The MLL1 Complex Direct Activity Chemiluminescent Assay kit is designed to measure MLL1 activity for screening and profiling applications, using purified MLL1 and its complex components: WDR5, RbBP5,Ash2, and DPY30. The key to the MLL1 Complex Chemiluminescent Assay Kit is a highly specific antibody that recognizes methylated K4 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 the addition of the HRP substrate to produce chemiluminescence that can be measured using a chemiluminescence reader.