Enzymatic detoxification: a sustainable means of degrading toxic organophosphate pesticides and chemical warfare nerve agents

Organophosphorus (OP) compounds are highly toxic molecules mainly used as pesticides. OP compounds also include nerve gases used in the past as chemical warfare agents and collectively OP pesticides and nerve gases are referred to as nerve agents (NA). An intensive, widespread use of pesticides since the 20th century has resulted in the emergence of an urgent global issue concerning both environment and human health. In addition, past terroristic acts and the recent dramatic events in Syria highlighted more than ever the need to explore applicable strategies for the sensing, decontamination and detoxification of these compounds in stored bulks, on critical surfaces and media (food, water and air) and for in vivo prophylaxes and therapies. OP compounds, act as covalent inhibitors of acetylcholinesterase (AChE) in the nerve system of vertebrates, thus posing a substantial threat to the ecosystem. In order to address a strong demand for the establishment of an environmental monitoring system and remediation process for NA, an increasing number of studies have been focused on the enzymatic degradation in vitro. Use of enzymes for detoxification and decontamination of toxic NA could provide a long-term benefit as it is environmentally friendly compared with conventional methods such as chemical treatments and incineration. This review presents an overview of the current state of enzymatic detoxification research against NA. This includes the detailed characterization and protein engineering for the improvement in NA-degrading activities of such enzymes. Research on biosensors for NA detection and identification, although important in the field, has not been treated in this review. Instead special attention has been paid to the Phosphotriesterase-Like-Lactonase (PLL) enzyme family. Several PLL enzymes have been isolated from hyperthermophilic Archaea or thermophilic/extremophilic Bacteria, and exhibit exceptional thermal stability. Extremophilic PLLs therefore hold promise for potential industrial application towards NA detoxification. (c) 2018 Society of Chemical Industry