis of (+)-Cocaine. Theor Chem Acc 2016; 135. [PMID: 28250715 DOI: 10.1007/s00214-015-1788-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A recently designed and discovered cocaine hydrolase (CocH), engineered from human butyrylcholinesterase (BChE), has been proven promising as a novel enzyme therapy for treatment of cocaine overdose and addiction because it is highly efficient in catalyzing hydrolysis of naturally occurring (-)-cocaine. It has been known that the CocH also has a high catalytic efficiency against (+)-cocaine, a synthetic enantiomer of cocaine. Reaction pathway and the corresponding free energy profile for the CocH-catalyzed hydrolysis of (+)-cocaine have been determined, in the present study, by performing first-principles pseudobond quantum mechanical/molecular mechanical (QM/MM)-free energy (FE) calculations. Acordingt to the QM/MM-FE results, the catalytic hydrolysis process is initiated by the nucleophilic attack on carbonyl carbon of (-)-cocaine benzoyl ester via hydroxyl oxygen of S198 side chain, and the second reaction step (i.e. dissociation of benzoyl ester) is rate-determining. This finding for CocH-catalyzed hydrolysis of (+)-cocaine is remarkably different from that for the (+)-cocaine hydrolysis catalyzed by bacterial cocaine esterase in which the first reaction step of the deacylation is associated with the highest free energy barrier (~17.9 kcal/mol). The overall free energy barrier (~16.0 kcal/mol) calculated for the acylation stage of CocH-catalyzed hydrolysis of (+)-cocaine is in good agreement with the experimental free energy barrier of ~14.5 kcal/mol derivated from the experimental kinetic data.
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Affiliation(s)
- Yuan Yao
- Molecular Modeling and Biopharmaceutical Center and Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, 789 South Limestone, Lexington, KY 40536; The Academy of Fundamental and Interdisciplinary Sciences, Harbin Institute of Technology, Harbin 150080, P.R. China
| | - Junjun Liu
- Molecular Modeling and Biopharmaceutical Center and Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, 789 South Limestone, Lexington, KY 40536; Tongji School of Pharmacy, Huazhong University of Science and Technology, 13 Hangkong Road, Wuhan, Hubei 430030, P.R. China
| | - Fang Zheng
- Molecular Modeling and Biopharmaceutical Center and Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, 789 South Limestone, Lexington, KY 40536
| | - Chang-Guo Zhan
- Molecular Modeling and Biopharmaceutical Center and Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, 789 South Limestone, Lexington, KY 40536
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18
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Reilly PJ, Rovira C. Computational Studies of Glycoside, Carboxylic Ester, and Thioester Hydrolase Mechanisms: A Review. Ind Eng Chem Res 2015. [DOI: 10.1021/acs.iecr.5b01312] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Peter J. Reilly
- Department
of Chemical and Biological Engineering, Iowa State University, Ames, Iowa 50011-2230, United States
| | - Carme Rovira
- Departament de Química Orgànica
and Institut de Química Teòrica i Computacional (IQTCUB), Universitat de Barcelona, 08028 Barcelona, Spain
- Institució
Catalana de Recerca i Estudis Avançats (ICREA), 08010 Barcelona, Spain
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19
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Qiao Y, Han K, Zhan CG. Reaction pathways and free energy profiles for cholinesterase-catalyzed hydrolysis of 6-monoacetylmorphine. Org Biomol Chem 2014; 12:2214-27. [PMID: 24595354 DOI: 10.1039/c3ob42464b] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
As the most active metabolite of heroin, 6-monoacetylmorphine (6-MAM) can penetrate into the brain for the rapid onset of heroin effects. The primary enzymes responsible for the metabolism of 6-MAM to the less potent morphine in humans are acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). The detailed reaction pathways for AChE- and BChE-catalyzed hydrolysis of 6-MAM to morphine have been explored, for the first time, in the present study by performing first-principles quantum mechanical/molecular mechanical free energy calculations. It has been demonstrated that the two enzymatic reaction processes follow similar catalytic reaction mechanisms, and the whole catalytic reaction pathway for each enzyme consists of four reaction steps. According to the calculated results, the second reaction step associated with the transition state TS2(a)/TS2(b) should be rate-determining for the AChE/BChE-catalyzed hydrolysis, and the free energy barrier calculated for the AChE-catalyzed hydrolysis (18.3 kcal mol(-1)) is 2.5 kcal mol(-1) lower than that for the BChE-catalyzed hydrolysis (20.8 kcal mol(-1)). The free energy barriers calculated for the AChE- and BChE-catalyzed reactions are in good agreement with the experimentally derived activation free energies (17.5 and 20.7 kcal mol(-1) for the AChE- and BChE-catalyzed reactions, respectively). Further structural analysis reveals that the aromatic residues Phe295 and Phe297 in the acyl pocket of AChE (corresponding to Leu286 and Val288 in BChE) contribute to the lower energy of TS2(a) relative to TS2(b). The obtained structural and mechanistic insights could be valuable for use in future rational design of a novel therapeutic treatment of heroin abuse.
