Chemical Library Screening Using a SPR-Based Inhibition in Solution Assay: Simulations and Experimental Validation

摘要

We have developed a surface plasmon resonance (SPR)-based inhibition in solution assay (ISA) to search for inhibitors of the medium affinity (K_D = 0.8 μM) interaction between an E6-derived peptide (E6_(peptide)) immobilized on the sensor and a PDZ domain (MAGI-1 PDZ1) in the mobile phase. DZ domains are widespread protein-protein interaction modules that recognize the C-terminus of various partners. Simulations indicated that relatively low compound concentrations (10 μM) and limited peptide densities (R_(max) < 200 resonance units) should allow the detection of inhibitors with a target affinity close to 100 μM, which was then demonstrated experimentally. ISA screening, carried out on the Prestwick Chemical Library (1120 compounds), identified 36 compounds that inhibited the interaction by more than 5%. Concentration-dependent ISA, carried out on a subset of 19 potential inhibitors, indicated that 13 of these indeed affected the interaction between MAGI-1 PDZ1 and the E6_(peptide). No effect was observed for 84 compounds randomly chosen among noninhibitors. One of the four best inhibitors was a peptide binder, and three were PDZ binders with K_D in the 10-50 μM range. We propose that a medium (μM) affinity between the target and surface-bound partner is optimal for SPR-based ISA screening.