E-Mail Alert

Add your e-mail address to receive forthcoming issues of this journal:

Journal Browser

Journal Browser

Special Issue "The Cholinesterases—Structure, Mechanism, Function and Drug Design: The 25th Anniversary of the Solution of the Crystal Structure of Acetylcholinesterase by Joel L. Sussman and Israel Silman"

A special issue of Molecules (ISSN 1420-3049). This special issue belongs to the section "Medicinal Chemistry".

Deadline for manuscript submissions: closed (30 October 2017)

Special Issue Editors

Guest Editor
Prof. Anthony H. Futerman

Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot 7610001, Israel
Website | E-Mail
Interests: acetylcholinestersae; sphingolipids; Gaucher disease
Guest Editor
Dr. Yacov Ashani

Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot 7610001, Israel
Website | E-Mail
Interests: cholinesterases; paraoxonases; phosphotriesterases; organophosphates; enzyme kinetics
Guest Editor
Dr. Gabriel (Gabi) Amitai

The Wohl Drug Discovery Institute, The Nancy & Stephen Grand, Israel National Center for Personalized Medicine, Weizmann Institute of Science, Rehovot, Israel
E-Mail
Interests: acetylcholinesterase (AChE); AChE inhibitors and reactivators; OP hydrolases; small-molecule high throughput screening (HTS); hit-to-lead optimization
Guest Editor
Dr. Lev Weiner

Department of Chemical Research Support, Weizmann Institute of Science, Rehovot, Israel
Website | E-Mail
Interests: in vivo ESR; spin label; spin trap; oxidative stress; reactive oxygen species; photosensitizer; acetylcholinesterase; antitumor drug

Special Issue Information

Dear Colleagues,

Solution of the crystal structure of acetylcholinesterase (AChE) using an atomic resolution, in 1991, by Professors Joel Sussman and Israel Silman, revolutionized our understanding of structure/function relationships in this enzyme. Not only the structure itself, but also the concepts that they developed, stimulated major research efforts, both fundamental and applied, that come not only from the laboratories of these two scientists, but also from many other groups worldwide. The importance of their contribution is testified to by the fact that their original publication in Science in 1991 has already been cited more than 2700 times.

Prior to initiation of their collaboration, in 1985, both had already made seminal discoveries. Prof Israel Silman returned to the Weizmann Institute in Israel, in 1968, from a postdoctoral fellowship in the laboratory of Prof David Nachmansohn (Columbia University, New York), where he had initiated his studies on structure-function relationships in proteins of the cholinergic system, a theme that remains his principal focus. Back in Israel, Prof Silman devoted his main efforts to purification and characterization of AChE from electric organ tissue of the electric eel, Electrophorus electricus (Ee), and the electric ray, Torpedo californica (Tc). His notable achievements included, initially, characterization of the collagen-tailed asymmetric forms of the enzyme. Subsequently, he characterized the glycophosphatidylinositol (GPI)-anchored form of AChE, the first member of the large class of GPI-anchored proteins to be identified. This proved to be an essential first step in the eventual crystallization of TcAChE in 1988. Prof. Sussman is amongst the pioneers of macromolecular refinement, developing the CORELS program, and applying it to structural studies on yeast tRNAphe. After moving to the Weizmann Institute from Duke University in North Carolina, in 1976, he continued his studies on nucleic acids, determining the structure of 'bulge'-containing DNA fragments, models for insertion mutations, and also worked on the structures of halophilic proteins isolated from bacteria that grow in the Dead Sea. He was a pioneer in developing methods of flash freezing protein and nucleic acid molecules to cryogenic temperatures in order to greatly prolong their lifetime under X-ray irradiation. He was the Director of the Protein Data Bank at Brookhaven National Laboratory from 1994–1999, where he helped to transform it into an interactive resource on the internet, to aid researchers in visualizing the structure/function relationships of biological macromolecules. The major focus of his work, since the late 1980s, has been on proteins of the nervous system in particular on AChE.

