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在体外,利用圆二色和等温滴定微量热技术获得人血清白蛋白与钙、镁、锌三种人体微量元素相互作用的二级结构信息与热力学参数。圆二色检测到不同浓度Ca2+、Mg2+、Zn2+与HSA相互作用后二级结构存在差异,Ca2+、Mg2+的浓度比例变化对HSA二级结构变化作用不大,但受到Zn2+离子浓度变化的影响;进而所进行的ITC实验获得了结合常数(Kb)、反应的化学计量数(N)、熵(ΔS)和焓(ΔH)等一系列分子相互作用的热力学信息,发现Zn2+-HSA表现出了更好的亲和力和结合稳定性。因此,对于重度或急症缺锌患者血液注射将比口服治疗获得更迅速疗效。验证了HSA是人体内是重要的Zn2+转运载体,而Ca2+、Mg2+在体内的转运并不以HSA为主,Ca2+、Mg2+与蛋白的结合方式相似。两种技术的联用为探索一套快速、高效的人体微量元素血液研究的系统方法提供理论基础。
In vitro, circular dichroism and isothermal titration calorimetry were used to obtain the secondary structure information and thermodynamic parameters of human serum albumin and trace elements of calcium, magnesium and zinc. Circular dichroism showed that the secondary structure of Ca2 +, Mg2 + and Zn2 + interacted with HSA at different concentrations. The change of Ca2 + and Mg2 + concentration did not affect the secondary structure of HSA, but was affected by the change of Zn2 + ion concentration. The ITC experiments carried out obtained thermodynamic information on a series of molecular interactions such as the binding constant (Kb), the stoichiometry (N), the entropy (ΔS) and the enthalpy (ΔH) of the reaction and found that Zn2 + -HSA showed better Affinity and binding stability. Therefore, blood injections for patients with severe or acute zinc deficiency will achieve more rapid response than oral treatment. It was verified that HSA is an important Zn2 + transporter in the human body, whereas Ca2 + and Mg2 + are not mainly transported in HSA. Ca2 + and Mg2 + are bound to proteins in a similar manner. The combination of the two technologies provides a theoretical basis for exploring a systematic and rapid method of studying human blood trace elements in human body.