Figure 6. IC₅₀ of cE5 for thrombin.

(a) Residual thrombin activity as a function of different cE5 concentrations. Three different concentrations of thrombin (2 nM, 5 nM and 15 nM) were incubated with increasing amounts of cE5 in the presence of the fluorogenic substrate Boc-Ile-Glu-Gly-Arg-7-amido-4-methylcoumarin hydrochloride. IC₅₀ were, respectively: 10,43 ± 1 nM for 15 nM of thrombin, 2,9 ± 0,16 nM for 5 nM of thrombin and 1,38 ± 0,09 nM for 2 nM of thrombin. (b) Residual thrombin activity as a function of the cE5/thrombin molar ratio. The IC₅₀ was achieved at a cE5/thrombin ratio of 0.7 ± 0.07 for 15 nM thrombin, 0.59 ± 0.03 for 5 nM thrombin and 0.69 ± 0.05 for 2 nM thrombin, respectively. Data represent the mean of triplicates and error bars refer to Standard Error of the Mean (SEM). The activity of thrombin in the absence of inhibitor was assumed as 100%.