Profs. Silman and Sussman chose to initiate their collaborative effort by focusing on TcAChE, after unsuccessful attempts by others to solve the crystal structure of the 11S tetramer from EeAChE. The TcAChE dimer has a simpler quaternary structure than that of the EeAChE tetramer, and unlike it, the integrity of the TcAChE catalytic subunit is well preserved during a mild isolation and purification procedure. Solution of the 3D structure of TcAChE, and their continuing collaborative endeavors, have provided answers to numerous questions that had previously puzzled those working on AChE, and also established conceptual breakthroughs that gave both theoreticians and experimentalists a totally new perspective on the function of AChE itself, and on the cholinergic synapse. Their findings have not only had major ramifications in their particular area of research, but have also impacted greatly upon other fields. Sussman and Silman went on to solve the 3D structures of many complexes of AChE with reversible ligands—such as edrophonium, tacrine, donepezil (E2020), huperzine A and methylene blue—and of covalent conjugates with soman, sarin, VX, and rivastigmine. They elucidated the structural and functional significance of the conserved aromatic residues that line the narrow gorge leading to the buried active site, including recognition of the important roles played by some of them in π-cation and π-π interactions with substrates and inhibitors, in particular of the quaternary group of acetylcholine (ACh) with the indole rings of two conserved tryptophan residues. They also investigated the catalytic machinery of the enzyme, the functional and structural roles of conserved water molecules in binding and catalysis, and the functional significance of the high dipole moment aligned along the axis of the active-site gorge, which generates a large potential gradient pulling ACh towards the active site. The findings of Sussman and Silman have provide important input for the design and synthesis of anti-AChE drugs that are used in the management of neurodegenerative and neuromuscular diseases, such as Alzheimer’s and myasthenia gravis, for the development of improved antidotes and bioscavengers for the treatment of nerve agent intoxication, and for design of novel anticholinesterase insecticides. These latter studies were facilitated by their subsequent solution, in 2000, of the crystal structures of human AChE, and of that of Drosophila melanogaster AChE, the only insect AChE structure solved to date.

In recent years, Silman and Sussman have also collaborated with colleagues in the Department of Biomolecular Sciences Chemistry at the Weizmann, and extended their interests to structural studies of two other enzymes associated with degenerative diseases. With Prof. Tony Futerman, they were able to crystallize and determine the 3D structure of acid-β-glucosidase, the enzyme whose malfunction, due to mutation, results in Gaucher disease. The structural and functional data so generated have already resulted in novel approaches to the treatment of the disease. With Prof. Dan Tawfik, they solved the 3D structures of the serum enzyme, paraoxonase (PON), and of bacterial phosphotriesterases (PTEs), both of which hydrolyze organophosphate-based pesticides and nerve agents, and thus comprise a new generation of catalytic bioscavengers. PON is of interest, however, not only to toxicologists, but also to cardiovascular clinicians working in the field of atherosclerosis, the major degenerative disease in ageing populations.

Currently, Profs. Silman and Sussman are both Emeritus Professors at the Weizmann Institute of Science.

This Special Issue of Molecules, in honor of Profs. Silman and Sussman, welcomes manuscripts describing original work, as well as review articles, on the structures, modes of action and biological roles of AChE and the butyrylcholinesterase (BChE). The Guest Editors will be pleased to accept and review manuscripts that address the topics listed below, but not restricted to them:

  • Methodological advances in research on the ChEs, both experimental and theoretical
  • 3D-Structural studies on native ChEs, their complexes and their conjugates
  • Kinetics and mechanism of action of ChEs
  • Inhibition by natural and synthetic ligands
  • Reactivation of ChEs inhibited by nerve agents and insecticides
  • SAR studies on drugs acting on the ChEs in the central and peripheral nervous systems
  • Non-cholinergic functions of the ChEs

Prof. Dr. Anthony H. Futerman
Dr. Yacov Ashani
Dr. Gabi Amitai
Dr. Lev Weiner
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Molecules is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1800 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Acetylcholinesterase
  • Butyrylcholinestersae
  • 3D structure
  • Inhibitors and reactivators
  • Enzymic mechanism
  • Biological role

Published Papers (18 papers)

View options order results:
result details:
Displaying articles 1-18
Export citation of selected articles as:

Research

Jump to: Review, Other

Open AccessArticle Bacterial Expression of Human Butyrylcholinesterase as a Tool for Nerve Agent Bioscavengers Development
Molecules 2017, 22(11), 1828; doi:10.3390/molecules22111828
Received: 11 October 2017 / Accepted: 23 October 2017 / Published: 27 October 2017
PDF Full-text (3474 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Human butyrylcholinesterase is a performant stoichiometric bioscavenger of organophosphorous nerve agents. It is either isolated from outdated plasma or functionally expressed in eukaryotic systems. Here, we report the production of active human butyrylcholinesterase in a prokaryotic system after optimization of the primary sequence
[...] Read more.
Human butyrylcholinesterase is a performant stoichiometric bioscavenger of organophosphorous nerve agents. It is either isolated from outdated plasma or functionally expressed in eukaryotic systems. Here, we report the production of active human butyrylcholinesterase in a prokaryotic system after optimization of the primary sequence through the Protein Repair One Stop Shop process, a structure- and sequence-based algorithm for soluble bacterial expression of difficult eukaryotic proteins. The mutant enzyme was purified to homogeneity. Its kinetic parameters with substrate are similar to the endogenous human butyrylcholinesterase or recombinants produced in eukaryotic systems. The isolated protein was prone to crystallize and its 2.5-Å X-ray structure revealed an active site gorge region identical to that of previously solved structures. The advantages of this alternate expression system, particularly for the generation of butyrylcholinesterase variants with nerve agent hydrolysis activity, are discussed. Full article
Figures

