Study Of The Interaction Between Phthalate Plasticizer And Bovine Serum Albumin By Spectroscopic

With the rapid development of the industry,plasticizers are widely used in agriculture,industry,food industry and medical industry,but the harm of plasticizers has become increasingly prominent.Phthalates plasticizers are widely used in industrial production because of their good ductility and flexibility,as well as their low cost and ease of preparation.However,a large amount of phthalate compounds will escape into the environment through plastic products,and it will be difficult to degrade in the atmosphere,water and soil for a long time,causing pollution to the environment.In addition,the phthalate plasticizers in the environment enter the human body through food intake,respiration,skin contact,and the like.They causes chronic toxicity to organs,such as reproduction and development of the human body,leading to genetic damage of germ cells,malformation of male reproductive organs,abnormal changes in female egg quality,and ultimately leading to serious health problems such as habitual abortion,discontinuation,premature delivery and fetal malformation.Bovine serum albumin?BSA?has the functions of transporting,metabolizing,and maintaining the homeostasis of the organism.It is the most abundant carrier protein in plasma,and it can be specific to exogenous and endogenous small molecule substances.Binding plays a role in transport and storage,so bovine serum albumin is widely used in the study of the interaction between biological macromolecules and exogenous small molecules.In this paper,BSA was used as a model protein to study the diethyl phthalate?DEP?and its metabolite monoethyl phthalate?MEP?and phthalic acid by various spectroscopic methods.Mechanism of interaction between dioctyl phthalate?DOP?and BSA.This provides a basis for further exploration of the interaction mechanism between phthalate compounds and BSA,as well as understanding the metabolism and transport of phthalate plasticizers in vivo.1.The interaction mechanism between DEP and BSA was studied byfluorescencespectroscopy,UV-Visabsorptionspectraand time-resolved fluorescence spectroscopy.The experimental results showed that DEP quenched the fluorescence of BSA,under simulated physiological conditions?pH=7.4?,The results of fluorescence titration experiments showed that DEP was mainly static quenching.The binding constants of DEP-BSA were 1.81×10⁴ L·mol^-1,3.85×10⁴ L·mol^-11 and7.48×10⁴ L·mol^-11 at 290 K,300 K and 309 K.The number n of binding sites was about 1,indicating that a 1:1 complex was formed between DEP and BSA.From the Van't Hoff equation and the thermodynamic formula,the thermodynamic constant?H and?S of DEP and BSA were 89.7kJ·mol^-11 and 382.88 J·mol^-1·K^-11 respectively,indiced the binding force was hydrophobic interaction in between DEP and BSA.?G was-24.4kJ·mol^-1,indicating that the reaction between DEP and BSA was spontaneous.The results of synchronous fluorescence spectroscopy revealed that DEP induced changes in the conformation of BSA.2.The interaction mechanism between MEP and BSA was studied by fluorescence spectroscopy and UV-Vis absorption specta.The experimental results showed that the quenching constants K_SVV of MEP and BSA are 5.75×10⁴ L·mol^-1,4.66×10⁴ L·mol^-11 and 3.71×10⁴ L·mol^-11 at290 K,300 K and 309 K.The rate constant K_q was greater than 2×10¹⁰mol·L^-1·S^-1,which inferred that the quenching of BSA by MEP was static quenching.The thermodynamic constant?H<0,?S>0,which indicated that the binding force was mainly hydrophobic force and hydrogen bond,the results of UV-Vis absorption specta and the synchronous fluorescence specta.Suggested that MEP changed the conformation of BSA by changing the polarity around the BSA microenvironment.3.The interaction mechanism between DOP and BSA was studied byfluorescencespectroscopy,UV-Visabsorptionspectaand time-resolved fluorescence spectroscopy.The experimental results showed that the quenching type of BSA by DOP was mainly static quenching,which was reform provede by fluorescence lifetime.The rseults of binding constants and the number of binding sites showed that a1:1 complex is formed between DOP and BSA.From the thermodynamic constant?H and?S,it was concluded that the hydrophobic interaction and the hydrogen bonding force between DOP and BSA.The binding distance was 4.29 nm between DOP and BSA,and non-radiative energy transfer was highly passible.The results of synchronous fluorescence spectrum.Suggested that DOP reduced the hydrophobicity of tryptophan residues of BSA.