Dept. of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel.
Dept. of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel.
Chem Biol Interact. 2018 Aug 25;292:50-64. doi: 10.1016/j.cbi.2018.07.006. Epub 2018 Jul 7.
Recent years have seen an increasing number of incidence, in which organophosphate nerve agents (OPNAs) have been used against civilians with devastating outcomes. Current medical countermeasures against OPNA intoxications are aimed at mitigating their symptoms, but are unable to effectively prevent them. In addition, they may fail to prevent the onset of a cholinergic crisis in the brain and its secondary toxic manifestations. The need for improved medical countermeasures has led to the development of bioscavengers; proteins and enzymes that may prevent intoxication by binding and inactivating OPNAs before they can reach their target organs. Non-catalytic bioscavengers such as butyrylcholinesterase, can rapidly bind OPNA molecules in a stoichiometric and irreversible manner, but require the administration of large protein doses to prevent intoxication. Thus, many efforts have been made to develop catalytic bioscavengers that could rapidly detoxify OPNAs without being inactivated in the process. Such enzymes may provide effective prophylactic protection and improve post-exposure treatments using much lower protein doses. Here we review attempts to develop catalytic bioscavengers using molecular biology, directed evolution and enzyme engineering techniques; and natural or computationally designed enzymes. These include both stoichiometric scavengers and enzymes that can hydrolyze OPNAs with low catalytic efficiencies. We discuss the catalytic parameters of evolved and engineered enzymes and the results of in-vivo protection and post-exposure experiments performed using OPNAs and bioscavengers. Finally, we briefly address some of the challenges that need to be met in order to transition these enzymes into clinically approved drugs.
近年来，越来越多的有机磷神经毒剂（OPNAs）被用于攻击平民，造成了毁灭性的后果。目前针对 OPNA 中毒的医疗对策旨在减轻其症状，但无法有效预防。此外，它们可能无法预防大脑中胆碱能危机及其继发性毒性表现的发生。对改进医疗对策的需求促使生物清除剂的发展；这些蛋白质和酶可以通过与 OPNAs 结合并使其失活来防止其到达靶器官，从而预防中毒。非催化型生物清除剂，如丁酰胆碱酯酶，可以以化学计量比和不可逆的方式快速结合 OPNAs 分子，但需要大剂量的蛋白质才能防止中毒。因此，许多努力都致力于开发催化型生物清除剂，使其能够在不失活的情况下快速解毒 OPNAs。这些酶可以提供有效的预防性保护，并使用低得多的蛋白质剂量改善暴露后的治疗。在这里，我们综述了使用分子生物学、定向进化和酶工程技术开发催化型生物清除剂的尝试；以及天然或计算设计的酶。这些酶包括化学计量清除剂和可以低催化效率水解 OPNAs 的酶。我们讨论了进化和工程酶的催化参数，以及使用 OPNAs 和生物清除剂进行体内保护和暴露后实验的结果。最后，我们简要讨论了需要满足的一些挑战，以便将这些酶转化为临床批准的药物。