Open AccessFeature PaperArticle An Unusual Dimeric Inhibitor of Acetylcholinesterase: Cooperative Binding of Crystal Violet
Molecules 2017, 22(9), 1433; doi:10.3390/molecules22091433
Received: 30 June 2017 / Accepted: 16 August 2017 / Published: 30 August 2017
PDF Full-text (3070 KB) | HTML Full-text | XML Full-text
Abstract
Acetylcholinesterase (AChE) is an essential enzyme that terminates cholinergic transmission by a rapid hydrolysis of the neurotransmitter acetylcholine. AChE is an important target for treatment of various cholinergic deficiencies, including Alzheimer’s disease and myasthenia gravis. In a previous high throughput screening campaign, we
[...] Read more.
Acetylcholinesterase (AChE) is an essential enzyme that terminates cholinergic transmission by a rapid hydrolysis of the neurotransmitter acetylcholine. AChE is an important target for treatment of various cholinergic deficiencies, including Alzheimer’s disease and myasthenia gravis. In a previous high throughput screening campaign, we identified the dye crystal violet (CV) as an inhibitor of AChE. Herein, we show that CV displays a significant cooperativity for binding to AChE, and the molecular basis for this observation has been investigated by X-ray crystallography. Two monomers of CV bind to residues at the entrance of the active site gorge of the enzyme. Notably, the two CV molecules have extensive intermolecular contacts with each other and with AChE. Computational analyses show that the observed CV dimer is not stable in solution, suggesting the sequential binding of two monomers. Guided by the structural analysis, we designed a set of single site substitutions, and investigated their effect on the binding of CV. Only moderate effects on the binding and the cooperativity were observed, suggesting a robustness in the interaction between CV and AChE. Taken together, we propose that the dimeric cooperative binding is due to a rare combination of chemical and structural properties of both CV and the AChE molecule itself. Full article
Figures

Figure 1

Open AccessArticle Development of 2-Methoxyhuprine as Novel Lead for Alzheimer’s Disease Therapy
Molecules 2017, 22(8), 1265; doi:10.3390/molecules22081265
Received: 3 July 2017 / Revised: 21 July 2017 / Accepted: 22 July 2017 / Published: 28 July 2017
PDF Full-text (2402 KB) | HTML Full-text | XML Full-text
Abstract
Tacrine (THA), the first clinically effective acetylcholinesterase (AChE) inhibitor and the first approved drug for the treatment of Alzheimer’s disease (AD), was withdrawn from the market due to its side effects, particularly its hepatotoxicity. Nowadays, THA serves as a valuable scaffold for the
[...] Read more.
Tacrine (THA), the first clinically effective acetylcholinesterase (AChE) inhibitor and the first approved drug for the treatment of Alzheimer’s disease (AD), was withdrawn from the market due to its side effects, particularly its hepatotoxicity. Nowadays, THA serves as a valuable scaffold for the design of novel agents potentially applicable for AD treatment. One such compound, namely 7-methoxytacrine (7-MEOTA), exhibits an intriguing profile, having suppressed hepatotoxicity and concomitantly retaining AChE inhibition properties. Another interesting class of AChE inhibitors represents Huprines, designed by merging two fragments of the known AChE inhibitors—THA and (−)-huperzine A. Several members of this compound family are more potent human AChE inhibitors than the parent compounds. The most promising are so-called huprines X and Y. Here, we report the design, synthesis, biological evaluation, and in silico studies of 2-methoxyhuprine that amalgamates structural features of 7-MEOTA and huprine Y in one molecule. Full article
Figures

Figure 1

Open AccessArticle Rapid Mechanistic Evaluation and Parameter Estimation of Putative Inhibitors in a Single-Step Progress-Curve Analysis: The Case of Horse Butyrylcholinesterase
Molecules 2017, 22(8), 1248; doi:10.3390/molecules22081248
Received: 30 June 2017 / Accepted: 21 July 2017 / Published: 26 July 2017
PDF Full-text (776 KB) | HTML Full-text | XML Full-text
Abstract
Highly efficient and rapid lead compound evaluation for estimation of inhibition parameters and type of inhibition is proposed. This is based on a single progress-curve measurement in the presence of each candidate compound, followed by the simultaneous analysis of all of these curves
[...] Read more.
Highly efficient and rapid lead compound evaluation for estimation of inhibition parameters and type of inhibition is proposed. This is based on a single progress-curve measurement in the presence of each candidate compound, followed by the simultaneous analysis of all of these curves using the ENZO enzyme kinetics suite, which can be implemented as a web application. In the first step, all of the candidate ligands are tested as competitive inhibitors. Where the theoretical curves do not correspond to the experimental data, minimal additional measurements are added, with subsequent processing according to modified reaction mechanisms. Full article
Figures

