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Modeling Kinetics of Protein-Ligand Systems

Time: Wed 2020-06-03 10.00

Location: ​, Stockholm (English)

Subject area: Theoretical Chemistry and Biology

Doctoral student: Yang Zhou , Teoretisk kemi och biologi

Opponent: Professor David van der Spoel,

Supervisor: Lektor Yaoquan Tu, Teoretisk kemi och biologi; Professor Hans Ågren, Teoretisk kemi och biologi, Bioteknologi, Kemi, Albanova VinnExcellence Center for Protein Technology, ProNova

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Protein-ligand interactions dominate many life activities and are crucial for thedevelopment of tracers for diagnosing diseases and drugs for treating diseases.For protein-ligand interactions, the binding affinity is conventionally believedto be the most important indicator. However, there is increasing evidencethat the binding affinity alone is not sufficient for providing comprehensiveinformation about protein-ligand interactions. Kinetics, which describes theduration of the interactions and is closely related to the interaction mechanism,is considered as important as, or even more important than, the binding affinityin the study of the mechanisms of protein-ligand interactions.Although kinetics parameters of a protein-ligand system can be measuredexperimentally, the underlying molecular mechanism for the kinetics is difficultto reveal by experiment, which is, however, essential for understanding theorigin of the kinetics and for the rational design of drugs or tracers. In the lastdecade, computer simulations have emerged as a powerful tool for studying biomolecularsystems. Computer simulation methods have also been developedfor modeling kinetics of protein-ligand systems.In this thesis, I explored computer simulations for modeling kinetics propertiesof four different protein-ligand systems. In paper I, I studied the relationshipbetween the ligand binding and conformational changes of the ATAD2-BRD protein. In paper II, I investigated the free energy profile for the coupledfolding and binding of the intrinsically disordered protein p53 with MDM2and calculated the rate constants for the binding and unbinding processes. Inpaper III, I revealed the unbinding paths of the PET tracer ASEM from the  a7-nAChR, calculated the unbinding rate, and explored a way of how to findthe key protein conformational changes strongly coupled to the ligand unbindingprocess. In paper IV, I further refined our methodology for finding theunbinding paths and clarified the unbinding mechanism of the metabolite ofraloxifene from the enzyme CYP3A4.