Peroxidases are promising catalysts for oxidation reactions, yet their practical utility has been hindered by the fact that they require hydrogen peroxide (H₂O₂), which at high concentrations can cause deactivation of enzymes. Practical processes involving the use of peroxidases require the frequent addition of low concentrations of H₂O₂. In situ generation of H₂O₂ can be achieved using oxidase-type enzymes. In this study, a three-enzyme cascade system comprised of a H₂O₂ generator (glucose oxidase (GOx)), H₂O₂-dependent enzymes (chloroperoxidase (CPO) or horseradish peroxidase (HRP)), and a H₂O₂ scavenger (catalase (CAT)) was deployed in a flow reactor. Immobilization of the enzymes on a graphite rod was achieved through electrochemically driven physical adsorption, followed by cross-linking with glutaraldehyde. Modeling studies indicated that the flow in the reactor was laminar (Reynolds number, R_e < 2000) and was nearly fully developed at the midplane of the annular reactor. Immobilized CAT and GOx displayed good stability, retaining 79% and 84% of their initial activity, respectively, after three cycles of operation. Conversely, immobilized CPO exhibited a considerable reduction in activity after one use, retaining only 30% of its initial activity. The GOx-CAT-GRE system enabled controlled delivery of H₂O₂ in a more stable manner with a 4-fold enhancement in the oxidation of indole compared to the direct addition of H₂O₂. Using CPO in solution coupled with GOx-CAT-GRE yields of 90% for the oxidation of indole to 2-oxyindole and of 93% and 91% for the chlorination of thymol and carvacrol, respectively.

中文翻译：

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H2O2 的受控传递：用于过氧化物酶催化反应的三酶级联流反应器


过氧化物酶是氧化反应的有前途的催化剂，但它们的实际应用受到了以下事实的阻碍：它们需要过氧化氢（H ₂ O ₂ ），高浓度的过氧化氢会导致过氧化氢失活。酶。涉及使用过氧化物酶的实际过程需要频繁添加低浓度的 H ₂ O ₂ 。 H ₂ O ₂ 的原位生成可以使用氧化酶型酶来实现。在本研究中，三酶级联系统由 H ₂ O ₂ 发生器（葡萄糖氧化酶 (GOx)）、H ₂ O ₂ 依赖性酶（氯过氧化物酶 (CPO) 或辣根过氧化物酶 (HRP)）和 H ₂ O ₂ 清除剂（过氧化氢酶 (CAT)）部署在流中反应堆。通过电化学驱动的物理吸附，然后与戊二醛交联，实现了酶在石墨棒上的固定化。模型研究表明，反应器中的流动是层流（雷诺数，R _e < 2000），并且在环形反应器的中平面处几乎完全发展。固定化的CAT和GOx表现出良好的稳定性，在三个操作周期后分别保留了其初始活性的79%和84%。相反，固定化 CPO 在一次使用后活性显着降低，仅保留其初始活性的 30%。 GOx-CAT-GRE 系统能够以更稳定的方式控制 H ₂ O ₂ 的输送，与直接添加 H 相比，吲哚的氧化增强了 4 倍 ₂ O ₂ 。 使用溶液中的 CPO 与 GOx-CAT-GRE 结合，将吲哚氧化为 2-羟基吲哚，产率分别为 90%，百里酚和香芹酚的氯化产率分别为 93% 和 91%。