利用差异蛋白质组学方法解析人乳与牛乳糖基化蛋白质的变化规律

The complete understanding of differences between human and bovine milk is becoming imperative in order to improve the similarity of infant formula and human milk for providing essential nutrients. Glycosylation is one of the important post translational modification of proteins which influence their biological activity. More than 50% of milk proteins are glycosylated. However, the types and function of these glycoproteins in milk are not well examined. A suitable glycoproteomic technique has been established in our group for milk protein. In present project, the glycoproteomic technique will be used to constitute a blue print of differences in glycoproteins in human and bovine milk. The effect of lactation stage on the changes of glycoproteins in human and bovine milk will also be investaged. Finally, the influence of glycoproteins on function and nutritional value of milk will be investigated and the reason for the changes in glycoproteins in milk will be explored by bioinformatic analysis. Hopefully, the present project can provide useful information which can guide the design of infant formula.

为提高婴幼儿配方奶粉与母乳的相似性，全面研究人乳与牛乳之间的差异是亟欲解决的问题。蛋白的糖基化对其生理功能及加工性质影响显著，乳中含有大量糖基化蛋白，但对其在乳中的种类及功能研究较少。本项目拟采用蛋白质组学技术（凝集素层析法富集乳中糖基化蛋白，PNGase F 法和β-消除米氏加成法解离糖支链，HPLC-Orbitrap-MS/MS测定糖基化蛋白质种类及糖基化位点，MALDI-TOF-MS测定糖支链种类及结构）系统比较人乳与牛乳糖基化蛋白的种类及糖基化结构差别，建立人乳与牛乳糖基化蛋白数据库；对比泌乳初期(<1个月)，中期(6-7个月) 及末期(11-12个月)人乳与牛乳中糖基化蛋白变化，阐明乳中糖基化蛋白随泌乳期的变化规律；分析糖基化蛋白质的差异性对乳功能性质及营养价值的影响，初步阐明糖基化蛋白质差异性产生原因。相关研究成果为开发不同阶段婴幼儿配方奶粉提供理论指导。

为提高婴幼儿配方奶粉与母乳的相似性，全面研究人乳与不同乳源之间的差异是亟欲解决的问题。蛋白的糖基化对其生理功能及加工性质影响显著，乳中含有大量糖基化蛋白，但对其在乳中的种类及功能研究较少。本研究利用蛋白质组学技术解析了人乳、牛乳、羊乳及牦牛乳蛋白质及糖基化蛋白质的差异性。进一步研究了泌乳期对人乳及牛乳糖基化蛋白质的影响。人乳中含有特有的蛋白质，对婴幼儿免疫系统的建立及营养物质的消化吸收具有重要作用。而动物乳中免疫蛋白与人乳有较大差别，主要为抗菌物质。人乳中大部分糖基化蛋白质的糖支链含有岩藻糖，而动物乳中含有岩藻糖的糖支链数量低于人乳。人及牛初乳中低聚糖的含量及种类较成熟乳高。对婴幼儿及牛犊生命初期免疫系统及肠道菌群的建立具有一定的作用。本研究从蛋白质及蛋白质的糖基化后修饰角度解析了人乳及常用替代乳源的差异性，解析了泌乳期对乳中糖基化蛋白质的影响，为优化婴幼儿奶粉配方提供基础数据及理论支持。