Carbohydrate content of acid alpha-glucosidase (gamma-amylase) from human liver

The presence of carbohydrates in homogeneous preparations of human liver acid alpha-glucosidase has been established and the carbohydrate content of the enzyme determined. The enzyme was purified with the specific purpose of removing all low-molecular-weight carbohydrates. It was specifically adsorbed on Concanavalin A-Sepharose, eluted with methyl-alpha-D-mannopyranoside and gave a positive reaction with the phenol-sulphuric acid reagent. These facts taken together provide evidence that the enzyme studied is a glycoprotein. The analysis of the carbohydrate content of human liver acid alpha-glucosidase showed that there were 8.3 glucosamine, 13.2 mannose and possibly 3--4 glucose residues per molecule of the enzyme with a molecular weight of 98,000.