Enzymatic Epoxidation of Long-Chain Terminal Alkenes by Fungal Peroxygenases.

Terminal alkenes are among the most attractive starting materials for the synthesis of epoxides, which are essential and versatile intermediate building blocks for the pharmaceutical, flavoring, and polymer industries. Previous research on alkene epoxidation has focused on the use of several oxidizing agents and/or different enzymes, including cytochrome P450 monooxygenases, as well as microbial whole-cell catalysts that have several drawbacks. Alternatively, we explored the ability of unspecific peroxygenases (UPOs) to selectively epoxidize terminal alkenes. UPOs are attractive biocatalysts because they are robust extracellular enzymes and only require H 2 O 2 as cosubstrate. Here, we show how several UPOs, such as those from Cyclocybe ( Agrocybe ) aegerita ( Aae UPO), Marasmius rotula ( Mro UPO), Coprinopsis cinerea (r Cci UPO), Humicola insolens (r Hin UPO), and Daldinia caldariorum (r Dca UPO), are able to catalyze the epoxidation of long-chain terminal alkenes (from C 12:1 to C 20:1 ) after an initial optimization of several reaction parameters (cosolvent, cosubstrate, and pH). In addition to terminal epoxides, alkenols and other hydroxylated derivatives of the alkenes were formed. Although all UPOs were able to convert and epoxidize the alkenes, notable differences were observed between them, with r Cci UPO being responsible for the highest substrate turnover and Mro UPO being the most selective with respect to terminal epoxidation. The potential of peroxygenases for epoxidizing long-chain terminal alkenes represents an interesting and green alternative to the existing synthesis technologies.