Exploring PTDH-P450BM3 variants for the synthesis of drug metabolites

The conversion of a series of pharmaceutical compounds was examined with three variants of cytochrome P450BM3 fused to phosphite dehydrogenase to enable cofactor recycling. Conditions for enzyme production were optimized and the purified PTDH-P450BM3 variants were tested against 32 commercial drugs using rapid UPLC-MS analysis. The sets of mutations (R47L/F87V/L188Q and R47L/F87V/L188Q/E267V/G415S) improved conversion for all compounds and a variety of products were detected. Product analysis showed that reaction types included C-hydroxylation, N-oxidation, demethylation, and aromatization. Interestingly, enzymatic aromatization could occur independent of the addition of reducing coenzyme. These results identified new conversions catalyzed by P450BM3 variants and show that a small set of mutations in the oxygenase domain can broaden both substrate range and reaction type.