TAFI Activity assay (incl. Controls and Calibrator)
INTENDED USE
The TAFI Activity assay is a plasma based chromogenic assay for the determination of Thrombin Activatable Fibrinolysis Inhibitor (TAFI) enzyme activity.
INTRODUCTION
TAFI (Thrombin Activatable Fibrinolysis Inhibitor) is a proenzyme similar to carboxypeptidase B and is activated to TAFIa by thrombin and probably plasmin [1,2]. Thrombomodulin accelerates TAFI activation about 1250 times. TAFIa is an important inhibitor of fibrinolysis by cleaving C-terminal lysine and arginine residues in the fibrin clot. Thereby the carboxy-terminal plasminogen binding sites in the fibrin clot are degraded, plasminogen activation by t-PA and in consequence fibrinolysis is most effectively inhibited [3,4,5,6]. High levels of TAFIa may be an indication for thrombotic risk [7,8,9,10]. Properties of TAFI:
• Plasma concentration: 4–15 μg/ml
• Molecular weight: 55 kDa (401 aa, glycoprotein containing zinc)
• Conversion to TAFIa: by cleavage at Arg-92 to a 36 kDa peptide
• Mode of action of TAFIa: basic carboxypeptidase, cleaves C-terminal lysine and more specifi cally
arginine residues. Inhibition of fibrinolysis by removal of plasminogen binding sites in the fibrin clot.
• Stability of TAFIa: from several hours at 22 °C to 10 min at 37 °C by conformational instability.
PRINCIPLE OF THE METHOD
The synthetic substrate is a substituted peptide mimetic consisting of an amino-protected L-lysine connected with an L-arginine of which the α-position of the side chain is a sulphur atom. It is degraded selectively and irreversibly by TAFIa producing a thiol derivative. This thiol reacts chemically with the colourless Ellman’s reagent (5,5’-Dithio-bis-(2-nitrobenzoic acid), DTNB) splitting off the yellow coloured 5-mercapto-2-nitro-benzoic acid. The extinction measurable at the wavelength of 405 nm at the end of the enzymatic reaction is directly proportional to the concentration of TAFI activated by thrombin/thrombomodulin.
Category: Research use only
Type: Activity assay
Product Availability: Worldwide
Manufacturer: ImmBioMed GmbH & Co KG, Germany
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TAFI Activity assay (incl. Controls and Calibrator)
Cat.No. ADG871
Article no.: 938608
Unit: 80 Tests
Code: ADG871
Manufacturer: ImmBioMed GmbH & Co. KG
BIBLIOGRAPHY
- Purification and characterization of TAFI, a thrombin-activatable fibrinolysis inhibitor. Bajzar L et al., J Biol Chem 1995; 270:14477-84
- Purification and characterization of a novel carboxypeptidase B from human plasma. Hendriks D et al., Biochim Biophys Acta 1990; 1034:86- 92
- Plasma carboxypeptidases as regulators of the plasminogen system. Redlitz A et al., J Clin Invest 1995; 96:2534-8
- The profibrinolytic effect of activated protein C in clots formed from plasma is TAFI-dependent. Bajzar L et al., Blood 1996; 88: 2093-100
- On the mechanism of the antifi brinolytic activity of plasma carboxy-peptidase B. Sakharov DV et al., J Biol Chem 1997; 272: 14477-82
- A study of the mechanism of inhibition of fi brinolysis by activated thrombin-activatable fibrinolysis inhibitor. Wang W et al., J Biol Chem 1998; 273:27176-81
- Thrombin activatable fibrinolysis inhibitor and the risk for deep vein thrombosis. van Tilburg NH et al., Blood 2000; 95:2855-9
- Plasma procarboxypeptidase U in men with symptomatic coronary artery disease. Silveira A, et al., Thromb Haemost 2000; 84: 364-8
- Thrombin activatable fibrinolysis inhibitor (TAFI) levels in patients with coronary artery disease investigated by angiography. Schroeder V, et al., Thromb Haemost 2002; 88: 1020-5
- Plasma thrombin-activatable fibrinolysis inhibitor antigen concentration and genotype in relation to myocardial infarction in the north and south of Europe. Juhan-Vague I et al., Aterioscler Thromb Vasc Biol 2002; 22:867-73
- National Committee for Clinical Laboratory Standards. Collection, transport and processing of blood specimens for coagulation testing and performance of coagulation assays. NCCLS Document H21-A2; vol 11 No 23.
- The profibrinolytic effect of activated protein C in clots formed plasma is TAFI-dependent. Bajzar L, et al., Blood 1996; 88:2093-100
- An inhibitor of activated thrombin-activatable fibrinolysis inhibitor potentiates tissue-type plasminogen activator-induced thrombolysis in a rabbit jugular vein thrombolysis model. Nagashima M, et al., Thromb Res 2000; 98:333-42