Substrate Promiscuity of Thermoplasma acidophilum Malic Enzyme for CO 2 Fixation Reaction

CO fixation technology has gained attention as a method to effectively utilize the abundant CO in the atmosphere by converting it into useful chemicals. However, since CO is a highly stable molecule, many of the currently developed methods for chemical CO fixation require harsh conditions and reactive reagents. The establishment of efficient and sustainable processes is eagerly awaited. In this study, we investigated a biocatalytic process and achieved a carboxylation reaction under mild conditions (37 °C, 0.1 MPa CO ) using a biocatalyst, NADP -malic enzyme ( ME), and gaseous CO by coupling enzymatic coenzyme regeneration. We also demonstrated for the first time that the carboxylation reaction by ME proceeds not only with pyruvate, a natural substrate, but also with 2-ketoglutarate.