Abstract：
The significant health risks of nanoplastics (NPs) and cadmium (Cd) are currently attracting a great deal of attention and research. At present, the effects and mechanisms of NPs and Cd on human serum albumin (HSA), a key functional protein in the organism on transportation, remain unknown. Here, the differences in the effects and mechanisms of action of Cd alone and composite systems (NPsCd) were explored by enzyme activity assay, multi-spectroscopy analysis and molecular docking. The results showed that HSA activity was inhibited and decreased to 80 % and 69.55 % (Cd = 30 mg/L) by Cd alone and NPs-Cd exposure, respectively. Exposure to Cd induced backbone disruption and protein defolding of HSA, and secondary structure disruption was manifested by the reduction of α-helix. Cd exposure also induces fluorescence sensitization of HSA. Notably, the addition of NPs further exacerbated the effects associated with Cd exposure, which was consistent with the changes in HSA activity. Thus, the above conformational changes may be responsible for inducing the loss of enzyme activity. Moreover, it was determined by RLS spectroscopy that NPs-Cd bound to HSA in the form of protein crowns. Molecular docking has further shown that Cd binds to the surface of Sudlow site II of HSA, suggesting that Cd impairs the function of HSA by affecting the protein structure. More importantly, the addition of NPs further exacerbated the disruption of the protein structure by the adherent binding of HSA on the surface of the plastic particles, which induced a greater change in the enzyme activity. This study provides useful perspectives for investigating the impact of composite pollution on HSA of human functional proteins.
摘要：
纳米塑料（NP）和镉（Cd）的重大健康风险目前正在吸引大量的关注和研究。目前,NPs和Cd对人血清白蛋白（HSA）的影响及其机制，生物体中的关键功能蛋白质在运输中，仍然未知。这里,通过酶活性测定探讨了Cd单独和复合系统（NPsCd）的作用和作用机理的差异，多光谱分析和分子对接。结果表明，Cd单独和NPs-Cd暴露对HSA活性有抑制作用，并降低至80％和69.55％（Cd=30mg/L），分别。暴露于Cd诱导HSA的骨架破坏和蛋白质去折叠，二级结构的破坏表现为α-螺旋的减少。Cd暴露还诱导HSA的荧光敏化。值得注意的是,NPs的添加进一步加剧了与Cd暴露相关的影响，这与HSA活性的变化一致。因此，上述构象变化可能是导致酶活性丧失的原因。此外，通过RLS光谱法确定，NPs-Cd以蛋白质冠的形式与HSA结合。分子对接进一步表明，Cd与HSA的Sudlow位点II的表面结合，表明Cd通过影响蛋白质结构来损害HSA的功能。更重要的是,NPs的加入进一步加剧了HSA在塑料颗粒表面的粘附结合对蛋白质结构的破坏，这引起了酶活性的更大变化。本研究为研究复合污染对人功能蛋白HSA的影响提供了有益的视角。
