天冬氨酸和谷氨酸及其甘氨酸二肽调控Caco-2细胞钙离子吸收的研究

Regulation of Calcium Absorption in Caco-2 Cells by Aspartic Acid,Glutamic Acid and Their Glycine Dipeptides

为了探究天冬氨酸和谷氨酸及其甘氨酸二肽对钙离子吸收的影响机理,本文利用等温滴定量热技术、电化学、Caco-2细胞模型结合量子化学计算(密度泛函理论)对天冬氨酸和谷氨酸及其甘氨酸二肽与钙离子的相互作用进行了探究。结果表明,天冬氨酸和谷氨酸通过焓和熵驱动的放热反应与钙离子形成复合物,而其形成的二肽则是通过熵驱动的吸热反应与钙离子结合。此外,二肽比单独的氨基酸表现出更强的钙离子结合能力。量子化学计算表明,氨基酸/二肽中的羧基为钙离子的主要结合位点,在碱性条件下,会导致钙离子结合位点转移,氨基也可以参与钙离子结合。Caco-2细胞吸收实验表明,天冬氨酸和谷氨酸及其二肽均可促进钙的吸收,其中甘氨酸-谷氨酸二肽(Gly-Glu)的促进效果最好,促钙吸收率为1.33±0.115。此外,促钙吸收能力与钙离子结合能力之间没有明确的相关性,与其电子亲和力的关系更为密切。研究结果解释了天冬氨酸、谷氨酸及其甘氨酸二肽与钙之间的相互作用,为进一步开发钙补充剂提供科学依据。

In order to investigate the mechanism of aspartic acid,glutamic acid and their glycine dipeptides on calcium ion uptake,the isothermal titration calorimetry technique,electrochemistry,and Caco-2 cell model combined with quantum mechanical calculation(density functional theory)were used to investigate the interactions between aspartic acid and glutamic acid,as well as their glycine dipeptides.The results showed that aspartic acid and glutamic acid form complexes with calcium ions through exothermic reactions driven by enthalpy and entropy,while their dipeptides interacted with calcium ions by entropy-driven endothermic reactions.In addition,dipeptides exhibited stronger calcium binding capacity than the single amino acids.Quantum chemical calculations showed that the carboxyl groups in the amino acid/dipeptide were the main binding site of calcium ions,while under alkaline conditions,the amino group could also participate in calcium binding,leading to a calcium binding site shift.Caco-2 cell uptake experiments showed that aspartic acid,glutamic acid and their dipeptides could promote calcium absorption.Among them,Gly-Glu dipeptide had the best promotion effect,and the calcium absorption rate was 1.33±0.115.Furthermore,there was no clear correlation between the ability to promote calcium absorption and the ability to bind calcium ions.However,it was more closely related to its electron affinity.The results elucidated the interactions between aspartic acid,glutamic acid and their glycine dipeptides and calcium ions,providing scientific basis for further development of calcium supplements。