Oxidation is one of the most important processes used by the chemical industry. However, many of the methods that are used pose significant sustainability and environmental issues. Biocatalytic oxidation offers an alternative to these methods, with a now significant enzymatic oxidation toolbox on offer to chemists. Oxidases are one of these options, and as they only depend on molecular oxygen as a terminal oxidant offer perfect atom economy alongside the selectivity benefits afforded by enzymes. This review will focus on examples of oxidase biocatalysts that have been used for the sustainable production of important molecules and highlight some important processes that have been significantly improved through the use of oxidases. It will also consider emerging classes of oxidases, and how they might fit in a future biorefinery approach for the sustainable production of important chemicals.

b-Mannosides are ubiquitous in nature, with diverse roles in many biological processes. Notably, Manb1,4GlcNAc a constituent of the core N-glycan in eukaryotes, was recently identified as a STING immune pathway activator, highlighting its potential for use in immunotherapy. Despite their biological significance, the synthesis of b-mannosidic linkages remains one of the major challenges in glycoscience. Here we present a chemoenzymatic strategy that affords a series of novel unnatural Manb1,4GlcNAc analogues using the b-1,4-d-mannosyl-N-acetyl-d-glucosamine phosphorylase, BT1033. We show that the presence of fluorine in the GlcNAc acceptor facilitates the formation of longer -mannan-like glycans. We also pioneer a reverse thiophosphorylase enzymatic activity, favouring the synthesis of longer glycans by catalysing the formation of a phosphorylysis-stable thioglycoside linkage, an approach that may be generally applicable to other phosphorylases.