Comparative studies of two acid beta-galactosidases from rabbit and bovine kidney

Comparative studies of two acid beta-galactosidases from rabbit and bovine kidney have been made. The enzyme from rabbit (enzyme I) was purified 450-fold, and the activity of the bovine enzyme (enzyme II) was enriched 250-fold using conventional purification methods. Both purified enzymes were characterized and their properties were compared. Enzyme I showed a lower optimal temperature and was less pH stable. Enzyme II appeared to be homogeneous in charge, in contrast to the heterogeneity observed for enzyme I. Studies on their specificity using natural substrates showed that enzyme I hydrolyzed GM1, asialofetuin and lactose. However, enzyme II was only able to cleave galactose from the disaccharide. Some of the carbohydrates tested acted as activators for enzyme II, suggesting a mechanism of transglycosilation. Using lactose as substrate we confirmed the ability of enzyme II to transfer galactose residues to D-maltose and N-acetylgalactosamine.