National Key Laboratory of Organic Chemistry, Lanzhou University, Lanzhou 730000, China.
J Hazard Mater. 2011 Sep 15;192(3):1291-8. doi: 10.1016/j.jhazmat.2011.06.038. Epub 2011 Jun 25.
Phthalate esters (PAEs) are globally pervasive contaminants that are considered to be endocrine disruptor chemicals and toxic environmental priority pollutants. In this paper, the interactions between PAEs and human serum albumin (HSA) were examined by molecular modelling, steady state and time-resolved fluorescence, ultraviolet-visible spectroscopy (UV-vis) and circular dichroism spectroscopy (CD). The association constants between PAEs and HSA were determined using the Stern-Volmer and Scatchard equations. The binding of dimethyl phthalate (DMP) to HSA has a single class of binding site and its binding constants (K) are 4.08 × 10(3), 3.97 × 10(3), 3.45 × 10(3), and 3.20 × 10(3)L mol(-1) at 289, 296, 303, and 310K, respectively. The Stern-Volmer and Scatchard plots both had two regression curves for HSA-butylbenzyl phthalate (BBP) and HSA-di-2-ethylhexyl phthalate (DEHP), which indicated that these bindings were via two types of binding sites: the numbers of binding site for the first type were lower than for the second type. The binding constants of the first type binding site were higher than those of the second type binding site at corresponding temperatures, the results suggesting that the first type of binding site had high affinity and the second binding site involved other sites with lower binding affinity and selectivity. The thermodynamic parameters of the binding reactions (ΔG°, ΔH° and ΔS°) were measured, and they indicated the presences of hydrophobic forces and hydrogen interactions in the PAEs-HSA interactions, which agreed well with the results from molecular modelling. The alterations of protein secondary structure in the presence of PAEs were confirmed by UV-vis and CD spectroscopy. The time-resolved fluorescence study showed that the lifetime of Trp residue of HSA decreased after the addition of PAEs, which implied that the Trp residue of HSA was the main binding site.
邻苯二甲酸酯（PAEs）是一种普遍存在的全球性污染物，被认为是内分泌干扰化学物质和有毒的环境优先污染物。在本文中，通过分子建模、稳态和时间分辨荧光、紫外可见光谱（UV-vis）和圆二色性光谱（CD）研究了 PAEs 与人血清白蛋白（HSA）之间的相互作用。使用 Stern-Volmer 和 Scatchard 方程确定了 PAEs 与 HSA 之间的结合常数。二甲基邻苯二甲酸酯（DMP）与 HSA 的结合具有单个结合位点，其结合常数（K）分别为 289、296、303 和 310K 时为 4.08×10(3)、3.97×10(3)、3.45×10(3)和 3.20×10(3)L/mol(-1)。对于 HSA-丁基苯甲基邻苯二甲酸酯（BBP）和 HSA-邻苯二甲酸二（2-乙基己基）酯（DEHP），Stern-Volmer 和 Scatchard 图都有两个回归曲线，这表明这些结合是通过两种类型的结合位点进行的：第一种结合位点的数量少于第二种结合位点。在相应的温度下，第一种结合位点的结合常数高于第二种结合位点的结合常数，这表明第一种结合位点具有高亲和力，第二种结合位点涉及其他结合亲和力和选择性较低的位点。测量了结合反应的热力学参数（ΔG°、ΔH°和ΔS°），它们表明在 PAEs-HSA 相互作用中存在疏水作用力和氢键相互作用，这与分子建模的结果一致。通过 UV-vis 和 CD 光谱证实了 PAEs 存在时蛋白质二级结构的变化。时间分辨荧光研究表明，添加 PAEs 后 HSA 中色氨酸残基的寿命降低，这表明 HSA 中色氨酸残基是主要的结合位点。