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Affiliation(s)
- Yan Qiao
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Science, Zhongshan Road 457, Dalian 116023, P. R. China
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20
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Hou S, Xue L, Yang W, Fang L, Zheng F, Zhan CG. Substrate selectivity of high-activity mutants of human butyrylcholinesterase. Org Biomol Chem 2013; 11:7477-85. [PMID: 24077614 PMCID: PMC3836059 DOI: 10.1039/c3ob41713a] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Cocaine is one of the most addictive drugs, and there is still no FDA (Food and Drug Administration)-approved medication specific for cocaine abuse. A promising therapeutic strategy is to accelerate cocaine metabolism, producing biologically inactive metabolites via a route similar to the primary cocaine-metabolizing pathway, i.e. cocaine hydrolysis catalyzed by butyrylcholinesterase (BChE) in plasma. However, the native BChE has a low catalytic efficiency against the abused cocaine, i.e. (-)-cocaine. Our recently designed and discovered A199S/F227A/S287G/A328W/Y332G mutant and other mutants of human BChE have a considerably improved catalytic efficiency against (-)-cocaine. In the present study, we carried out both computational modeling and experimental kinetic analysis on the catalytic activities of these promising new BChE mutants against other known substrates, including neurotransmitter acetylcholine (ACh), acetylthiocholine (ATC), butyrylthiocholine (BTC), and (+)-cocaine, in comparison with the corresponding catalytic activity against (-)-cocaine. Both the computational modeling and kinetic analysis have consistently revealed that all the examined amino acid mutations only considerably improve the catalytic efficiency of human BChE against (-)-cocaine, without significantly improving the catalytic efficiency of the enzyme against any of the other substrates examined. In particular, all the examined BChE mutants have a slightly lower catalytic efficiency against neurotransmitter ACh compared to the wild-type BChE. This observation gives us confidence in developing an anti-cocaine enzyme therapy by using one of these BChE mutants, particularly the A199S/F227A/S287G/A328W/Y332G mutant.
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Affiliation(s)
- Shurong Hou
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, 789 South Limestone Street, Lexington, KY 40536, USA.
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21
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Wei D, Fang L, Tang M, Zhan CG. Fundamental reaction pathway for peptide metabolism by proteasome: insights from first-principles quantum mechanical/molecular mechanical free energy calculations. J Phys Chem B 2013; 117:13418-34. [PMID: 24111489 DOI: 10.1021/jp405337v] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Proteasome is the major component of the crucial non-lysosomal protein degradation pathway in the cells, but the detailed reaction pathway is unclear. In this study, first-principles quantum mechanical/molecular mechanical free energy calculations have been performed to explore, for the first time, possible reaction pathways for proteasomal proteolysis/hydrolysis of a representative peptide, succinyl-leucyl-leucyl-valyl-tyrosyl-7-amino-4-methylcoumarin (Suc-LLVY-AMC). The computational results reveal that the most favorable reaction pathway consists of six steps. The first is a water-assisted proton transfer within proteasome, activating Thr1-O(γ). The second is a nucleophilic attack on the carbonyl carbon of a Tyr residue of substrate by the negatively charged Thr1-O(γ), followed by the dissociation of the amine AMC (third step). The fourth step is a nucleophilic attack on the carbonyl carbon of the Tyr residue of substrate by a water molecule, accompanied by a proton transfer from the water molecule to Thr1-N(z). Then, Suc-LLVY is dissociated (fifth step), and Thr1 is regenerated via a direct proton transfer from Thr1-N(z) to Thr1-O(γ). According to the calculated energetic results, the overall reaction energy barrier of the proteasomal hydrolysis is associated with the transition state (TS3(b)) for the third step involving a water-assisted proton transfer. The determined most favorable reaction pathway and the rate-determining step have provided a reasonable interpretation of the reported experimental observations concerning the substituent and isotopic effects on the kinetics. The calculated overall free energy barrier of 18.2 kcal/mol is close to the experimentally derived activation free energy of ∼18.3-19.4 kcal/mol, suggesting that the computational results are reasonable.
