Institute of Technical Biocatalysis, Hamburg University of Technology, Denickestraße 15, 21073 Hamburg, Germany.
Institute of Technical Biocatalysis, Hamburg University of Technology, Denickestraße 15, 21073 Hamburg, Germany.
N Biotechnol. 2023 Dec 25;78:95-104. doi: 10.1016/j.nbt.2023.10.007. Epub 2023 Oct 16.
The electroenzymatic hydroxylation of 4-ethylbenzoic acid catalyzed by the recombinant unspecific peroxygenase from the fungus Agrocybe aegerita (rAaeUPO) was performed in a gas diffusion electrode (GDE)-based system. Enzyme stability and productivity are significantly affected by the way the co-substrate hydrogen peroxide (HO) is supplied. In this study, two in-situ electrogeneration modes of HO were established and compared. Experiments under galvanostatic conditions (constant productivity of HO) were conducted at current densities spanning from 0.8 mA cm to 6.4 mA cm. For comparison, experiments under HO-stat mode (constant HO concentration) were performed. Here, four HO concentrations between 0.06 mM and 0.28 mM were tested. A maximum HO productivity of 5.5 µM min cm and productivity of 10.5 g L d were achieved under the galvanostatic condition at 6.4 mA cm. Meanwhile, the highest total turnover number (TTN) of 710,000 mol mol and turnover frequency (TOF) of 87.5 s were obtained under the HO-stat mode at concentration limits of 0.15 mM and 0.28 mM, respectively. The most favorable outcome in terms of maximum achievable TTN, TOF and productivity was found under the HO-stat mode at concentration limit of 0.2 mM. Here, a TTN of 655,000 mol mol, a TOF of 80.3 s and a productivity of 6.1 g L d were achieved. The electrochemical HO-stat mode not only offers a promising alternative reaction concept to the well-established galvanostatic mode but also enhances the process performance of unspecific peroxygenases.
真菌糙皮侧耳（Agrocybe aegerita）中重组非特异性过氧化物酶（rAaeUPO）催化的 4-乙基苯甲酸的电酶羟化作用是在基于气体扩散电极（GDE）的系统中进行的。共底物过氧化氢（HO）的供应方式会显著影响酶的稳定性和生产力。在这项研究中，建立并比较了两种原位电生成 HO 的模式。在恒电流密度（恒定 HO 生产力）条件下进行实验，电流密度范围为 0.8 mA cm 至 6.4 mA cm。为了进行比较，还进行了 HO-静态模式（恒定 HO 浓度）下的实验。在此，测试了 0.06 mM 至 0.28 mM 之间的四种 HO 浓度。在 6.4 mA cm 的恒电流密度条件下，实现了 5.5 µM min cm 的最大 HO 生产力和 10.5 g L d 的生产力。同时，在 HO-静态模式下，在浓度限制为 0.15 mM 和 0.28 mM 时，分别获得了 710,000 mol mol 的最高总转化数（TTN）和 87.5 s 的转化频率（TOF）。在浓度限制为 0.2 mM 的 HO-静态模式下，获得了最大可达 TTN、TOF 和生产力的最有利结果。在此，获得了 655,000 mol mol 的 TTN、80.3 s 的 TOF 和 6.1 g L d 的生产力。电化学 HO-静态模式不仅为建立良好的恒电流模式提供了一种很有前途的替代反应概念，而且还提高了非特异性过氧化物酶的过程性能。
