In this study, we determined the crystal structure of an engineered human adenosine A2A receptor bound to a partial agonist and compared it to structures cocrystallized with either a full agonist... Show moreIn this study, we determined the crystal structure of an engineered human adenosine A2A receptor bound to a partial agonist and compared it to structures cocrystallized with either a full agonist or an antagonist/inverse agonist. The interaction between the partial agonist, belonging to a class of dicyanopyridines, and amino acids in the ligand binding pocket inspired us to develop a small library of derivatives and assess their affinity in radioligand binding studies and potency and intrinsic activity in a functional, label-free, intact cell assay. It appeared that some of the derivatives retained the partial agonist profile, whereas other ligands turned into inverse agonists. We rationalized this remarkable behavior with additional computational docking studies. Show less
The present thesis focuses on the pharmacological concept of drug-target interaction, which dates back to the beginning of modern pharmacology. A traditional equilibrium metrics-based... Show moreThe present thesis focuses on the pharmacological concept of drug-target interaction, which dates back to the beginning of modern pharmacology. A traditional equilibrium metrics-based rationale (i.e. optimization of drug affinity leads to better efficacy and safety) is unable to prevent current high attrition rates in the early phase of drug discovery. In the past decade drug-target binding kinetics (i.e. association and dissociation rate constants, residence time) has been gaining more and more attention, which constitutes a paradigm shift to better predict parameters of drug efficacy and safety. We decided to investigate binding kinetics of G protein-coupled receptors (GPCR), since GPCR are involved in various critical physiological and pharmacological functions, being the target of about 30% of all drugs on the market. Both the human cannabinoid receptor 1 and the human adenosine A1 and A3 receptors were chosen as prototypical GPCR as well as potential drug targets. The binding kinetics investigations described in this thesis provide a better and multi-faceted understanding of drug-target interactions and offer suggestions for the design of better ligands with an appropriate kinetic profile, new technologies for rapid kinetic assessment, and ultimately suitable evaluation schemes for a better translation towards effective and safe drugs. Show less