Figure 1

Open AccessArticle New Cinchona Oximes Evaluated as Reactivators of Acetylcholinesterase and Butyrylcholinesterase Inhibited by Organophosphorus Compounds
Molecules 2017, 22(7), 1234; doi:10.3390/molecules22071234
Received: 30 June 2017 / Revised: 18 July 2017 / Accepted: 19 July 2017 / Published: 22 July 2017
PDF Full-text (1522 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
For the last six decades, researchers have been focused on finding efficient reactivators of organophosphorus compound (OP)-inhibited acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). In this study, we have focused our research on a new oxime scaffold based on the Cinchona structure since it was
[...] Read more.
For the last six decades, researchers have been focused on finding efficient reactivators of organophosphorus compound (OP)-inhibited acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). In this study, we have focused our research on a new oxime scaffold based on the Cinchona structure since it was proven to fit the cholinesterases active site and reversibly inhibit their activity. Three Cinchona oximes (C1, C2, and C3), derivatives of the 9-oxocinchonidine, were synthesized and investigated in reactivation of various OP-inhibited AChE and BChE. As the results showed, the tested oximes were more efficient in the reactivation of BChE and they reactivated enzyme activity to up to 70% with reactivation rates similar to known pyridinium oximes used as antidotes in medical practice today. Furthermore, the oximes showed selectivity towards binding to the BChE active site and the determined enzyme-oxime dissociation constants supported work on the future development of inhibitors in other targeted studies (e.g., in treatment of neurodegenerative disease). Also, we monitored the cytotoxic effect of Cinchona oximes on two cell lines Hep G2 and SH-SY5Y to determine the possible limits for in vivo application. The cytotoxicity results support future studies of these compounds as long as their biological activity is targeted in the lower micromolar range. Full article
Figures

Figure 1

Open AccessArticle The Evaluation of the Reactivating and Neuroprotective Efficacy of Two Newly Prepared Bispyridinium Oximes (K305, K307) in Tabun-Poisoned Rats—A Comparison with Trimedoxime and the Oxime K203
Molecules 2017, 22(7), 1152; doi:10.3390/molecules22071152
Received: 19 June 2017 / Revised: 4 July 2017 / Accepted: 5 July 2017 / Published: 11 July 2017
PDF Full-text (381 KB) | HTML Full-text | XML Full-text
Abstract
The ability of two newly developed oximes (K305, K307) to protect tabun-poisoned rats from tabun-induced inhibition of brain acetylcholinesterase, acute neurotoxic signs and symptoms and brain damage was compared with that of the oxime K203 and trimedoxime. The reactivating and neuroprotective effects of
[...] Read more.
The ability of two newly developed oximes (K305, K307) to protect tabun-poisoned rats from tabun-induced inhibition of brain acetylcholinesterase, acute neurotoxic signs and symptoms and brain damage was compared with that of the oxime K203 and trimedoxime. The reactivating and neuroprotective effects of the oximes studied combined with atropine on rats poisoned with tabun at a sublethal dose were evaluated. The reactivating efficacy of a newly developed oxime K305 is lower compared to the reactivating efficacy of the oxime K203 and trimedoxime while the ability of the oxime K307 to reactivate tabun-inhibited acetylcholinesterase (AChE) in the brain roughly corresponds to the reactivating efficacy of the oxime K203 and it is slightly lower compared to trimedoxime. In addition, only one newly developed oxime (K307) combined with atropine was able to markedly decrease tabun-induced neurotoxicity although it did not eliminate all tabun-induced acute neurotoxic signs and symptoms. These results correspond to the histopathological evaluation of tabun-induced brain damage. Therefore, the newly developed oximes are not suitable for the replacement of commonly used oximes (especially trimedoxime) in the treatment of acute tabun poisonings. Full article
Figures

Open AccessFeature PaperArticle Therapeutic Delivery of Butyrylcholinesterase by Brain-Wide Viral Gene Transfer to Mice
Molecules 2017, 22(7), 1145; doi:10.3390/molecules22071145
Received: 29 June 2017 / Revised: 5 July 2017 / Accepted: 6 July 2017 / Published: 8 July 2017
PDF Full-text (917 KB) | HTML Full-text | XML Full-text
Abstract
Recent research shows that butyrylcholinesterase (BChE) is not simply a liver enzyme that detoxifies bioactive esters in food and medications. In fact, in pursuing other goals, we recently found that it has an equally important role in regulating the peptide hormone ghrelin and
[...] Read more.
Recent research shows that butyrylcholinesterase (BChE) is not simply a liver enzyme that detoxifies bioactive esters in food and medications. In fact, in pursuing other goals, we recently found that it has an equally important role in regulating the peptide hormone ghrelin and its impact on hunger, obesity, and emotions. Here, we present and examine means of manipulating brain BChE levels by viral gene transfer, either regionally or globally, to modulate ghrelin signaling for long-term therapeutic purposes and to set the stage for exploring the neurophysiological impact of such an intervention. Full article
Figures

