CHEMBL5737505

LSD1 Activity: Human recombinant LSD1 protein expressed in E. coli cells was purchased from Active Motif (Carlsbad, Calif.). Biotin-labeled Histone H3K4Me peptide (residues 1-21 with Lys 4 monomethylated) substrate was purchased from Anaspec (Fremont, Calif.). Enzymatic activity was assessed using the AlphaLISA technology from Perkin Elmer Life Sciences (Waltham, Mass.). 2.5 μL of compound solution and 5 μL of LSD1 solutions in the assay buffer (50 mM Tris, pH 9.0, 50 mM NaCl with 0.01% Tween20 and 1 mM DTT added right before the assay) were added into a white low volume 384 well microtiter plate. This mixture solution was incubated for 15 minutes with gentle shaking at room temperature. Demethylation reaction was initiated by adding 2.5 μL of Biotin-H3K4Me peptide substrate solution in the assay buffer. Final concentrations of LSD1, Biotin-H3K4Me peptide substrate, and DMSO were 4 nM, 80 nM, and 1%, respectively. The reaction was allowed to proceed for 60 minutes in dark with gentle shaking at room temperature, after which 5 μL of Anti-H3K4 AlphaLISA acceptor beads in detection buffer from the manufacturer was added into the reaction mixture followed by incubation for 60 minutes. 10 μL of Streptavidin labeled AlphaLISA donor beads in detection buffer was added into the mixture followed by 30-minute incubation. Final acceptor and donor beads concentrations were both at 10 μg/mL. Plates were read on a BMG CLARIOStar multimode plate reader from BMG Labtech (Ortenberg, Germany) with an excitation wavelength of 680 nm and emission wavelength of 615 nm. IC50 values of inhibitors were obtained by fitting the fluorescence intensity vs inhibitor concentrations in a sigmoidal dose-response curve (variable slope) with a non-linear regression using Prism 7 (La Jolla, Calif.).