Study On The Interaction Of Triclosan With Bovine Serum Albumin And Trypsin And The Effect Of Metal Ions On The Interactions

Triclosan?TCS?is a broad-spectrum antibacterial agent,widely used in the production of personal care products,medical products and other fields.The production volume of TCS is increasing year by year.About 90%of products containing TCS are discharged into the sewage treatment plants for treatment.However,current processing techniques can not completely remove TCS,so it is distributed across environments with the migration.In recent years,TCS has been detected in water,soil,aquatic plants,mammals,and even human.TCS is chemically stable and has strong bioaccumulation capacity,which poses potential risks to water,soil ecological environment and human health.Existing studies on the toxic effects of TCS mainly focus on the level of biological individuals,but there are few studies on the microscopic mechanism of the toxic effects of TCS.First,from the molecular level,this study selected the transport protein bovine serum albumin?BSA?and the functional protein trypsin to simulate and explore the mechanism of transport and toxicity after TCS entering the body.Secondly,on the basis of exploring the interaction mechanism between trypsin and TCS,animal experiments were used to make up for the deficiency of using traditional spectroscopy alone.Finally,the effects of metal ions(Mg²⁺,Ca²⁺and Al³⁺)on TCS and protein interactions were investigated.The main results are as follows:?1?The interaction between TCS and transport protein BSA was explored at the molecular level by using traditional spectroscopy and molecular docking simulation technology.The results of fluorescence spectra showed that TCS and BSA spontaneously bound through hydrogen bond and the binding point number was 1.Under the conditions of300 K and 310 K,the binding constants of TCS and BSA were 16.78×10⁶ L·mol^-1 and5.94×10⁶ L·mol^-1,respectively,and TCS and BSA could combine strongly.Molecular probe experiments and molecular docking simulation methods determined that the specific binding point of TCS on BSA was the II?subdomain IIIA?site.?2?Animal experiments showed that TCS could significantly inhibit trypsin activity.The interaction between TCS and trypsin is mainly dominated by hydrogen bond and van der Waals force,TCS and trypsin combine at a ratio of 1?1 to form TCS-trypsin complex.Circular dichroism showed that TCS mainly changed the irregular curl content in the secondary structure of trypsin,which changed the structure and function of trypsin.Finally,it is verified by computer simulation that hydrogen bond and van der Waals force are the main types of interaction forces.?3?Animal experiments and various spectral experiments were used to study the interaction mechanism between TCS and proteins under the co-existence conditions of Mg²⁺,Ca²⁺and Al³⁺.In the metal ion-TCS-trypsin system,TCS is the main factor to inhibit trypsin activity.The content of glutathione?GSH?and malonaldehyde?MDA?in carassius auratus liver decreased,indicating that TCS caused oxidative damage to trypsin.Fluorescence spectrum experiments showed that the presence of metal ions reduced the binding constant of TCS and protein and weakened the binding ability.Metal ions hindered the binding of TCS to proteins,Mg²⁺had the greatest influence on the weakening effect of TCS binding to BSA,and Al³⁺had the greatest influence on the weakening effect of TCS binding to trypsin.The UV-vis spectroscopy experiments have verified the competitive binding relationship between metal ions and TCS,which is the main reason for the weakened binding ability of TCS to proteins.