Figure 1

Open AccessFeature PaperArticle The C5 Variant of the Butyrylcholinesterase Tetramer Includes a Noncovalently Bound 60 kDa Lamellipodin Fragment
Molecules 2017, 22(7), 1083; doi:10.3390/molecules22071083
Received: 3 June 2017 / Revised: 27 June 2017 / Accepted: 27 June 2017 / Published: 29 June 2017
Cited by 1 | PDF Full-text (2914 KB) | HTML Full-text | XML Full-text
Abstract
Humans with the C5 genetic variant of butyrylcholinesterase (BChE) have 30–200% higher plasma BChE activity, low body weight, and shorter duration of action of the muscle relaxant succinylcholine. The C5 variant has an extra, slow-moving band of BChE activity on native polyacrylamide gel
[...] Read more.
Humans with the C5 genetic variant of butyrylcholinesterase (BChE) have 30–200% higher plasma BChE activity, low body weight, and shorter duration of action of the muscle relaxant succinylcholine. The C5 variant has an extra, slow-moving band of BChE activity on native polyacrylamide gel electrophoresis. This band is about 60 kDa larger than wild-type BChE. Umbilical cord BChE in 100% of newborn babies has a C5-like band. Our goal was to identify the unknown, 60 kDa protein in C5. Both wild-type and C5 BChE are under the genetic control of two independent loci, the BCHE gene on Chr 3q26.1 and the RAPH1 (lamellipodin) gene on Chr 2q33. Wild-type BChE tetramers are assembled around a 3 kDa polyproline peptide from lamellipodin. Western blot of boiled C5 and cord BChE showed a positive response with an antibody to the C-terminus of lamellipodin. The C-terminal exon of lamellipodin is about 60 kDa including an N-terminal polyproline. We propose that the unknown protein in C5 and cord BChE is encoded by the last exon of the RAPH1 gene. In 90% of the population, the 60 kDa fragment is shortened to 3 kDa during maturation to adulthood, leaving only 10% of adults with C5 BChE. Full article
Figures

Figure 1

Open AccessArticle Design, Synthesis and Evaluation of Hesperetin Derivatives as Potential Multifunctional Anti-Alzheimer Agents
Molecules 2017, 22(7), 1067; doi:10.3390/molecules22071067
Received: 11 May 2017 / Revised: 15 June 2017 / Accepted: 25 June 2017 / Published: 26 June 2017
PDF Full-text (1891 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
In this study we designed and synthesized a series of new hesperetin derivatives on the basis of the structural characteristics of acetylcholinesterase (AChE) dual-site inhibitors. The activity of the novel derivatives was also evaluated. Results showed that the synthesized hesperetin derivatives displayed stronger
[...] Read more.
In this study we designed and synthesized a series of new hesperetin derivatives on the basis of the structural characteristics of acetylcholinesterase (AChE) dual-site inhibitors. The activity of the novel derivatives was also evaluated. Results showed that the synthesized hesperetin derivatives displayed stronger inhibitory activity against AChE and higher selectivity than butyrylcholine esterase (BuChE) (selectivity index values from 68 to 305). The Lineweaver-Burk plot and molecular docking study showed that these compounds targeted both the peripheral anionic site (PAS) and catalytic active site (CAS) of AChE. The derivatives also showed a potent self-induced β-amyloid (Aβ) aggregation inhibition and a peroxyl radical absorbance activity. Moreover, compound 4f significantly protected PC12 neurons against H2O2-induced cell death at low concentrations. Cytotoxicity assay showed that the low concentration of the derivatives does not affect the viability of the SH-SY5Y neurons. Thus, these hesperetin derivatives are potential multifunctional agents for further development for the treatment of Alzheimer’s disease. Full article
Figures

