The SUV39H2 Direct Activity Assay Kit is designed to measure SUV39H2 activity for profiling and screening applications, using purified SUV39H2. The SUV39H2 Direct Activity Assay Kit comes in a convenient format, with a 96-well plate precoated with histone H3 peptide substrate, the antibody against methylated lysine residue of Histone H3, the secondary HRP-labeled antibody, S-adenosylmethionine, methyltransferase assay buffer, and purified SUV39H2 enzyme for 100 enzyme reactions. The key to the SUV39H2 Activity Assay Kit is a highly specific antibody that recognizes methylated K9 residue of Histone H3. With this kit, only three simple steps on a microtiter plate are required for methyltransferase detection. First, S-adenosylmethionine is incubated with a sample containing assay buffer and methyltransferase enzyme for one hour. Next, primary antibody is added. Finally, the plates are treated with an HRP-labeled secondary antibody followed by addition of the HRP substrate is added to produce chemiluminescence that can then be measured using a chemiluminescence reader.