酒曲发酵产凝乳酶及其酶学特性研究  

Production of a milk-clotting enzyme by Jiuqu starter fermentation and enzymatic properties of the enzyme

作　　者：赵爱梅[1] 赵笑[1] 段紫怡[1] 杨亚威[1] 滕军伟[1] 杨贞耐[1] 

机构地区：[1]北京工商大学食品质量与安全北京实验室,北京100048

出　　处：《中国乳品工业》2016年第2期16-21,共6页China Dairy Industry

基　　金：公益性行业(农业)科研专项(201303085);北京市百千万人才工程资助项目;国家自然科学基金项目(31371804)

摘　　要：通过研究不同因素对酒曲发酵产凝乳酶的影响,确定适宜的产酶条件:酒曲添加量3%(质量分数),发酵时间4 d,培养基初始p H值为6.0,摇床转速120 r/min。利用乙醇分级沉淀对酒曲发酵液中的凝乳酶进行提取,得到体积分数为70%乙醇沉淀蛋白具有凝乳活力;进一步进行Sephadex G-75凝胶过滤得到纯化凝乳酶,并经SDS-PAGE电泳分析,确定酶的分子量为35.6 ku。对此纯化酶的酶学特性的研究表明,该酶的最适温度为40℃,p H值为5.4时酶活性最高,Ca2+,Zn2+,Mg2+和K+对酶活性具有促进作用,其中以Ca2+和Zn2+促进作用较强;Cu2+,Na+和Fe2+对酶活性有抑制作用,其中Cu2+的作用较为显著。该凝乳酶在干酪加工中具有潜在的应用前景。By studying different factors influencing production of a milk-clotting enzyme by Jiuqu starter fermentation, the suitable conditions for producing the enzyme were determined： addition of Jiuqu starter 3%, fermentation time 4 days, initial medium pH6.0 and rotation speed 120rpm. The enzyme was extracted from the fermentation liquor by step-wise ethanol precipitation from 50% to 60%, 70% and 80%, and the 70% ethanol precipitate was found with milk-clotting activity. This active fraction was further purified by Sephadex G-75 gel filtra- tion and analyzed by SDS-PAGE electrophoresis, showing the molecular weight of the enzyme of 35.6 ku. The purified enzyme had an optimal reaction temperature of 40℃, and the optimal pH of 5.4. Ca2＋, Zn2＋, Mg2＋ and K＋ stimulated the enzyme activity, with Ca2＋ and Zn2＋ having stronger effect. Cu2＋, Na＋ and Fe2＋ had inhibitory effect on the enzyme activity, with Cu2＋ having stronger effect. The milk-clotting enzyme could be potentially used in cheese processing.

关 键 词：酒曲发酵 凝乳酶 提纯 酶学特性 

分 类 号：Q93-33[生物学—微生物学]