Figure 1

Open AccessArticle Cholinesterase Inhibitory Activities of Adamantyl-Based Derivatives and Their Molecular Docking Studies
Molecules 2017, 22(6), 1005; doi:10.3390/molecules22061005
Received: 23 May 2017 / Revised: 10 June 2017 / Accepted: 14 June 2017 / Published: 17 June 2017
PDF Full-text (2888 KB) | HTML Full-text | XML Full-text
Abstract
Adamantyl-based compounds are clinically important for the treatments of type 2 diabetes and for their antiviral abilities, while many more are under development for other pharmaceutical uses. This study focused on the acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory activities of adamantyl-based ester derivatives
[...] Read more.
Adamantyl-based compounds are clinically important for the treatments of type 2 diabetes and for their antiviral abilities, while many more are under development for other pharmaceutical uses. This study focused on the acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory activities of adamantyl-based ester derivatives with various substituents on the phenyl ring using Ellman’s colorimetric method. Compound 2e with a 2,4-dichloro electron-withdrawing substituent on the phenyl ring exhibited the strongest inhibition effect against AChE, with an IC50 value of 77.15 µM. Overall, the adamantyl-based ester with the mono-substituent at position 3 of the phenyl ring exhibited good AChE inhibition effects with an ascending order for the substituents: Cl < NO2 < CH3 < OCH3. Furthermore, compounds with electron-withdrawing groups (Cl and NO2) substituted at position 3 on their phenyl rings demonstrated stronger AChE inhibition effects, in comparison to their respective positional isomers. On the other hand, compound 2j with a 3-methoxyphenyl ring showed the highest inhibition effect against BChE, with an IC50 value of 223.30 µM. Molecular docking analyses were conducted for potential AChE and BChE inhibitors, and the results demonstrated that the peripheral anionic sites of target proteins were predominant binding sites for these compounds through hydrogen bonds and halogen interactions instead of hydrophobic interactions in the catalytic active site. Full article
Figures

Figure 1

Open AccessArticle DL0410 Ameliorates Memory and Cognitive Impairments Induced by Scopolamine via Increasing Cholinergic Neurotransmission in Mice
Molecules 2017, 22(3), 410; doi:10.3390/molecules22030410
Received: 19 December 2016 / Accepted: 3 March 2017 / Published: 6 March 2017
Cited by 3 | PDF Full-text (3300 KB) | HTML Full-text | XML Full-text
Abstract
Deficiency of the cholinergic system is thought to play a vital role in cognitive impairment of dementia. DL0410 was discovered as a dual inhibitor of acetylcholinesterase (AChE) and butyrylcholinestease (BuChE), with potent efficiency in in-vitro experiments, but its in vivo effect on the
[...] Read more.
Deficiency of the cholinergic system is thought to play a vital role in cognitive impairment of dementia. DL0410 was discovered as a dual inhibitor of acetylcholinesterase (AChE) and butyrylcholinestease (BuChE), with potent efficiency in in-vitro experiments, but its in vivo effect on the cholinergic model has not been evaluated, and its action mechanism has also not been illustrated. In the present study, the capability of DL0410 in ameliorating the amnesia induced by scopolamine was investigated, and its effect on the cholinergic system in the hippocampus and its binding mode in the active site of AChE was also explored. Mice were administrated DL0410 (3 mg/kg, 10 mg/kg, and 30 mg/kg), and mice treated with donepezil were used as a positive control. The Morris water maze, escape learning task, and passive avoidance task were used as behavioral tests. The test results indicated that DL0410 could significantly improve the learning and memory impairments induced by scopolamine, with 10 mg/kg performing best. Further, DL0410 inhibited the AChE activity and increased acetylcholine (ACh) levels in a dose-dependent manner, and interacted with the active site of AChE in a similar manner as donepezil. However, no difference in the activity of BuChE was found in this study. All of the evidence indicated that its AChE inhibition is an important mechanism in the anti-amnesia effect. In conclusion, DL0410 could be an effective therapeutic drug for the treatment of dementia, especially Alzheimer’s disease. Full article
Figures

Figure 1

Review

Jump to: Research, Other

Open AccessReview Acetylcholinesterase and Nicotinic Acetylcholine Receptors in Schistosomes and Other Parasitic Helminths
Molecules 2017, 22(9), 1550; doi:10.3390/molecules22091550
Received: 23 August 2017 / Revised: 11 September 2017 / Accepted: 14 September 2017 / Published: 14 September 2017
PDF Full-text (399 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Schistosomiasis, which is caused by helminth trematode blood flukes of the genus Schistosoma, is a serious health and economic problem in tropical areas, and the second most prevalent parasitic disease after malaria. Currently, there is no effective vaccine available and treatment is
[...] Read more.
Schistosomiasis, which is caused by helminth trematode blood flukes of the genus Schistosoma, is a serious health and economic problem in tropical areas, and the second most prevalent parasitic disease after malaria. Currently, there is no effective vaccine available and treatment is entirely dependent on a single drug, praziquantel (PZQ), raising a significant potential public health threat due to the emergence of PZQ drug resistance. It is thus urgent and necessary to explore novel therapeutic targets for the treatment of schistosomiasis. Previous studies demonstrated that acetylcholinesterase (AChE) and nicotinic acetylcholine receptors (nAChRs) play important roles in the schistosome nervous system and ion channels, both of which are targeted by a number of currently approved and marketed anthelminthic drugs. To improve understanding of the functions of the cholinergic system in schistosomes, this article reviews previous studies on AChE and nAChRs in schistosomes and other helminths and discusses their potential as suitable targets for vaccine development and drug design against schistosomiasis. Full article
Figures

