Purification and Properties of α-Glucosidases of the Honey BeeApis melliferaL.

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Abstract
Two kinds of α-glucosidase (I and II) were isolated from honey bees by salting-out chromatography with ammonium sulfate. α-Glucosidase I was purified by chromatography on CM-cellulose and gel filtration on Sephadex G-100. α-Glucosidase II was purified by chromatographies on DEAE- and CM-cellulose and by gel filtration on Bio-Gel P-150. Both enzyme preparations were homogeneous in tests by disc electrophoresis. The molecular weight of α-glucosidases I and II was estimated to be approximately 9.8 × 104 and 7.6 × 104, respectively, by SDS disc electrophoresis. α-Glucosidases I and II were glycoproteins whose carbohydrate moieties were about 25% and 15%, respectively. Their pH optima were 5.0. Both α-glucosidases readily hydrolyzed phenyl-α-glucoside, sucrose and maltose. α-Glucosidase I showed no activity toward isomaltose and soluble starch, but α-glucosidase II showed relatively high activity toward isomaltose and slight activity toward soluble starch.