RESUMO
The p53 pathway is inactivated in almost all types of cancer by mutations in the p53 encoding gene or overexpression of the p53 negative regulators, Mdm2 and/or Mdmx. Restoration of the p53 function by inhibition of the p53-Mdm2/Mdmx interaction opens up a prospect for a nongenotoxic anticancer therapy. Here, we present the syntheses, activities, and crystal structures of two novel classes of Mdm2-p53 inhibitors that are based on the 3-pyrrolin-2-one and 2-furanone scaffolds. The structures of the complexes formed by these inhibitors and Mdm2 reveal the dimeric protein molecular organization that has not been observed in the small-molecule/Mdm2 complexes described until now. In particular, the 6-chloroindole group does not occupy the usual Trp-23 pocket of Mdm2 but instead is engaged in dimerization. This entirely unique binding mode of the compounds opens new possibilities for optimization of the Mdm2-p53 interaction inhibitors.
Assuntos
4-Butirolactona/análogos & derivados , Mapas de Interação de Proteínas/efeitos dos fármacos , Proteínas Proto-Oncogênicas c-mdm2/antagonistas & inibidores , Pirróis/química , Pirróis/farmacologia , Proteína Supressora de Tumor p53/antagonistas & inibidores , 4-Butirolactona/química , 4-Butirolactona/farmacologia , Cristalografia por Raios X , Desenho de Fármacos , Humanos , Modelos Moleculares , Conformação Proteica , Multimerização Proteica/efeitos dos fármacos , Proteínas Proto-Oncogênicas c-mdm2/química , Proteínas Proto-Oncogênicas c-mdm2/metabolismo , Relação Estrutura-Atividade , Proteína Supressora de Tumor p53/química , Proteína Supressora de Tumor p53/metabolismoRESUMO
Interactions between bovine and goat ß-lactoglobulin and tetracaine and pramocaine were investigated with isothermal titration calorimetry, X-ray crystallography and molecular modelling. Tetracaine and pramocaine binding to lactoglobulin is an entropy driven endothermic reaction. In this work, we found that determined association constants and thermodynamic parameters indicate that pramocaine has a higher affinity to lactoglobulin than tetracaine. Crystal structures that were determined with resolutions in the range from 1.90 to 2.30 Å revealed in each case the presence of a single drug molecule bound in the ß-barrel in a mode similar to that observed for 14- and 16-carbon fatty acids. The position of the ligand in the ß-barrel indicates the optimal fit of 6-carbon aromatic rings to the binding pocket and the major role of hydrophobic interactions in ligand binding. Calculations of tetracaine and pramocaine docking to lactoglobulin revealed that molecular modelling overestimated the role of polar protein-drug interactions.
