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To elucidate enzymatic properties of α-galactosidase (EC 3, 2, 1, 22) from germinated soybean, changes in the enzyme activities and oligosaccharide contents during germination of soybean were determined. α-Galactosidase from germinated soybean was purified by ammonium sulfate fractionation, ion exchange chromatography and gel filtration. Their chemical and enzymatic properties was investigated. α-galactosidase activity of sobeam was maximized when it was germinated at 25℃ for 120 hour. Raffinose and stachyose in soybean were decomposed completely after 96 hours and 120 hours of germination, respectively. Soybean α-galactosidase was purified by 6.6 fold by ammonium sulfate fractionation, ion exchange chromatography on DEAE-Cellulose and Sephadex A-50, and gel filtration on Sephadex G-150. Its specific activity was 825 Units/㎎ protein and the yield was 2.5% of the total activity of crude extracts. The purified α-galactosidase of soybean was found to be homogeneous by polyacrylamide gel electrophoresis and by HPLC. Isoelectric point of soybean α-galactosidase was determined analytical isoelectric focusing to be pH 4.8. The soybean α-galactosidase was monomeric and its molecular weight was estimated to be 30,000 by SDS-PAGE. The optimal temperature and pH for the soybeam α-galactosidase activity were 40℃ and pH 6.0 and 75% of its activity was lost by heating at 60℃ for 10 min. The enzyme was appeared to have higher affinity to raffinose than to stachyose. The Km value of soybean enzyme was 5.3 mM for ρ-nitrophenyl-α-D-galactopyranoside and the activation energy on PNPG was calculated to be 13.02 K㎈ per mole.
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