Recombinant α-Glucosidase from Aspergillus niger. Overexpression by Emericella nidulans, Purification and Characterization

Abstract

An expression plasmid containing the aglA gene encoding Aspergillus niger GN-3 α-glucosidase was constructed and inserted into Emericella nidulans JCM10259. The transformant secreted about 61 mg/L of the recombinant α-glucosidase into its culture medium. The recombinant enzyme was purified from the culture filtrate through ammonium sulfate precipitation and three chromatographic steps. It was confirmed that, like wild-type A. niger GN-3 α-glucosidase, the purified recombinant enzyme consisted of two subunits. Although the molecular mass of the recombinant enzyme was slightly smaller than that of wild-type A. niger α-glucosidase (attributed to differences in glycosylation), the pH optima and substrate specificities of the wild-type and recombinant enzymes were comparable.