K7431-100? Microwells coated with Streptavidin ? PSA Standard* ? Anti-PSA Conjugate Reagent ? Wash Buffer (20X) ? TMB Substrate ? Stop Solution Serum Prostate Specific Antigen (Total, human) ELISA Kit: Rapid & convenient colorimetric assay for quantitative measurement of human total Prostate Specific Antigen. Sensitivity: 0.0144 ng/ml. 100 assays. Prostate Specific Antigen (PSA) is useful in the management of patients with prostate cancer. It is a single chain glycoprotein produced by epithelial cells of the prostate gland. The measurement of serum PSA has become the most accepted test to indicate men who are at risk of having prostate cancer and who should be examined by other tests. Using a cut-off of 4 ng/ml, 92% of men over 50 years of age with malignant prostatic tissues, 8% of healthy men and 28% of men with benign prostate hyperplasia (BPH) test positive for PSA. Three major forms of PSA exist in the serum: free PSA, bound PSA and complex PSA. Bound PSA is found in higher concentrations in patients with prostate cancer; whereas, free PSA is detected in higher concentrations in patients with BPH. If the free PSA to total PSA ratio is >25%, it is unlikely that the patient has prostate cancer; whereas, if free PSA is <16% then prostate cancer is likely to be the cause. Serial measurement of PSA concentration in the serum is an important tool in monitoring patients with prostatic cancer and determining the potential and actual effectiveness of surgery or other therapies, or may allow for earlier discovery of residual or recurrent carcinoma after radical prostatectomy or radiotherapy. BioVision’s PSA ELISA kit is a solid phase assay based on a streptavidin-biotin principle. The standards, samples and a reagent mixture of Anti-PSA Enzyme and Biotin conjugates (conjugate reagent) are added into the wells, coated with Streptavidin. PSA in the serum sample forms a sandwich between two highly specific Anti-PSA antibodies, labeled with Biotin and HRP. Simultaneously, the biotinylated antibody is immobilized onto the well through a high affinity Streptavidin-Biotin interaction. Unbound protein and excess biotin/enzyme conjugated reagent are washed off, by washing buffer. Upon the addition of the substrate, the intensity of color developed is directly proportional to the concentration of PSA in the samples. A standard curve is prepared relating color intensity to the concentration of the PSA.