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Affiliation(s)
- Donghui Wei
- Department of Chemistry, Zhengzhou University , 75 Daxue Road, Zhengzhou, Henan 450052, China
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22
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Qiao Y, Han K, Zhan CG. Fundamental reaction pathway and free energy profile for butyrylcholinesterase-catalyzed hydrolysis of heroin. Biochemistry 2013; 52:6467-79. [PMID: 23992153 DOI: 10.1021/bi400709v] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The pharmacological function of heroin requires an activation process that transforms heroin into 6-monoacetylmorphine (6-MAM), which is the most active form. The primary enzyme responsible for this activation process in human plasma is butyrylcholinesterase (BChE). The detailed reaction pathway of the activation process via BChE-catalyzed hydrolysis has been explored computationally, for the first time, in this study via molecular dynamics simulation and first-principles quantum mechanical/molecular mechanical free energy calculations. It has been demonstrated that the whole reaction process includes acylation and deacylation stages. The acylation consists of two reaction steps, i.e., the nucleophilic attack on the carbonyl carbon of the 3-acetyl group of heroin by the hydroxyl oxygen of the Ser198 side chain and the dissociation of 6-MAM. The deacylation also consists of two reaction steps, i.e., the nucleophilic attack on the carbonyl carbon of the acyl-enzyme intermediate by a water molecule and the dissociation of the acetic acid from Ser198. The calculated free energy profile reveals that the second transition state (TS2) should be rate-determining. The structural analysis reveals that the oxyanion hole of BChE plays an important role in the stabilization of rate-determining TS2. The free energy barrier (15.9 ± 0.2 or 16.1 ± 0.2 kcal/mol) calculated for the rate-determining step is in good agreement with the experimentally derived activation free energy (~16.2 kcal/mol), suggesting that the mechanistic insights obtained from this computational study are reliable. The obtained structural and mechanistic insights could be valuable for use in the future rational design of a novel therapeutic treatment of heroin abuse.
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Affiliation(s)
- Yan Qiao
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Science , Zhongshan Road 457, Dalian 116023, P. R. China
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23
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Wei D, Huang X, Tang M, Zhan CG. Reaction pathway and free energy profile for papain-catalyzed hydrolysis of N-acetyl-Phe-Gly 4-nitroanilide. Biochemistry 2013; 52:5145-54. [PMID: 23862626 PMCID: PMC3770148 DOI: 10.1021/bi400629r] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Possible reaction pathways for papain-catalyzed hydrolysis of N-acetyl-Phe-Gly 4-nitroanilide (APGNA) have been studied by performing pseudobond first-principles quantum mechanical/molecular mechanical-free energy (QM/MM-FE) calculations. The whole hydrolysis process includes two stages: acylation and deacylation. For the acylation stage of the catalytic reaction, we have explored three possible paths (A, B, and C) and the corresponding free energy profiles along the reaction coordinates. It has been demonstrated that the most favorable reaction path in this stage is path B consisting of two reaction steps: the first step is a proton transfer to form a zwitterionic form (i.e., Cys-S⁻/His-H⁺ ion-pair), and the second step is the nucleophilic attack on the carboxyl carbon of the substrate accompanied by the dissociation of 4-nitroanilide. The deacylation stage includes the nucleophilic attack of a water molecule on the carboxyl carbon of the substrate and dissociation between the carboxyl carbon of the substrate and the sulfhydryl sulfur of Cys25 side chain. The free energy barriers calculated for the acylation and deacylation stages are 20.0 and 10.7 kcal/mol, respectively. Thus, the acylation is rate-limiting. The overall free energy barrier calculated for papain-catalyzed hydrolysis of APGNA is 20.0 kcal/mol, which is reasonably close to the experimentally derived activation free energy of 17.9 kcal/mol.
