Prostate Specific Antigen (PSA, EC 3.4.21.77), or Kallikrein-related peptidase 3, is a serine protease. It proteolyses the Semenogelin I and Semenogelin II of seminal fluid and thus liquefies it. PSA also shows antiangiogenic activity. The significance of the level of enzymatically active PSA is emerging in diagnosis and prognosis of prostate cancer. Growing number of evidence suggests that PSA plays an important role in prostate tumor growth, invasion and metastasis. Assay Genie's PSA Activity Assay Kit enables the research in this field. This kit utilizes the ability of an active PSA to cleave a synthetic AMC based peptide substrate to release a free fluorophore. The released AMC can be easily quantified using a fluorescent microplate reader. This assay kit is simple and can be used in a high-throughput format. This assay can detect as low as 1 ng of purified active PSA.