Curious Effect of Isotope-Labelled Substrate/Co-Enzyme on Catalytic Activity of CO2 Reduction by Formate Dehydrogenase from Candida Boidinii

Abstract The effects of isotope-labelled NADH and CO2 on formate dehydrogenase from Candida boidinii (CbFDH)-catalyzed CO2 reduction activity were investigated. It was found that the rate of CO2 reduction to formate with CbFDH decreased by using deuterium-labelled NADH (NADH-d4) as a co-enzyme. In contrast, the rate of CbFDH-catalyzed CO2 reduction to formate was unchanged in the use of 13CO2 as a substrate. In the substrate 12CO2 and 13CO2 is mixed, however, curious phenomenon on CbFDH-catalyzed CO2 reduction activity decrease was observed.