Efficient hydroxylation of cycloalkanes by co-addition of decoy molecules to variants of the cytochrome P450 CYP102A1.

The wild-type cytochrome P450 (CYP) monooxygenase enzyme CYP102A1 (P450Bm3) has low activity for cycloalkane oxidation. The oxidation of these substrates by variants of this enzyme in combination with perfluorinated decoy molecules (PFCs) was investigated to improve productivity. The use of rate accelerating variants, which have mutations located outside of the substrate binding pocket as well as an active site variant of CYP102A1 (A74G/F87V/L188Q) all enhanced cycloalkane oxidation (C5 to C10). The addition of the decoy molecules to the wild-type and the rate accelerating mutants of CYP102A1 boosted the substrate oxidation rates even further. However, the levels of cycloalkanol product decreased with the larger alkanes when the decoy molecules were used with the variant A74G/F87V/L188Q, which contained mutations within the substrate binding pocket. For the majority of the enzymes and PFC decoy molecule combinations the highest levels of oxidation were obtained with cyclooctane. When larger second generation decoy molecules, based on modified amino acids were utilised there was a significant improvement in the oxidation of the smaller cycloalkanes by the wild-type enzyme and one other variant. This resulted in significant improvements in biocatalytic oxidation of cyclopentane and cyclohexane. However, the use of these optimised decoy molecules did not significantly improve cycloalkane oxidation over the fluorinated fatty acid derivatives when combined with the best rate accelerating variant, R47L/Y51F/I401P. Overall our approach enabled the cycloalkanes to be oxidised 300- to 8000-fold more efficiently than the wild-type enzyme at product formation rates in excess of 500 and up to 1700 nmol·nmol-CYP·min.