K7432-100? Microwells coated with f-PSA MAb ? f-PSA Standard ? Anti-f-PSA Conjugate Reagent ? Wash Buffer (20X) ? TMB Substrate ? Stop Solution Serum Prostate Specific Antigen (Free, human) ELISA Kit: Rapid & convenient colorimetric assay for quantitative measurement of human free Prostate Specific Antigen. Sensitivity: 0.1 ng/ml. 100 assays. Human Prostate Specific Antigen (PSA) is a 33 kD serine proteinase which, in human serum, is predominantly bound to alpha 1-antichymotrypsin (PSA-ACT) and alpha 2-macroglobulin (PSAAMG). Trace amounts of alpha 1-antitrypsin and inter-alpha trypsin inhibitor bound to PSA can also be found. Any remaining PSA is in the free form (f-PSA). 1-3 Current methods of screening men for prostate cancer utilize the detection of the major PSA-ACT form. Levels of 4.0 ng/ml or higher are strong indicators of the possibility of prostatic cancer.4 However, elevated serum PSA levels have also been attributed to benign prostatic hyperplasia and prostatitis, leading to a large percentage of false positive screening results.5 A potential solution to this problem involves the determination of free PSA levels.6-17 Preliminary studies have suggested that the percentage of free PSA is lower in patients with prostate cancer than those with benign prostatic hyperplasia.2 Thus, the measurement of free serum PSA in conjunction with total PSA, can improve specificity of prostate cancer screening in selected men with elevated total serum PSA levels, which would subsequently reduce unnecessary prostate biopsies with minimal effects on cancer detection rates. BioVision’s free-PSA kit is a solid phase direct sandwich ELISA method. The samples and diluted anti-f-PSA-HRP conjugate are added to the wells coated with MAb to f-PSA. The f-PSA molecules present in the standard solution or sera are "sandwiched" between the two antibodies. Following the formation of the coated antibody-antigen-antibody-enzyme complex, the unbound protein and HRP-conjugate are washed off by wash buffer. Upon the addition of the substrate, the intensity of color is proportional to the concentration of f-PSA. Sensitivity: 0.1 ng/ml