초록
Glycosidase activities were tested from the grape berries, Vitis labruscana B. Takasumi. Among various glycosidases, $\alpha$-D-galactosidase was found to be the most active in the flesh and other glycosidases were considerably active in the order of the following: $\alpha$-D-mannosidase>$\alpha$-D-glucosidase>$\beta$-D-glucosidase>$\beta$-D-galactosidase. In the seeds, $\alpha$-D-glucosidase activity was the highest and other glycosidases such as $\alpha$-D-galactosidase, $\beta$-D-glucosidase, and $\beta$-D-galactosidase were still significantly active. The $\alpha$-D-galactosidase in the grape flesh was purified over 83-folds through salting-out with $(NH_4)_2SO_4$ and a series of chromatographies employing Sephadex G-50, Octyl-Sepharose, Q-Sepha- rose, and Biogel P-100. The enzyme was a monomer of 45 kDs as determined through SDS-PAGE and Sephacryl S-200 chromatography. The purified enzyme showed a preference of $\alpha$-D-galactose to $\beta$-D-galactose as a substrate about 5.4 times. Sulfhydryl specific reagents such as N-ethylmaleimide and iodoacetamide significantly inhibited the enzyme activity to the extents of 48 and 52% of its initial activity, respectively. The optimumpH range of $\alpha$-D-galactosidase was around 6.5-7.0. The enzyme activity increased by 46% in the presence of 1mM $Fe^{2+}$.