Regio‐ and stereo‐selective 1β‐hydroxylation of lithocholic acid by cytochrome P450 BM3 mutants

Abstract Regio‐ and stereo‐selective hydroxylation of bile acids is a valuable reaction but often lacks suitable catalysts. In the research, semi‐rational design in protein engineering techniques had been applied on cytochrome P450 monooxygenase CYP102A1 (P450 BM3) from Bacillus megaterium , and a mutation library had been set up for the 1β‐hydroxylation of lithocholic acid (LCA) to produce 1β‐OH‐LCA. After four rounds of mutagenesis, a key residue at W72 was identified to regulate the regio‐ and stereo‐selectivity at C1 of LCA. A quadruple variant (G87A/W72T/A74L/L181M) was identified to reach 99.4% selectivity of 1β‐hydroxylation and substrate conversion of 68.1% resulting in a 21.5‐fold higher level of 1β‐OH‐LCA production than the template LG‐23. Molecular docking indicated that introducing hydrogen bonds at W72 was responsible for enhancing selectivity and catalytic activity, which gave some insights into the structure‐based understanding of Csp 3 ‐H activation by the developed P450 BM3 mutants.