A tailor-made, self-sufficient and recyclable monooxygenase catalyst based on coimmobilized cytochrome P450 BM3 and glucose dehydrogenase

Cytochrome P450 monooxygenases (P450s) promote hydroxylations in a broad variety of substrates. Their prowess in C–H bond functionalization renders P450s promising catalysts for organic synthesis. However, operating P450 reactions involve complex management of the main substrates, O₂ and nicotinamide adenine dinucleotide phosphate (NAD(P)H) reducing equivalents against an overall background of low operational stability. Whole-cell biocatalysis, although often used, offers no general solution to these problems. Herein, we present the design of a tailor-made, self-sufficient, operationally stabilized and recyclable P450 catalyst on porous solid support. Using enzymes as fusion proteins with the polycationic binding module Z_basic2, the P450s BM3 (from Bacillus megaterium) was coimmobilized with glucose dehydrogenase (type IV; from B. megaterium) on anionic sulfopropyl-activated carrier (ReliSorb SP). Immobilization via Z_basic2 enabled each enzyme to be loaded in controllable amount, thus maximizing the relative portion of the rate limiting P450 BM3 (up to 19.5 U/g_carrier) in total enzyme immobilized. Using lauric acid as a representative P450 substrate that is poorly accessible to whole-cell catalysts, we demonstrate complete hydroxylation at low catalyst loading (≤0.1 mol%) and efficient electron coupling (74%), inside of the catalyst particle, to the regeneration of NADPH from glucose (27 cycles) was achieved. The immobilized P450 BM3 showed a total turnover number of ∼18,000, thus allowing active catalyst to be recycled up to 20 times. This study therefore supports the idea of practical heterogeneous catalysis by P450s systems immobilized on solid support.