突变微小毛霉天冬氨酸蛋白酶的纯化及性质研究.doc

突变微小毛霉天冬氨酸蛋白酶的纯化及性质研究突变微小毛霉天冬氨酸蛋白酶的纯化及性质研究农产食品科技2011,5(1):35,43uhuralFoodProductsScienceandTechnolPurificationandCharacterizatiOnofaMutatedFungalAsparticProtejnasefrOmMucorPusillusLIYu—qiu,WANGJing—hui,LITie—zhu,ZHENGLi,ZHANGLi,LIZhou一?nYANGZhen-nai(-foodTechnology,JilinAcademyofAgriculturalSciences,Changchun130033,China;,JinlinUnivercity,Changchun130024,China)Abstract:Site——(M),E13D,withdecreasedproteolyticactivitywasexpressedinPichiapastoris,—(—)—clottingactivity(MCA),Fe,CuandZn.),-—,mercialcoagulantcheese,exceptforlowersolublenitrogencontentandhighervalueofhardnessofmutantcheesethanthoseofthenon—,insomeextent,coulddecreasehydrolysisofproteinduringripeningofcheese,:Asparticproteinase;MucorPusillusrennin;Mutation;Proteolyticactivity突变微小毛霉天冬氨酸蛋白酶的纯化及性质研究李玉秋,王景会,李铁柱1,郑丽,张莉,李倬林,杨贞耐1※(,长春130033;,长春130024)摘要:本文利用定点突变技术改造微小毛霉凝乳酶,将突变体(E13D)在毕赤酵母中表达,并对其进行纯化及性质研究,—,,温度为60?时酶活力最高,,+,Fe3+,Cu+和zn是酶的机制剂,",Mn和Mg+是酶的激活剂,,进行质构分析,同时与未突变酶及商品凝乳酶制作的干酪进行比对分析,发现除突变酶制作的干酪的可溶性氮含量低,硬度较其它两种干酪高外,其它性质没有明显的变化,这一结果某种程度上说明突变降低了酶的水解活性,使其在干酪成熟过程中抑制了干酪的过度水解,:天冬氨酸蛋白酶;微小毛霉凝乳酶;突变;水解活力中图分类号:Q937文献标识码:AAsparticproteasesthathavebeentraditionallyex-