1
|
Li K, Liu Y, Liu Y, Li Q, Guo L, Xie J. The reactivation kinetic analysis, molecular docking, and dynamics of oximes against three V-type nerve agents inhibited four human cholinesterases. Chem Biol Interact 2024; 396:111061. [PMID: 38763347 DOI: 10.1016/j.cbi.2024.111061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2024] [Revised: 05/06/2024] [Accepted: 05/16/2024] [Indexed: 05/21/2024]
Abstract
Nerve agents pose significant threats to civilian and military populations. The reactivation of acetylcholinesterase (AChE) is critical in treating acute poisoning, but there is still lacking broad-spectrum reactivators, which presents a big challenge. Therefore, insights gained from the reactivation kinetic analysis and molecular docking are essential for understanding the behavior of reactivators towards intoxicated AChE. In this research, we present a systematic determination of the reactivation kinetics of three V agents-inhibited four human ChEs [(AChE and butyrylcholinesterase (BChE)) from either native or recombinant resources, namely, red blood cell (RBC) AChE, rhAChE, hBChE, rhBChE) reactivated by five standard oximes. We unveiled the effect of native and recombinant ChEs on the reactivation kinetics of V agents ex vitro, where the reactivation kinetics characteristic of Vs-inhibited BChE was reported for the first time. In terms of the inhibition type, all of the five oxime reactivators exhibited noncompetitive inhibition. The inhibition potency of these reactivators would not lead to the difference in the reactivation kinetics between native and recombinant ChE. Despite the significant differences between the native and recombinant ChEs observed in the inhibition, aging, and spontaneous reactivation kinetics, the reactivation kinetics of V agent-inhibited ChEs by oximes were less differentiated, which were supported by the ligand docking results. We also found differences in the reactivation efficiency between five reactivators and the phosphorylated enzyme, and molecular dynamic simulations can further explain from the perspectives of conformational stability, hydrogen bonding, binding free energies, and amino acid contributions. By Poisson-Boltzmann surface area (MM-PBSA) calculations, the total binding free energy trends aligned well with the experimental kr2 values.
Collapse
Affiliation(s)
- Kexin Li
- Laboratory of Toxicant Analysis, Institute of Pharmacology and Toxicology, Academy of Military Medical Sciences, 27 Taiping Road, Haidian District, 100850, Beijing, China
| | - Yulong Liu
- Laboratory of Toxicant Analysis, Institute of Pharmacology and Toxicology, Academy of Military Medical Sciences, 27 Taiping Road, Haidian District, 100850, Beijing, China
| | - Yanqin Liu
- Laboratory of Toxicant Analysis, Institute of Pharmacology and Toxicology, Academy of Military Medical Sciences, 27 Taiping Road, Haidian District, 100850, Beijing, China
| | - Qian Li
- Beijing Institute of Pharmacology and Toxicology, 27 Taiping Road, Haidian District, 100850, Beijing, China
| | - Lei Guo
- Laboratory of Toxicant Analysis, Institute of Pharmacology and Toxicology, Academy of Military Medical Sciences, 27 Taiping Road, Haidian District, 100850, Beijing, China.
| | - Jianwei Xie
- Laboratory of Toxicant Analysis, Institute of Pharmacology and Toxicology, Academy of Military Medical Sciences, 27 Taiping Road, Haidian District, 100850, Beijing, China
| |
Collapse
|
2
|
Ahmed M, Ahmad A, Mushtaq N, Sher N, Khan RA. Protective Role of Antibiotics (Anisomycin and Puromycin) Against Snake Venom Acetylcholinesterase (AChE). Int J Pept Res Ther 2022. [DOI: 10.1007/s10989-022-10482-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
|
3
|
Estévez J, Terol M, Sogorb MÁ, Vilanova E. Interactions of human acetylcholinesterase with phenyl valerate and acetylthiocholine: Thiocholine as an enhancer of phenyl valerate esterase activity. Chem Biol Interact 2022; 351:109764. [PMID: 34875277 DOI: 10.1016/j.cbi.2021.109764] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Revised: 11/11/2021] [Accepted: 11/25/2021] [Indexed: 11/03/2022]
Abstract
Phenyl valerate (PV) is a neutral substrate for measuring the PVase activity of neuropathy target esterase (NTE), a key molecular event of organophosphorus-induced delayed neuropathy. This substrate has been used to discriminate and identify other proteins with esterase activity and potential targets of organophosphorus (OP) binding. A protein with PVase activity in chicken (model for delayed neurotoxicity) was identified as butyrylcholinesterase (BChE). Further studies in human BChE suggest that other sites might be involved in PVase activity. From the theoretical docking analysis, other more favorable sites for binding PV related to the Asn289 residue located far from the catalytic site ("PVsite") were deduced.In this paper, we demonstrate that acetylcholinesterase is also able to hydrolyze PV. Robust kinetic studies of interactions between substrates PV and acetylthiocholine (AtCh) were performed. The kinetics did not fit the classic competition models among substrates. While PV interacts as a competitive inhibitor in AChE activity, AtCh at low concentrations enhances PVase activity and inhibits this activity at high concentrations. Kinetic behavior suggests that the potentiation effect is caused by thiocholine released at the active site, where AtCh could act as a Trojan Horse. We conclude that the products released at the active site could play an important role in the hydrolysis reactions of different substrates in biological systems.
Collapse
Affiliation(s)
- Jorge Estévez
- Nstitute of Bioengineering, University Miguel Hernández, Elche (Alicante), Spain.
| | - Marina Terol
- Nstitute of Bioengineering, University Miguel Hernández, Elche (Alicante), Spain
| | - Miguel Ángel Sogorb
- Nstitute of Bioengineering, University Miguel Hernández, Elche (Alicante), Spain
| | - Eugenio Vilanova
- Nstitute of Bioengineering, University Miguel Hernández, Elche (Alicante), Spain
| |
Collapse
|
4
|
Lopez SMM, Aguilar JS, Fernandez JBB, Lao AGJ, Estrella MRR, Devanadera MKP, Ramones CMV, Villaraza AJL, Guevarra LA, Santiago-Bautista MR, Santiago LA. Neuroactive venom compounds obtained from Phlogiellus bundokalbo as potential leads for neurodegenerative diseases: insights on their acetylcholinesterase and beta-secretase inhibitory activities in vitro. J Venom Anim Toxins Incl Trop Dis 2021; 27:e20210009. [PMID: 34249120 PMCID: PMC8237997 DOI: 10.1590/1678-9199-jvatitd-2021-0009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2021] [Accepted: 03/31/2021] [Indexed: 11/22/2022] Open
Abstract
Background Spider venom is a rich cocktail of neuroactive compounds designed to prey capture and defense against predators that act on neuronal membrane proteins, in particular, acetylcholinesterases (AChE) that regulate synaptic transmission through acetylcholine (ACh) hydrolysis - an excitatory neurotransmitter - and beta-secretases (BACE) that primarily cleave amyloid precursor proteins (APP), which are, in turn, relevant in the structural integrity of neurons. The present study provides preliminary evidence on the therapeutic potential of Phlogiellus bundokalbo venom against neurodegenerative diseases. Methods Spider venom was extracted by electrostimulation and fractionated by reverse-phase high-performance liquid chromatography (RP-HPLC) and characterized by matrix-assisted laser desorption ionization-time flight mass spectrometry (MALDI-TOF-MS). Neuroactivity of the whole venom was observed by a neurobehavioral response from Terebrio molitor larvae in vivo and fractions were screened for their inhibitory activities against AChE and BACE in vitro. Results The whole venom from P. bundokalbo demonstrated neuroactivity by inducing excitatory movements from T. molitor for 15 min. Sixteen fractions collected produced diverse mass fragments from MALDI-TOF-MS ranging from 900-4500 Da. Eleven of sixteen fractions demonstrated AChE inhibitory activities with 14.34% (± 2.60e-4) to 62.05% (± 6.40e-5) compared with donepezil which has 86.34% (± 3.90e-5) inhibition (p > 0.05), while none of the fractions were observed to exhibit BACE inhibition. Furthermore, three potent fractions against AChE, F1, F3, and F16 displayed competitive and uncompetitive inhibitions compared to donepezil as the positive control. Conclusion The venom of P. bundokalbo contains compounds that demonstrate neuroactivity and anti-AChE activities in vitro, which could comprise possible therapeutic leads for the development of cholinergic compounds against neurological diseases.
