CHEMBL5734835

Enzyme Assay: HIS-tagged IDO1 protein was recombinantly expressed in Escherichia coli using ZYP5052 autoinduction media supplemented with 500 uM delta aminolevulinic acid for 48 h at 16° C. IDO1 protein was purified using Ni2+-affinity resin and size exclusion chromatography. Purified protein was then diluted in assay buffer (50 mM Tris pH 7.0, 1% glycerol, 20 uM methylene blue, 0.05% Tween-20, 20 mM sodium ascorbate, 100 units/mL catalase to obtain a final IDO1 concentration of 40 nM. IDO1 solution (30 uM) or buffer alone (30 uM) were dispensed to wells of the assay plate using a BioRAPTR liquid dispenser (Beckman Coulter). Assay plates containing compound and IDO1 enzyme were incubated at RT for 30 min. Afterwards, 10 uL of 400 uM tryptophan in assay buffer were added to each well of the assay plate using a BioRAPTR liquid dispenser. Plates were incubated at RT for 60 min and reactions were quenched by addition of 10 uL of 0.5 M methyl isonipecotate in dimethyl sulfoxide. Plates were sealed and incubated at 37° C. for 4 h or 50° C. for 2 h. The plates are allowed to cool and then centrifuged for 1 min at 1000 ug. The resulting fluorescence was measured in an Envision plate reader (Perkin Elmer) with a 400/25 nm excitation filter and an 510/20 nm emission filter.