Figure 1

Open AccessReview Human Erythrocyte Acetylcholinesterase in Health and Disease
Molecules 2017, 22(9), 1499; doi:10.3390/molecules22091499
Received: 10 August 2017 / Accepted: 4 September 2017 / Published: 8 September 2017
PDF Full-text (1114 KB) | HTML Full-text | XML Full-text
Abstract
The biochemical properties of erythrocyte or human red blood cell (RBC) membrane acetylcholinesterase (AChE) and its applications on laboratory class and on research are reviewed. Evidence of the biochemical and the pathophysiological properties like the association between the RBC AChE enzyme activity and
[...] Read more.
The biochemical properties of erythrocyte or human red blood cell (RBC) membrane acetylcholinesterase (AChE) and its applications on laboratory class and on research are reviewed. Evidence of the biochemical and the pathophysiological properties like the association between the RBC AChE enzyme activity and the clinical and biophysical parameters implicated in several diseases are overviewed, and the achievement of RBC AChE as a biomarker and as a prognostic factor are presented. Beyond its function as an enzyme, a special focus is highlighted in this review for a new function of the RBC AChE, namely a component of the signal transduction pathway of nitric oxide. Full article
Figures

Open AccessReview Why is Aged Acetylcholinesterase So Difficult to Reactivate?
Molecules 2017, 22(9), 1464; doi:10.3390/molecules22091464
Received: 1 August 2017 / Revised: 29 August 2017 / Accepted: 29 August 2017 / Published: 4 September 2017
PDF Full-text (738 KB) | HTML Full-text | XML Full-text
Abstract
Organophosphorus agents are potent inhibitors of acetylcholinesterase. Inhibition involves successive chemical events. The first is phosphylation of the active site serine to produce a neutral adduct, which is a close structural analog of the acylation transition state. This adduct is unreactive toward spontaneous
[...] Read more.
Organophosphorus agents are potent inhibitors of acetylcholinesterase. Inhibition involves successive chemical events. The first is phosphylation of the active site serine to produce a neutral adduct, which is a close structural analog of the acylation transition state. This adduct is unreactive toward spontaneous hydrolysis, but in many cases can be reactivated by nucleophilic medicinal agents, such as oximes. However, the initial phosphylation reaction may be followed by a dealkylation reaction of the incipient adduct. This reaction is called aging and produces an anionic phosphyl adduct with acetylcholinesterase that is refractory to reactivation. This review considers why the anionic aged adduct is unreactive toward nucleophiles. An alternate approach is to realkylate the aged adduct, which would render the adduct reactivatable with oxime nucleophiles. However, this approach confronts a considerable—and perhaps intractable—challenge: the aged adduct is a close analog of the deacylation transition state. Consequently, the evolutionary mechanisms that have led to transition state stabilization in acetylcholinesterase catalysis are discussed herein, as are the challenges that they present to reactivation of aged acetylcholinesterase. Full article
Figures

Figure 1

Open AccessReview In Vitro Innervation as an Experimental Model to Study the Expression and Functions of Acetylcholinesterase and Agrin in Human Skeletal Muscle
Molecules 2017, 22(9), 1418; doi:10.3390/molecules22091418
Received: 24 July 2017 / Revised: 18 August 2017 / Accepted: 23 August 2017 / Published: 27 August 2017
PDF Full-text (627 KB) | HTML Full-text | XML Full-text
Abstract
Acetylcholinesterase (AChE) and agrin, a heparan-sulfate proteoglycan, reside in the basal lamina of the neuromuscular junction (NMJ) and play key roles in cholinergic transmission and synaptogenesis. Unlike most NMJ components, AChE and agrin are expressed in skeletal muscle and α-motor neurons. AChE and
[...] Read more.
Acetylcholinesterase (AChE) and agrin, a heparan-sulfate proteoglycan, reside in the basal lamina of the neuromuscular junction (NMJ) and play key roles in cholinergic transmission and synaptogenesis. Unlike most NMJ components, AChE and agrin are expressed in skeletal muscle and α-motor neurons. AChE and agrin are also expressed in various other types of cells, where they have important alternative functions that are not related to their classical roles in NMJ. In this review, we first focus on co-cultures of embryonic rat spinal cord explants with human skeletal muscle cells as an experimental model to study functional innervation in vitro. We describe how this heterologous rat-human model, which enables experimentation on highly developed contracting human myotubes, offers unique opportunities for AChE and agrin research. We then highlight innovative approaches that were used to address salient questions regarding expression and alternative functions of AChE and agrin in developing human skeletal muscle. Results obtained in co-cultures are compared with those obtained in other models in the context of general advances in the field of AChE and agrin neurobiology. Full article
Figures

