CHEMBL5734209

In Vitro Measurements of human D-Amino Acid Oxidase (DAAO) Activities: The hDAAO (human DAAO) activity was measured by using D-serine as a substrate to produce H2O2. The produced H2O2 would be oxidized by peroxidase, and the produced free radicals would further react with Amplex Red reagent to emit fluorescence. The intensity of fluorescence at 590 nm would be measured to represent the activity of hDAAO. All compounds were dissolved in DMSO. Each compound was diluted with DMSO in 3-fold serial dilution to create a 9-point dose response curve. Each sample was added in triplicate, 1 μL/well, into 96-well black plates. Positive control wells were added with 1 μL of DMSO. Then 49 μL of assay buffer (100 mM Tris-HCl, pH 8.5) containing 1.2 ng/mL hDAAO, 900 nM FAD, 0.2 units/mL HRP, and 100 μM Amplex Red was added to each well of the plate using a multichannel pipette. Next, 50 μL of 100 mM D-Serine in assay buffer was added. The reaction plates were then incubated in the dark at room temperature. The fluorescence readout was detected at 0 and 20 minute by Molecular Device Gemini EM fluorescence reader using the following settings: excitation filter 530 nm, and emission filter 590 nm. The percentage of inhibition values for each well was calculated with the following equation:The percentage of inhibition=(fluorescencesample, 20 min−fluorescencesample, 0 min)/(fluorescenceDMSO, 20 min−fluorescenceDMSO, 0 min)×100%The nonlinear curve fitting model in GraphPad Prism 5 was used to calculate IC50 value for each compound.