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预期应用
ELISA法定量测定兔血浆或其它相关液体中TAFI活性。
实验原理
本试剂盒应用双抗体夹心酶标免疫分析法测定标本中TAFI水平。用纯化的抗体包被微孔板，制成固相抗体，往包被单抗的微孔中依次加入TAFI抗原、生物素化的抗兔TAFI抗体、HRP标记的亲和素，经过彻底洗涤后用底物TMB显色。TMB在过氧化物酶的催化下转化成蓝色，并在酸的作用下转化成最终的黄色。颜色的深浅和样品中的TAFI呈正相关。用酶标仪在450nm波长下测定吸光度（OD值），计算样品浓度。
Intended use
This immunoassay kit allows for the specific measurement of rabbit TAFI concentrations in cell culture supernates, serum, and plasma.
Introduction
TAFI, Thrombin Activatable Fibrinolytic Inhibitor, (also known as carboxypeptidase U and plasma carboxypeptidase B) is a 60,000 D molecular ratio glycoprotein (proenzyme form) present in rabbit plasma1 that modulates fibrinolysis in vivo. This proenzyme is converted to a 35,000 D molecular ratio active form, TAFIa, following proteolytic cleavage by the thrombin/ thrombomodulin complex. TAFIa possesses carboxypeptidase activity with a preference for cleaving lysine and arginine residues from the c-terminus of proteins. Modulation of fibrinolysis occurs when TAFIa cleaves C-terminal arginine and lysine residues of partially degraded fibrin.2,4,5 The removal of the c-terminus arginine and lysine residues from fibrin inhibits the continued degradation of fibrin by tPA activated plasmin.3
Plasma also contains carboxypeptidase N (CPN), which has enzymatic activity similar to that of TAFI. The total carboxypeptidase activity in plasma is found to be TAFI + CPN. TAFI, but not CPN, is inhibited by potato tuber carboxypeptidase inhibitor (PTCI). The ability of PTCI to selectively inhibit TAFI is used to determine that portion of the total carboxypeptidase activity contributed by TAFI.
TAFI may play a central role in thrombosis and fibrinolysis due to its ability to retard fibrin clot lysis3. Therefore, accurate quantitation of TAFI levels in plasma may provide important information in the understanding and diagnosis of vascular and heart diseases and stroke.
Test principle
This assay employs the quantitative sandwich enzyme immunoassay technique. A monoclonal antibody specific for TAFI has been pre-coated onto a microplate. Standards and samples are pipetted into the wells and any TAFI present is bound by the immobilized antibody. An enzyme-linked monoclonal antibody specific for TAFI is added to the wells. Following a wash to remove any unbound antibody-enzyme reagent, a substrate solution is added to the wells and color develops in proportion to the amount of TAFI bound in the initial step. The color development is stopped and the intensity of the color is measured.
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