School of Environmental and Municipal Engineering, Qingdao University of Technology, Qingdao, 266033, PR China.
School of Environmental and Municipal Engineering, Qingdao University of Technology, Qingdao, 266033, PR China.
Chem Biol Interact. 2023 Sep 1;382:110648. doi: 10.1016/j.cbi.2023.110648. Epub 2023 Jul 24.
Nanoplastics are emerging pollutants that pose a potential threat to the environment and organisms and are widely distributed in environmental samples and food chains. The accumulation of polystyrene nanoplastics (PS-NPs) in an organism can cause oxidative stress. Currently, toxicity studies of PS-NPs mainly focus on the individual and cellular levels, whereas few studies have been conducted on the molecular mechanisms of the interaction between PS-NPs and catalase (CAT). Based on this, CAT was chosen as the target receptor for molecular toxicity research to reveal the interaction mechanism at the molecular level between PS-NPs and CAT by using various spectroscopic means and enzyme activity detection methods. The results indicated that PS-NPs destroyed the secondary structure of CAT, causing its protein skeleton to loosen and unfold, increasing the content of α-helices, decreasing the content of β-sheets, and exposing the position of the heme group. After exposure to PS-NPs, the internal fluorophore of CAT underwent fluorescence sensitization, resulting in a micelle-like structure, which enhanced the hydrophobicity of aromatic amino acids but did not change their polarity. In addition, the aggregation state of CAT was altered upon binding to PS-NPs, and the volume was further increased. Finally, these structural changes led to a gradual decrease in CAT activity. This study presents a comprehensive assessment of the toxicity of PS-NPs at the molecular level, which can provide more experimental support for the study of the biotoxicological efficacy of PS-NPs.
纳米塑料是新兴污染物，对环境和生物具有潜在威胁，广泛分布于环境样品和食物链中。聚苯乙烯纳米塑料（PS-NPs）在生物体内的积累会导致氧化应激。目前，PS-NPs 的毒性研究主要集中在个体和细胞水平，而关于 PS-NPs 与过氧化氢酶（CAT）相互作用的分子机制的研究较少。基于此，选择 CAT 作为靶受体进行分子毒性研究，通过使用各种光谱手段和酶活性检测方法，揭示 PS-NPs 与 CAT 之间在分子水平上的相互作用机制。结果表明，PS-NPs 破坏了 CAT 的二级结构，使其蛋白质骨架松散展开，增加α-螺旋含量，减少β-折叠含量，暴露出血红素基团的位置。暴露于 PS-NPs 后，CAT 的内部荧光团发生荧光敏化，形成胶束样结构，增强了芳香族氨基酸的疏水性，但没有改变其极性。此外，CAT 与 PS-NPs 结合后，其聚集状态发生改变，体积进一步增大。最后，这些结构变化导致 CAT 活性逐渐降低。该研究从分子水平全面评估了 PS-NPs 的毒性，为 PS-NPs 的生物毒性效应研究提供了更多的实验支持。
