Discovery of a new metal and NAD-dependent formate dehydrogenase from Clostridium ljungdahlii.

Over the next decades， with the growing concern of rising atmospheric carbon dioxide (CO) levels， the importance of investigating new approaches for its reduction becomes crucial. Reclamation of CO for conversion into biofuels represents an alternative and attractive production method that has been studied in recent years， now with enzymatic methods gaining more attention. Formate dehydrogenases (FDHs) are NAD(P)H-dependent oxidoreductases that catalyze the conversion of formate into CO and have been extensively used for cofactor recycling in chemoenzymatic processes. A new FDH from Clostridium ljungdahlii (ClFDH) has been recently shown to possess activity in the reverse reaction: the mineralization of CO into formate. In this study， we show the successful homologous expression of ClFDH in Escherichia coli. Biochemical and kinetic characterization of the enzyme revealed that this homologue also demonstrates activity toward CO reduction. Structural analysis of the enzyme through homology modeling is also presented.