Purification of glucoamylase by acarbose (BAY g-5421) affinity chromatography

Aspergillus niger and Rhizopus sp. glucoamylases were purified on an affinity chromatography column from commercially available, impure enzyme preparations. Up to 2 mg of glucoamylase protein was bound without leakage to a 1-ml affinity gel column (0.7 X 2.5 cm) possessing a covalently linked acarbose ligand (1 mg acarbose/g wet gel), and the bound enzyme was specifically released by irrigation of the column with a solution of maltose. A complete cycle of purification was accomplished in about 8 h. Glucoamylases were recovered, in more than 80% yield, free of alpha-amylase activity and possessing specific activities comparable to those of preparations obtained by time-consuming, multistep procedures involving several ion-exchange and hydrophobic column fractionations. Thus, acarbose affinity chromatography provides a general method for the rapid and efficient purification of the glucoamylases, and seems to be ideally suited for scale-up for the commercial purification of these enzymes.