Myoglobin-Catalyzed Efficient In Situ Regeneration of NAD(P)+ and Their Synthetic Biomimetic for Dehydrogenase-Mediated Oxidations

On the basis of its catalytic promiscuity, wild-type myoglobin (Mb) from horse heart was used for in situ regeneration of oxidized nicotinamide cofactors. Mb proved to be a versatile catalyst, since it was capable of efficient oxidation of both natural cofactors NAD(P)H and their synthetic biomimetic BNAH with H2O2. Mb-catalyzed oxidation of reduced nicotinamide cofactors was promoted significantly in the presence of mediators such as scopoletin and acetaminophen. A cofactor total turnover number (TTN) up to 50 000 was obtained in glucose dehydrogenase-catalyzed oxidation of glucose coupled with the Mb/scopoletin regeneration system. Approximately 4 mol of glucose was enzymatically oxidized with 1 mol of H2O2. Besides, this system is well compatible with various dehydrogenases. The desired products were afforded with yields of 93-97% in dehydrogenase-catalyzed oxidations. A radical mechanism was proposed for Mb/scopoletin-catalyzed recycling of NAD(P)(+). The Mb-based recycling system may create opportunities for academic and industrial biocatalytic applications.