Collapse
Affiliation(s)
- Simon Miguel M Lopez
- Department of Biochemistry, Faculty of Pharmacy, University of Santo Tomas, Manila, Philippines, 1008.,Institute of Chemistry, College of Science, University of the Philippines Diliman, Quezon City, Philippines, 1101
| | - Jeremey S Aguilar
- Department of Biochemistry, Faculty of Pharmacy, University of Santo Tomas, Manila, Philippines, 1008
| | - Jerene Bashia B Fernandez
- Department of Biochemistry, Faculty of Pharmacy, University of Santo Tomas, Manila, Philippines, 1008
| | - Angelic Gayle J Lao
- Department of Biochemistry, Faculty of Pharmacy, University of Santo Tomas, Manila, Philippines, 1008.,Research Center for Natural and Applied Sciences, University of Santo Tomas, Manila, Philippines, 1015.,The Graduate School, University of Santo Tomas, Manila, Philippines, 1015.,Institute of Chemistry, College of Science, University of the Philippines Diliman, Quezon City, Philippines, 1101
| | - Mitzi Rain R Estrella
- Department of Biochemistry, Faculty of Pharmacy, University of Santo Tomas, Manila, Philippines, 1008
| | - Mark Kevin P Devanadera
- Department of Biochemistry, Faculty of Pharmacy, University of Santo Tomas, Manila, Philippines, 1008.,Research Center for Natural and Applied Sciences, University of Santo Tomas, Manila, Philippines, 1015.,The Graduate School, University of Santo Tomas, Manila, Philippines, 1015
| | - Cydee Marie V Ramones
- Institute of Chemistry, College of Science, University of the Philippines Diliman, Quezon City, Philippines, 1101
| | - Aaron Joseph L Villaraza
- Institute of Chemistry, College of Science, University of the Philippines Diliman, Quezon City, Philippines, 1101
| | - Leonardo A Guevarra
- Department of Biochemistry, Faculty of Pharmacy, University of Santo Tomas, Manila, Philippines, 1008.,Research Center for Natural and Applied Sciences, University of Santo Tomas, Manila, Philippines, 1015
| | - Myla R Santiago-Bautista
- Department of Biochemistry, Faculty of Pharmacy, University of Santo Tomas, Manila, Philippines, 1008.,Research Center for Natural and Applied Sciences, University of Santo Tomas, Manila, Philippines, 1015.,The Graduate School, University of Santo Tomas, Manila, Philippines, 1015
| | - Librado A Santiago
- Department of Biochemistry, Faculty of Pharmacy, University of Santo Tomas, Manila, Philippines, 1008.,Research Center for Natural and Applied Sciences, University of Santo Tomas, Manila, Philippines, 1015.,The Graduate School, University of Santo Tomas, Manila, Philippines, 1015
| |
Collapse
|
5
|
Ahmed M, Khan SZ, Sher N, Rehman ZU, Mushtaq N, Khan RA. Kinetic and toxicological effects of synthesized palladium(II) complex on snake venom (Bungarus sindanus) acetylcholinesterase. J Venom Anim Toxins Incl Trop Dis 2021; 27:e20200047. [PMID: 33889183 PMCID: PMC8034821 DOI: 10.1590/1678-9199-jvatitd-2020-0047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Accepted: 10/29/2020] [Indexed: 11/27/2022] Open
Abstract
BACKGROUND The venom of the krait (Bungarus sindanus), an Elapidae snake, is highly toxic to humans and contains a great amount of acetylcholinesterase (AChE). The enzyme AChE provokes the hydrolysis of substrate acetylcholine (ACh) in the nervous system and terminates nerve impulse. Different inhibitors inactivate AChE and lead to ACh accumulation and disrupted neurotransmission. METHODS The present study was designed to evaluate the effect of palladium(II) complex as antivenom against krait venom AChE using kinetics methods. RESULTS Statistical analysis showed that krait venom AChE inhibition decreases with the increase of Pd(II) complex (0.025-0.05 µM) and exerted 61% inhibition against the AChE at a fixed concentration (0.5 mM) of ACh. Kinetic analysis using the Lineweaver Burk plot showed that Pd(II) caused a competitive inhibition. The compound Pd(II) complex binds at the active site of the enzyme. It was observed that K m (Michaelis-Menten constant of AChE-ACh into AChE and product) increased from 0.108 to 0.310 mM (45.74 to 318.35%) and V max remained constant with an increase of Pd(II) complex concentrations. In AChE K Iapp was found to increase from 0.0912 to 0.025 µM (29.82-72.58%) and did not affect the V maxapp with an increase of ACh from (0.05-1 mM). K i (inhibitory constant) was estimated to be 0.029 µM for snake venom; while the K m was estimated to be 0.4 mM. The calculated IC50 for Pd(II) complex was found to be 0.043 µM at constant ACh concentration (0.5 mM). CONCLUSIONS The results show that the Pd(II) complex can be deliberated as an inhibitor of AChE.
Collapse
Affiliation(s)
- Mushtaq Ahmed
- Department of Biotechnology, University of Science and Technology
Bannu-KPK, Pakistan
| | - Shahan Zeb Khan
- Department of Chemistry, Quaid-i-Azam University, Islamabad,
Pakistan
| | - Naila Sher
- Department of Biotechnology, University of Science and Technology
Bannu-KPK, Pakistan
| | - Zia Ur Rehman
- Department of Chemistry, Quaid-i-Azam University, Islamabad,
Pakistan
| | - Nadia Mushtaq
- Department of Botany, University of Science and Technology
Bannu-KPK, Pakistan
| | - Rahmat Ali Khan
- Department of Biotechnology, University of Science and Technology
Bannu-KPK, Pakistan
| |
Collapse
|
6
|
Rosenberry TL, Cheung J. Rate-limiting step in the decarbamoylation of acetylcholinesterases with large carbamoyl groups. Chem Biol Interact 2019; 308:392-395. [PMID: 31175846 DOI: 10.1016/j.cbi.2019.06.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Revised: 05/16/2019] [Accepted: 06/03/2019] [Indexed: 11/30/2022]
Abstract
Carbamates are esters of substituted carbamic acids that react with acetylcholinesterase (AChE) by initially transferring the carbamoyl group to a serine residue in the enzyme active site accompanied by loss of the carbamate leaving group followed by hydrolysis of the carbamoyl enzyme. This hydrolysis, or decarbamoylation, is relatively slow, and half-lives of carbamoylated AChEs range from 4 min to more than 30 days. Therefore, carbamates are effective AChE inhibitors that have been developed as insecticides and as therapeutic agents. In this report, we review recent data showing that decarbamoylation rate constants are independent of the ester leaving group for a series of carbamic acid esters with the same carbamoyl group and that decarbamoylation rate constants decreased by 800-fold when the alkyl substituents on the carbamoyl group increased in size from N-monomethyl- to N,N-diethyl-. We also review data showing that solvent deuterium oxide isotope effects for decarbamoylation decreased from 2.8 for N-monomethylcarbamoyl AChE to 1.1 for N,N-diethylcarbamoyl AChE, indicating a shift in the rate-limiting step from general acid-base catalysis to a likely conformational change in the distorted active site in N,N-diethylcarbamoyl AChE. The nature of such a conformational change is suggested from X-ray crystal structures of AChE phosphorylated by paraoxon.
