Efficient Bi-enzymatic synthesis of aldonic acids

Abstract

Aldonic acids have already found many applications in food, pharmaceutical, and cosmetics industries and there are many new ones likely to come. One of the limiting factors, which stalls further research and uses of this broad class of sugar acids, is a lack of efficient and environmentally friendly production methods. Here we report a novel bi-enzymatic thionine-mediated PQQ-dependent glucose dehydrogenase and heme peroxidase system that allows efficient production of aldonic acids. Structurally diverse aldoses, including mono-, di-, and oligosaccharides, can be oxidized this way to the corresponding aldonic acids. The reaction proceeds under mild conditions – water solution and ambient temperature. Due to the total turnover number of PQQ-dependent dehydrogenase reaching 3.5 × 10⁶ (for lactose), the developed method is very efficient. This allows a space–time yield up to 11 g (L h)⁻¹ (for xylose), making the overall process industrially attractive.