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Darvesh S, Banfield S, Dufour M, Forrestall KL, Maillet H, Reid GA, Sands D, Pottie IR. A method for the efficient evaluation of substrate-based cholinesterase imaging probes for Alzheimer's disease. J Enzyme Inhib Med Chem 2023; 38:2225797. [PMID: 38061987 PMCID: PMC10294744 DOI: 10.1080/14756366.2023.2225797] [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: 03/24/2023] [Revised: 05/11/2023] [Accepted: 06/10/2023] [Indexed: 08/16/2023] Open
Abstract
Cholinesterase (ChE) enzymes have been identified as diagnostic markers for Alzheimer disease (AD). Substrate-based probes have been synthesised to detect ChEs but they have not detected changes in ChE distribution associated with AD pathology. Probes are typically screened using spectrophotometric methods with pure enzyme for specificity and kinetics. However, the biochemical properties of ChEs associated with AD pathology are altered. The present work was undertaken to determine whether the Karnovsky-Roots (KR) histochemical method could be used to evaluate probes at the site of pathology. Thirty thioesters and esters were synthesised and evaluated using enzyme kinetic and KR methods. Spectrophotometric methods demonstrated all thioesters were ChE substrates, yet only a few provided staining in the brain with the KR method. Esters were ChE substrates with interactions with brain ChEs. These results suggest that the KR method may provide an efficient means to screen compounds as probes for imaging AD-associated ChEs.
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Affiliation(s)
- Sultan Darvesh
- Department of Medical Neuroscience, Dalhousie University, Halifax, Nova Scotia, Canada
- Department of Medicine (Geriatric Medicine & Neurology), Halifax, Nova Scotia, Canada
- Department of Chemistry and Physics, Mount St. Vincent University, Halifax, Nova Scotia, Canada
| | - Scott Banfield
- Department of Medical Neuroscience, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Maeve Dufour
- Department of Medical Neuroscience, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Katrina L. Forrestall
- Department of Medical Neuroscience, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Hillary Maillet
- Department of Medical Neuroscience, Dalhousie University, Halifax, Nova Scotia, Canada
| | - G. Andrew Reid
- Department of Medical Neuroscience, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Dane Sands
- Department of Medical Neuroscience, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Ian R. Pottie
- Department of Chemistry and Physics, Mount St. Vincent University, Halifax, Nova Scotia, Canada
- Department of Chemistry, Saint Mary’s University, Halifax, Nova Scotia, Canada
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Masson P, Mukhametgalieva AR. Partial Reversible Inhibition of Enzymes and Its Metabolic and Pharmaco-Toxicological Implications. Int J Mol Sci 2023; 24:12973. [PMID: 37629158 PMCID: PMC10454656 DOI: 10.3390/ijms241612973] [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: 07/07/2023] [Revised: 08/16/2023] [Accepted: 08/18/2023] [Indexed: 08/27/2023] Open
Abstract
Partial reversible inhibition of enzymes, also called hyperbolic inhibition, is an uncommon mechanism of reversible inhibition, resulting from a productive enzyme-inhibitor complex. This type of inhibition can involve competitive, mixed, non-competitive and uncompetitive inhibitors. While full reversible inhibitors show linear plots for reciprocal enzyme initial velocity versus inhibitor concentration, partial inhibitors produce hyperbolic plots. Similarly, dose-response curves show residual fractional activity of enzymes at high doses. This article reviews the theory and methods of analysis and discusses the significance of this type of reversible enzyme inhibition in metabolic processes, and its implications in pharmacology and toxicology.
