Significance of different molecular forms of serum PSA. The free, noncomplexed form of PSA versus that complexed to alpha 1-antichymotrypsin
Prostate specific antigen is an abundant prostate-derived serine protease in the seminal fluid. Low concentrations of the protein are normally released into blood, but above normal concentrations are frequently detected in prostate disease. The PSA-ACT complex is the predominant molecular form of serum PSA (up to approximately 95%) although complex formation is slow between the purified proteins i