Herold Ryan A, Schofield Christopher J, Armstrong Fraser A
Department of Chemistry, University of Oxford, Mansfield Road, Oxford, OX1 3QY, United Kingdom.
Current Address: Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA, 92093, USA.
Angew Chem Int Ed Engl. 2025 Mar 3;64(10):e202414176. doi: 10.1002/anie.202414176. Epub 2025 Feb 11.
The catalytic action of enzymes in a cascade trapped within a mesoporous electrode material is simultaneously energized, controlled and observed through the efficient, reversible electrochemical NAD(P)(H) recycling catalyzed by one of the enzymes. In their nanoconfined state, nicotinamide cofactors are tightly channeled current carriers, mediating multi-step reactions in either direction (oxidation or reduction) with a rapid response time. By incorporating a hydrogen-borrowing enzyme pair, the internal action of which opposes the external voltage bias driving oxidation or reduction, a reduction process can be performed under overall oxidizing conditions, and vice versa. The power of the method to control and resolve complex metabolic pathways is demonstrated using a non-linear, three-enzyme cascade extended by incorporating a fourth enzyme, urease. The latter generates in situ ammonia, which is enzymatically consumed in a reductive process, but the immediate current response to each addition of urea is observed, unusually, by applying an oxidizing potential. A practical consequence is that enzyme-catalyzed electrochemical reduction reactions requiring anaerobic conditions (to avoid O interference) can readily be studied under ambient aerobic conditions. The results illustrate how a complex enzyme cascade confined within a porous electrode and connected to an electrical power source manifests characteristics associated with electronic circuits.
困于介孔电极材料内的级联酶的催化作用，通过其中一种酶催化的高效、可逆电化学NAD(P)(H)循环同时得到激发、控制和观测。在其纳米受限状态下，烟酰胺辅因子是紧密引导电流的载体，介导多步反应向任一方向（氧化或还原）进行，响应时间迅速。通过纳入一对借氢酶，其内部作用与驱动氧化或还原的外部电压偏置相反，还原过程可在整体氧化条件下进行，反之亦然。通过纳入第四种酶脲酶扩展的非线性三酶级联，证明了该方法控制和解析复杂代谢途径的能力。后者原位产生氨，氨在还原过程中被酶消耗，但异常的是，通过施加氧化电位可观测到每次添加尿素后的即时电流响应。一个实际结果是，需要厌氧条件（以避免氧气干扰）的酶催化电化学还原反应可在环境有氧条件下轻松研究。结果说明了困于多孔电极内并连接到电源的复杂酶级联如何表现出与电子电路相关的特性。
