Radical fluorine transfer catalysed by an engineered nonheme iron enzyme

Abstract

Nonheme iron enzymes stand out as one of the most versatile biocatalysts for molecular functionalization. They facilitate a wide array of chemical transformations within biological processes, including hydroxylation, chlorination, epimerization, desaturation, cyclization, and more. Beyond their native biological functions, these enzymes possess substantial potential as powerful biocatalytic platforms for achieving abiological metal-catalyzed reactions, owing to their functional and structural diversity and high evolvability. To this end, our group has recently engineered a series of nonheme iron enzymes to employ non-natural radical-relay mechanisms for abiological radical transformations not previously known in biology. Notably, we have demonstrated that a nonheme iron enzyme, (S)-2-hydroxypropylphosphonate epoxidase from Streptomyces viridochromogenes (SvHppE), can be repurposed into an efficient and selective biocatalyst for radical fluorine transfer reactions. This marks the first known instance of a redox enzymatic process for C(sp³)F bond formation. This chapter outlines the detailed experimental protocol for engineering SvHPPE for fluorination reactions. Furthermore, the provided protocol could serve as a general guideline that might facilitate other engineering endeavors targeting nonheme iron enzymes for novel catalytic functions.

Keywords: directed evolution; fluorine transfer; nonheme iron enzyme.