Electrosynthesis of formate is a promising technology to convert CO₂ and electricity from renewable sources into a biocompatible, soluble, non-flammable, and easily storable compound. In the model methanogen Methanococcus maripaludis, uptake of cathodic electrons was shown to proceed indirectly via formation of formate or H₂ by undefined, cell-derived enzymes. Here, we identified that the multi-enzyme heterodisulfide reductase supercomplex (Hdr-SC) of M. maripaludis is capable of direct electron uptake and catalyzes rapid H₂ and formate formation in electrochemical reactors (−800 mV vs Ag/AgCl) and in Fe(0) corrosion assays. In Fe(0) corrosion assays and electrochemical reactors, purified Hdr-SC primarily catalyzed CO₂ reduction to formate with a coulombic efficiency of 90% in the electrochemical cells for 5 days. Thus, this report identified the first enzyme that stably catalyzes the mediator-free electrochemical reduction of CO₂ to formate, which can serve as the basis of an enzyme electrode for sustained electrochemical production of formate.

甲酸的电合成是一种有前途的技术，可将来自可再生资源的CO ₂和电转化为生物相容，可溶，不可燃且易于储存的化合物。在模型产甲烷菌马氏甲烷球菌中，阴极电子的摄取显示为通过不确定的细胞衍生酶形成甲酸酯或H ₂间接进行。在这里，我们确定了M. maripaludis的多酶杂二硫键还原酶超复合物（Hdr-SC）能够直接吸收电子并催化快速的H _2。在电化学反应器（-800 mV，相对于Ag / AgCl）和Fe（0）腐蚀分析中形成甲酸盐。在Fe（0）腐蚀分析和电化学反应器中，纯化的Hdr-SC主要催化CO ₂还原生成甲酸，在电化学电池中连续90天的库仑效率为90％。因此，本报告确定了第一种稳定催化无CO _2的电化学还原反应生成甲酸的酶，该酶可作为持续电化学生成甲酸的酶电极的基础。