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Affiliation(s)
- Patrick Masson
- Biochemical Neuropharmacology Laboratory, Kazan Federal University, 18 ul. Kremlevskaya, 420008 Kazan, Russia
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Mukhametgalieva AR, Nemtarev AV, Sykaev VV, Pashirova TN, Masson P. Activation/Inhibition of Cholinesterases by Excess Substrate: Interpretation of the Phenomenological b Factor in Steady-State Rate Equation. Int J Mol Sci 2023; 24:10472. [PMID: 37445649 DOI: 10.3390/ijms241310472] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2023] [Revised: 06/19/2023] [Accepted: 06/19/2023] [Indexed: 07/15/2023] Open
Abstract
Cholinesterases (ChEs) display a non-michaelian behavior with positively charged substrates. In the steady-state rate equation, the b factor describes this behavior: if b > 1 there is substrate activation, if b < 1 there is substrate inhibition. The mechanistic significance of the b factor was investigated to determine whether this behavior depends on acylation, deacylation or on both steps. Kinetics of human acetyl- (AChE) and butyryl-cholinesterase (BChE) were performed under steady-state conditions and using a time-course of complete substrate hydrolysis. For the hydrolysis of short acyl(thio)esters, where acylation and deacylation are partly rate-limiting, steady-state kinetic analysis could not decide which step determines b. However, the study of the hydrolysis of an arylacylamide, 3-(acetamido)-N,N,N-trimethylanilinium (ATMA), where acetylation is rate-limiting, showed that b depends on the acylation step. The magnitude of b and opposite b values between AChE and BChE for the hydrolysis of acetyl(thio)- versus benzoyl-(thio) esters, then indicated that the productive adjustment of substrates in the active center at high concentration depends on motions of both the Ω and the acyl-binding loops. Benzoylcholine was shown to be a poor substrate of AChE, and steady-state kinetics showed a sudden inhibition at high concentration, likely due to the non-dissociation of hydrolysis products. The poor catalytic hydrolysis of this bulky ester by AChE illustrates the importance of the fine adjustment of substrate acyl moiety in the acyl-binding pocket. Molecular modeling and QM/MM simulations should definitively provide evidence for this statement.
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Affiliation(s)
- Aliya R Mukhametgalieva
- Biochemical Neuropharmacology Laboratory, Kazan Federal University, 18 Ul. Kremlevskaya, 420008 Kazan, Russia
| | - Andrey V Nemtarev
- Arbuzov Institute of Organic and Physical Chemistry, Kazan Scientific Center, Russian Academy of Sciences, 8 Ul. Arbuzov, 420088 Kazan, Russia
| | - Viktor V Sykaev
- Arbuzov Institute of Organic and Physical Chemistry, Kazan Scientific Center, Russian Academy of Sciences, 8 Ul. Arbuzov, 420088 Kazan, Russia
| | - Tatiana N Pashirova
- Arbuzov Institute of Organic and Physical Chemistry, Kazan Scientific Center, Russian Academy of Sciences, 8 Ul. Arbuzov, 420088 Kazan, Russia
| | - Patrick Masson
- Biochemical Neuropharmacology Laboratory, Kazan Federal University, 18 Ul. Kremlevskaya, 420008 Kazan, Russia
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Mukhametgalieva AR, Lushchekina SV, Aglyamova AR, Masson P. Steady-state kinetic analysis of human cholinesterases over wide concentration ranges of competing substrates. BIOCHIMICA ET BIOPHYSICA ACTA. PROTEINS AND PROTEOMICS 2022; 1870:140733. [PMID: 34662731 DOI: 10.1016/j.bbapap.2021.140733] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2021] [Revised: 10/08/2021] [Accepted: 10/12/2021] [Indexed: 06/13/2023]
Abstract
Substrate competition for human acetylcholinesterase (AChE) and human butyrylcholinesterase (BChE) was studies under steady-state conditions using wide range of substrate concentrations. Competing couples of substates were acetyl-(thio)esters. Phenyl acetate (PhA) was the reporter substrate and competitor were either acetylcholine (ACh) or acetylthiocholine (ATC). The common point between investigated substrates is that the acyl moiety is acetate, i.e. same deacylation rate constant for reporter and competitor substrate. Steady-state kinetics of cholinesterase-catalyzed hydrolysis of PhA in the presence of ACh or ATC revealed 3 phases of inhibition as concentration of competitor increased: a) competitive inhibition, b) partially mixed inhibition, c) partially uncompetitive inhibition for AChE and partially uncompetitive activation for BChE. This sequence reflects binding of competitor in the active centrer at low concentration and on the peripheral anionic site (PAS) at high concentration. In particular, it showed that binding of a competing ligand on PAS may affect the catalytic behavior of AChE and BChE in an opposite way, i.e. inhibition of AChE and activation of BChE, regardless the nature of the reporter substrate. For both enzymes, progress curves for hydrolysis of PhA at very low concentration (≪Km) in the presence of increasing concentration of ATC showed that: a) the competing substrate and the reporter substrate are hydrolyzed at the same time, b) complete hydrolysis of PhA cannot be reached above 1 mM competing substrate. This likely results from accumulation of hydrolysis products (P) of competing substrate and/or accumulation of acetylated enzyme·P complex that inhibit hydrolysis of the reporter substrate.
