Description
Introduction: Tissue factor pathway inhibitor (or TFPI) is a single-chain polypeptide which can reversibly inhibit Factor Xa (Xa) and Thrombin (Factor IIa). While Xa is inhibited, the Xa-TFPI complex can subsequently also inhibit the FVIIa-TF complex. TFPI contributes significantly to the inhibition of Xa in vivo, despite being present at concentrations of only 2.5 nM. The gene for TFPI is located on chromosome 2q31-q32.1, and has nine exons which span 70 kb. The gene has not been completely sequenced yet. A similar gene, termed TFPI2, has been identified on chromosome 7q22; in addition to TFPI activity, its product also has retinal pigment epithelial cell growth-promoting properties. Tissue factor pathway inhibitor 2 is a protein that in humans is encoded by the TFPI2 gene.
Principle of the Assay: The microtiter plate provided in this kit has been pre-coated with an antibody specific to TFPI-2. Standards or samples are then added to the appropriate microtiter plate wells with a biotin-conjugated antibody preparation specific for TFPI-2 and Avidin conjugated to Horseradish Peroxidase (HRP) is added to each microplate well and incubated. Then a TMB (3,3',5,5' tetramethyl-benzidine) substrate solution is added to each well. Only those wells that contain TFPI-2, biotin-conjugated antibody and enzyme-conjugated Avidin will exhibit a change in color. The enzyme-substrate reaction is terminated by the addition of a sulphuric acid solution and the color change is measured spectrophotometrically at a wavelength of 450 nm +/- 2 nm. The concentration of TFPI-2 in the samples is then determined by comparing the O.D. of the samples to the standard curve