The JARID1B TR-FRET Assay Kit is designed to measure activity of JARID1B in a homogeneous 384 reaction format. This FRET-based assay requires no time-consuming washing steps, making it especially suitable for high throughput screening applications. The JARID1B TR-FRET Assay Kit comes in a convenient format, with histone H3 peptide substrate, a Eu-labeled antibody against methylated K4 residue of Histone H3, demethylase assay buffer, TR-FRET detection buffer, dye-labeled acceptor, and purified JARID1B for 384 enzyme reactions. The key to the JARID1B Assay Kit is a highly specific antibody that recognizes demethylated substrate. With this kit, only three simple steps on a microtiter plate are required for demethylase activity detection. First, a sample containing JARID1B enzyme is incubated with the biotinylated substrate. Next, antibody is added. Finally, dye-labeled acceptor is added followed by fluorescence reading.