Recombinant human acid alpha-glucosidase generated in bacteria: antigenic, but enzymatically inactive

Genetic deficiency of acid alpha-glucosidase (GAA) results in glycogen storage disease type II. To investigate whether we could generate a functional recombinant human GAA protein for future enzyme replacement therapy, we subcloned the GAA cDNA into the bacterial expression plasmid pMaI and analyzed the recombinant protein produced. This nonglycosylated recombinant human GAA was found to be antigenic by reacting with polyclonal rabbit antibody to human placental GAA using ELISA and Western techniques. However, the protein was not enzymatically active, suggesting that glycosylation may play a role in enzymatic function.