超高压加工对菊糖果糖转移酶活力和构象的影响  

Effect of high pressure processing on the activity and conformation of inulin fructotransferase

作　　者：刘苗[1] 缪铭[1] 张涛[1] 张瑜[1] 江波[1] 

机构地区：[1]江南大学食品科学与技术国家重点实验室,江苏无锡214122

出　　处：《食品工业科技》2012年第23期49-52,56,共5页Science and Technology of Food Industry

基　　金：国家自然科学基金项目(20976073);江苏省自然基金创新学者攀登项目(BK2008003);江南大学食品科学与技术国家重点实验室目标导向资助项目(SKLF-MB-200804)

摘　　要：运用高效液相、荧光光谱和圆二色谱等方法研究了超高压加工对菊糖果糖转移酶活力和构象的影响,并分析了压力处理后的酶构象变化与酶活力大小之间的联系。结果表明:在80℃的条件下,与未处理组相比,经压力处理后的菊糖果糖转移酶活力随处理压力的升高及保压时间的延长先上升后下降,200MPa处理30min后相对酶活力达最高,为124.08%。菊糖果糖转移酶的内源荧光主要来自Trp残基,压力处理后酶的相对荧光强度和相对酶活力之间呈正线性相关,表明酶活力变化与压力处理后的Trp微环境的变化有关。圆二色谱的结果显示该酶仅在219nm有负峰,表明β-折叠是菊糖果糖转移酶的主要二级结构;219nm负峰的峰值大小与相对酶活力呈负线性相关,表明β-折叠是该酶发挥催化活力的结构基础。压力引起酶构象变化的研究为超高压加工提高酶活力的机理研究提供了一定的理论依据。Abstract：The effect of high pressure processing on the activity and conformation of inulin fructotransferase （IFTase） were investigated with high performance liquid chromatography,fluorescence spectroscopy and circular dichroism, moreover the relationship between enzyme conformation and enzyme activity after high pressure processing （HPP）was analyzed.The results showed enzyme activity after HPP increased firstly and then decreased with elevated pressure and extended dewell time at 80~C.The relative enzyme activity at 200MPa for 30min was the maximum and reached 124.08%.Trp residues contributed to intrinsic fluorescence of IFTase.The positive linear correlation between relative enzyme activity and relative fluorescence intensity indicated enzyme activity had some connection with microenvironment changed by pressure.The results of circular dichroism spectrum showed IFTase had only one characteristic negative peak at 219nm, moreover,the value of characteristic negative peak at 219rim and relative enzyme activity presented a negative linear correlation, which indicated β-sheet was the structural base of IFTase for catalytic activity.The study of conformation changed by pressure would provide some theoretical evidences about high pressure enhancement of enzyme.

关 键 词：超高压加工 菊糖果糖转移酶 活力 构象 

分 类 号：TS201.1[轻工技术与工程—食品科学]