Collapse
Affiliation(s)
- Terrone L Rosenberry
- Mayo Clinic College of Medicine, Departments of Neuroscience and Pharmacology, Jacksonville, FL, 32224, USA.
| | - Jonah Cheung
- New York Structural Biology Center, New York, NY, 10027, USA
| |
Collapse
|
7
|
Xu Y, Zhang J, Wang H, Mao F, Bao K, Liu W, Zhu J, Li X, Zhang H, Li J. Rational Design of Novel Selective Dual-Target Inhibitors of Acetylcholinesterase and Monoamine Oxidase B as Potential Anti-Alzheimer's Disease Agents. ACS Chem Neurosci 2019; 10:482-496. [PMID: 30110536 DOI: 10.1021/acschemneuro.8b00357] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Multifunctional agents aiming at cholinesterases (ChEs) and monoamine oxidases (MAOs) are promising therapy for Alzheimer's disease (AD). Herein, a series of novel propargylamine-modified pyrimidinylthiourea derivatives (1-4) were designed and synthesized as dual inhibitors of ChEs and MAOs with other functions against AD. Most of these derivatives inhibited ChEs and MAOs with IC50 values in the micro- or nanomolar ranges. Compound 1c displayed the dual functional profile of targeting the AChE (IC50 = 0.032 ± 0.007 μM) and MAO-B (IC50 = 2.117 ± 0.061 μM), along with the improved blood-brain barrier (BBB) permeability, antioxidant ability, and good copper chelating property in vitro. Animal studies showed that compound 1c·HCl could inhibit the cerebral AChE/MAO-B activities and alleviate scopolamine-induced cognitive impairment in mice. Combined with good oral bioavailability ( F = 45.55%), these findings demonstrated that compound 1c may be a potent brain permeable multifunctional candidate for the treatment of AD.
Collapse
Affiliation(s)
- Yixiang Xu
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Mei Long Road, Shanghai 200237, China
- Shanghai Key Laboratory of New Drug Design, School of Pharmacy, East China University of Science and Technology, 130 Mei Long Road, Shanghai 200237, China
| | - Jian Zhang
- CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zu Chong Zhi Road, Shanghai 201203, China
| | - Huan Wang
- CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zu Chong Zhi Road, Shanghai 201203, China
| | - Fei Mao
- Shanghai Key Laboratory of New Drug Design, School of Pharmacy, East China University of Science and Technology, 130 Mei Long Road, Shanghai 200237, China
| | - Keting Bao
- Shanghai Key Laboratory of New Drug Design, School of Pharmacy, East China University of Science and Technology, 130 Mei Long Road, Shanghai 200237, China
| | - Wenwen Liu
- Shanghai Key Laboratory of New Drug Design, School of Pharmacy, East China University of Science and Technology, 130 Mei Long Road, Shanghai 200237, China
| | - Jin Zhu
- Shanghai Key Laboratory of New Drug Design, School of Pharmacy, East China University of Science and Technology, 130 Mei Long Road, Shanghai 200237, China
| | - Xiaokang Li
- Shanghai Key Laboratory of New Drug Design, School of Pharmacy, East China University of Science and Technology, 130 Mei Long Road, Shanghai 200237, China
| | - Haiyan Zhang
- CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zu Chong Zhi Road, Shanghai 201203, China
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 201203, China
| | - Jian Li
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Mei Long Road, Shanghai 200237, China
- Shanghai Key Laboratory of New Drug Design, School of Pharmacy, East China University of Science and Technology, 130 Mei Long Road, Shanghai 200237, China
| |
Collapse
|
8
|
Wei Z, Bi H, Liu YQ, Nie HF, Yao L, Wang SZ, Yang J, Wang YA, Liu X, Zheng ZB. Design, synthesis and evaluation of new classes of nonquaternary reactivators for acetylcholinesterase inhibited by organophosphates. Bioorg Chem 2018; 81:681-688. [DOI: 10.1016/j.bioorg.2018.09.025] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Revised: 09/13/2018] [Accepted: 09/17/2018] [Indexed: 12/15/2022]
|
9
|
Venkatasubban KS, Johnson JL, Thomas JL, Fauq A, Cusack B, Rosenberry TL. Decarbamoylation of acetylcholinesterases is markedly slowed as carbamoyl groups increase in size. Arch Biochem Biophys 2018; 655:67-74. [PMID: 30098983 DOI: 10.1016/j.abb.2018.08.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Revised: 08/06/2018] [Accepted: 08/08/2018] [Indexed: 12/27/2022]
Abstract
Carbamates are esters of substituted carbamic acids that react with acetylcholinesterase (AChE) by initially transferring the carbamoyl group to a serine residue in the enzyme active site accompanied by loss of the carbamate leaving group followed by hydrolysis of the carbamoyl enzyme. This hydrolysis, or decarbamoylation, is relatively slow, and half-lives of carbamoylated AChEs range from 4 min to more than 30 days. Therefore, carbamates are effective AChE inhibitors that have been developed as insecticides and as therapeutic agents. We show here, in contrast to a previous report, that decarbamoylation rate constants are independent of the leaving group for a series of carbamates with the same carbamoyl group. When the alkyl substituents on the carbamoyl group increased in size from N-monomethyl- to N,N-dimethyl-, N-ethyl-N-methyl-, or N,N-diethyl-, the decarbamoylation rate constants decreased by 4-, 70-, and 800-fold, respectively. We suggest that this relationship arises as a result of active site distortion, particularly in the acyl pocket of the active site. Furthermore, solvent deuterium oxide isotope effects for decarbamoylation decreased from 2.8 for N-monomethylcarbamoyl AChE to 1.1 for N,N-diethylcarbamoyl AChE, indicating a shift in the rate-limiting step from general acid-base catalysis to a likely conformational change in the distorted active site.
Collapse
Affiliation(s)
| | - Joseph L Johnson
- Mayo Clinic College of Medicine, Departments of Neuroscience and Pharmacology, Jacksonville, FL, 32224, USA
| | - Jamie L Thomas
- Mayo Clinic College of Medicine, Departments of Neuroscience and Pharmacology, Jacksonville, FL, 32224, USA
| | - Abdul Fauq
- Mayo Clinic College of Medicine, Departments of Neuroscience and Pharmacology, Jacksonville, FL, 32224, USA
| | - Bernadette Cusack
- Mayo Clinic College of Medicine, Departments of Neuroscience and Pharmacology, Jacksonville, FL, 32224, USA
| | - Terrone L Rosenberry
- Mayo Clinic College of Medicine, Departments of Neuroscience and Pharmacology, Jacksonville, FL, 32224, USA.
| |
Collapse
|
10
|
The assessment of cholinesterase from the liver of Puntius javanicus as detection of metal ions. ScientificWorldJournal 2014; 2014:571094. [PMID: 25401148 PMCID: PMC4225846 DOI: 10.1155/2014/571094] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2014] [Revised: 06/27/2014] [Accepted: 07/30/2014] [Indexed: 11/18/2022] Open
Abstract
Crude extract of ChE from the liver of Puntius javanicus was purified using procainamide-sepharyl 6B. S-Butyrylthiocholine iodide (BTC) was selected as the specific synthetic substrate for this assay with the highest maximal velocity and lowest biomolecular constant at 53.49 µmole/min/mg and 0.23 mM, respectively, with catalytic efficiency ratio of 0.23. The optimum parameter was obtained at pH 7.5 and optimal temperature in the range of 25 to 30°C. The effect of different storage condition was assessed where ChE activity was significantly decreased after 9 days of storage at room temperature. However, ChE activity showed no significant difference when stored at 4.0, 0, and −25°C for 15 days. Screening of heavy metals shows that chromium, copper, and mercury strongly inhibited P. javanicus ChE by lowering the activity below 50%, while several pairwise combination of metal ions exhibited synergistic inhibiting effects on the enzyme which is greater than single exposure especially chromium, copper, and mercury. The results showed that P. javanicus ChE has the potential to be used as a biosensor for the detection of metal ions.
