BACKGROUND Milk is the most important food for growth and development of the neonate, because of its nutrient composition and presence of many bioactive proteins. Differences between human and bovine milk in low abundant proteins have not been extensively studied. To better understand the differences between human and bovine milk, the qualitative and quantitative differences in the milk proteome as well as their changes over lactation were compared using both label-free and labelled proteomics techniques. These datasets were analysed and compared, to better understand the role of milk proteins in development of the newborn. METHODS Human and bovine milk samples were prepared by using filter-aided sample preparation (FASP) combined with dimethyl labelling and analysed by nano LC LTQ-Orbitrap XL mass spectrometry. RESULTS The human and bovine milk proteome show similarities with regard to the distribution over biological functions, especially the dominant presence of enzymes, transport and immune-related proteins. At a quantitative level, the human and bovine milk proteome differed not only between species but also over lactation within species. Dominant enzymes that differed between species were those assisting in nutrient digestion, with bile salt-activated lipase being abundant in human milk and pancreatic ribonuclease being abundant in bovine milk. As lactation advances, immune-related proteins decreased slower in human milk compared to bovine milk. Notwithstanding these quantitative differences, analysis of human and bovine co-expression networks and protein-protein interaction networks indicated that a subset of milk proteins displayed highly similar interactions in each of the different networks, which may be related to the general importance of milk in nutrition and healthy development of the newborn. CONCLUSIONS Our findings promote a better understanding of the differences and similarities in dynamics of human and bovine milk proteins, thereby also providing guidance for further improvement of infant formula.

中文翻译：

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泌乳过程中人和牛蛋白质组的相互作用组学概述。

背景技术牛奶由于其营养成分和许多生物活性蛋白的存在，是新生儿生长发育最重要的食物。低丰度蛋白质中人乳和牛乳之间的差异尚未得到广泛研究。为了更好地了解人乳和牛乳之间的差异，使用无标记和标记蛋白质组学技术比较了牛奶蛋白质组的定性和定量差异，以及它们在泌乳过程中的变化。对这些数据集进行了分析和比较，以更好地了解乳蛋白在新生儿发育中的作用。方法采用过滤辅助样品制备（FASP）结合二甲基标记制备人和牛样品，并通过纳米LC LTQ-Orbitrap XL质谱进行分析。结果人类和牛乳蛋白质组在生物学功能上的分布表现出相似性，尤其是酶，转运蛋白和免疫相关蛋白的显性存在。在数量上，人和牛的蛋白质组不仅在物种之间存在差异，而且在物种内部的泌乳方面也存在差异。物种之间不同的主要酶是有助于营养消化的酶，人乳中胆盐激活脂肪酶丰富，牛乳中胰腺核糖核酸酶丰富。随着泌乳的发展，与牛乳相比，人乳中免疫相关蛋白的下降速度较慢。尽管存在数量上的差异，人与牛共表达网络和蛋白质-蛋白质相互作用网络的分析表明，乳蛋白的一个子集在每个不同的网络中显示出高度相似的相互作用，这可能与牛奶在营养和健康发展中的普遍重要性有关。新生。结论我们的发现促进了对人类和牛乳蛋白动力学差异和相似性的更好理解，从而为进一步改善婴儿配方食品提供了指导。