Control of stereoselectivity of benzylic hydroxylation catalysed by wild-type cytochrome P450BM3 using decoy molecules

The hydroxylation of non-native substrates catalysed by wild-type P450BM3 is reported, wherein “decoy molecules”, i.e., native substrate mimics, controlled the stereoselectivity of hydroxylation reactions. We employed decoy molecules with diverse structures, resulting in either a significant improvement in enantioselectivity or clear inversion of stereoselectivity in the benzylic hydroxylation of alkylbenzenes and cycloalkylbenzenes. For example, supplementation of wild-type P450BM3 with 5-cyclohexylvaleric acid-L-phenylalanine (5CHVA-Phe) and Z-proline-L-phenylalanine yielded 53% (R) ee and 56% (S) ee for indane hydroxylation, respectively, although 16% (S) ee was still observed in the absence of any additives. Moreover, we performed a successful crystal structure analysis of 5CHVA-L-tryptophan-bound P450BM3 at 2.00 Å, which suggests that the changes in selectivity observed were caused by conformational changes in the enzyme induced by binding of the decoy molecules.