Continuous low-level supply or in situ generation of hydrogen peroxide (H₂O₂) is essential for the stability of unspecific peroxygenases, which are deemed ideal biocatalysts for the selective activation of C–H bonds. To envisage potential large scale applications of combined catalytic systems the reactions need to be simple, efficient and produce minimal by-products. We show that gold-palladium nanoparticles supported on TiO₂ or carbon have sufficient activity at ambient temperature and pressure to generate H₂O₂ from H₂ and O₂ and supply the oxidant to the engineered unspecific heme-thiolate peroxygenase PaDa-I. This tandem catalyst combination facilitates efficient oxidation of a range of C-H bonds to hydroxylated products in one reaction vessel with only water as a by-product under conditions that could be easily scaled.

Covering: up to end of June 2018 Baeyer–Villiger monooxygenases (BVMOs) are flavin-dependent enzymes that catalyse the oxidation of ketones and cyclic ketones to esters and lactones, respectively, by using molecular oxygen and NAD(P)H. BVMOs also catalyse sulfoxidations and N-oxidations. BVMOs are widely studied as attractive biocatalysts, but also catalyse key reactions in metabolic pathways of the organisms from which they are sourced. BVMOs are involved in the primary metabolism of atypical carbon sources, thereby conferring an evolutionary advantage to the host organism. In addition, BVMOs catalyse a plethora of diverse Baeyer–Villiger and heteroatom oxidations in the construction of complex secondary metabolites. These natural products often have attractive biological properties, such as anti-bacterial, anti-cancer and anti-proliferative activity, and can have clinical applications. In contrast, BVMOs are also involved in the synthesis of microbial toxins. This review will discuss the inherent roles of type I, type II and type O BVMOs in the metabolism of microorganisms.

Mild oxyfunctionalization reactions driven by hydrogen peroxide using cytochrome P450 monooxygenases with alternative heme environments.