Assay Method Information

Assay Name:  G9a Enzyme Activity Assay
Description:  The biochemical assay to measure G9a enzyme activity relies on time-resolved fluorescence energy transfer (TR-FRET) between europium cryptate (donor) and XL665 (acceptor). TR-FRET is observed when biotinylated histone monomethyl-H3K9 peptide is incubated with cryptate-labeled anti-dimethyl-histone H3K9 antibody (CisBio Cat#61KB2KAE) and streptavidin XL665 (CisBio Cat#610SAXLA), after enzymatic reaction of G9a.The human G9a enzyme expressed in a baculovirus infected Sf9 cell expression system was obtained from BPS Biosciences (Cat. #51001). Enzyme activity assay was carried out in a white 384-well plate in a final volume of 20 μl, as follow: 4 μl of vehicle or studied compound 2.5× concentrated prepared in assay buffer (50 mM Tris-HCl, 10 mM NaCl, 4 mM DTT, 0.01% Tween-20 pH9). Final percentage of DMSO was 0.5%. 2 μl of 1 nM G9a enzyme diluted in assay buffer. Final concentration was 0.2 nM. Start the reaction by adding 4 μl of substrate mixture containing 20 μM S-adenosylmethionine and 40 nM biotinylated histone monomethyl-H3K9 peptide. Reaction was carried out during 1 hour at room temperature. Enzyme activity was stopped by adding 5 μl of cryptate-labeled anti-dimethyl-histone H3K9 antibody. Final concentration 150 nM. Then, add 5 μl of streptavidin XL665 beads. Final concentration of 16 μM. Read the plate after 1 hour of incubation at room temperature.For each well, fluorescence was measured at 620 nm and 665 nm. A ratio (665 nm/620 nm) was then calculated in order to minimize medium interferences. Positive control was obtained in the presence of the vehicle of the compounds. Negative control was obtained in the absence of G9a enzyme activity. Calculated IC50 values were determined using GraphPrism using 4-parameters inhibition curve.
Affinity data for this assay
 

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