Heterogeneity of pig lysosomal acid alpha-glucosidase. Affinity to Sephacryl S-200 gel and tissue distribution.

Acid alpha-glucosidase purified from pig liver showed heterogeneity in its affinity to Sephacryl S-200 gel. Acid alpha-glucosidase was separated into two fractions (S1 and S2) by Sephacryl S-200 affinity chromatography. Each fraction contained components at apparent 76 kDa and 67 kDa on SDS/PAGE. The amount of S1 fraction was about 1.3 times that of the S2 fraction. In the kidney the ratio of S1 to S2 fraction was similar to that in the liver. However, the heart contained 1.3 times as much S2 fraction as S1 fraction. The spleen acid alpha-glucosidase consisted mainly of S1 fraction, containing only a 76 kDa component. Immunohistochemically, acid alpha-glucosidase was demonstrated in the macrophages of the spleen. Thus the 76 kDa component in the spleen must come mainly from the macrophages. Lectin-binding analysis was carried out on the components present in the S1 and S2 fractions after electrophoresis and transfer to nitrocellulose sheets. Slight differences in binding observed suggest differences in the structure of the sugar side chains.