Biocatalytic Isocitrate Production from Low-Concentration Gaseous CO2 and Biobased 2-Oxogultarate

Isocitrate dehydrogenase (IDH) from yeast (EC 1.1.1.42) is an enzyme that catalyzes the decarboxylating isocitrate into 2-oxogurtarate and carbon dioxide and the reverse process of the introducing carbon dioxide as a carboxy-group to 2-oxogurtarate to produce isocitrate via oxalosuccinate in the presence of co-enzyme NADP⁺/NADPH. Thus, IDH is an attractive biocatalyst for carbon recycle technology based on the building carbon-carbon bonds due to carboxylation of 2-oxogurtarate with carbon dioxide. Enhancing the carboxylation of 2-oxogurtarate by the addition of metal ions with carbon dioxide using IDH as a catalyst will lead to the establishment of biocatalytic carbon dioxide utilization. Especially, it is found that the addition of divalent manganese ion accelerates IDH-catalyzed carboxylation of 2-oxogurtarate with carbon dioxide. The direct use of carbon dioxide in the carboxylation of 2-oxoglutarate catalyzed by IDH using the capture function of gaseous carbon dioxide in 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES)-NaOH buffer in the presence of manganese ion is attempted and a low concentration of gaseous carbon dioxide of about 5% is successfully used as a feedstock for isocitrate production.