By 30%-60% (NH4)2SO4 fractional precipitation, anion-exchange chromatography on DEAE-Sepharose CL-6B, gel filtration on Sephacryl S-200 and anion-exchange chromatography on Waters AP-1 column (ProteinPM-Pak DEAE 15HR), a proteinase which can inactivate soybean trypsin inhibitor (STI) was purified from mung bean (Vigna rabiata (L.) Wilczek) sprouts. Its molecular weight was estimated to be 29.8 kD by SDS-PAGE, and its Km and Vmax for STI were 769.2N-α-benzoyl-L-arginine ethyl ester BAEE/mL and 115.3 BAEE·mL-1·min-1 respectively. This proteinase was stable at temperatures lower than 50℃ and pH 6.5-8.5, and 90.91% STI activity of defatted soybean powder was inactivated by this preparation, with proteolytic activity 5 000 BAEE/mL at 50℃ and pH 8.0 in 4 h.
萌发绿豆种子中的一种大豆胰蛋白酶抑制剂钝化酶
陈中 杨晓泉 赵谋明
（华南理工大学食品与生物工程学院，广州510641）
摘要: 通过30％－60％（NH4）2SO4分级沉淀、DEAE－Sepharose CL-6B离子交换层析、Sephacryl S-200凝胶过滤层析和Waters AP-1离子交换层析，从萌发的绿豆（Vigna rabiata(L.)Wilczek）种子中分离纯化出一种可降解大豆胰蛋白酶抑制剂（STI)的蛋白酶。SDS－PAGE测定该酶的分子量为29.8kD。该酶催化降解STI的Km值为769.2BAEE/mL，Vmax为115.3BAEE·min^-1。该酶在50℃、pH8．0，相对酶活力5000BAEE／mL和4h的反应时可将脱脂大豆粉中的STI活性钝化90.91%。该酶在温度低于50℃及pH6.5-8.5时能保持其活性。
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