Prostate specific antigen (PSA), a neutral serine protease with chymotrypsin-like activity, is composed of a single polypeptide chain of 237 amino acids. It is an intracellular glycoprotein containing 7-8% carbohydrate as a single N-linked oligosaccharide side chain and has a molecular weight of approximately 34,000 Da. PSA is exclusively synthesized by the prostate epithelium and mainly released into the semen. Normally very small amounts of PSA are secreted and detected in male blood. The elevated levels of PSA in male blood are known to be associated with some prostatic disorders such as prostatitis, benign prostatic hyperplasia (BPH) or prostate cancer.