IDO/TDO Inhibitor Mechanism of Action Screening Services


BPS is now offering IDO1 and TDO Inhibitor Mechanism of Action Screening Services to complement its suite of biochemical and cell-based
screening and profiling services for this hot immunotherapy target. As an example, using our standard IDO1 absorbance-based assay kit (BPS Cat. #72021) and a modified protocol, one can distinguish between reversible and irreversible inhibitors. The protocol modification
involves pre-incubating the enzyme with a large amount of inhibitor. Then, through a large dilution of inhibitor (well below IC50), the
enzymatic activity is restored if the inhibitor is reversible, whereas an irreversible inhibitor will maintain inhibition after the dilution as
shown in the figure below. This same modified protocol can be applied to TDO inhibitors.                                               


Assay Description: The compounds were diluted in DMSO and pre-incubated with IDO1 in the absence of substrate, then
diluted into reaction solution containing substrate, the coupled reaction components, and the indicated concentrations of
inhibitor. The reaction mixture incubated at room temperature reading UV absorption signal every 5 min.

The controls included are the negative control (NC), in which assay buffer was added instead of IDO1, (PC) no inhibitor
throughout to reflect full enzyme activity at the amount of DMSO tested, (0.3x) 0.3×IC50 throughout to reflect the expected
amount of inhibition remaining after dilution (if fully and rapidly reversible) and (10x) 10×IC50 throughout to achieve 100%
inhibition (and signal expected for irreversible inhibition). The (test) conditions were pre-incubated at 10×IC50 and then diluted
to 0.3×IC50.

Also, our services portfolio is always expanding. Visit our Cell Based Immunotherapy Screening Services page for the latest additions. 

Cell Based Assays Services Directory