Transglucosylation of ascorbic acid to ascorbic acid 2‐glucoside by a truncated version of α‐glucosidase from Aspergillus niger

A truncated version of α-glucosidase gene (AglA) from Aspergillus niger, named as AglA-t in this study, was expressed in Pichia pastoris, and the enzyme was purified and characterized. Phylogenetic analysis demonstrated that AglA was most close to the α-glucosidase from Aureobasidium pullulans. In our research, we found that AglA-t could promote the formation of 2-O-α-d-glucopyranosyl-l-ascorbic acid (AA-2G) under optimized conditions. The major product was detected by high performance liquid chromatography, and confirmed to be by LC-MS analysis. The optimum pH and temperature for the transglucosylation reaction were 6.0°C and 40°C, respectively. The yield of AA-2G was significantly enhanced by metal ions Fe3+, Zn2+, Mg2+, and Al3+, and organic solvent isopropanol. Practical applications Here, we described the biochemical properties of recombinant enzyme AglA-t which was used to promote AA-2G production. The high yield of AglA-t in Pichia pastoris makes it potentially useful for large-scale industrial application. Meanwhile, the chemically stable AA-2G, enzymatic product of AglA-t, could be applied to a wide range of fields due to its antioxidative ability, iron absorption, and carnitine synthesis. AA-2G plays an important role in maintaining skin elasticity and repairing damaged skin. Therefore, AA-2G could be used as a primary skin care ingredient in commercial cosmetics. In addition, AA-2G has great potential in human food and medical industries. In the animal husbandry and aquaculture fields, AA-2G is also widely added to forage as an important nutrition component. Taken together, the characterization of AglA-t in our research provides an alternative way for mass production of AA-2G which could be used for a variety of commercial applications.