The Studies Of Interaction Between Some Food Flavors, Drug Carriers, Azo Dyes And Protein

As people focus on life science, the interaction of protein and ligands has become a hot spot. Human serum albumin as a major component of plasma plays an important role in the course of human life. The study of interaction mechanism of food flavors, drug carriers, azo dyes and protein show an important theoretical value in the food industry, material science, life science and biotechnology fields. The experimental data can provide more theoretical basis for the development of food, medicine, cosmetics, dyeing chemicals and other fields. The following major innovative works were carried out in this dissertation:(1) The molecular modeling method was used to reveal the binding mode of vanillin with human serum albumin (HSA), obtain the molecule model of vanillin with HSA.(2) Fluorescence spectrum, UV absorption spectrum, fourier transform infrared (FT-IR) spectrum and circular dichroism (CD) spectrum were used to study the interactions of vanillin, P(AAm-co-AAPBA), Marshall Red (MR) with HSA, respectively. The experimental data provided some valuable information for the application of these three substances.(3) The numbers of binding site, the binding constants and the interaction force involving in the interaction of vanillin, P(AAm-co-AAPBA) and HSA were confirmed by modified Stern-Volmer equation and Van't Hoff equation.(4) The information obtained from the synchronous fluorescence spectra were used to determine the microenvironment changes of chromophore in HSA when the three ligand molecules present.(5) The secondary structure compositions of the free HSA, HSA and vanillin, P(AAm-co-AAPBA) complexes were estimated by quantitative analysis using self deconvolution with second-derivative resolution enhancement and curve-fitting procedure.This dissertation consists of four chapters.Chapter 1:The structures, functions of proteins and the methods used to study interaction of ligands with proteins were reviewed. Meanwhile, the developments of interaction between food flavors, drug carriers, azo dyes and HSA were summarized.Chapter 2:The interaction of vanillin and HSA has been characterized by molecular modeling and spectroscopic methods. The results of molecular modeling suggested that vanillin was located within the binding pocket of subdomain IIA of HSA mainly by hydrophobic forces. The quenching of HSA fluorescence takes place with a binding constant (K) at four different temperatures, respectively. The number of binding site was obtained from fluorescence titration data. Theâ–³H0 andâ–³S0 were calculated according to the Van't Hoff equation. The alterations of protein secondary structure in the presence of vanillin were explored by FT-IR and CD spectra. The distance between the tryptophan residues in HSA and vanillin was estimated using Foster's equation on the basis of fluorescence energy transfer.Chapter 3:The interactions between P(AAm-co-AAPBA) and HSA were investigated by UV-vis, CD, FT-IR and fluorescence spectroscopic methods. The result from UV-vis spectra indicated that P(AAm-co-AAPBA) could bind with HSA and change the secondary structure of HSA. FT-IR and CD spectra indicated the different degree on the changes of the secondary structure compositions of HSA. The binding parameters including the affinity constant, the number of binding sites and the thermodynamic parameters of this drug delivery material bound to HSA were calculated according to modified Stern-Volmer and Van't Hoff equation, respectively. The distance between the HSA donor and the acceptor P(AAm-co-AAPBA) was calculated from fluorescence resonance energy transfer.Chapter 4:The interaction of MR and HSA has been characterized by spectroscopic methods. The result from fluorescence spectra indicated that this azo dye could bind with HSA and quench the fluorescence of HSA. UV-vis, CD and FT-IR spectra showed that MR could change the secondary structure of HSA. The distance between the tryptophan residues in HSA and MR was estimated using Foster's equation on the basis of fluorescence energy transfer.