Method for measuring the activity of the blood clotting factor XIIIA

#The present invention relates to a method for measuring the activity of the blood clotting factor XIIIa, in particular for the application of test systems that have a high throughput.

#The blood clotting factor XIIIa (FXIIIa) is as transglutaminase the sole enzyme not having a protoelytic effect in the plasmatic coagulation system. The inactive proenzyme factor XIII (FXIII) circulating in the plasma is being activated by thrombin during the blood coagulation process and catalyzes cross-linking of fibrin monomer molecules and incorporation of other plasma proteins (such as α2-antiplasmin) in the fibrin network by the formation of ε-(-γ-glutamyl)-lysine compounds. Due to this effect, the mechanic strength and resistance of the fibrin clot to fibrinolytic degradation are increased.

#Apart from blood coagulation, FXIIIa has a function in wound healing processes. FXIII has also been detected in various cells (thrombocytes, macrophage) and tissues (placenta). To date, the function(s) of cellular FXIIIa is (are) less known (L. Muszbek et al.: Thromb. Res. 94, 1999, 271-305).

#The present invention is further illustrated with reference to the following four examples demonstrated in the figures.

#The figures show:

#FIG. 1: Coagulation of citrate-anticoagulated plasma with batroxobin in the presence of activated FXIII

#Coagulation of Citrate-Anticoagulated Plasma with Batroxobin in the Presence of Activated FXIII

#Activation of FXIII:

#865 μl of TRIS buffer (0.05 M; 0.154 M NaCl; pH 7.4), 25 μl of CaCl2 (0.2 M), 100 μl of thrombin (from beef plasma, 100 U/ml) and 10 μl of cellular recombinant FXIII (Aventis-Behring, Marburg, Germany; 8.6 mg/ml or 1155 U/ml) are mixed and incubated at 37° C. for 10 min. Afterwards, 25 μl of recombinant hirudin (HBW 023, Höchst, Frankfurt, Germany; 1000 E/ml) are added.