章鱼消化道蛋白酶的分离纯化及性质

以章鱼加工下脚料消化道为原料，经硫酸铵沉淀、纤维素CM-52阳离子交换层析、DEAE-Sephadex A50阴离子交换层析、SDS-PAGE电泳等方法，从中提取纯化出一种蛋白酶电泳纯样品OP-I，并对其性质进行研究。结果表明：该酶分子质量为80.5kD。最适反应温度为55～60℃，pH值为7～9。金属蛋白酶抑制剂(EDTA)可以完全抑制该酶的活性。Mn2+、Ca2+、Mg2+对OP-I有激活作用，酶促动力学研究显示其米氏常数Km为0.33mmol/L，Vmax为66.7mg/(mL ·min)。

Extraction,Purification and Characterization of Protease from Digestive Tract of Octopus vulgaris

An electrophoretically pure protease,named as OP-I,was obtained from the digestive tract of Octopus vulgaris by ammonium sulfate precipitation,cellulose CM-52 cation-exchange chromatography,DEAE-Sephadex A50 anion-exchange chromatography and SDS-PAGE.Its properties were also characterized.The results showed that the molecular weight of the protease was 80.5 kD and its optimal reaction temperature and pH were 55-60 ℃ and 7-9,respectively.OP-I could be completely inhibited by EDTA,a metalloproteinase inhibitor.In contrast,Mn2+,Ca2+and Mg2+could stimulate OP-I activity.Moreover,the Kmof OP-I was 0.33 mmol/L and Vmax was 66.7 mg/(mL.min)as determined by kinetic studies.