The air-inactivation of formate dehydrogenase FdsDABG from Cupriavidus necator

The Reversible Electrochemical Interconversion of Formate and CO2 by Formate Dehydrogenase from Cupriavidus necator

“…Subsequently, the FdsDABG enzyme electrode lost all of its catalytic activity after 72 h (data not shown). These observations are consistent with a recent mechanistic study on air inactivation of C. necator FdsDABG . It was shown that FdsDABG degraded under aerobic conditions due to attack by superoxide, resulting in desulfuration of the MoS active site and sulfite formation.…”

“…C. necator FdsDABG was purified as described previously. 25 Immobilizing a small amount of active enzyme on the GC electrode surface as a thin layer can give rise to measurable voltammetry currents under turnover conditions when they are amplified by catalytic substrate oxidation/reduction processes. The integrity of the enzyme film is important for practical applications.…”

“…These observations are consistent with a recent mechanistic study on air inactivation of C. necator FdsDABG. 25 It was shown that FdsDABG degraded under aerobic conditions due to attack by superoxide, resulting in desulfuration of the Mo�S active site and sulfite formation. However, FdsDABG may be protected from degradation by incubation with nitrate, which acts as an inhibitor.…”

“…The smallest subunit FdsD bears no redox-active cofactors but is implicated in Mo cofactor insertion . The X-ray crystal structure of the FdsBG subcomplex from C. necator has previously been determined, demonstrating that the FMN cofactor (of FdsB) is the site at which reduction of NAD + occurs, as is known to be the case in other members of the NADH dehydrogenase superfamily of enzymes, of which FdsDABG is a member. ,− An unusual and convenient property of FdsDABG is its relatively high stability under aerobic conditions, although stabilizing inhibitors such as potassium nitrate or sodium azide are required for long-term retention of activity …”

“…7,21−24 An unusual and convenient property of FdsDABG is its relatively high stability under aerobic conditions, although stabilizing inhibitors such as potassium nitrate or sodium azide are required for long-term retention of activity. 25 Electrochemical methods are well-suited to the study of oxidoreductase enzymes as the need for stoichiometric oxidants and reductants (e.g., NAD + /NADH) is removed by the working electrode. Electrochemical communication with the enzyme may occur directly or indirectly via mediators which act as electron shuttles between the enzyme and the electrode surface.…”