Study On The Interaction Between Novel Pollutants And Human Functional Proteins

In recent years,with the deepening of research on new pollutants,the impact of nano plastics and perfluorinated compounds(PFCs),as two typical pollutants,on the environment and human health is gradually attracting the attention of scholars at home and abroad.Both new pollutants are active in our daily lives and enter the human body through contact and biological accumulation.After pollutants enter the organism,most of them will bind to proteins or be transported to other parts of the body through serum proteins,affecting various functional proteins in the human body and causing cell damage.Studying the interaction between pollutants and functional proteins in the human body helps to analyze the binding mode of pollutants and proteins at the molecular level,as well as their impact on protein structure.It is of great significance for understanding the distribution and biological toxicity of pollutants in the body.Therefore,studying the interaction mechanism between pollutants and proteins has become an effective way to explore the toxicity of pollutants.This study utilized multispectral technology and computer molecular simulation technology to investigate the interaction between polystyrene nanoplastics(PSNPs),perfluorooctanoic acid(PFOA),and perfluorooctane sulfonate(PFOS)with human functional proteins.The main research results are divided into three parts:(1)The degree of influence of PSNPs on catalase(CAT)varies under two physiological conditions(p H 7.4 and p H 4.0).The study mainly focuses on three aspects:the interaction mechanism between PSNPs and CAT,the influence of PSNPs on CAT conformation,and the influence of CAT on the aggregation degree of PSNPs during the binding process.The research results indicate that PSNPs can stimulate the enzyme activity of CAT,quench the intrinsic fluorescence of CAT,and the quenching mechanism is static quenching.There is only one binding site between PSNPs and CAT,and the binding degree is deeper under acidic conditions.PSNPs can change the secondary structure of CAT and affect the conformation and microenvironment of CAT,which is greatly affected by the p H environment.The two p H environments also exhibit opposite trends in the aggregation state of PSNPs.(2)Compared with PFOA,PFOS has a deeper impact on the structure of HSA.The results indicate that both PFCs can quench the fluorescence of HSA and exhibit a blue shift.The quenching mechanism is a combination of dynamic and static quenching.Both HSA and PFCs have only one binding site.The UV spectrum,3D fluorescence spectrum and circular dichroism spectrum indicate that PFOS can change the conformation and microenvironment of HSA more than PFOA,reducing the polarity of HSA and increasing its hydrophobicity.In addition,molecular docking technology and site competition experiments have shown that the interaction site between PFOS and HSA is located at the Sudlow I site in the IIA domain of HSA.(3)The results obtained from the joint toxicity investigation of PSNPs and PFCs on HSA indicate that the addition of PFCs hinders the fluorescence quenching of PSNPs on HSA,particularly in the presence of PFOS.However,PSNPs did not significantly affect the toxic effects of the two PFCs on HSA.Through transmission electron microscopy,it was found that a thin mist like film,protein halo,was formed on the surface of PSNPs combined with HSA,which weakened or disappeared after the addition of PFCs.Particle size analysis showed the same experimental phenomenon as transmission electron microscopy.