| Serum albumin is a protein that plays an important role in human body. It can complex various endogenous and exogenous drugs, transporting drugs to the specific site where the cure happens. The research of the complexation between protein and drugs can help people understand the distribution of drugs in human body as well as its metabolism and transport process. Furthermore, the efficiency of the drugs depends on the value of the binding constant with the carrier protein. Therefore, the interaction between serum albumin and drugs has a special improtance to the medical treatment and drug development.In the thesis, the method of fluorescence spectroscopy combined with molecular docking was adopted to investigate the interaction between serum albumin and drugs.Some experimental results are listed below:(1) Under simulated physiological conditions, bovine serum albumin(BSA) could interact with genistein(Gen) to form the non-covalent complex and this process could be monitored by a series of fluorescence quenching experiments. Stern-Volmer function and the double logarithm curve equation were used to analyze theses fluorescence quenching experimental data. It was found that the quenching mechanism is static quenching and the binding constant between those compounds are calculated as KA=6.4×105 L/mol. The average binding ratio of BSA and Gen was also calculated as about 1:1. The complexation between BSA and Gen can change the micro-environment of the Trp134 residue of BSA and the hydrophobic effect and hydrogen bonding are the primary factor to the fluorescence quenching which was revealed by synchronous fluorescence spectroscopy and molecular docking simulation.(2) Fluorescence quenching experiments were conducted to investigate the interactions between BSA and Cytisine(Cy). Experimental results indicated that the quenching mechanism is static quenching and binding constant is KA=5.6×103 L/mol.Molecular docking simulation also showed that the combining site is the hydrophobic pocket around Trp213 residue of BSA.(3) Naringenin and naringin, are typical flavonoid aglycone and glycoside,respectively, which can both quench the fluorescent emission of BSA. Experimental results showed that the quenching mechanism for naringenin and naringin to BSA are static quenching but the binding constants for both compounds are slightly different, which are 1.31×105 L/mol(for the complex of BSA-Naringin) and1.08×105L/mol(for the complex of BSA- naringin), respectively. It can be seen that the complex formed by BSA and naringenin are more stable compared with that formed by BSA and naringin, which is in line with the molecular docking simulation results. The binding site of BSA for these two compounds are Trp213 residue with highly possibility. The difference of the guest location may leads to the difference of the binding constants.(4) Two isomers, oleanolic acid(OA) and ursolic acid(UA) are differentiated by fluorescence quenching under simulated physiological conditions. Experimental results showed that both OA and UA can quench BSA or HSA under a static quenching mode, but the binding constants of the formed complexes are different,which are KA(BSA-OA) is 6.54×104 L?mol-1;KA(BSA-UA) is 4.80×104 L?mol-1; KA(HSA-OA) is7.30×103 L?mol-1; KA(HSA-UA) is 9.37×105 L?mol-1. Molecular docking simulations were used to help build modelling of these complexes. By comparing these binding constants, it can be clearly seen that HSA can be used to form non-covalent complexes with OA and UA for their discrimination. |
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