Kudou S, Tsuizaki I, Uchida T, Okubo K
Kanesa Miso Co., Ltd., Aomori, Japan.
Agric Biol Chem. 1991 Jan;55(1):31-6.
We had investigated the enzymatic hydrolysis of soybean saponins and selected soybean saponin hydrolase from Aspergillus oryzae KO-2. We attempted purification of this enzyme for further characterization. This enzyme was purified 1500-fold using ammonium sulfate fractionation and Sephadex G-200 gel filtrations. The enzyme was electrophoretically homogeneous and a glycoprotein by PAS staining. By gel filtration, the molecular weight of enzyme was 158,000 and SDS-PAGE showed the enzyme to have a tetrameric structure composed of heterogeneous subunits of 35,000 and 45,000. The enzyme activity was stable at temperatures below 40 degrees C and stable from pH 5.0 to 8.0. The optimum pH was pH 4.5 to 5.0 and the optimum temperature was 50 degrees C. The Km and Vmax for soyasaponin I were 0.48 mM and 9.8 mumol/hr mg protein, respectively. After hydrolysis with the enzyme, soyasapogenol B and alpha-L-rhamnopyranosyl (1----2)-beta-D-galactopyranosyl (1----2)-D-glucuronopyranoside were released from soyasaponin I.
我们研究了大豆皂苷的酶促水解，并从米曲霉KO-2中筛选出大豆皂苷水解酶。我们尝试对该酶进行纯化以进一步表征。通过硫酸铵分级分离和Sephadex G-200凝胶过滤，该酶被纯化了1500倍。该酶在电泳上是均一的，经PAS染色为糖蛋白。通过凝胶过滤，该酶的分子量为158,000，SDS-PAGE显示该酶具有由35,000和45,000的异源亚基组成的四聚体结构。该酶活性在40℃以下温度稳定，在pH 5.0至8.0之间稳定。最适pH为4.5至5.0，最适温度为50℃。大豆皂苷I的Km和Vmax分别为0.48 mM和9.8 μmol/hr mg蛋白。用该酶水解后，大豆皂苷元B和α-L-鼠李吡喃糖基(1→2)-β-D-吡喃半乳糖基(1→2)-D-葡萄糖醛酸吡喃糖苷从大豆皂苷I中释放出来。
