CHEMBL5736996

Menin Binding Affinity: A fluorescence polarization (FP) competitive binding assay was used to determine the binding affinities of representative menin inhibitors. A FAM labeled fluorescent probe was designed and synthesized based on a MLL1 peptide (FAM-MM2). Equilibrium dissociation constant (Kd) value of FAM-MM2 to menin protein was determined from protein saturation experiments by monitoring the total fluorescence polarization of mixtures composed with the fluorescent probe at a fixed concentration and the protein with increasing concentrations up to full saturation. Serial dilutions of the protein were mixed with FAM-MM2 to a final volume of 200 μl in the assay buffer (PBS with 0.02% Bovine γ-Globulin and 4% DMSO. 0.01% Triton X-100 was added right before assays). Final FAM-MM2 concentration was 2 nM. Plates were incubated at room temperature for 30 minutes with gentle shaking to assure equilibrium. FP values in millipolarization units (mP) were measured using the Infinite M-1000 plate reader (Tecan U.S., Research Triangle Park, N.C.) in Microfluor 1 96-well, black, v-bottom plates (Thermo Scientific, Waltham, Mass.) at an excitation wavelength of 485 nm and an emission wavelength of 530 nm. Kd value of FAM-MM2, which was calculated by fitting the sigmoidal dose-dependent FP increases as a function of protein concentrations using Graphpad Prism 6.0 software (Graphpad Software, San Diego, Calif.), was determined as 1.4 nM.