Deciphering calcium-binding behaviors of casein phosphopeptides by experimental approaches and molecular simulation
Deciphering calcium-binding behaviors of casein phosphopeptides by experimental approaches and molecular simulation
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DOI：
10.1039/d0fo00844c
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发表时间：
2020-06-01
期刊：
影响因子：
6.1
通讯作者：
Cao, Yong
中科院分区：
文献类型：
--
作者：
Luo, Minna;Xiao, Jie;Cao, Yong
酪蛋白磷酸肽（CPPs）作为功能食品中的优质添加剂，可以促进钙的运输和吸附。钙- cpp结合行为的原子分辨率解析对于了解cpp的钙生物利用度增强潜力至关重要。本研究结合实验方法（UV-vis、FTIR和等温滴定量热法）和分子动力学模拟，揭示了携带钙离子能力最强的β -酪蛋白磷酸肽（1-25）（P5）的钙结合行为。我们发现它可以携带大约6个钙离子，钙结合位点主要位于Glu-2的羰基和磷酸化Ser-15、Ser-18和Ser-19的磷酸基。一个有趣的发现是，钙离子可以通过三种协调模式结合，包括未识别、双齿和三齿几何形状，从而产生很强的结合能力。钙离子与P5的结合是自发的，结合自由能为-5.2 kcal mol（-1）。疏水相互作用被认为是钙离子结合的主要驱动力。本研究为Ca（2+）和钙结合肽之间的结合过程提供了新的分子见解。
Casein phosphopeptides (CPPs) as premium additives in functional foods can facilitate the transport and adsorption of calcium. The atomic resolution decipherment of calcium-CPP binding behaviors is critical for understanding the calcium bioavailability enhancement potential of CPPs. In the present study, the experimental methods (UV-vis, FTIR and isothermal titration calorimetry) and molecular dynamics simulation were combined to reveal the calcium-binding behaviors of beta-casein phosphopeptides (1-25) (P5) with the best capability in carrying calcium ions. We found that it could carry approximately six calcium ions, and the calcium-binding sites were primarily located at the carbonyl group of Glu-2 and the phosphate group of phosphorylated Ser-15, Ser-18, and Ser-19. An interesting finding was that calcium ions could be bound by three coordinated modes, including unidentate, bidentate and tridentate geometries, resulting in the strong binding abilities. The binding process of calcium ions to P5 was spontaneous with the binding free energies of -5.2 kcal mol(-1). Hydrophobic interactions were considered to be the major driving force for the calcium ion binding. The present study provides novel molecular insights into the binding process between Ca(2+)and calcium-binding peptides.