Purification and Some Properties of α-Galactosidase from Tubers of Stachys affinis

Abstract

An α-galactosidase from tubers of S. affinis was purified about 130 fold by ammonium sulfate fractionation, chromatography on DEAE-cellulose and gel filtration on Sephadex G-75. The purified enzyme showed a single protein band on disc gel electrophoresis. The molecular weight of the enzyme was determined to be approximately 42, 000 by gel filtration and 44, 000 by SDS disc gel electrophoresis. The optimum reaction pH was 5.2. The enzyme hydrolyzed raffinose more rapidly than planteose. The activation energy of raffinose and planteose by the enzyme was estimated to be 7.89 and 11.4 kcal/mol, respectively. The enzyme activity was inhibited by various galactosides and structural analogs of n-galactose. Besides hydrolytic activity, the enzyme also catalyzed the transfer reaction of D-galactosyl residue from raffinose to methanol.