Collapse
|
11
|
Wei Z, Liu YQ, Zhou XB, Luo Y, Huang CQ, Wang YA, Zheng ZB, Li S. New efficient imidazolium aldoxime reactivators for nerve agent-inhibited acetylcholinesterase. Bioorg Med Chem Lett 2014; 24:5743-5748. [PMID: 25453812 DOI: 10.1016/j.bmcl.2014.10.055] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2014] [Revised: 09/26/2014] [Accepted: 10/17/2014] [Indexed: 10/24/2022]
Abstract
Herein, we described a new class of uncharged non-pyridinium reactivators for nerve agent-inhibited acetylcholinesterase (AChE). Based on a dual site binding strategy, we conjugated the imidazolium aldoxime to different peripheral site ligands (PSLs) of AChE through alkyl chains. Compared with the known quaternary pyridinium reactivators, two of the resulting conjugates (7g and 7h) were highlighted to be the first efficient non-pyridinium oxime conjugates exhibiting similar or superior ability to reactivate sarin-, VX- and tabun-inhibited AChE. Moreover, they were more broad-spectrum reactivators.
Collapse
Affiliation(s)
- Zhao Wei
- Laboratory of Computer-Aided Drug Design & Discovery, Beijing Institute of Pharmacology and Toxicology, Beijing 100850, China
| | - Yan-Qin Liu
- Department of Military Toxicology and Biochemical Pharmacology, Institute of Pharmacology and Toxicology, Academy of Military Medical Sciences, Beijing 100850, China
| | - Xin-Bo Zhou
- Laboratory of Computer-Aided Drug Design & Discovery, Beijing Institute of Pharmacology and Toxicology, Beijing 100850, China
| | - Yuan Luo
- Department of Military Toxicology and Biochemical Pharmacology, Institute of Pharmacology and Toxicology, Academy of Military Medical Sciences, Beijing 100850, China
| | - Chun-Qian Huang
- Department of Military Toxicology and Biochemical Pharmacology, Institute of Pharmacology and Toxicology, Academy of Military Medical Sciences, Beijing 100850, China
| | - Yong-An Wang
- Department of Military Toxicology and Biochemical Pharmacology, Institute of Pharmacology and Toxicology, Academy of Military Medical Sciences, Beijing 100850, China
| | - Zhi-Bing Zheng
- Laboratory of Computer-Aided Drug Design & Discovery, Beijing Institute of Pharmacology and Toxicology, Beijing 100850, China.
| | - Song Li
- Laboratory of Computer-Aided Drug Design & Discovery, Beijing Institute of Pharmacology and Toxicology, Beijing 100850, China
| |
Collapse
|
12
|
Ahmed M, Latif N, Khan RA, Ahmad A, Schetinger MRC, Rocha JBT. Toxicological effect of N, N, N′, N′-tetramethylethylene on rat brain acetylcholinesterase. Toxicol Ind Health 2014; 30:415-20. [DOI: 10.1177/0748233712457443] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
N, N, N′, N′-tetramethylethylenediamine (TEMED) is extensively used for initiating polymerization of acrylamide and bisacrylamide gel for electrophoresis and for inorganic complex structure formation. The present study evaluates the toxicological effect of TEMED on structures of rat brain acetylcholinesterase (AChE) activity . In vitro study showed that the Ki values for striatum, cortex, cerebellum and hypothalamus were found to be 1.24, 1.4, 1.45 and 1.47 mM. Kinetics studies indicated that TEMED caused mixed type of inhibition that is a combination of competitive and noncompetitive inhibition in striatum, cortex, hypothalamus and cerebellum. The result showed that km increased and Vmax decreased with increase in TEMED concentration. The IC50 values calculated for striatum, cortex, cerebellum and hypothalamus were found to be as 0.92, 0.92, 1.44 and 1.42 mM. The present study indicates that TEMED is a toxicant for brain via inhibition of AChE. Therefore, proper precaution should be made during its handling.
Collapse
Affiliation(s)
- Mushtaq Ahmed
- Department of Biotechnology, University of Science and Technology, Bannu, KPK, Pakistan
- Departamento de Bioquímica, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, Santa Maria, RS, Brazil
| | - Nadia Latif
- Departamento de Bioquímica, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, Santa Maria, RS, Brazil
| | - Rahmat Ali Khan
- Department of Biotechnology, University of Science and Technology, Bannu, KPK, Pakistan
| | - Akhlaq Ahmad
- Department of Biotechnology, University of Science and Technology, Bannu, KPK, Pakistan
| | - Maria RC Schetinger
- Departamento de Bioquímica, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, Santa Maria, RS, Brazil
| | - João BT Rocha
- Departamento de Bioquímica, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, Santa Maria, RS, Brazil
| |
Collapse
|
13
|
Campanha HM, Carvalho F, Schlosser PM. Active and peripheral anionic sites of acetylcholinesterase have differential modulation effects on cell proliferation, adhesion and neuritogenesis in the NG108-15 cell line. Toxicol Lett 2014; 230:122-31. [PMID: 24680925 DOI: 10.1016/j.toxlet.2014.03.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2013] [Revised: 03/02/2014] [Accepted: 03/19/2014] [Indexed: 11/26/2022]
Abstract
The classical enzymatic role of acetylcholinesterase (AChE) is to terminate impulse transmission at cholinergic synapses through rapid hydrolysis of acetylcholine (ACh). Inactivation of this enzyme's catalytic site is the primary mechanism of acute toxicity of OP insecticides (e.g. parathion, chlorpyrifos). There is now sufficient evidence to suggest that AChE has a neurotrophic function that may be altered by organophosphate (OP) exposure, resulting in defects of neuronal growth and development, though the clarification of the mechanisms involved require further in vitro investigation. In the present study, the mouse neuroblastoma×rat glioma hybrid NG108-15 cell line was used to investigate the differential effects between inhibition of the catalytic site and peripheral anionic site (PAS) of acetylcholinesterase (AChE) on cell adhesion, proliferation and neuritogenesis, in the presence and absence of human red blood cell (hRBC) AChE (ED3.1.1.7). AChE active-site inhibitor paraoxon (PO; 0.1-1.0μM), when added to NG108-15 cells grown on AChE-coated plates, had no effect on cell proliferation, but exerted a significant reduction in strongly adherent viable cells accompanied by mostly short process formations, with 18% of cells considered to be neuritogenic, similar to that observed on uncoated plates. In contrast, PO had no significant effect on cell adhesion and proliferation of NG108-15 cells on uncoated plates. The PAS-ligand thioflavin-T (Th-T; 0.5-25μM), however, decreased cell adhesion and proliferation, on both uncoated and ACh-E coated plates, with less magnitude on AChE-coated plates. Taken together, these results suggest that strong cell adherence and neuritogenesis are sensitive to PO in this cell culture model, with no impact on proliferation, in the presence of membrane bound AChE-coating, while there is no sensitivity to PO on uncoated plates. On the other hand, binding of Th-T directly to the PAS affects both cell adherence and proliferation, with less magnitude in the presence of membrane-bound AChE. The current study indicates that PO is deleterious in neural development during critical periods of strong cell adhesion and differentiation, interfering with AChE trophic function.
