The Study Of The Interaction Of Polyphenolic Compounds With Bovine Serum Albumin

In this thesis, both spectroscopy, including fluorescence spectroscopy, synchronous fluorescence, circular dichroism and UV-visible spectroscopy, and molecular modeling techniques were used to study the interaction of polyphenolic compounds and bovine serum albumin (BSA).The experimental results revealed that the quenching of BSA by cyanidin-3-glucoside(Cy-3-G) and isoliquiritigenin(ISL) were both static quenching. The number of binding sites (n) for Cy-3-G and ISL binding on BSA were approximately equal to1, formed1:1conjugates. The binding constant (K) of Cy-3-G and ISL were5.13×105and5.26×104at310K.The thermodynamic parameters results of BSA combined with Cy-3-G and ISL showed that the process is spontaneous (△G0<0). Moreover, enthalpy change (△H0) and entropy change (△S0) are negative, indicating that the main force in the process of BSA combined with Cy-3-G and ISL was hydrogen bonding and Van der Waals forces.The synchronous fluorescence and CD results revealed that the secondary structure of BSA was less affected by the binding of Cy-3-G and BSA. The results of ISL revealed that the secondary structure of BSA and the micro-environment near Trp and Tyr might be changed.Molecular Simulation results showed that Cy-3-G was inserted into the hydrophobic cavity of BSA (Site Ⅱ’) in the binding process of Cy-3-G with BSA, and hydrogen bonds were formed between Cy-3-G and PHE229, ARG232, SER503, LEU504residues of BSA. ISL was inserted into the hydrophobic cavity of BSA (Site I), and hydrogen bonds were formed between ISL and ARG222, ARG280, ALA314, GLU315residues of BSA. And, the conformation of Cy-3-G and ISL changed significantly after the combination.