Figure 1

Open AccessFeature PaperReview Computational Studies on Acetylcholinesterases
Molecules 2017, 22(8), 1324; doi:10.3390/molecules22081324
Received: 10 July 2017 / Revised: 7 August 2017 / Accepted: 7 August 2017 / Published: 10 August 2017
Cited by 1 | PDF Full-text (2209 KB) | HTML Full-text | XML Full-text
Abstract
Functions of biomolecules, in particular enzymes, are usually modulated by structural fluctuations. This is especially the case in a gated diffusion-controlled reaction catalyzed by an enzyme such as acetylcholinesterase. The catalytic triad of acetylcholinesterase is located at the bottom of a long and
[...] Read more.
Functions of biomolecules, in particular enzymes, are usually modulated by structural fluctuations. This is especially the case in a gated diffusion-controlled reaction catalyzed by an enzyme such as acetylcholinesterase. The catalytic triad of acetylcholinesterase is located at the bottom of a long and narrow gorge, but it catalyzes the extremely rapid hydrolysis of the neurotransmitter, acetylcholine, with a reaction rate close to the diffusion-controlled limit. Computational modeling and simulation have produced considerable advances in exploring the dynamical and conformational properties of biomolecules, not only aiding in interpreting the experimental data, but also providing insights into the internal motions of the biomolecule at the atomic level. Given the remarkably high catalytic efficiency and the importance of acetylcholinesterase in drug development, great efforts have been made to understand the dynamics associated with its functions by use of various computational methods. Here, we present a comprehensive overview of recent computational studies on acetylcholinesterase, expanding our views of the enzyme from a microstate of a single structure to conformational ensembles, strengthening our understanding of the integration of structure, dynamics and function associated with the enzyme, and promoting the structure-based and/or mechanism-based design of new inhibitors for it. Full article
Figures

Figure 1

Open AccessReview Ultrafast and Slow Cholinergic Transmission. Different Involvement of Acetylcholinesterase Molecular Forms
Molecules 2017, 22(8), 1300; doi:10.3390/molecules22081300
Received: 29 June 2017 / Revised: 21 July 2017 / Accepted: 22 July 2017 / Published: 4 August 2017
PDF Full-text (4062 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Acetylcholine (ACh), an ubiquitous mediator substance broadly expressed in nature, acts as neurotransmitter in cholinergic synapses, generating specific communications with different time-courses. (1) Ultrafast transmission. Vertebrate neuromuscular junctions (NMJs) and nerve-electroplaque junctions (NEJs) are the fastest cholinergic synapses; able to transmit brief
[...] Read more.
Acetylcholine (ACh), an ubiquitous mediator substance broadly expressed in nature, acts as neurotransmitter in cholinergic synapses, generating specific communications with different time-courses. (1) Ultrafast transmission. Vertebrate neuromuscular junctions (NMJs) and nerve-electroplaque junctions (NEJs) are the fastest cholinergic synapses; able to transmit brief impulses (1–4 ms) at high frequencies. The collagen-tailed A12 acetylcholinesterase is concentrated in the synaptic cleft of NMJs and NEJs, were it curtails the postsynaptic response by ultrafast ACh hydrolysis. Here, additional processes contribute to make transmission so rapid. (2) Rapid transmission. At peripheral and central cholinergic neuro-neuronal synapses, transmission involves an initial, relatively rapid (10–50 ms) nicotinic response, followed by various muscarinic or nicotinic effects. Acetylcholinesterase (AChE) being not concentrated within these synapses, it does not curtail the initial rapid response. In contrast, the late responses are controlled by a globular form of AChE (mainly G4-AChE), which is membrane-bound and/or secreted. (3) Slow ACh signalling. In non-neuronal systems, in muscarinic domains, and in most regions of the central nervous system (CNS), many ACh-releasing structures (cells, axon terminals, varicosities, boutons) do not form true synaptic contacts, most muscarinic and also part of nicotinic receptors are extra-synaptic, often situated relatively far from ACh releasing spots. A12-AChE being virtually absent in CNS, G4-AChE is the most abundant form, whose function appears to modulate the “volume” transmission, keeping ACh concentration within limits in time and space. Full article
Figures

Figure 1

Other

Jump to: Research, Review

Open AccessErratum Erratum: Xu, Y., et al. Computational Studies on Acetylcholinesterases. Molecules 2017, 22, 1324.
Molecules 2017, 22(9), 1486; doi:10.3390/molecules22091486
Received: 1 September 2017 / Revised: 1 September 2017 / Accepted: 4 September 2017 / Published: 6 September 2017
PDF Full-text (124 KB) | HTML Full-text | XML Full-text
Back to Top