AssayPro—Human Factor XII(FXII

Introduction
Human coagulation factor XII (FXII), Hageman factor, is a plasma serine protease existing in the zymogen form. Upon contacting with negatively charged artificial or biologic surfaces, FXII is autoactivated into FXIIa that initiates intrinsic blood coagulation, fibrinolysis, and activation of the inflammatory kallikrein-kinin and complement systems (1 - 3). FXII has 615 amino acids, weighs 80 kDa, and circulates in normal plasma at a concentration of 30 μg/ml (4 - 5). It is a multidomain protein with structure similarity to EGF, single chain urokinase, and tissue plasminogen activator. In the intravascular compartment, FXII binds to endothelial cell urokinase plasminogen activator receptor, cytokeratin 1, and the complement receptor (6). FXII deficiency or blockade protects from cerebral ischemia without overtly affecting hemostasis. FXII inhibition could be a novel target for safer anticoagulation and stroke prevention without the side effect of increased bleeding (7 - 8).

Principle of the Assay
The AssayMax Human Factor XII (FXII) ELISA kit is designed for detection of human Factor XII in plasma, serum, milk, urine, and cell culture supernatants. This assay employs a quantitative sandwich enzyme immunoassay technique that measures FXII in less than 4 hours. A murine antibody specific for FXII has been pre-coated onto a 96-well microplate with removable strips. FXII in standards and samples is sandwiched by the immobilized antibody and the biotinylated polyclonal antibody specific for FXII, which is recognized by a streptavidin-peroxidase conjugate. All unbound material is then washed away and a peroxidase enzyme substrate is added. The color development is stopped and the intensity of the color is measured.