Abstract: 2-O-α-D-Glucopyranosyl-L-ascorbic acid (AA-2G) is an important
industrial derivative of L-ascorbic acid (AA), which has the distinct
advantages of non-reducibility, antioxidation, and reproducible
decomposition into L-ascorbic acid and glucose. Enzymatic synthesis is a
preferred method for AA-2G production over alternative chemical
synthesis owing to the regioselective glycosylation reaction.
α-Glucosidase, an enzyme classed into O- glycoside hydrolases, may be
used in glycosylation reactions to synthesize AA-2G. Here, one
α-glucosidase from Oryza sativa (rAGL) was recombinantly produced in
Pichia pastoris GS115 and used for biosynthesis of AA-2G with few
intermediates and byproducts. The extracellular rAGL reached 9.11 U/mL
after fed-batch cultivation for 102 h in a 5-L fermenter. The specific
activity of purified rAGL is 49.83 U/mg at 37 °C and pH 4.0. The optimal
temperature of rAGL was 65 °C, and it was stable below 55 °C. rAGL was
active over the range of pH 3.0–7.0, with the maximal activity at pH
4.0. Under the condition of 37 °C , pH 4.0, equimolar maltose and AA·Na,
8.7±0.4 g/L of AA-2G was synthesized by rAGL. These studies lay the
basis for the industrial application of recombinant α-glucosidase.
Keywords: α-Glucosidase; Oryza sativa; 2-O-α-D-glucopyranosyl-L-ascorbic
acid; Transglycosylation; Pichia pastoris
Extracellular expression and characterization of an α-glucosidase from Oryza sativa and its transglycosylation for synthesis of 2-O-α-D-glucopyranosyl-L-ascorbic acid