Regiodivergent Baeyer-Villiger oxidation of fused ketones by recombinant whole-cell biocatalysts.

Recombinant Escherichia coli cells expressing monooxygenases of different bacterial origin were evaluated in microbial Baeyer-Villiger oxidations of racemic fused ketones. During the enzymatic oxidation process, both the "normal" lactone generated by migration of the more-substituted carbon atom and/or the "abnormal" lactone resulting from migration of the less-substituted carbon atom can be formed. Depending on the nature of the Baeyer-Villiger monooxygenase, either a regiodivergent biooxygenation to both lactones in high optical purities was observed or essentially racemic "normal" rearrangement product was formed. The complementary behavior of enzymes was found to correlate with our previous observation of clustering of cycloketone-oxidizing proteins into two distinct clusters based on phylogenetic relationship and biocatalyst performance.