College of Life Science, Zhejiang Sci-Tech University, Hangzhou 310018, China.
College of Biological and Environmental Engineering, Zhejiang University of Technology, Hangzhou 310014, China.
Spectrochim Acta A Mol Biomol Spectrosc. 2018 Oct 5;203:383-396. doi: 10.1016/j.saa.2018.05.125. Epub 2018 Jun 2.
The interaction between Gd@C(OH) and serum albumin (HSA and BSA) were investigated by spectroscopic analysis. From the characteristic feature of fluorescence quenching spectra at different temperatures, the inherent binding information including quenching mechanism, association constants, number of binding site, fraction of initial fluorescence and basic thermodynamic parameters were calculated. The binding of Gd@C(OH) to serum albumin caused strong quenching of protein intrinsic fluorescence and the structural changes of serum albumin. At lower concentrations, Gd@C(OH) was likely to rise fluorescence quenching of serum albumin through individual static quenching process by forming a ground-state complex, while dynamic and static coexisting quenching mechanism occurred in high concentration. Bimolecular quenching (K) value is twice the diffusion-controlled quenching constant (2.0 × 10 L mol s); binding sites of BSA were slightly more than those of HAS, and all of them reached to 1; the distance r between donor and acceptor was found to be 3.1494 nm and 3.6479 nm for HSA and BSA, respectively, both of which were fewer than 7 nm. It is confirmed that binding interaction for proteins in the presence of drugs was strong, the binding ratio was 1:1, and non-radiative energy transfer from protein to drug was extremely high probability in lower density. Binding process of Gd@C(OH)-HSA was driven mainly through van der Waals forces and hydrogen bonding formation, however more likely to be electrostatic interaction involved in the Gd@C(OH)-BSA binding process; Binding sites of Gd@C(OH) to serum albumin were near tryprophan (HSA) and tyrosine residues (BSA), respectively. Moreover, a theoretical model of predicting the binding rate of drug to serum albumin was estimated, further analyzed that the binding rate was dynamically altered in various dose of protein and drug. Overall, these results provide potentially significant information for elucidating the distribution, transportation, the apparent relationship between pharmacologic activity and total plasma drug concentration as well as anti-carcinogenic activity and mechanisms in vivo.
通过光谱分析研究了 Gd@C(OH) 与血清白蛋白（HSA 和 BSA）之间的相互作用。从不同温度下荧光猝灭光谱的特征，可以计算出包括猝灭机制、结合常数、结合位点数、初始荧光分数和基本热力学参数在内的固有结合信息。Gd@C(OH) 与血清白蛋白的结合导致蛋白质固有荧光的强烈猝灭和血清白蛋白的结构变化。在较低浓度下，Gd@C(OH) 可能通过形成基态复合物通过单个静态猝灭过程增加血清白蛋白的荧光猝灭，而在高浓度下则发生动态和静态共存猝灭机制。双分子猝灭（K）值是扩散控制猝灭常数（2.0×10 L mol s）的两倍；BSA 的结合位点数略多于 HAS，均达到 1；发现供体和受体之间的距离 r 分别为 3.1494nm 和 3.6479nm，均小于 7nm。证实了在药物存在的情况下蛋白质的结合相互作用很强，结合比为 1:1，并且在较低密度下，药物与蛋白质之间的非辐射能量转移极有可能发生。Gd@C(OH)-HSA 的结合过程主要是通过范德华力和氢键形成驱动的，然而，Gd@C(OH)-BSA 结合过程中更可能涉及静电相互作用；Gd@C(OH) 与血清白蛋白的结合位点分别靠近色氨酸（HSA）和酪氨酸残基（BSA）。此外，还估计了预测药物与血清白蛋白结合速率的理论模型，进一步分析了在不同剂量的蛋白质和药物下，结合速率是如何动态变化的。总的来说，这些结果为阐明药物在体内的分布、运输、药效学活性与总血浆药物浓度之间的表观关系以及抗癌活性和机制提供了潜在的重要信息。
