Study On The Interaction Of Hterocyclic Comounds With Protease

Proteins are main executors in the life processes owing to the important role in the main activities of life.Meanwhile,heterocyclic compounds are selected as drugs because of their special physiological activity.The interaction protein molecule with heterocyclic compounds acts on the active site of the protein and generates physiologically active complexes.Changing the structure of the protein could be affected their functions.Once entering human body,the drug could change the conformation of digestion enzymes and alter the function of protein.Much efforts have been devoted to the interactions between heterocyclic compounds and digestion enzymes.Hence,we have designed the desired indole derivative and fanatizole from available mater ials to investigate the interaction between heterocyclic compounds and trypsin and pepsin.Finally,punicalagin was applied to the interaction with pepsin.The interaction was investigated by molecular docking methods and several spectroscopic techniques,which confirmed the mechanistic of interaction.The main chapters are summarized as follows:1.We have developed an easy and efficient route for the construction of fanetizole from phenylethylene and thiocarbamide.Data obtained by fluorescence spectroscopy indicated that quenching mechanism was the feature recognition of static quenching.Then,thermodynamic analysis of binding forces showed that the binding activity of trypsin-fanetizole was stronger than the system of pepsinfanetizole due to the difference of their structure.In addition,the hydrophobic force seemed to be main acting force between pepsin/trypsin and fanetizole.Analysis of molecular docking revealed the difference of two system,which provide the theoretical basis for the interaction between drug and protein.2.The Pd catalyzed oxidative cascade reaction delivered the desired 4b-phenyl-4b,13-dihydrobenzo [c] indolo [2,3-a] carbazole(PDIC).Firstly,different spectroscopic technique were applied to investigate the binding activity of pepsin-PDIC,affording the thermodynamic data.Transient fluorescence confirmed that the static quenching was observed in above system.The results obtained from CD and FTIR demonstrated that PDIC caused an decrease in the ?-sheet content of pepsin,and a conformational change of pepsin happened.Finally,molecular docking showed the primary binding site of pepsin-PDIC,affording the important model of heterocyclic compound and pepsin.3.The binding of punicalagin and pepsin was investigated by the fluorescence,circular dichroism(CD),transient fluorescence,fourier transform infrared spectroscopy(FT-IR)and the molecular modelling study.The data from the fluorescence and transient fluorescence confirmed that the feature recognition of static quenching was obtained.The binding parameters,primary binding site and the thermodynamic data were achieved by the control experiments,which confirmed the types of action in the system.The interaction of punicalagin with pepsin could induce the changes of secondary structure of pepsin by UV and FT-IR.In addition,the thermodynamic functions for this system indicated that hydrogen bond interaction and Van der Waals force involved the above process.Subsequently,the data of circular dichroism showed that the interaction of punicalagin and pepsin effected on pepsin conformation.In addition,the docking showed the primary binding site of pepsin-punicalagin,providing the theoretical bas is on the reaction of pepsin and heterocyclic compounds.