A high effective NADH-ferricyanide dehydrogenase coupled with laccase for NAD + regeneration

Objectives To find an efficient and cheap system for NAD + regeneration Results A NADH-ferricyanide dehydrogenase was obtained from an isolate of Escherichia coli . Optimal activity of the NADH dehydrogenase was at 45 °C and pH 7.5, with a K m value for NADH of 10 μM. By combining the NADH dehydrogenase, potassium ferricyanide and laccase, a bi-enzyme system for NAD + regeneration was established. The system is attractive in that the O 2 consumed by laccase is from air and the sole byproduct of the reaction is water. During the reaction process, 10 mM NAD + was transformed from NADH in less than 2 h under the condition of 0.5 U NADH dehydrogenase, 0.5 U laccase, 0.1 mM potassium ferricyanide at pH 5.6, 30 °C Conclusion The bi-enzyme system employed the NADH-ferricyanide dehydrogenase and laccase as catalysts, and potassium ferricyanide as redox mediator, is a promising alternative for NAD + regeneration.