STD-NMR experiments on tumor cells to investigate RGD ligand - membrane protein interactions

NMR experiments (transferred NOE and Saturation Transfer Difference) were used to shed light on the binding epitope of a small library of DKP - RGD peptidomimetics with integrin alphavbeta3, expressed on the membrane of ECV304 bladder cancer cells. The NMR results were supported by docking calculations of these ligands in the active sites of alphavbeta3 integrin receptor and were compared to the results of competitive alphavbeta3 receptor binding assays and competitive ECV304 cell adhesion experiments. The different stereochemistry and the different substitution at the nitrogen atoms of the scaffold strongly influences the conformations adopted in the free-state and the binding mode of these ligands in the active site of the integrin receptor.