BINDING OF HUMAN LIVER HYDROLASES BY IMMOBILIZED LECTINS

The binding of 22 human liver hydrolase activities by immobilized lectins of six different carbohydrate specificities, namely α-D-mannose (glucose), D-N-acetylglucosamine, D-N-acetylglucosamine, D-N-acetylgalactosamine, L-fucose, α-D-galactose, and β-D-galactose were examined. Differences in binding among these enzymes and within specific enzymes were observed. For example, the neutral forms of α-mannosidase and β-xylosidase were bound by the Ulex europaeus lectin I (specific for L-fucose), whereas the acidic forms were not. Bandierea simplicifolia lectin (specific for α-galactose) bound 65% of β-glucuronidase activity; recycling experiments demonstrated complete binding of the enzyme that had been eluted with the competitor D-galactose and no binding of the fraction that was not initially bound. These results suggested the presence of two forms of this enzyme. Similar data were obtained for acidic β-galctosidase activity. These experiments may provide the basis for the expanded use of immobilized lectins for purification and characterization of hydrolases and other glycoproteins.