Assay Method Information

Assay Name:  IDH2 Enzymatic Assay
Description:  Compounds were assayed for IDH2 R140Q inhibitory activity through a cofactor depletion assay. Compounds were preincubated with enzyme, then the reaction was started by the addition of NADPH and α-KG, and allowed to proceed for 60 minutes under conditions previously demonstrated to be linear with respect for time for consumption of both cofactor and substrate. The reaction was terminated by the addition of a second enzyme, diaphorase, and a corresponding substrate, resazurin. Diaphorase reduces resazurin to the highly fluorescent resorufin with the concomitant oxidation of NADPH to NADP, both halting the IDH2 reaction by depleting the available cofactor pool and facilitating quantitation of the amount of cofactor remaining after a specific time period through quantitative production of an easily detected fluorophore.Specifically, into each of 12 wells of a 384-well plate, 1 μl of compound dilution series was placed, followed by the addition of 40 μl of buffer (50 mM potassium phosphate, pH 7.5; 150 mM NaCl; 10 mM MgCl2, 10% glycerol, 0.05% bovine serum albumin, 2 mM beta-mercaptoethanol) containing 1.25 μg/ml IDH2 R140Q. The compound was then incubated for one hour at room temperature with the enzyme; before starting the IDH2 reaction with the addition of 10 μl of substrate mix containing 50 μM NADPH and 6.3 mM α-KG in the buffer described above. After a further one hour of incubation at room temperature, the reaction was halted and the remaining NADPH measured through conversion of resazurin to resorufin by the addition of 25 μl Stop Mix (36 μg/ml diaphorase enzyme and 60 μM resazurin; in buffer). After one minute of incubation the plate was read on a plate reader at Ex544/Em590.
Affinity data for this assay
 

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