The p300 Chemiluminescent Assay Kit is an enzyme-linked immunosorbent assay (ELISA) designed to screen for inhibitors of p300 or to measure histone acetyltransferase (HAT) activity for screening and profiling applications. Histone acetyltransferase p300 (also known as KAT3B) is involved in various cellular events, and its dysfunction is linked to a number of human diseases including Parkinson's, Huntington's, and Alzheimer's diseases. The P300 Chemiluminescent Assay Kit is based on the p300 enzyme transferring an acetyl group from an acetyl donor (acetyl CoA) to a histone substrate. The acetylated histone is recognized by a highly specific primary antibody, followed by an HRP-labeled secondary antibody. The chemiluminescence produced by HRP can be measured using a chemiluminescence reader.