Department of Nutrition, University of California, Davis, CA 95616, USA; Institute of Dairy Science, MoE Key Laboratory of Molecular Animal Nutrition, College of Animal Sciences, Zhejiang University, Hangzhou, 310058, PR China.
Department of Nutrition, University of California, Davis, CA 95616, USA.
J Nutr Biochem. 2019 Jul;69:10-18. doi: 10.1016/j.jnutbio.2019.03.016. Epub 2019 Mar 28.
Lactoferrin (LF) and osteopontin (OPN) are both multi-functional whey proteins present at high levels in human milk. These two proteins have a high affinity for each other due to their opposite charges; LF is a basic glycoprotein while OPN is an acidic phosphorylated glycoprotein. LF and OPN were identified to bind to each other over a decade ago, but potential functions of their complex remain unexplored. In this work, we investigated the characteristics of the LF-OPN complex with a focus on its bioactivities. Our results reveal a stronger stability of the LF-OPN complex towards in vitro digestion and more effective binding and uptake by human intestinal cells (HIEC) than LF or OPN alone show. Moreover, the LF-OPN complex promotes proliferation and differentiation of intestinal cells significantly more than the individual proteins do and shows an effect on anti-bacterial function and immune-stimulatory activities intermediate between those of LF and OPN. Thus, by forming a complex in human milk, LF and OPN may protect each other against proteolysis and enhance their individual bioactivities.
乳铁蛋白 (LF) 和骨桥蛋白 (OPN) 都是人乳中高浓度存在的多功能乳清蛋白。这两种蛋白质由于电荷相反，具有很高的亲和力；LF 是一种碱性糖蛋白，而 OPN 是一种酸性磷酸化糖蛋白。十多年前，人们就已经发现 LF 和 OPN 能够相互结合，但它们复合物的潜在功能仍未被探索。在这项工作中，我们研究了 LF-OPN 复合物的特性，重点研究了其生物活性。我们的结果表明，与 LF 或 OPN 单独相比，LF-OPN 复合物在体外消化过程中具有更强的稳定性，并且更有效地与人体肠道细胞 (HIEC) 结合和摄取。此外，LF-OPN 复合物对肠道细胞的增殖和分化有显著的促进作用，其抗菌功能和免疫刺激活性介于 LF 和 OPN 之间。因此，LF 和 OPN 在人乳中形成复合物可能相互保护免受蛋白酶的降解，并增强它们各自的生物活性。
