Styrene Oxide Isomerase Catalyzed Meinwald Rearrangement Reaction: Discovery and Application in Single-Step and One-Pot Cascade Reactions

Styrene oxide isomerase (SOI) is a unique enzyme that catalyzes the Meinwald rearrangement of aryl epoxides into carbonyl compounds. In this review, we first summarize the scientific literature on the discovery and characterization of SOI's catalytic properties such as activity, substrate scope, and enantioselectivity. We then discuss its potential use for biocatalytic synthesis of aldehydes via single-step reactions using cell-free extracts and whole cells. Emerging technologies, such as the use of a stability tag, could enhance SOI biotransformation to reach product concentrations as high as 3.37 M. SOI has also been utilized in the engineering of biocatalytic cascades to produce valuable compounds such as chiral acids, alcohols, and amines from styrene. The best systems developed to date could reach product concentrations up to 100 mM. Additionally, recent efforts are focused on the metabolic engineering of the "styrene-derived " pathway involving SOI for microbial production of the aroma compound 2-phenylethanol (2-PE) from renewable sources such as L-phenylalanine, glucose, or glycerol, achieving concentrations up to 85 mM. The application of two-phase aqueous-organic systems in practical biotransformation reactions involving SOI is also notable. Finally, some perspectives and recommendations for future work are given to set the stage for development of SOI research toward applications in sustainable industrial biocatalysis.