An efficient catalytic route in haem peroxygenases mediated by O2/small-molecule reductant pairs for sustainable applications

Abstract

Haem peroxygenases are attractive biocatalysts for incorporating oxygen into organic molecules using H2O2. However, their practical applications are hindered by irreversible oxidative inactivation due to exogenous H2O2 usage. Here we present an alternative catalytic route in haem peroxygenases that uses O2 and small-molecule reductants such as ascorbic acid and dehydroascorbic acid (DHA) to drive reactions. Our experimental and computational studies indicated that DHAA, the hydrated form of DHA, serves as the key co-substrate that activates oxygen to generate the active oxyferryl haem compound I. We also demonstrate the broad applicability of this O2/reductant-dependent route across various haem peroxygenases, highlighting its biological significance for mono-oxygenase functionality. Importantly, this innovative route avoids the use of H2O2, thereby preventing the risk of irreversible enzyme inactivation. Finally, scaled-up reactions yielded chiral, value-added products with excellent productivity, underscoring the synthetic potential of this developed peroxygenase technology for sustainable chemical transformations. H2O2-dependent haem-peroxygenase-catalysed C–H bond oxyfunctionalization reactions have attracted much attention, but elevated concentrations of H2O2 are detrimental to the enzyme. Now, it is reported that this biocatalyst can operate via an alternative pathway using O2 and small-molecule reductants.