Enzymatic Decontamination of G-Type, V-Type and Novichok Nerve Agents

Abstract

Organophosphorus nerve agents (OPNAs) are highly toxic compounds inhibiting cholinergic enzymes in the central and autonomic nervous systems and neuromuscular junctions, causing severe intoxications in humans. Medical countermeasures and efficient decontamination solutions are needed to counteract the toxicity of a wide spectrum of harmful OPNAs including G, V and Novichok agents. Here, we describe the use of engineered OPNA-degrading enzymes for the degradation of various toxic agents including insecticides, a series of OPNA surrogates, as well as real chemical warfare agents (cyclosarin, sarin, soman, tabun, VX, A230, A232, A234). We demonstrate that only two enzymes can degrade most of these molecules at high concentrations (25 mM) in less than 5 minutes. Using surface assays adapted from NATO AEP-65 guidelines, we further show that enzyme-based solutions can decontaminate 97.6% and 99.4% of 10 g∙m−² of soman- and VX-contaminated surfaces, respectively. Finally, we demonstrate that these enzymes can degrade ethyl-paraoxon down to sub-inhibitory concentrations of acetylcholinesterase, confirming their efficacy from high to micromolar doses.

Changes in Active Site Loop Conformation Relate to the Transition toward a Novel Enzymatic Activity

“…Specifically, we adapted a previously reported procedure based on the inhibition of Human AChE , to evaluate their capacity to protect the enzyme target of OP compounds. We used a previously reported stabilized rHAChE. , rHAChE inhibition assays were performed with ethyl-paraoxon, although rHAChE inhibition by this substrate is not irreversible. rHAChE activity was measured at different time points to evaluate the rate of detoxification of the phosphotriester by the Sso Pox variants.…”

“…PLL and PTE share a (β/α) 8 fold with highly mobile loops that contribute to broadening their promiscuity to other substrates such as aryl-esters . Bacterial PTEs, although naturally efficient for the degradation of OP insecticides, have been further engineered in vitro for the development of biocatalysts close to catalytic perfection for decontaminating insecticides or chemical warfare agents. − These variants may find application in bioremediation of agricultural contaminations or for prophylaxis protection against OP poisoning. , However, most PTEs have been isolated from mesophilic microorganisms and show moderate stability limiting their potential for bioremediation or development of medical countermeasures to face OP poisoning. , A subfamily of PLL, namely, PLL-A, is composed of enzymes isolated from thermostable and hyperthermostable bacteria or archaea. Special attention has thus been paid to PLL-A for developing high-potential biocatalysts as robust enzymes that may offer numerous biotechnological advantages including resistance to high temperatures, tolerance to solvents and denaturants, and long-term storage .…”

Tabún, sarín, somán, VX y novichoks: agentes neurotóxicos organofosforados con finalidad bélica o criminal

“…Los OF, industriales o ANOF, pueden determinarse por cromatografía de gases y espectrometría de masas 33 .…”

Novichok Nerve Agents as Inhibitors of Acetylcholinesterase—In Silico Study of Their Non-Covalent Binding Affinity

“…There are reports on the analysis of these compounds using theoretical and spectroscopic methods [ 9 , 10 , 13 , 15 , 16 ], and scarce in vitro research [ 17 ], yet there is, to the best of our knowledge, no information about any extensive in silico examinations of Novichoks’ mechanism of action and their potential reactivators. In reactivating the enzyme from OPNAs, several oxime-based compounds [ 18 , 19 , 20 , 21 , 22 ] as well as several engineered OPNA-degrading enzymes [ 14 ] are effective, and purely theoretical studies were conducted (e.g., [ 23 , 24 ]). Regarding Novichoks however, there is a lack of both QM and molecular mechanics (MM) investigations of Novichok–AChE interactions, including the noncovalent ones; yet, obviously, the noncovalent interplay between the ligand and the enzyme contributes to and facilitates the irreversible phosphonylation of the AChE catalytic-triad serine e.g., by adjusting the ligand electron density distribution therefore stabilizing the ligand in the enzyme active centre gorge and making it thus more susceptible to nucleophilic enzyme attack.…”