Determination of the kinetic constants of tissue factor/factor VII/factor VIIA and antithrombin/heparin using surface plasmon resonance.
Association of factor VIIa (FVIIa) with tissue factor (TF) is generally believed to be a critical step in the initiation of blood coagulation. In this study the rate constants for the complex formation and dissociation between FVII/FVIIa and TF were studied in real time using surface plasmon resonance, the BIAcore technique. Employing this technique ka and kd were determined and yielded a KD of 1 nM for FVII and 0.5 nM for FVII, respectively. The association and dissociation between antithrombin (AT) and the FVIIa/TF complex was also studied. In the presence of heparin, AT was bound to the FVIIa/TF complex in a dose-dependent manner with ka of 2 x 10(3) M-1 s-1. The binding of AT to FVIIa/TF increased the dissociation of FVIIa from TF about 20-fold.
Björquist
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Astra Hässle AB, Mölndal, Sweden.
Boström
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D000990:Antithrombin III / Q000378:metabolism*; D001665:Binding Sites; D005167:Factor VII / Q000378:metabolism*; D015942:Factor VIIa / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D013917:Thrombin / Q000378:metabolism*; D013925:Thromboplastin / Q000378:metabolism*
D000990:Antithrombin III; D005167:Factor VII; D013925:Thromboplastin; D015942:Factor VIIa; D013917:Thrombin