Biocatalytic Oxidation in Continuous Flow for the Generation of Carbohydrate Dialdehydes

Galactose Oxidase (GOase) has been used for the scalable and selective C-6′ oxidation of lactose, a waste material from the dairy industry. Generation of the 6′-oxo lactose was achieved with full conversion in batch mode at milligram scale, but further scale-up to gram quantities proved to be challenging because of requirements for high enzyme concentrations and limitation in oxygen cosubstrate availability. To overcome these issues, a continuous-flow system was developed for the bio-oxidation of lactose yielding multigram quantities of product. Using the variant GOase F2, terminal selective oxidations were also observed on a range of oligoglucosides such as maltose. The carbohydrate dialdehydes that were obtained by this highly selective oxidation were chemically further functionalized, establishing the biooxidation as a route to valorize cheap carbohydrates, including waste materials, for building blocks of polymers.