Spectroscopic Investigation Of The Interaction Of Proteinswith Drugs And Analogs

In this thesis, the five group of interactions between proteins with drugs, include pepsin with three nucleoside analogues(cytidine, FNC and cytidine acid), human serum albumin with three nucleoside analogues(cytidine, FNC and cytidine monophosphate), bovine serum albumin with two compounds(w10, w22), FTO with diprophylline, pepsin with antipyrine and its analogues were studied under mimic physiological conditions by fluorescence spectroscopy, ultraviolet-visible spectroscopy, synchronous fluorescence spectroscopy, three-dimensional fluorescence spectroscopy and molecular modeling. The main research contents are as follows:(1) Introduction summarized the interaction between protein and micromolecule, common research methods, research content and significance of this study.(2) Investigated the interaction of pepsin with three nucleoside analogues(Cytidine, FNC and Cytidylic acid) under simulated physiological conditions. The results show that, three nucleoside analogs could quench the fluorescence by the formating of a compound with pepsin. Binding constants and thermodynamic parameters at three different temperatures were calculated. Electrostatic attraction and hydrophobic force played a major role in forming chemical bonds. The results showed that the strongest quencher is cytidine, it could bind pepsin with higher affinity than the other two nucleoside analogs. In FNC, F atom may weaken the binding of nucleoside analogues with pepsin.(3) Investigated the interaction of human serum albumin with three nucleoside analogues(cytidine, FNC and cytidylic acid) under simulated physiological conditions. The results show that the three nucleoside analogs can bind human serum albumin, and quench the intrinsic fluorescence by static quenching. The stability of the chemical bonds would decreases with the rising the temperature. Binding constants and thermodynamic parameters at three different temperatures were calculated. For FNC and cytidylic acid, hydrophobic interaction and electrostatic attraction played a major role in forming chemical bonds. While for cytidine, hydrophobic interaction dominates the formation of chemical bonds. The results show that cytidylic acid is the strongest quencher, it could bind human serum albumin with higher affinity than the other two nucleoside analogues binding to human serum albumin and higher affinity. The phosphate groups in cytidylic acid may enhance the binding of nucleoside analogues with human serum proteins.(4) Investigated the interaction of bovine serum albumin with two compounds(w10, w22) under simulated physiological conditions. The results showed that the quenching mechanism of both compounds with BSA is static quenching; interactions occured between two compounds with bovine serum albumin, and form a complex, which suggested the conformation of bovine serum albumin has changed; stability of the compound decreases with increasing temperature; binding constants and thermodynamic parameters at two different temperatures were calculated; hydrophobic interaction and electrostatic forces play an important role in the formation of the complex.(5) Investigated the interaction between FTO and diprophylline under simulated physiological conditions. The results showed that, the quenching mechanism of diprophylline with FTO is static quenching; diprophylline interacted with FTO, and formed complexes, thus the conformation of FTO has changed; stability of the complex decreases with increasing temperature; binding constants and thermodynamic parameters at three different temperatures were calculated; hydrophobic forces and electrostatic forces played an important role in the formation of the complexes.(6) Investigated the interaction of pepsin with antipyrine and its analogues under simulated physiological conditions. The results showed that, antipyrine and aminopyrine could quench intrinsic fluorescence of pepsin by static quenching, but for 4-aminoantipyrine, the quenching mechanism may be mixed quenching; antipyrine and aminopyrine interacted with pepsin, and formed complexes, thus the conformation of pepsin has changed, stability of the complex decreases with increasing temperature; binding constants and thermodynamic parameters at two different temperatures were calculated; hydrophobic forces and electrostatic forces played an important role in the formation of complexes.