New insight into cofactor-free oxygenation from combined experimental and computational approaches

Molecular oxygen (O 2 ), in spite being a potentially strong oxidant, typically displays very poor reactivity with organic molecules. This is largely due to quantum chemical reasons as O 2 in its ground state is a diradical ( 3 O 2 ) whilst common organic substrates are in a singlet state. For this reason catalysis involving O 2 as a reactant is typically mediated by enzymes containing redox metal and/or organic co-factors. Cofactor-independent oxygenases (and oxidases) are therefore intriguing enzymes from a fundamental viewpoint. This review looks at recent advances that have been made in understanding of this class of intriguing biocatalysts highlighting the power of an inter-disciplinary approach involving structural biology, spectroscopy and theoretical methods.