Collapse
Affiliation(s)
- Helen M Campanha
- Rutgers, New Jersey Medical School-Graduate School of Biomedical Sciences, 185 South Orange Avenue, MSB H609, Newark, NJ 07103, United States.
| | - Félix Carvalho
- REQUIMTE, Laboratory of Toxicology, Department of Biological Sciences, Faculty of Pharmacy, University of Porto, Rua de Jorge Viterbo Ferreira no. 228, 4050-313 Porto, Portugal
| | - Paul M Schlosser
- U.S. Environmental Protection Agency, National Center for Environmental Assessment, Washington, DC, United States
| |
Collapse
|
14
|
Changeux JP. The concept of allosteric interaction and its consequences for the chemistry of the brain. J Biol Chem 2013; 288:26969-26986. [PMID: 23878193 DOI: 10.1074/jbc.x113.503375] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Throughout this Reflections article, I have tried to follow up on the genesis in the 1960s and subsequent evolution of the concept of allosteric interaction and to examine its consequences within the past decades, essentially in the field of the neuroscience. The main conclusion is that allosteric mechanisms built on similar structural principles operate in bacterial regulatory enzymes, gene repressors (and the related nuclear receptors), rhodopsin, G-protein-coupled receptors, neurotransmitter receptors, ion channels, and so on from prokaryotes up to the human brain yet with important features of their own. Thus, future research on these basic cybernetic sensors is expected to develop in two major directions: at the elementary level, toward the atomic structure and molecular dynamics of the conformational changes involved in signal recognition and transduction, but also at a higher level of organization, the contribution of allosteric mechanisms to the modulation of brain functions.
Collapse
Affiliation(s)
- Jean-Pierre Changeux
- Collège de France, 75005 Paris and the Institut Pasteur, 75724 Paris Cedex 15, France.
| |
Collapse
|
15
|
Jiang S, Wang X, Xi R, Zhang Y. Research on the regulation of the spatial structure of acetylcholinesterase tetramer with high efficiency by AFM. Int J Nanomedicine 2013; 8:1095-102. [PMID: 23515568 PMCID: PMC3600998 DOI: 10.2147/ijn.s41591] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Atomic force microscopy (AFM) was applied for obtaining structural information about acetylcholinesterase (AChE) tetramer (AChE G4) before and after reaction with S-acetylcholine iodide (S-ACh), in the presence or absence of propidium iodide (PI), an inhibitor for peripheral anionic sites (PAS). An iced-bath ultrasound was used to prepare the phospholipid membrane. Ves-fusion technique was applied for incorporating AChE G4 in a lipid layer on mica. Before reaction with substrates, the single AChE G4 particle was ellipsoid in shape with a clear border. It had a smooth surface with a central projection. The four subunits of a single enzyme particle were arranged tightly (no separated subunits being found, with an average size of 89 ± 7 nm in length, 68 ± 9 nm in width, and 6 ± 3 nm in height). After reaction with S-ACh in the absence of PI, the loose arrangement of subunits of AChE G4 was seen, with an average size of 104 ± 7 nm in length, 91 ± 5 nm in width, and 8 ± 2 nm in height. Also there was free-flowing space amongst the four subunits of the AChE G4. This was consistent with the results of the ×-ray diffraction crystallography and molecular dynamics studies. The apparent free space was the central path of AChE G4, changing from small to big, to small, to lateral door appearance, with an average size of 60 ± 5 nm in length and 51 ± 9 nm in width. The size of lateral door was 52 ± 5 nm in width and 32 ± 3 nm in depth on average. In the presence of PI, S-ACh could not cause topological structure changes of AChE G4. AFM verified that the central path might govern the turnover of the enzyme morphologically, and the interactions between PI and S-ACh might gate the creation of a central path and the opening of ACG in monomer; and the combination of S-ACh with peripheral anionic sites is conducive to the opening of ACG while PI can inhibit this action. Resolution at the inframolecular level is favorable in providing substantial information on how the spatial structure is adapted to the high efficiency of AChE molecules.
Collapse
Affiliation(s)
- Shuang Jiang
- 210th Hospital of People Liberation Army, Dalian, People's Republic of China
| | | | | | | |
Collapse
|
16
|
Somji M, Dounin V, Muench SB, Schulze H, Bachmann TT, Kerman K. Electroanalysis of amino acid substitutions in bioengineered acetylcholinesterase. Bioelectrochemistry 2012; 88:110-3. [DOI: 10.1016/j.bioelechem.2012.07.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2012] [Revised: 07/01/2012] [Accepted: 07/13/2012] [Indexed: 10/28/2022]
|
17
|
Ahmed M, Latif N, Khan RA, Ahmad A. Toxicological effect of herbicides (diuron and bentazon) on snake venom and electric eel acetylcholinesterase. BULLETIN OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2012; 89:229-233. [PMID: 22653306 DOI: 10.1007/s00128-012-0684-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2012] [Accepted: 05/09/2012] [Indexed: 06/01/2023]
Abstract
The toxicological effects of the active ingredients of the herbicides diuron and bentazon on the activity of acetylcholinesterase (AChE) of krait (Bungarus sindanus) venom and electric eel (Electrophorus electricus) were studied. The diuron and entazon caused non-competitive inhibition of AChE from both species. For the venom AChE, the calculated IC50 for diuron and bentazon were found to be 3.25 and 0.14 μM, while for eel AChE, the respective IC50 values were 3.6 and 0.135 μM. In comparison, bentazon was a more potent inhibitor than diuron of AChE from both species. The insecticide lindane did not have any inhibitory effect on AChE activity in either species, even when tested at high concentrations (200-800 μM).
Collapse
Affiliation(s)
- Mushtaq Ahmed
- Department of Biotechnology, University of Science and Technology, Bannu, KPK, Pakistan.
| | | | | | | |
Collapse
|
18
|
Šinko G, Kovarik Z, Reiner E, Simeon-Rudolf V, Stojan J. Mechanism of stereoselective interaction between butyrylcholinesterase and ethopropazine enantiomers. Biochimie 2011; 93:1797-807. [DOI: 10.1016/j.biochi.2011.06.023] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2011] [Accepted: 06/17/2011] [Indexed: 10/18/2022]
|
19
|
Dounin V, Constantinof A, Schulze H, Bachmann TT, Kerman K. Electrochemical detection of interaction between Thioflavin T and acetylcholinesterase. Analyst 2011; 136:1234-8. [DOI: 10.1039/c0an00743a] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
20
|
Peripheral site ligand-oxime conjugates: A novel concept towards reactivation of nerve agent-inhibited human acetylcholinesterase. Bioorg Med Chem 2010; 19:588-94. [PMID: 21112787 DOI: 10.1016/j.bmc.2010.10.059] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2010] [Revised: 10/14/2010] [Accepted: 10/28/2010] [Indexed: 11/20/2022]
Abstract
A conceptually novel approach to the design of reactivators of nerve agent-inhibited acetylcholinesterase (AChE) is presented. The concept comprises the linkage of a peripheral site ligand via a spacer to a reactivating moiety with the eventual goal to develop non-ionic reactivators with sufficient affinity for AChE to induce reactivation and potentially improved blood-brain barrier penetration. Herein, the first step towards that goal-the synthesis and biological evaluation of a peripheral site ligand conjugated to a charged pyridinium oxime is discussed. It was found, that the introduction of the peripheral site ligand not only increased affinity of the construct for AChE but also enhanced reactivation of nerve agent-inhibited AChE.
