AssayPro—Human Complement Fact

Introduction
Complement Factor I (FI), known as C3b/C4b inactivator, is a glycosylated plasma serine proteinase of complement regulatory enzyme. FI is synthesized as a 583-residue single-chain precursor (88 kDa) which is processed into a heterodimer consisting of disulfide-linked heavy (50 kDa) and light (38 kDa) chains (1, 2). It circulates in an inactive zymogen-like state despite being fully processed to the 321-residue mature protein (3). In the presence of additional regulatory cofactors such as C4b-binding protein, factor H, complement receptor 1, and membrane cofactor protein, FI can cleave and inactivate the complement components C3b and C4b to regulate the levels of C3 convertases. FI deficiency is associated with atypical hemolytic uraemic syndrome, primary glomerulonephritis, and recurrent pyogenic infections (4, 5).

Principle of the Assay
The AssayMax Complement Factor I ELISA (Enzyme-Linked Immunosorbent Assay) kit is designed for detection of complement factor I in plasma, serum, milk, saliva, and cell culture supernatant. This assay employs a quantitative competitive enzyme immunoassay technique that measures factor I in less than 3 hours. A polyclonal antibody specific for factor I has been pre-coated onto a 96-well microplate with removable strips. Factor I in standards and samples is competed with a biotinylated factor I sandwiched by the immobilized antibody and 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.