Developmental study of α‐glucosidases in japanese quails with acid maltase deficiency

Abstract

In Japanese quails with late-onset acid maltase deficiency (AMD), the activity of acid α-glucosidase was severely reduced to approximately 16% of the normal level from an embryonic age. The kinetic characteristics and inhibition by Zn indicated that the residual activity was responsible for the intrinsic activity of acid α-glucosidase. However, in affected embryos, the glycogen content and other lysosomal enzyme activities were normal, despite the low acid α-glucosidase activity. In a separate study, we found the existence of two age-dependent neutral α-glucosidases— “embryonic” and “adult” α-glucosidases. In affected quails, the transition from the embryonic neutral α-glucosidase to the adult type was not influenced by the disease. The activity toward maltose and glycogen of the embryonic neutral α-glucosidase may explain the normal glycogen content in the affected embryos.