Collapse
|
21
|
Wong KKK, Ngo JCK, Liu S, Lin HQ, Hu C, Shaw PC, Wan DCC. Interaction study of two diterpenes, cryptotanshinone and dihydrotanshinone, to human acetylcholinesterase and butyrylcholinesterase by molecular docking and kinetic analysis. Chem Biol Interact 2010; 187:335-9. [DOI: 10.1016/j.cbi.2010.03.026] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2009] [Revised: 02/26/2010] [Accepted: 03/12/2010] [Indexed: 10/19/2022]
|
22
|
Auletta JT, Johnson JL, Rosenberry TL. Molecular basis of inhibition of substrate hydrolysis by a ligand bound to the peripheral site of acetylcholinesterase. Chem Biol Interact 2010; 187:135-41. [PMID: 20493829 DOI: 10.1016/j.cbi.2010.05.009] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2010] [Revised: 05/11/2010] [Accepted: 05/13/2010] [Indexed: 10/19/2022]
Abstract
Acetylcholinesterase (AChE) contains a narrow and deep active site gorge with two sites of ligand binding, an acylation site (or A-site) at the base of the gorge and a peripheral site (or P-site) near the gorge entrance. The P-site contributes to the catalytic efficiency of substrate hydrolysis by transiently binding substrates on their way to the acylation site, where a short-lived acyl enzyme intermediate is produced. Ligands that bind to the A-site invariably inhibit the hydrolysis of all AChE substrates, but ligands that bind to the P-site inhibit the hydrolysis of some substrates but not others. To clarify the basis of this difference, we focus here on second-order rate constants for substrate hydrolysis (k(E)), a parameter that reflects the binding of ligands only to the free form of the enzyme and not to enzyme-substrate intermediates. We first describe an inhibitor competition assay that distinguishes whether a ligand is inhibiting AChE by binding to the A-site or the P-site. We then show that the P-site-specific ligand thioflavin T inhibits the hydrolysis of the rapidly hydrolyzed substrate acetylthiocholine but fails to show any inhibition of the slowly hydrolyzed substrates ATMA (3-(acetamido)-N,N,N-trimethylanilinium) and carbachol. We derive an expression for k(E) that accounts for these observations by recognizing that the rate-limiting steps for these substrates differ. The rate-limiting step for the slow substrates is the general base-catalyzed acylation reaction k(2), a step that is unaffected by bound thioflavin T. In contrast, the rate-limiting step for acetylthiocholine is either substrate association or substrate migration to the A-site, and these steps are blocked by bound thioflavin T.
Collapse
Affiliation(s)
- Jeffrey T Auletta
- Mayo Clinic College of Medicine, Department of Neuroscience and Pharmacology, 4500 San Pablo Road, Jacksonville, FL 32224, USA
| | | | | |
Collapse
|
23
|
Rosenberry TL. Strategies to resolve the catalytic mechanism of acetylcholinesterase. J Mol Neurosci 2010; 40:32-9. [PMID: 19757206 DOI: 10.1007/s12031-009-9250-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2009] [Accepted: 07/20/2009] [Indexed: 11/25/2022]
Abstract
Acetylcholinesterase (AChE) hydrolyzes its physiological substrate acetylcholine at one of the highest known catalytic rates. Two sites of ligand interaction have been identified: an acylation site or A-site at the base of the active-site gorge and a peripheral site or P-site at its mouth. Although much is known about AChE structure and the role of specific residues in catalysis, a detailed understanding of the catalytic mechanism and the role of the P-site has lagged far behind. In recent years, we have clarified how the P-site and A-site interact to promote catalysis. Our studies revealed that the P-site mediates substrate trapping and that ligand binding to the P-site can result in steric blockade of the A-site as well as allosteric activation of substrate hydrolysis. Because a general, nonequilibrium treatment of AChE catalysis results in complex enzyme kinetic formulations, three simpler, overlapping strategies are presented here that provide significant insights into the AChE catalytic mechanism. The strategies are (1) to choose substrates, preferably close analogs of acetylcholine, that render some intermediates in the general reaction scheme negligible; (2) obtain some of the thermodynamic parameters in this scheme with experiments that are independent of kinetic measurements.
Collapse
Affiliation(s)
- Terrone L Rosenberry
- Departments of Neuroscience and Pharmacology, College of Medicine, Mayo Clinic, Jacksonville, FL 32224, USA.
| |
Collapse
|
24
|
Lv W, Xue Y. Prediction of acetylcholinesterase inhibitors and characterization of correlative molecular descriptors by machine learning methods. Eur J Med Chem 2010; 45:1167-72. [DOI: 10.1016/j.ejmech.2009.12.038] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2009] [Revised: 12/15/2009] [Accepted: 12/17/2009] [Indexed: 11/28/2022]
|
25
|
Wyman IW, Macartney DH. Host-guest complexes and pseudorotaxanes of cucurbit[7]uril with acetylcholinesterase inhibitors. J Org Chem 2010; 74:8031-8. [PMID: 19799399 DOI: 10.1021/jo901861e] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Pseudorotaxanes may be assembled in aqueous solution using dicationic acetylcholinesterase inhibitors, such as succinylcholine, BW284c51, and alpha,omega-bis(trialkylammonium)alkane dications (or their phosphonium analogues), as bolaform axles and cucurbit[7]uril (CB[7]) as the wheel. With the exceptions of the shorter [(CH(3))(3)N(CH(2))(n)N(CH(3))(3)](2+) (n = 6, 8) dications, the addition of a second CB[7] results in the translocation of the first CB[7], such that the hydrophobic -NR(3)(+) and -PR(3)(+) end groups (R = Me or Et) are located in the cavities of the wheels, while the central portion of the axles extend through the CB[7] portals into the bulk solvent. In the case of the [Quin(CH(2))(10)Quin](2+) (Quin = quinuclidinium) dication, the CB[7] host(s) resides only on the quinuclidinium end group(s). The 1:1 host-guest stability constants range from 8 x 10(6) to 3 x 10(10) M(-1) and are dependent on both the nature of the end group as well as the length and hydrophobicity of the central linker. The magnitude of the stability constants for the 2:1 complexes closely follow the trend observed previously for CB[7] binding with the NR(4)(+) and PR(4)(+) cations.
Collapse
Affiliation(s)
- Ian W Wyman
- Department of Chemistry, Queen's University, Kingston, ON K7L 3N6, Canada
| | | |
Collapse
|
26
|
Sanson B, Nachon F, Colletier JP, Froment MT, Toker L, Greenblatt HM, Sussman JL, Ashani Y, Masson P, Silman I, Weik M. Crystallographic snapshots of nonaged and aged conjugates of soman with acetylcholinesterase, and of a ternary complex of the aged conjugate with pralidoxime. J Med Chem 2009; 52:7593-603. [PMID: 19642642 DOI: 10.1021/jm900433t] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Organophosphate compounds (OP) are potent inhibitors of acetylcholinesterases (AChEs) and can cause lethal poisoning in humans. Inhibition of AChEs by the OP soman involves phosphonylation of the catalytic serine, and subsequent dealkylation produces a form known as the "aged" enzyme. The nonaged form can be reactivated to a certain extent by nucleophiles, such as pralidoxime (2-PAM), whereas aged forms of OP-inhibited AChEs are totally resistant to reactivation. Here, we solved the X-ray crystal structures of AChE from Torpedo californica (TcAChE) conjugated with soman before and after aging. The absolute configuration of the soman stereoisomer adduct in the nonaged conjugate is P(S)C(R). A structural reorientation of the catalytic His440 side chain was observed during the aging process. Furthermore, the crystal structure of the ternary complex of the aged conjugate with 2-PAM revealed that the orientation of the oxime function does not permit nucleophilic attack on the phosphorus atom, thus providing a plausible explanation for its failure to reactivate the aged soman/AChE conjugate. Together, these three crystal structures provide an experimental basis for the design of new reactivators.
