Abstract The enantioselective catabolism of the two enantiomers of the aryloxyphenoxypropionate (AOPP) herbicide, quizalofop-ethyl (QE), in environment by microorganisms is of great interest. In this study, Sphingobium sp. strain QE-1, capable of transforming both enantiomers of QE, was successfully isolated. A novel gene qeH, encoding an esterase capable of initially transforming (R)/(S)-QE to (R)/(S)-quizalofop acid [(R)/(S)-QA], was cloned. QeH showed the highest identity (36.9%) to the β-lactamase MT1414, and the purified QeH displayed optimal activity for (R)-QE at 40 °C and pH 7.0. QeH preferentially hydrolyzed (R)-QE than (S)-QE. Based on molecular docking analyses, the distance between the ligand molecule and the coordination atom was shorter when (R)-QE occupied the active sites as compared to that of (S)-QE, which resulted in a stronger ligand binding affinity for (R)-QE. Besides the two enantiomers of QE, QeH could also convert many other AOPP herbicides with different catalytic efficiency (clodinafop-propargyl > fenoxaprop-P-ethyl > fluazifop-P-butyl > cyhalofop-butyl). This study will enhance our understandings of the enantioselective catabolism of AOPP herbicides by microorganisms.

中文翻译：

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来自鞘氨醇 sp. quizalofop-乙基转化菌株的对映选择性酯酶的表征。QE-1

摘要 微生物对环境中芳氧基苯氧基丙酸酯 (AOPP) 除草剂喹禾灵 (QE) 的两种对映异构体的对映选择性分解代谢具有重要意义。在这项研究中，Sphingobium sp。能够转化 QE 的两种对映异构体的菌株 QE-1 被成功分离。克隆了一种新基因 qeH，它编码一种酯酶，能够最初将 (R)/(S)-QE 转化为 (R)/(S)-quizalofop 酸 [(R)/(S)-QA]。QeH 与 β-内酰胺酶 MT1414 显示出最高的同一性 (36.9%)，并且纯化的 QeH 在 40 °C 和 pH 7.0 下对 (R)-QE 显示出最佳活性。QeH 比 (S)-QE 优先水解 (R)-QE。基于分子对接分析，与（S）-QE相比，当（R）-Q​​E占据活性位点时，配体分子与配位原子之间的距离更短，这导致对 (R)-QE 的配体结合亲和力更强。除了 QE 的两种对映异构体之外，QeH 还可以转化许多其他具有不同催化效率的 AOPP 除草剂（炔草酯 > fenoxaprop-P-乙基 > 氟草灵-P-丁基 > 氰氟草酯-丁基）。这项研究将增进我们对微生物对 AOPP 除草剂的对映选择性分解代谢的理解。