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

CO 2 fixation technology has gained attention as a method to effectively utilize the abundant CO 2 in the atmosphere by converting it into useful chemicals. However, since CO 2 is a highly stable molecule, many of the currently developed methods for chemical CO 2 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 2 ) using a biocatalyst, Thermoplasma acidophilum NADP + -malic enzyme ( Ta ME), and gaseous CO 2 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.