Department of Structural Biology, The Weizmann Institute of Science, Rehovot 76100, Israel.
Toxicol Lett. 2011 Sep 25;206(1):24-8. doi: 10.1016/j.toxlet.2011.07.017. Epub 2011 Jul 23.
An ex vivo protocol was developed to assay the antidotal capacity of rePON1 variants to protect endogenous acetylcholinesterase and butyrylcholinesterase in human whole blood against OP nerve agents. This protocol permitted us to address the relationship between blood rePON1 concentrations, their kinetic parameters, and the level of protection conferred by rePON1 on the cholinesterases in human blood, following a challenge with cyclosarin (GF). The experimental data thus obtained were in good agreement with the predicted percent residual activities of blood cholinesterases calculated on the basis of the rate constants for inhibition of human acetylcholinesterase and butyrylcholinesterase by GF, the concentration of the particular rePON1 variant, and its k(cat)/K(m) value for GF. This protocol thus provides a rapid and reliable ex vivo screening tool for identification of rePON1 bioscavenger candidates suitable for protection of humans against organophosphorus-based toxicants. The results also permitted the refinement of a mathematical model for estimating the efficacious dose of rePON1s variants required for prophylaxis in humans.
建立了一种离体测定方案，以评估 rePON1 变体对人全血中内源性乙酰胆碱酯酶和丁酰胆碱酯酶的解毒能力，使其免受 OP 神经毒剂的影响。该方案使我们能够解决血液 rePON1 浓度、其动力学参数以及 rePON1 对人血液中胆碱酯酶的保护水平之间的关系，在使用环沙林（GF）进行挑战后。根据 GF 对人乙酰胆碱酯酶和丁酰胆碱酯酶的抑制速率常数、特定 rePON1 变体的浓度及其对 GF 的 k(cat)/K(m) 值，计算得出的血液胆碱酯酶的预测残留活性百分比与实验数据吻合良好。因此，该方案为鉴定适合保护人类免受有机磷类毒物影响的 rePON1 生物清除候选物提供了一种快速可靠的体外筛选工具。该结果还改进了一种数学模型，用于估计预防人类所需的 rePON1 变体的有效剂量。
