125

I-rhirudin was prepared by chloramine-T method. The affinity of rhirudin with thrombin-fibrin complex was analyzed with solid phase saturation method and competitive method. The kinetics of the rhirudin-thromb in-fibrin complex formation was studied too. Results indicated that rhirudin was able to bind with thrombin-fibrin complex as a tenary complex

but not directly with fibrinogen. The molecular binding ratio was 14:14:1 for rhirudin:thrombin:fibrinogen. The affinity constant of rhirudin with thrombin-fibrin complex was 9.72×10

6

L/mol

and the physiological Ca

2+

concentration was their optimal binding environment. The binding reaction of rhirudin with thrombin-fibrin complex could reach the equilibrium in 30 to 45 minutes. All these results indicate that rhirudin is hopefully a new ligand for thrombotic image.