Study On The Interaction Between Vanillin And Protein

Vanillin is a type of spice with strong scent of milk. It’s extracted from plants, and the structure of which contains benzene ring. As we know, aromatic compounds containing benzene ring structure may have certain impact on human health. In recents years vanillin has become more and more widely used in food industry and production. Therefore the study of interaction between vanillin and proteins on human health is necessary. It is believed that the study of interaction mechanism of vanillin and proteins will show an important theorectical value in the food industry, life science and biotechnology fields.Meanwhile the experimental data can provide more theoretical basis for the development of food, medicine and other fields. In this paper four proteins including bovine serum albumin(BSA), bovine hemoglobin(BHb), human immunoglobulin G(HIgG)and collagen protein were chosen to examine the interaction with vanillin. And a variety of spectroscopic methods were utilized to discuss the interaction between vanillin and proteins.The following major innovative works were achieved in this dissertation:(1)The molecular modeling method was used to reveal the binding mode of vanillin with BSA, BHb, HIgG and collagen protein. In addition, the molecule models of vanillin with proteins were built.(2) Fluorescence(FL) spectrum, UV absorption(UV-vis) spectrum, fourier transform infrared(FT-IR) spectrum and circular dichroism(CD) spectrum were used to study the interactions of BSA, BHb, HIgG and collagen protein with vanillin, respectively. The experimental data provided the binding constants, binding sites and thermodynamic parameters. The alterations of protein secondary structure in the presence of vanillin were explored too.(3) In order to examine the influence of the interaction between protein and vanillin on the physiological functions of the protein, the mimic peroxidase activity of hemoglobin was detected.This dissertation consists of five 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 and proteins were summarized.Chapter 2: The interaction between vanillin and four proteins were investigated by fluorescence spectroscopy. The fluorescence quenching type was determined according to the quenching constants at different temperatures. The binding parameters including the affinity constant, the number of binding sites and the thermodynamic parameters of vanillin bounding to proteins were calculated according to modified Stern-Volmer and Van’t Hoff equation, respectively. And the type of force was roughly determined.Chapter 3: The effect of pH and metal ions on the interaction between vanillin and proteins was performed. The results showed that the interaction between vanillin and protein was different on account of differen pH conditions. In addition, different metal ions have a great influence on the interaction between vanillin and protein.Chapter 4: FL, UV-vis, FT-IR, CD methods were utilized to explore the effects of vanillin and protein interactions on the secondary structure of protein. At the same time, by taking hemoglobin as an example, the effect of vanillin on physiological function of protein was studied. The experimental data showed that the interaction between vanillin and protein leads to obvious change on the secondary structure of protein. Furthermore the interaction between hemoglobin and vanillin reduced peroxidase activity of hemoglobin.Chapter 5: The molecular modeling method was used to investigate the interaction between vanillin and proteins. The results of molecular modeling revealed the bonding region, bonding mode and bond free energy of the interactions between vanillin and proteins.