Collapse
Affiliation(s)
- Benoît Sanson
- Laboratoire de Biophysique Moléculaire, Institut de Biologie Structurale Jean-Pierre Ebel, Commissariat à l'Energie Atomique, Centre National de la Recherche Scientifique, Université Joseph Fourier, 41 Rue Jules Horowitz, 38027 Grenoble, France
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
27
|
Ahmed M, Batista J, Rocha T, Mazzanti CM, Hassan W, Morsch VM, Loro VL, Thomé G, Schetinger MRC. Comparative study of the inhibitory effect of antidepressants on cholinesterase activity in Bungarus sindanus (krait) venom, human serum and rat striatum. J Enzyme Inhib Med Chem 2009; 23:912-7. [PMID: 18608756 DOI: 10.1080/14756360701809977] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
Cholinesterases are divided into two classes based on differences in their substrate specificity and tissue distribution: acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). These enzymes may be inhibited by several compounds, such as antidepressants. The antidepressants paroxetine, imipramine, clomipramine and sertraline inhibited both venom AChE as well as human serum BChE in a concentration-dependent manner but had no effect on AChE in the rat brain striatum. The IC(50) of venom calculated for imipramine was 0.3 mM, paroxetine 0.38 mM, clomipramine 0.34 mM and sertraline 0.35 mM. Analysis of kinetic data indicated that the inhibition caused by sertraline and paroxetine was mixed, i.e. K(m) values increased and V(max) decreased in a concentration dependent manner. Imipramine and clomipramine exhibited competitive inhibition, i.e. K(m) values increased and V(max) remained constant. The present results suggest that these therapeutic agents used for depression can also be considered as inhibitors of snake venom and human serum cholinesterase.
Collapse
Affiliation(s)
- Mushtaq Ahmed
- Departamento de Quimica, Centro de Ciencias Naturais e Exatas, Universidade Federal de Santa Maria, Brazil
| | | | | | | | | | | | | | | | | |
Collapse
|
28
|
Rosenberry TL, Sonoda LK, Dekat SE, Cusack B, Johnson JL. Analysis of the reaction of carbachol with acetylcholinesterase using thioflavin T as a coupled fluorescence reporter. Biochemistry 2008; 47:13056-63. [PMID: 19006330 PMCID: PMC2655144 DOI: 10.1021/bi8015197] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Acetylcholinesterase (AChE) contains a narrow and deep active site gorge with two sites of ligand binding, an acylation site (or A-site) at the base of the gorge and a peripheral site (or P-site) near the gorge entrance. The P-site contributes to catalytic efficiency by transiently binding substrates on their way to the acylation site, where a short-lived acylated enzyme intermediate is produced. Carbamates are very poor substrates that, like other AChE substrates, form an initial enzyme-substrate complex with free AChE (E) and proceed to an acylated enzyme intermediate (EC), which is then hydrolyzed. However, the hydrolysis of EC is slow enough to resolve the acylation and deacylation steps on the catalytic pathway. Here, we focus on the reaction of carbachol (carbamoylcholine) with AChE. The kinetics and thermodynamics of this reaction are of special interest because carbachol is an isosteric analogue of the physiological substrate acetylcholine. We show that the reaction can be monitored with thioflavin T as a fluorescent reporter group. The fluorescence of thioflavin T is strongly enhanced when it binds to the P-site of AChE, and this fluorescence is partially quenched when a second ligand binds to the A-site to form a ternary complex. Analysis of the fluorescence reaction profiles was challenging because four thermodynamic parameters and two fluorescence coefficients were fitted from the combined data both for E and for EC. Respective equilibrium dissociation constants of 6 and 26 mM were obtained for carbachol binding to the A- and P-sites in E and of 2 and 32 mM for carbachol binding to the A- and P-sites in EC. These constants for the binding of carbachol to the P-site are about an order of magnitude larger (i.e., indicating lower affinity) than previous estimates for the binding of acetylthiocholine to the P-site.
Collapse
Affiliation(s)
- Terrone L Rosenberry
- Mayo Clinic College of Medicine, Department of Neuroscience, Jacksonville, Florida 32224, USA.
| | | | | | | | | |
Collapse
|
29
|
Rosenberry TL, Sonoda LK, Dekat SE, Cusack B, Johnson JL. Monitoring the reaction of carbachol with acetylcholinesterase by thioflavin T fluorescence and acetylthiocholine hydrolysis. Chem Biol Interact 2008; 175:235-41. [PMID: 18602908 DOI: 10.1016/j.cbi.2008.06.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2008] [Accepted: 06/06/2008] [Indexed: 11/19/2022]
Abstract
Acetylcholinesterase (AChE) contains a narrow and deep active site gorge with two sites of ligand binding, an acylation site (or A-site) at the base of the gorge and a peripheral site (or P-site) near the gorge entrance. The P-site contributes to catalytic efficiency by transiently binding substrates on their way to the acylation site, where a short-lived acyl enzyme intermediate is produced. Carbamates are very poor substrates that, like other AChE substrates, form an initial enzyme-substrate complex and proceed to an acylated enzyme intermediate which is then hydrolyzed. However, the hydrolysis of the carbamoylated enzyme is slow enough to resolve the acylation and deacylation steps on the catalytic pathway. Here we show that the reaction of carbachol (carbamoylcholine) with AChE can be monitored both with acetylthiocholine as a reporter substrate and with thioflavin T as a fluorescent reporter group. The fluorescence of thioflavin T is strongly enhanced when it binds to the P-site of AChE, and this fluorescence is partially quenched when a second ligand binds to the A-site to form a ternary complex. These fluorescence changes allow not only the monitoring of the course of the carbamoylation reaction but also the determination of carbachol affinities for the A- and P-sites.
Collapse
Affiliation(s)
- Terrone L Rosenberry
- Mayo Clinic College of Medicine, Departments of Neuroscience and Pharmacology, 4500 San Pablo Road, Jacksonville, FL 32224, USA.
| | | | | | | | | |
Collapse
|
30
|
Musilek K, Holas O, Kuca K, Jun D, Dohnal V, Opletalova V, Dolezal M. Synthesis of monooxime-monocarbamoyl bispyridinium compounds bearing (E)-but-2-ene linker and evaluation of their reactivation activity against tabun- and paraoxon-inhibited acetylcholinesterase. J Enzyme Inhib Med Chem 2008; 23:70-6. [PMID: 18341256 DOI: 10.1080/14756360701383981] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
Abstract
Six AChE monooxime-monocarbamoyl reactivators with an (E)-but-2-ene linker were synthesized using modification of currently known synthetic pathways. Their potency to reactivate AChE inhibited by the nerve agent tabun and insecticide paraoxon was tested in vitro. The reactivation efficacies of pralidoxime, HI-6, obidoxime, K048, K075 and the newly prepared reactivators were compared. According to the results obtained, one reactivator seems to be promising against tabun-inhibited AChE and two reactivators against paraoxon-inhibited AChE. The best results were obtained for bisquaternary substances with at least one oxime group in position four.
Collapse
Affiliation(s)
- Kamil Musilek
- Department of Toxicology, Faculty of Military Health Sciences, Hradec Kralove, Czech Republic.
| | | | | | | | | | | | | |
Collapse
|
31
|
Xu Y, Colletier JP, Jiang H, Silman I, Sussman JL, Weik M. Induced-fit or preexisting equilibrium dynamics? Lessons from protein crystallography and MD simulations on acetylcholinesterase and implications for structure-based drug design. Protein Sci 2008; 17:601-5. [PMID: 18359854 DOI: 10.1110/ps.083453808] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Crystal structures of acetylcholinesterase complexed with ligands are compared with side-chain conformations accessed by native acetylcholinesterase in molecular dynamics (MD) simulations. Several crystallographic conformations of a key residue in a specific binding site are accessed in a simulation of native acetylcholinesterase, although not seen in rotomer plots. Conformational changes upon ligand binding thus involve preexisting equilibrium dynamics. Consequently, rational drug design could benefit significantly from conformations monitored by MD simulations of native targets.
