affinity biologicals/TAFI Antigen ELISA Kit/TAFI-AG

Description of TAFI

TAFI (Thrombin Activatable Fibrinolysis Inhibitor), also referred to as plasma procarboxypeptidase-B, procarboxypeptidase-U and R, circulates in plasma as a zymogen with a mass of 58,000 daltons. Proteolytic activation of TAFI yields an N-terminally derived activation peptide and the C-terminal portion corresponding to the metalloprotease, activated TAFI (TAFIa). TAFIa exhibits exopeptidase activity with carboxypeptidase B-like substrate specificity capable of catalyzing the hydrolysis of C-terminal lysine and arginine residues. Cleavage of these residues on fibrin by TAFIa attenuates clot lysis by inhibiting the formation of the ternary activation complex comprising fibrin cofactor, tPA and plasminogen, thereby inhibiting plasmin generation. Although TAFI can be activated by various proteases including thrombin and plasmin, the physiological activator is proposed to be the complex thrombin-thrombomodulin since the rate of activation is stimulated 1250-fold compared to thrombin alone¹. However, the rate of TAFI activation is highly dependent upon its plasma concentration. Since TAFIa apparently plays a key role in connecting coagulation and fibrinolysis and significantly increases clot stability, determination of plasma concentration of TAFI is likely crucial to assess its subsequent potential anti-fibrinolytic effects. This has been demonstrated in a report identifying high plasma concentration of TAFI as a risk factor for thrombosis².

References and Reviews

Bajzar, L., Morser, J., Nesheim, M.E. TAFI, or procarboxypeptidase B, couples the coagulation and fibrinolytic cascades through the thrombin-thrombomodulin complex. J.Biol.Chem. 271:16603-16608, 1996.

Van Tilburg, N.H., Rosendaal, F.R., Bertina R.M., Thrombin Activatable fibrinolysis inhibitor and the risk for deep vein thrombosis. Blood. 95:2855-2859, 2000.