Research On The Interaction Between Pesticides With Bovine Serum Albumin

The irrational application of pesticides has caused the ecological damage, environmental pollution and toxics of agricultural and sideline products. The concern of the quality and safety of food has attracted increasing attention of all aspects of the society. Although pesticides’toxicity to human being and animals exhibits damage to the target organ, the pesticide must bind to the carrier protein before it arrives at the target organ. The present thesis studies the interaction mechanism between several representative pesticides and pesticide adjuvants with the serum albumin aiming to provide scientific evidence to guide effective use of pesticides.The current research on the interaction of pesticides with Serum Albumin is reviewed by quoting more than 200 articles in the introduction. Chapter II is the core of this thesis. By employing various experimental techniques and computer simulation, we explored the molecular binding of the pesticide-BSA system and constructed a reasonable pesticide-BSA interaction information system which lays the foundation of theoretical framework and experiment for the follow-up study. ChapterⅢ-Chapter V is the expand part of this thesis. Chapter III presents the investigation in the interaction between six pyrethroids small molecules with BSA. The changes of interaction information which resulted from the structural change of small molecules in the process of integration with BSA is explored. Chapter IV studied the interaction mechanism of four polyoxyethylene nonyl phenyl ether nonionic surfactants with BSA by using fluorescence spectroscopy, isotherm titration microcalorimetry and circular dichromism spectra. The impaction of critical micelle concentration (CMC) and Hydrophic-Lipophile Balance (HLB) on the combination of non-ionic surfactant with BSA is discussed. Chapter V investigated the interaction mechanism of green non-ionic surfactant alkyl poly-glycosides 2000 with BSA similarly. The three-dimensional fluorescence spectra of the binding process of alkyl poly-glycosides 2000 with BSA is compared to that of deltamethrin with BSA. It could provide a scientific basis for further toxicity studies. Finally, Chapter VI summarizes the conclusions and future works of the thesis.The major findings of this thesis are the following:1. A reasonable reciprocity system of pesticide-BSA, which is mainly composed of the type of quenching、dynamic and static quenching constant Ksv、KLB、apparent binding constant KA、pesticide binding sitesn、binding space distancer、energy transferring efficiency E、conformation changes in BSA molecule、thermodynamic parameters of pesticide-BSA molecule interaction and main types of interaction has been constructed.2. Structure changes in pesticide molecule do influence its interaction with BSA. In terms of pyrethroids molecules, the groups may combine to BSA molecule include cyclopropyl, vinyl bromide, vinyl chloride and fluorine atoms. The results provide evidence for understanding the principle of combination of pesicide-BSA. The Binding site of six pyrethroids with BSA locations atⅢA district which is close to the Tyr411 residues. It is also found the highest toxicity of deltamethrin is in line with the biggest dynamic and static quenching constants and the largest changes of BSA secondary structure content.3. The HLB of surfactants and CMC influence the interaction between surfactant and BSA. It is also found that the highest toxicity of surfactants has the biggest dynamic and static quenching constants and the largest changes of BSA secondary structure content.4. The intrinsic fluorescence of six pyrethroids and five surfactants on BSA were all static quenching. Besides, Non-radiation energy transfer between alkyl poly-glycosides and BSA also plays a role in leading into fluorescence quenching endogenous of alkyl polyglycosides with BSA. Pesticide-BSA interaction is a spontaneous process accompanying with increasing in entropy and reducing in Gibbs free energy. The binding forces include intermolecular hydrophobic interaction, dipole-dipole electrostatic interactions and hydrogen bonding interactions. Through the comparison study of three-dimensional fluorescence spectra of interactions between alkyl polyglycosides and deltamethrin with the BSA. It is found that deltamethrin could destroy the structure of BSA, whereas even 10 times of polyglycosides has no significant impact on the main polypeptide chain of BSA.