Exploring Unspecific Peroxygenase Selectivity with Diverse Hydrocarbon Substrates

Unspecific peroxygenases (UPOs) are enzymes capable of oxidising various substrates using hydrogen peroxide as a co-substrate. UPOs have gained interest due to their broad substrate specificity, which includes relatively inexpensive precursors for valuable compounds, such as pharmaceuticals and chemical building blocks. In this study, the activity of a panel of 30 UPOs toward aliphatic and aromatic hydrocarbons was screened to assess variation in substrate selectivity. Most of the studied UPOs were able to oxidise the substrates efficiently, producing 2-5 products via hydrogen abstraction or epoxidation. Overall trends were observed, such as the preference for aromatic oxidation over benzylic hydroxylation in the case of toluene, while the opposite was observed with ethylbenzene. Different UPOs could also be categorized based on their reaction profiles with all substrates. Selectivity was generally low, as oxyfunctionalization reactions led to mixtures of products that were further oxidised. However, styrene and cyclohexene were converted rather exclusively to their epoxide products. The results indicate that the substrate scope of UPOs includes various types of hydrocarbons, which are oxidised depending on the individual enzyme's active site. They also hold potential for producing chemicals for industrial purposes more sustainably, but their selectivity should first be improved through protein engineering.