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. Author manuscript; available in PMC: 2014 Jan 8.
Published in final edited form as: Biochemistry. 2012 Dec 27;52(1):143–151. doi: 10.1021/bi301239z

Figure 4. Prothrombin activation by increasing concentration of wild type and mutant (R165A) FXa in the presence of C6PS and 5 mM Ca2+.

Figure 4

The initial rates of prothrombin activation by FXa in the presence of FVa and 400 µM C6PS at different of FXa concentrations were plotted as a function of FXa. The appearance of thrombin was determined by the rate of hydrolysis of DAPA (as described in Methods) at 37°C. The reaction was carried out at increasing concentrations of wild type FXa (closed circles) and mutant R165A FXa (open circles). The reaction mixture contained 1 µM prothrombin, FXa in 50 mM Tris, 175 nM NaCl, 0.6% poly(ethylene glycol), 5 mM Ca+2 and 400 µM C6PS. The dimerization Kds obtained in the presence of wild type and mutant FXa are 16 and 147 nM respectively.