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Affiliation(s)
- Donghui Wei
- Department of Chemistry, Zhengzhou University, 75 Daxue Road, Zhengzhou, Henan, 450052, P. R. China
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, 789 South Limestone Street, Lexington, KY 40536
| | - Xiaoqin Huang
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, 789 South Limestone Street, Lexington, KY 40536
| | - Mingsheng Tang
- Department of Chemistry, Zhengzhou University, 75 Daxue Road, Zhengzhou, Henan, 450052, P. R. China
| | - Chang-Guo Zhan
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, 789 South Limestone Street, Lexington, KY 40536
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24
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van der Kamp MW, Mulholland AJ. Combined quantum mechanics/molecular mechanics (QM/MM) methods in computational enzymology. Biochemistry 2013; 52:2708-28. [PMID: 23557014 DOI: 10.1021/bi400215w] [Citation(s) in RCA: 399] [Impact Index Per Article: 36.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Computational enzymology is a rapidly maturing field that is increasingly integral to understanding mechanisms of enzyme-catalyzed reactions and their practical applications. Combined quantum mechanics/molecular mechanics (QM/MM) methods are important in this field. By treating the reacting species with a quantum mechanical method (i.e., a method that calculates the electronic structure of the active site) and including the enzyme environment with simpler molecular mechanical methods, enzyme reactions can be modeled. Here, we review QM/MM methods and their application to enzyme-catalyzed reactions to investigate fundamental and practical problems in enzymology. A range of QM/MM methods is available, from cheaper and more approximate methods, which can be used for molecular dynamics simulations, to highly accurate electronic structure methods. We discuss how modeling of reactions using such methods can provide detailed insight into enzyme mechanisms and illustrate this by reviewing some recent applications. We outline some practical considerations for such simulations. Further, we highlight applications that show how QM/MM methods can contribute to the practical development and application of enzymology, e.g., in the interpretation and prediction of the effects of mutagenesis and in drug and catalyst design.
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Affiliation(s)
- Marc W van der Kamp
- Centre for Computational Chemistry, School of Chemistry, University of Bristol, Bristol BS8 1TS, UK.
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25
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Ciepluch K, Weber M, Katir N, Caminade AM, El Kadib A, Klajnert B, Majoral JP, Bryszewska M. Effect of viologen–phosphorus dendrimers on acetylcholinesterase and butyrylcholinesterase activities. Int J Biol Macromol 2013; 54:119-24. [DOI: 10.1016/j.ijbiomac.2012.12.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2012] [Revised: 11/19/2012] [Accepted: 12/03/2012] [Indexed: 11/29/2022]
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26
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Li D, Huang X, Lin J, Zhan CG. Catalytic mechanism of cytochrome P450 for N-methylhydroxylation of nicotine: reaction pathways and regioselectivity of the enzymatic nicotine oxidation. Dalton Trans 2013; 42:3812-20. [PMID: 23303461 DOI: 10.1039/c2dt32106h] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The fundamental reaction mechanism of cytochrome P450 2A6 (CYP2A6)-catalyzed N-methylhydroxylation of (S)-(-)-nicotine and the free energy profile have been studied by performing pseudobond first-principles quantum mechanical/molecular mechanical (QM/MM) reaction-coordinate calculations. In the CYP2A6-(S)-(-)-nicotine binding structures that allow for 5'-hydroxylation, the N-methyl group is also sufficiently close to the oxygen of Cpd I for the N-methylhydroxylation reaction to occur. It has been demonstrated that the CYP2A6-catalyzed N-methylhydroxylation reaction is a concerted process involving a hydrogen-transfer transition state on both the quartet and the doublet states. The N-methylhydroxylation reaction proceeds mainly in the doublet state, since the free energy barriers on the doublet state are lower than the corresponding ones on the quartet state. The calculated free energy barriers indicate that (S)-(-)-nicotine oxidation catalyzed by CYP2A6 proceeds with a high regioselective abstraction of the hydrogen at the 5'-position, rather than the hydrogen at the N-methyl group. The predicted regioselectivity of 93% is in agreement with the most recent experimentally reported regioselectivity of 95%. The binding mode of (S)-(-)-nicotine in the active site of CYP2A6 is an important determinant for the stereoselectivity of nicotine (S)-(-)-oxidation, whereas the regioselectivity of (S)-(-)-nicotine oxidation is determined mainly by the free energy barrier difference between the 5'-hydroxylation and N-methylhydroxylation reactions.