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Affiliation(s)
- Aliya R Mukhametgalieva
- Kazan Federal University, Neuropharmacology Laboratory, 18 ul. Kremlevskaya, 420008 Kazan, Russian Federation
| | - Sofya V Lushchekina
- Emanuel Institute of Biochemical Physics, Russian Academy of Sciences, 4 ul. Kosygina, Moscow 119334, Russian Federation
| | - Aliya R Aglyamova
- Kazan Federal University, Neuropharmacology Laboratory, 18 ul. Kremlevskaya, 420008 Kazan, Russian Federation
| | - Patrick Masson
- Kazan Federal University, Neuropharmacology Laboratory, 18 ul. Kremlevskaya, 420008 Kazan, Russian Federation.
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Computational studies on cholinesterases: Strengthening our understanding of the integration of structure, dynamics and function. Neuropharmacology 2020; 179:108265. [DOI: 10.1016/j.neuropharm.2020.108265] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Revised: 05/21/2020] [Accepted: 07/27/2020] [Indexed: 12/17/2022]
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Davletshina R, Ivanov A, Shamagsumova R, Evtugyn V, Evtugyn G. Electrochemical Biosensor Based on Polyelectrolyte Complexes with Dendrimer for the Determination of Reversible Inhibitors of Acetylcholinesterase. ANAL LETT 2020. [DOI: 10.1080/00032719.2020.1821700] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- R. Davletshina
- Analytical Chemistry Department, Kazan Federal University, Kazan, Russian Federation
| | - A. Ivanov
- Analytical Chemistry Department, Kazan Federal University, Kazan, Russian Federation
| | - R. Shamagsumova
- Analytical Chemistry Department, Kazan Federal University, Kazan, Russian Federation
| | - V. Evtugyn
- Interdisciplinary Centre of Analytical Microscopy, Kazan Federal University, Kazan, Russian Federation
| | - G. Evtugyn
- Analytical Chemistry Department, Kazan Federal University, Kazan, Russian Federation
- Analytical Chemistry Department, Chemical Technology Institute of Ural Federal University, Ekaterinburg, Russian Federation
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Abstract
Nerve agents and neurobiological weapons are among the most devastating and lethal of weapons. Acetylcholinesterase inhibitors act by increasing the amount of acetylcholine in the neuromuscular junction, resulting in flaccid paralysis. Tabun, VX, soman, and sarin are the major agents in this category. Exposure to nerve agents can be inhalational or through dermal contact. Neurotoxins may have peripheral and central effects on the nervous system. Atropine is an effective antidote to nerve agents. Neurobiological weapons entail using whole organisms or organism-synthesized toxins as agents. Some organisms that can be used as biological weapons include smallpox virus.
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Affiliation(s)
- James J Sejvar
- Division of High-Consequence Pathogens and Pathology, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, 1600 Clifton Road, Mailstop H24-12, Atlanta, GA 30033, USA.
