pH对中国人乳β-酪蛋白二级结构的圆二色和拉曼特征影响

发布时间：2018-05-05 23:26

本文选题：圆二色光谱 + 拉曼光谱　；参考：《光谱学与光谱分析》2015年02期

【摘要】：人乳中β-酪蛋白为婴儿的快速生长提供了最适宜的氨基酸、钙磷等。以往的研究均是对牛乳的β-酪蛋白二级结构进行分析,而牛乳β-酪蛋白对婴儿配方乳的指导意义不如人乳β-酪蛋白,且人乳β-酪蛋白难以获得合适的蛋白晶体,其三级结构不清楚。为了获得中国人乳β-酪蛋白二级结构的相关基础信息,采用圆二色光谱(CD)法和拉曼光谱(Raman)法分析在不同pH条件下其二级结构的变化,结果表明:pH值的改变能够诱导中国人乳β-酪蛋白二级结构的改变,CD分析表明β-酪蛋白各部分的二级结构分别是:0.5%~2%α-螺旋,16%~18%β-折叠,30%~34%β-转角,49%~51%无规则卷曲;随着pH的增加,部分结构发生了变化,α-螺旋在pH 8处含量增加,而在pH 10处含量减小。拉曼光谱分析表明:β-酪蛋白在酰胺I的特征峰在1 662cm-1处,分析出β-酪蛋白的无规则卷曲含量较高。同时,根据I850/I830的比值计算出β-酪蛋白的酪氨酸残基趋向于"暴露式"。圆二色光谱和拉曼光谱都证明了人乳β-酪蛋白二级结构中无规则卷曲的含量最高,而β-折叠和β-转角含量保持相对的稳定。并且,在pH 8条件下,α-螺旋含量高于在其他pH条件下的含量。
[Abstract]:尾-casein in human milk provides the most suitable amino acids, calcium and phosphorus for the rapid growth of infants. Previous studies have analyzed the secondary structure of 尾 -casein in milk, and the significance of 尾 -casein in guiding infant formula milk is not as good as human milk 尾 -casein, and it is difficult for human milk 尾 -casein to obtain suitable protein crystal. Its tertiary structure is unclear. In order to obtain the basic information about the secondary structure of Chinese milk 尾 -casein, circular dichroism (CD) method and Raman spectroscopy (Raman) method were used to analyze the changes of the secondary structure under different pH conditions. The results showed that the change of pH value could induce the change of the secondary structure of 尾 -casein in Chinese milk. CD analysis showed that the secondary structure of each part of 尾 -casein was 0.5% ~ 2% 伪 -helix 16% and 18% 尾 -fold 30% 尾 -fold 30%. The content of 伪 -helix increased at pH 8 and decreased at pH 10. Raman spectroscopy showed that the characteristic peak of 尾 -casein was at 1 662cm-1, and the irregular crimp content of 尾 -casein was higher. At the same time, according to the ratio of I850/I830, the tyrosine residues of 尾-casein tend to be exposed. Circular dichroism and Raman spectra showed that the content of irregular curls in the secondary structure of human milk 尾 -casein was the highest, while the contents of 尾 -fold and 尾 -rotation remained relatively stable. Moreover, the 伪 -helix content at pH 8 was higher than that at other pH conditions.
【作者单位】：国家乳业工程技术研究中心黑龙江省乳品工业技术开发中心;东北农业大学食品学院乳品科学教育部重点实验室(东北农业大学);食品安全与营养协同创新中心;
【基金】：国家“十二五”科技支撑计划课题(2011BAD09B03) 东北农业大学博士启动基金项目(2010RCB75)资助
【分类号】：O657.3;R155.5

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