ABSTRACT
Studies with oximes have been extensively developed to design new reactivators with better efficiency, and greater spectrum of action. In this study, we aimed to analyze the influence of the Carbamoyl group position change in two isomeric oximes, K203 and K206, on the reactivation percentage of Mus musculus Acetylcholinesterase (MmAChE), inhibited by different nerve agents. Theoretical calculations were performed to assess the difference for the oxime activity with inhibited AChE-complexes and the factors that govern this difference. Comparing theoretical and experimental data, it is possible to observe that this change between the oximes results in different reactivation percentage for the same nerve agent, due to the different interaction modes and activation energy for the studied systems.
Subject(s)
Acetylcholinesterase/metabolism , Cholinesterase Reactivators/chemistry , Organophosphorus Compounds/chemistry , Oximes/chemistry , Acetylcholinesterase/chemistry , Animals , Binding Sites , Cholinesterase Reactivators/metabolism , Drug Design , Mice , Molecular Docking Simulation , Nerve Agents/chemistry , Nerve Agents/metabolism , Organophosphorus Compounds/metabolism , Organothiophosphorus Compounds/chemistry , Organothiophosphorus Compounds/metabolism , Quantum Theory , ThermodynamicsABSTRACT
Neurotoxic organophosphorus compounds (OPs), which are used as pesticides and chemical warfare agents lead to more than 700,000 intoxications worldwide every year. The main target of OPs is the inhibition of acetylcholinesterase (AChE), an enzyme necessary for the control of the neurotransmitter acetylcholine (ACh). The control of ACh function is performed by its hydrolysis with AChE, a process that can be completely interrupted by inhibition of the enzyme by phosphylation with OPs. Compounds used for reactivation of the phosphylated AChE are cationic oximes, which usually possess low membrane and hematoencephalic barrier permeation. Neutral oximes possess a better capacity for hematoencephalic barrier permeation. NMR spectroscopy is a very confident method for monitoring the inhibition and reactivation of enzymes, different from the Ellman test, which is the common method for evaluation of inhibition and reactivation of AChE. In this work (1)H NMR was used to test the effect of neutral oximes on inhibition of AChE and reactivation of AChE inhibited with ethyl-paraoxon. The results confirmed that NMR is a very efficient method for monitoring the action of AChE, showing that neutral oximes, which display a significant AChE inhibition activity, are potential drugs for Alzheimer disease. The NMR method showed that a neutral oxime, previously indicated by the Ellman test as better in vitro reactivator of AChE inhibited with paraoxon than pralidoxime (2-PAM), was much less efficient than 2-PAM, confirming that NMR is a better method than the Ellman test.
Subject(s)
Acetylcholinesterase/metabolism , Cholinesterase Inhibitors/metabolism , Cholinesterase Reactivators/metabolism , Electrophorus/metabolism , Oximes/metabolism , Acetylcholinesterase/chemistry , Animals , Cholinesterase Inhibitors/chemistry , Cholinesterase Reactivators/chemistry , Magnetic Resonance Spectroscopy , Oximes/chemistry , Paraoxon/analogs & derivatives , Paraoxon/metabolism , PhosphorylationABSTRACT
We have applied a theoretical methodology, previously developed to evaluate the association and kinetic reactivation constants of oximes, comparing theoretical data obtained for human acetylcholinesterase (HsAChE) with in vitro results from Mus musculus AChE (MmAChE) previously reported in the literature. Our results, further checked by additional molecular dynamics simulations steps, showed a good correlation between the theoretical and experimental data, supporting the methodology as appropriate for prediction of thermodynamic and kinetic parameters and corroborated MmAChE as a suitable model for studies with HsAChE.
Subject(s)
Acetylcholinesterase/metabolism , Cholinesterase Reactivators/metabolism , Oximes/metabolism , Acetylcholinesterase/chemistry , Amino Acid Sequence , Animals , Cholinesterase Inhibitors/metabolism , Humans , Kinetics , Mice , Models, Molecular , Molecular Docking Simulation , Molecular Dynamics Simulation , Molecular Sequence Data , Oximes/chemistry , Sequence Alignment , Structure-Activity Relationship , ThermodynamicsABSTRACT
In this work a theoretical methodology for evaluation of the association and kinetic reactivation constants of oximes using the Molegro and Spartan softwares was proposed and validated facing in vitro data previously reported in the literature. Results showed a very good agreement between the theoretical binding free energies of the reactivators and experimental data, suggesting that the proposed methodology could work well in the prediction of kinetic and thermodynamics parameters for oximes that might be helpful for the design and selection of new and more effective oximes.
Subject(s)
Acetylcholinesterase/metabolism , Cholinesterase Reactivators/pharmacology , Drug Discovery/methods , Enzyme Activation/drug effects , Models, Molecular , Acetylcholinesterase/chemistry , Animals , Catalytic Domain , Cholinesterase Inhibitors/pharmacology , Cholinesterase Reactivators/metabolism , Mice , Organophosphates/pharmacology , Oximes/metabolism , Oximes/pharmacology , Quantum Theory , ThermodynamicsABSTRACT
In this work a theoretical methodology for evaluation of the association and kinetic reactivation constants of oximes using the Molegro and Spartan softwares was proposed and validated facing in vitro data previously reported in the literature. Results showed a very good agreement between the theoretical binding free energies of the reactivators and experimental data, suggesting that the proposed methodology could work well in the prediction of kinetic and thermodynamics parameters for oximes that might be helpful for the design and selection of new and more effective oximes.