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Affiliation(s)
- Dongmei Li
- College of Pharmacy, State Key Laboratory of Medicinal Chemical Biology, Nankai University, Tianjin 300071, China.
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27
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Beletskiy EV, Schmidt J, Wang XB, Kass SR. Three hydrogen bond donor catalysts: oxyanion hole mimics and transition state analogues. J Am Chem Soc 2012; 134:18534-7. [PMID: 23113730 DOI: 10.1021/ja3085862] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Enzymes and their mimics use hydrogen bonds to catalyze chemical transformations. Small-molecule transition state analogues of oxyanion holes have been characterized by computations, gas-phase IR and photoelectron spectroscopy, and determination of their binding constants in acetonitrile. A new class of hydrogen bond catalysts is proposed (donors that can contribute three hydrogen bonds to a single functional group) and demonstrated in a Friedel-Crafts reaction. The employed catalyst was observed to react 100 times faster than its rotamer that can employ only two hydrogen bonds. The former compound also binds anions more tightly and was found to have a thermodynamic advantage.
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Affiliation(s)
- Evgeny V Beletskiy
- Department of Chemistry, University of Minnesota, Minneapolis, 55455, United States
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28
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Wei D, Lei B, Tang M, Zhan CG. Fundamental reaction pathway and free energy profile for inhibition of proteasome by Epoxomicin. J Am Chem Soc 2012; 134:10436-50. [PMID: 22697787 DOI: 10.1021/ja3006463] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
First-principles quantum mechanical/molecular mechanical free energy calculations have been performed to provide the first detailed computational study on the possible mechanisms for reaction of proteasome with a representative peptide inhibitor, Epoxomicin (EPX). The calculated results reveal that the most favorable reaction pathway consists of five steps. The first is a proton transfer process, activating Thr1-O(γ) directly by Thr1-N(z) to form a zwitterionic intermediate. The next step is nucleophilic attack on the carbonyl carbon of EPX by the negatively charged Thr1-O(γ) atom, followed by a proton transfer from Thr1-N(z) to the carbonyl oxygen of EPX (third step). Then, Thr1-N(z) attacks on the carbon of the epoxide group of EPX, accompanied by the epoxide ring-opening (S(N)2 nucleophilic substitution) such that a zwitterionic morpholino ring is formed between residue Thr1 and EPX. Finally, the product of morpholino ring is generated via another proton transfer. Noteworthy, Thr1-O(γ) can be activated directly by Thr1-N(z) to form the zwitterionic intermediate (with a free energy barrier of only 9.9 kcal/mol), and water cannot assist the rate-determining step, which is remarkably different from the previous perception that a water molecule should mediate the activation process. The fourth reaction step has the highest free energy barrier (23.6 kcal/mol) which is reasonably close to the activation free energy (∼21-22 kcal/mol) derived from experimental kinetic data. The obtained novel mechanistic insights should be valuable for not only future rational design of more efficient proteasome inhibitors but also understanding the general reaction mechanism of proteasome with a peptide or protein.
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Affiliation(s)
- Donghui Wei
- Department of Chemistry, Zhengzhou University, Daxue Road, Zhengzhou, Henan 450052, China
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