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. Author manuscript; available in PMC: 2008 Aug 21.
Published in final edited form as: Biochemistry. 2007 Feb 27;46(11):3193–3199. doi: 10.1021/bi6025193

Figure 6.

Figure 6

Competitive effect of fX SI95A and PC fX-Gla on wild-type fX activation by fVIIa in complex with sTF2-219 derivatives. A, fX (150 nM) was incubated with fVIIa (0.3 nM) in complex with PC/PS vesicles (0.05 mM) and sTF2-219 (100 nM) in TBS/Ca2+ in the presence of increasing concentrations of fX S195A (0.03–2 μM). Following incubation for 3–5 min at room temperature, the reactions were terminated by adding 50 mM EDTA and the rate of fXa generation was determined as described under “Materials and Methods”. B, the same as A except that PC fX-Gla was used as the competitor in the activation reactions. The symbols in both panels are: wild-type sTF2-219 (○), R200A (●), and K201A (□). The Kd(app) values, obtained from the nonlinear regression analysis of data (average of 2–3 experiments), were ~200–300 ± 20–50 nM for both competitors with all sTF2-219 derivatives.