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Bosak A, Bavec A, Konte T, Šinko G, Kovarik Z, Goličnik M. Interactions of Paraoxonase-1 with Pharmacologically Relevant Carbamates. Molecules 2020; 25:E211. [PMID: 31947900 PMCID: PMC6983073 DOI: 10.3390/molecules25010211] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Revised: 12/30/2019] [Accepted: 01/02/2020] [Indexed: 12/12/2022] Open
Abstract
Mammalian paraoxonase-1 hydrolyses a very broad spectrum of esters such as certain drugs and xenobiotics. The aim of this study was to determine whether carbamates influence the activity of recombinant PON1 (rePON1). Carbamates were selected having a variety of applications: bambuterol and physostigmine are drugs, carbofuran is used as a pesticide, while Ro 02-0683 is diagnostic reagent. All the selected carbamates reduced the arylesterase activity of rePON1 towards the substrate S-phenyl thioacetate (PTA). Inhibition dissociation constants (Ki), evaluated by both discontinuous and continuous inhibition measurements (progress curves), were similar and in the mM range. The rePON1 displayed almost the same values of Ki constants for Ro 02-0683 and physostigmine while, for carbofuran and bambuterol, the values were approximately ten times lower and two times higher, respectively. The affinity of rePON1 towards the tested carbamates was about 3-40 times lower than that of PTA. Molecular modelling of rePON1-carbamate complexes suggested non-covalent interactions with residues of the rePON1 active site that could lead to competitive inhibition of its arylesterase activity. In conclusion, carbamates can reduce the level of PON1 activity, which should be kept in mind, especially in medical conditions characterized by reduced PON1 levels.
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Affiliation(s)
- Anita Bosak
- Institute for Medical Research and Occupational Health, HR 10000 Zagreb, Croatia (Z.K.)
| | - Aljoša Bavec
- Institute of Biochemistry, Faculty of Medicine, University of Ljubljana, SI 1000 Ljubljana, Slovenia; (A.B.); (T.K.)
| | - Tilen Konte
- Institute of Biochemistry, Faculty of Medicine, University of Ljubljana, SI 1000 Ljubljana, Slovenia; (A.B.); (T.K.)
| | - Goran Šinko
- Institute for Medical Research and Occupational Health, HR 10000 Zagreb, Croatia (Z.K.)
| | - Zrinka Kovarik
- Institute for Medical Research and Occupational Health, HR 10000 Zagreb, Croatia (Z.K.)
| | - Marko Goličnik
- Institute of Biochemistry, Faculty of Medicine, University of Ljubljana, SI 1000 Ljubljana, Slovenia; (A.B.); (T.K.)
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A new sensitive spectrofluorimetric method for measurement of activity and kinetic study of cholinesterases. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2019; 1868:140270. [PMID: 31518689 DOI: 10.1016/j.bbapap.2019.140270] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Revised: 08/22/2019] [Accepted: 09/02/2019] [Indexed: 01/24/2023]
Abstract
A new spectrofluorimetric method more sensitive than the Ellman method was developed for determination of both acetylcholinesterase and butyrylcholinesterase activity and for kinetic analysis of these enzymes and their mutants. Two selected mutants of human butyrylcholinesterase (E197Q and E197G) were included in this work. As for the Ellman's method, substrates are thiocholine esters, but the chromogenic reagent, DTNB (dithio-bisnitro benzoic acid) is replaced by a fluorogenic probe, "Calbiochem Probe IV", (3-(7-Hydroxy-2-oxo-2H-chromen-3-ylcarbamoyl)acrylic acid methylester). Compared to the classical Ellman's method, the sensitivity of this new spectrofluorimetric assay is 2 orders of magnitude higher. The method allows measurement of activity in media containing <10-11 M of cholinesterase active sites at low substrate concentrations, either under first order conditions, [S] << Km, or under conditions where kinetics obeys the Michaelis-Menten model, i.e. at [S] < 1 mM for wild-type enzymes. The method adapted to titration plate reader assays is suitable for clinical and toxicological routine analyses, for high throughput screening of novel cholinesterase mutants and screening of inhibitor libraries of pharmacological interest.
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Time-course of enzyme-catalyzed competing substrate degradation for michaelian behavior and for enzymes showing activation/inhibition by excess substrate. Chem Biol Interact 2019; 309:108704. [DOI: 10.1016/j.cbi.2019.06.017] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Revised: 06/04/2019] [Accepted: 06/10/2019] [Indexed: 11/23/2022]
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