Response surface methodology (RSM) was used to optimize the oxidizing the omeprazole sulfide to (S)-omeprazole catalyzed by environmentally friendly catalyst soybean pod peroxidase (SPP) in cetyltrimethylammonium bromide (CTAB)/isooctane/n-butyl alcohol/water water-in-oil microemulsions. With the initial concentration of SPP of 3200 U ml⁻¹, the conversion of the omeprazole sulfide, the (S)-omeprazole yield and ee were 93.75%, 91.56% and 96.08%, respectively, under the optimal conditions: Wo of 15.85, the concentration of H₂O₂ of 22.44 mM and reaction temperature of 49.68 °C, respectively. The proposed mechanism of asymmetric sulfoxidations catalyzed by SPP involves three concomitant mechanisms as follows: (1) a two-electron reduction of SPP-I, (2) a single-electron transfer to SPP-I and (3) nonenzymatic reactions. Based on the proposed mechanism which is reasonable and can express the oxidations, the reaction system includes five enzymatic and two nonenzymatic reactions. With 5.44% of the average relative error, a kinetic model based on the mechanisms fitting observed data very well was established, and the SPP-catalyzed reactions including both the two-electron reduction and the single-electron transfer mechanisms obey ping-pong mechanism with substrate and product inhibition, while nonenzymatic reactions follow a power law. This study has also demonstrated the feasibility of SPP as a substitute with low cost, excellent enantioselectivity and better thermal stability.

Graphic Abstract

中文翻译：

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大豆荚过氧化物酶催化油包水微乳中(S)-奥美拉唑的RSM合成工艺优化

响应面法 (RSM) 用于优化环境友好型催化剂大豆荚过氧化物酶 (SPP) 在十六烷基三甲基溴化铵 (CTAB)/异辛烷/正丁醇/水中的氧化奥美拉唑硫化物为 (S)-奥美拉唑-油微乳液。SPP初始浓度为3200 U ml ^{-1 时}，奥美拉唑硫化物的转化率、(S)-奥美拉唑的产率和ee分别为93.75%、91.56%和96.08%，在最佳条件下：Wo为15.85， H ₂ O ₂的浓度分别为 22.44 mM 和反应温度为 49.68 °C。由 SPP 催化的不对称亚砜氧化的拟议机制涉及以下三个伴随机制：（1）SPP-I 的双电子还原，（2）单电子转移到 SPP-I 和（3）非酶促反应。基于所提出的合理且可以表达氧化反应的机理，该反应体系包括五个酶促反应和两个非酶促反应。以5.44%的平均相对误差，建立了基于机制的动力学模型，与观测数据非常吻合，SPP催化的双电子还原和单电子转移机制均服从乒乓机制，底物和产物抑制，而非酶促反应遵循幂律。

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