Purification and biochemical characterisation of human placental acid alpha-glucosidase

An acid alpha-glucosidase (EC 3.2.1.3) has been purified to electrophoretic homogeneity from the soluble fraction of the human term placenta. In the presence of SDS, two doublets of 79 and 67 kDa were seen in addition to other bands of extremely low intensity. Each of these bands was seen to cross-react with polyclonal antiserum raised to the purified enzyme, thus confirming the homogeneity of the preparation. The purified enzyme exhibited a broad substrate specificity. The kinetic data revealed the possible presence of multiple substrate binding sites. Chemical modification using group specific reagents indicated the presence of a carboxyl group and tryptophan at the active site. Based on these results a possible structure for the active site of the human term placental acid alpha-glucosidase has been proposed.