Hydrogen-fueled CO reduction using oxygen-tolerant oxidoreductases.

Hydrogen gas obtained from cheap or sustainable sources has been investigated as an alternative to fossil fuels. By using hydrogenase (Hase) and formate dehydrogenase (FDH), H and CO gases can be converted to formate, which can be conveniently stored and transported. However, developing an enzymatic process that converts H and CO obtained from cheap sources into formate is challenging because even a very small amount of O included in the cheap sources damages most Hases and FDHs. In order to overcome this limitation, we investigated a pair of oxygen-tolerant Hase and FDH. We achieved the cascade reaction between Hase from H16 (ReSH) and FDH from (RcFDH) to convert H and CO to formate using regeneration of NAD/NADH in the presence of O.