人乳β-酪蛋白单体二级结构及胶束微观结构的研究

Micro-structure study of native β-casein micelles from human milk

以人乳β-酪蛋白为研究对象,使用圆二色光谱研究单体的二级结构后,借助透射电镜,扫描电镜,和共聚焦电子显微镜技术对β-酪蛋白胶束的微观结构进行观察。圆二色光谱结果表明,单体内部含有α螺旋1.33%,β-折叠17.3%,β-转角31.07%,无规则卷曲50.23%,二级结构相对较少,单体的内部构象疏松开放。共聚焦电子显微镜和扫描电镜结果表明胶束与胶束之间容易进一步缔合,形成直径大小不均的胶束团,透射电镜结果表明,人乳β-酪蛋白胶束最小直径约为20 nm,胶束内部呈现出疏松有孔的柔性结构,这种结构与β-酪蛋白胶束具有释放和保留某些免疫活性物质的功能相关。

β-casein is a kind of important nutrient in human milk,which has important functions such as combining,embedding,or transporting small molecules. This research studied on human β-casein,firstly,using circular dichroism spectra of the secondary structure of the monomer of humanβ-casein,then using transmission electron microscopy,scanning electron microscopy,electron microscopy and confocal techniques to observe microstructure ofβ-casein micelles.The results of circular dichroism spectra showed that there were 1.33% alfar helix,17.3% beta sheet,31.07% β- angle and 50.23% random coil in the internal helical monomers,and there was also fewer secondary structure. The internal monomers was loose and open.The results of confocal electron microscopy and scanning electron microscopy showed that the micelles was more easily to associate with each other to form micelles in different sizes.The results of TEM showed that the minimum diameter of Human β- casein micelles were 20 nm,and its internal present a kind of loose flexible porous structure which has a relationship to the functions to release and retain some immunological active molecule.