| 1. |
- Allgardsson, Anders, et al.
(författare)
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An unusual dimeric inhibitor of acetylcholinesterase : cooperative binding of crystal violet
- 2017
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Ingår i: Molecules. - : MDPI AG. - 1431-5157 .- 1420-3049. ; 22:9
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Tidskriftsartikel (refereegranskat)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 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.
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| 2. |
- Allgardsson, Anders, et al.
(författare)
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Structure of a prereaction complex between the nerve agent sarin, its biological target acetylcholinesterase, and the antidote HI-6
- 2016
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 113:20, s. 5514-5519
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Tidskriftsartikel (refereegranskat)abstract
- Organophosphorus nerve agents interfere with cholinergic signaling by covalently binding to the active site of the enzyme acetylcholinesterase (AChE). This inhibition causes an accumulation of the neurotransmitter acetylcholine, potentially leading to overstimulation of the nervous system and death. Current treatments include the use of antidotes that promote the release of functional AChE by an unknown reactivation mechanism. We have used diffusion trap cryocrystallography and density functional theory (DFT) calculations to determine and analyze prereaction conformers of the nerve agent antidote HI-6 in complex with Mus musculus AChE covalently inhibited by the nerve agent sarin. These analyses reveal previously unknown conformations of the system and suggest that the cleavage of the covalent enzyme-sarin bond is preceded by a conformational change in the sarin adduct itself. Together with data from the reactivation kinetics, this alternate conformation suggests a key interaction between Glu202 and the O-isopropyl moiety of sarin. Moreover, solvent kinetic isotope effect experiments using deuterium oxide reveal that the reactivation mechanism features an isotope-sensitive step. These findings provide insights into the reactivation mechanism and provide a starting point for the development of improved antidotes. The work also illustrates how DFT calculations can guide the interpretation, analysis, and validation of crystallographic data for challenging reactive systems with complex conformational dynamics.
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| 3. |
- Lindgren, Cecilia, et al.
(författare)
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Broad-Spectrum Antidote Discovery by Untangling the Reactivation Mechanism of Nerve-Agent-Inhibited Acetylcholinesterase
- 2022
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Ingår i: Chemistry - A European Journal. - : John Wiley & Sons. - 0947-6539 .- 1521-3765. ; 28:40
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Tidskriftsartikel (refereegranskat)abstract
- Reactivators are vital for the treatment of organophosphorus nerve agent (OPNA) intoxication but new alternatives are needed due to their limited clinical applicability. The toxicity of OPNAs stems from covalent inhibition of the essential enzyme acetylcholinesterase (AChE), which reactivators relieve via a chemical reaction with the inactivated enzyme. Here, we present new strategies and tools for developing reactivators. We discover suitable inhibitor scaffolds by using an activity-independent competition assay to study non-covalent interactions with OPNA-AChEs and transform these inhibitors into broad-spectrum reactivators. Moreover, we identify determinants of reactivation efficiency by analysing reactivation and pre-reactivation kinetics together with structural data. Our results show that new OPNA reactivators can be discovered rationally by exploiting detailed knowledge of the reactivation mechanism of OPNA-inhibited AChE.
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| 4. |
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