Репозиторий Университета

© 2020 Elsevier B.V. Herein, the synthesis, design, and the physicochemical characterization of phosphorus functionalized thiazolotriazole (PFT) compound are presented. The PFT tests on the biological activity revealed butyrylcholinesterase inhibition that was confirmed and explained with molecular docking studies. The pronounced reduction of optical density and biological activity was found as a result of irradiation of the PFT water solution with laser beam at wavelength 266 nm. The observed phenomenon was explained on the base of molecular dynamics, docking, and density functional theory modeling by the formation of PFT conformers via laser-induced phosphonate group twisting. The reorganization of the PFT geometry was found to be a reason of butyrylcholinesterase inhibition mechanism change and the site-specificity loss. These results demonstrate that PFT combines photoswitching and bioactive properties in one molecule that makes it promising as a molecular basis for the further design of bioactive substances with photosensitive properties based on the mechanism of the phosphonate group phototwisting.

© 2018 Zlobin, Mokrushina, Terekhov, Zalevsky, Bobik, Stepanova, Aliseychik, Kartseva, Panteleev, Golovin, Belogurov, Gabibov and Smirnov. Butyrylcholinesterase (BChE) is considered as an efficient stoichiometric antidote against organophosphorus (OP) poisons. Recently we utilized combination of calculations and ultrahigh-throughput screening (uHTS) to select BChE variants capable of catalytic destruction of OP pesticide paraoxon. The purpose of this study was to elucidate the molecular mechanism underlying enzymatic hydrolysis of paraoxon by BChE variants using hybrid quantum mechanical/molecular mechanical (QM/MM) calculations. Detailed analysis of accomplished QM/MM runs revealed that histidine residues introduced into the acyl-binding loop are always located in close proximity with aspartate residue at position 70. Histidine residue acts as general base thus leading to attacking water molecule activation and subsequent SN2 inline hydrolysis resulting in BChE reactivation. This combination resembles canonical catalytic triad found in active centers of various proteases. Carboxyl group activates histidine residue by altering its pKa, which in turn promotes the activation of water molecule in terms of its nucleophilicity. Observed re-protonation of catalytic serine residue at position 198 from histidine residue at position 438 recovers initial configuration of the enzyme's active center, facilitating next catalytic cycle. We therefore suggest that utilization of uHTS platform in combination with deciphering of molecular mechanisms by QM/MM calculations may significantly improve our knowledge of enzyme function, propose new strategies for enzyme design and open new horizons in generation of catalytic bioscavengers against OP poisons.

© 2018 Park-media, Ltd. In this paper, we, for the first time, describe the interaction between the butyrylcholinesterase enzyme and echothiophate, a popular model compound and an analogue of the chemical warfare agents VX and VR, at the atomistic level. Competition between the two echothiophate conformations in the active site was found using molecular modeling techniques. The first one is close to the mode of binding of the substrates of choline series (butyrylcholine and butyrylthiocholine) and is inhibitory, since it is unable to react with the enzyme. The second one is characterized by a significantly worse estimated binding affinity and is reactive. Thus, echothiophate combines the features of two types of inhibitors: competitive and suicidal. This observation will help clarify the kinetic reaction scheme in order to accurately assess the kinetic constants, which is especially important when designing new butyrylcholinesterase variants capable of full-cycle hydrolysis of organophosphorus compounds.