Collapse
Affiliation(s)
- Yechun Xu
- Department of Structural Biology, Weizmann Institute of Science, 76100 Rehovot, Israel
| | | | | | | | | | | |
Collapse
|
32
|
Ahmed M, Rocha JBT, Mazzanti CM, Morsch ALB, Cargnelutti D, Corrêa M, Loro V, Morsch VM, Schetinger MRC. Malathion, carbofuran and paraquat inhibit Bungarus sindanus (krait) venom acetylcholinesterase and human serum butyrylcholinesterase in vitro. ECOTOXICOLOGY (LONDON, ENGLAND) 2007; 16:363-9. [PMID: 17364237 DOI: 10.1007/s10646-007-0137-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2006] [Accepted: 02/13/2007] [Indexed: 05/14/2023]
Abstract
Carbofuran and malathion, well known pesticides, and paraquat, a world widely used herbicide, were tested on acetylcholinesterase (AChE) from Bungarus sindanus venom and butyrylcholinesterase (BChE) from human serum. The calculated IC(50 )values for inhibition of venom enzyme by malathion, carbofuran and paraquat were 2.5, 0.14, and 0.16 microM, respectively. The values for inhibition of serum butyrylcholinesterase (BChE) were 3.5, 0.09 and 0.18 microM, respectively. Analysis of kinetic data indicated that the inhibition caused by malathion, carbofuran and paraquat was mixed for venom AChE. For BChE from human serum, the inhibition caused by malathion and paraquat was mixed and for carbofuran it was uncompetitive. The present results suggest a commercial paraquat preparation (a popular herbicide) inhibits cholinesterases with similar or higher potency than classical pesticide inhibitors. Furthermore, this inhibition was observed both in human serum and snake venom, a newly studied source of AChE.
Collapse
Affiliation(s)
- Mushtaq Ahmed
- Departmento de Química, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, Santa Maria, RS, Brazil
| | | | | | | | | | | | | | | | | |
Collapse
|
33
|
Abstract
The use of organophosphorus pesticides results in toxicity risk to non-target organisms. Organophosphorus compounds share a common mode of action, exerting their toxic effects primarily via acetylcholinesterase (AChE) inhibition. Consequently, acetylcholine accumulates in the synaptic clefts of muscles and nerves, leading to overstimulation of cholinergic receptors. Acute cholinergic crisis immediately follows exposure to organophosphate and includes signs and symptoms resulting from hyperstimulation of central and peripheral muscarinic and nicotinic receptors. The current view of the treatment of organophosphate poisoning includes three strategies, i.e. the use of an anticholinergic drug (e.g., atropine), cholinesterase-reactivating agents (e.g., oximes) and anticonvulsant drugs (e.g., benzodiazepines). Oximes, as a part of antidotal therapy, ensure the recovery of phosphylated enzymes via a process denoted as reactivation of inhibited AChE. However, both experimental results and clinical findings have demonstrated that different oximes are not equally effective against poisonings caused by structurally different organophosphorus compounds. Therefore, antidotal characteristics of conventionally used oximes can be evaluated regarding how close the certain substance is to the theoretical concept of the universal oxime. Pralidoxime (PAM-2), trimedoxime (TMB-4), obidoxime (LüH-6), HI-6 and HLö-7 have all been demonstrated to be very effective in experimental poisonings with sarin and VX. TMB-4 and LüH-6 may reactivate tabun-inhibited AChE, whereas HI-6 possesses the ability to reactivate the soman-inhibited enzyme. An oxime HLö-7 seems to be an efficient reactivator of AChE inhibited by any of the four organophosphorus warfare agents. According to the available literature, the oximes LüH-6 and TMB-4, although relatively toxic, are the most potent to induce reactivation of AChE inhibited by the majority of organophosphorus pesticides. Since there are no reports of controlled clinical trials on the use of TMB-4 in human organophosphate pesticide poisoning, LüH-6 may be a better option.
Collapse
Affiliation(s)
- Biljana Antonijevic
- Institute of Toxicological Chemistry, Faculty of Pharmacy, University of Belgrade, Vojvode Stepe 450, 11221 Belgrade, Serbia.
| | | |
Collapse
|
34
|
Musilek K, Holas O, Kuca K, Jun D, Dohnal V, Dolezal M. Synthesis of asymmetrical bispyridinium compounds bearing cyano-moiety and evaluation of their reactivation activity against tabun and paraoxon-inhibited acetylcholinesterase. Bioorg Med Chem Lett 2006; 16:5673-6. [PMID: 16934462 DOI: 10.1016/j.bmcl.2006.08.011] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2006] [Revised: 07/31/2006] [Accepted: 08/01/2006] [Indexed: 10/24/2022]
Abstract
Three asymmetrical AChE reactivators with cyano-moiety and propane linker were synthesized using modification of currently known synthetic pathways. Their potency to reactivate AChE inhibited by nerve agent tabun and insecticide paraoxon was tested in vitro and compared to pralidoxime, HI-6, obidoxime, K027, and K048. According to the results, three compounds seem to be promising against paraoxon-inhibited AChE. Better results were obtained for bisquaternary substances at least with one oxime group in position four. None of tested substances was able to satisfactorily reactivate tabun-inhibited AChE at concentration applicable for in vivo experiments.
Collapse
Affiliation(s)
- Kamil Musilek
- Department of Pharmaceutical Chemistry and Drug Control, Faculty of Pharmacy in Hradec Kralove, Charles University in Prague, Heyrovskeho 1203, 50005 Hradec Kralove, Czech Republic
| | | | | | | | | | | |
Collapse
|
35
|
Ahmed M, Rocha JBT, Corrêa M, Mazzanti CM, Zanin RF, Morsch ALB, Morsch VM, Schetinger MRC. Inhibition of two different cholinesterases by tacrine. Chem Biol Interact 2006; 162:165-71. [PMID: 16860785 DOI: 10.1016/j.cbi.2006.06.002] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2006] [Revised: 06/10/2006] [Accepted: 06/12/2006] [Indexed: 10/24/2022]
Abstract
Kinetic parameters of the effect of tacrine as a cholinesterase inhibitor have been studied in two different sources: snake venom (Bungarus sindanus) acetylcholinesterase (AChE) and human serum butyrylcholinesterase (BChE). Tacrine inhibited both venom acetylcholinesterase (AChE) as well as human serum butyrylcholinesterase (BChE) in a concentration-dependent manner. Kinetic studies indicated that the nature of inhibition was mixed for both enzymes, i.e. Km values increase and Vmax decrease with the increase of the tacrine concentration. The calculated IC50 for snake venom and for human serum were 31 and 25.6 nM, respectively. Ki was observed to be 13 nM for venom acetylcholinesterase (AChE) and 12 nM for serum butyrylcholinesterase (BChE). KI (constant of AChE-ASCh-tacrine complex into AChE-ASCh complex and tacrine) was estimated to be 20 nM for venom and 10 nM for serum butyrylcholinesterase (BChE), while the gammaKm (dissociation constant of AChE-ASCh-tacrine complex into AChE-tacrine complex and ASCh) were 0.086 and 0.147 mM for snake venom AChE and serum BChE, respectively. The present results suggest that this therapeutic agent used for the treatment of Alzheimer's disease can also be considered an inhibitor of snake venom and human serum butyrylcholinesterase. Values of Ki and KI show that tacrine had more affinity with these enzymes as compared with other cholinesterases from the literature.
Collapse
Affiliation(s)
- Mushtaq Ahmed
- Departamento de Química, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, 97105-900 Santa Maria, RS, Brazil
| | | | | | | | | | | | | | | |
Collapse
|