牛乳乳铁蛋白的纯化及热处理对其分子特性的影响  

Purification and Effect of Heat Treatment on Molecular Characteristics of Lactoferrin

作　　者：刘猛[1] 杜明[1] 孔莹莹[1] 张兰威[1] 

机构地区：[1]哈尔滨工业大学食品科学与工程学院,黑龙江哈尔滨150090

出　　处：《食品科学技术学报》2013年第2期26-30,共5页Journal of Food Science and Technology

基　　金：国家自然科学基金资助项目(31101316);教育部新世纪优秀人才计划项目(NCET-11-0796);黑龙江省博士后研究人员落户黑龙江科研启动金;中央高校基本科研业务金项目(HIT.BRETⅢ.201231)

摘　　要：乳铁蛋白是牛乳中一种重要的碱性蛋白,相关基础与应用研究已引起广泛关注.首先以鲜牛乳为原料,通过脱脂、除酪蛋白、SP Sepharose Big Bead阳离子交换层析及Superdex 200凝胶层析组合方法、超滤浓缩等过程,最终获得乳铁蛋白样品,纯度约为94.71%.进而,研究了热处理对乳铁蛋白的分子特性的影响.通过差示扫描量热法测定得到的乳铁蛋白热变性温度为73.1℃.通过圆二色谱研究了热处理(63℃30 min;72～75℃20 s;85℃10 min;95℃10 min)对乳铁蛋白二级结构的影响,结果表明,随着处理温度的增加,乳铁蛋白的α-螺旋构象逐步转变为β-折叠构象,蛋白质分子排列更为有序,分子的结构变得更加紧密,蛋白质分子发生变性趋势明显增加.Lactoferrin is a kind of key basic proteins in bovine milk, which has attracted more and more research attentions. In the present study, lactoferrin was isolated from fresh bovine milk by defatting and casein-removing treatments, subsequently purified by SP Sepharose Big Bead ion exchange chromatography, Superdex 200 gel chromatography, and ultrafihration The purified form of lactoferrin was obtained with the purity of 94.71%. The denaturation temperature of lactoferrin was determined to be 73.1 ℃ by differential scanning calorimetry. Circular dichroism studies on the influence of heat treatment （63 ℃ 30 min,72 -75 ℃ 20 s,85 ℃ 10 min,95 ℃ 10 min） on the secondary structure of lactoferrin showed that, the α-helix conformation of lactoferrin was gradually transformed to β-sheet conformation with the increase of the treatment temperature, indicating that the protein molecules became better ordered and more compact with significantly increased trends of protein denaturation.

关 键 词：牛乳 乳铁蛋白 纯化 热处理 圆二色性 

分 类 号：TS252.1[轻工技术与工程—农产品加工及贮藏工程]