Goldsmith Moshe, Ashani Yacov, Simo Yair, Ben-David Moshe, Leader Haim, Silman Israel, Sussman Joel L, Tawfik Dan S
Department of Biological Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel.
Chem Biol. 2012 Apr 20;19(4):456-66. doi: 10.1016/j.chembiol.2012.01.017.
A preferred strategy for preventing nerve agents intoxication is catalytic scavenging by enzymes that hydrolyze them before they reach their targets. Using directed evolution, we simultaneously enhanced the activity of a previously described serum paraoxonase 1 (PON1) variant for hydrolysis of the toxic S(P) isomers of the most threatening G-type nerve agents. The evolved variants show ≤340-fold increased rates and catalytic efficiencies of 0.2-5 × 10(7) M(-1) min(-1). Our selection for prevention of acetylcholinesterase inhibition also resulted in the complete reversion of PON1's stereospecificity, from an enantiomeric ratio (E) < 6.3 × 10(-4) in favor of the R(P) isomer of a cyclosarin analog in wild-type PON1, to E > 2,500 for the S(P) isomer in an evolved variant. Given their ability to hydrolyze G-agents, these evolved variants may serve as broad-range G-agent prophylactics.
预防神经毒剂中毒的一种优选策略是通过酶进行催化清除，这些酶在神经毒剂到达其靶点之前将其水解。利用定向进化，我们同时增强了先前描述的血清对氧磷酶1（PON1）变体对最具威胁性的G型神经毒剂的有毒S（P）异构体的水解活性。进化后的变体显示速率增加了≤340倍，催化效率为0.2 - 5×10⁷ M⁻¹ min⁻¹。我们对预防乙酰胆碱酯酶抑制的选择还导致PON1的立体特异性完全逆转，从野生型PON1中对环沙林类似物的R（P）异构体有利的对映体比率（E）< 6.3×10⁻⁴，变为进化变体中对S（P）异构体的E > 2500。鉴于它们水解G型毒剂的能力，这些进化后的变体可作为广谱G型毒剂预防剂。
