FIGURE 1.
Kinetics of I-2581 binding to prothrombin and its derivatives. Fluorescence traces were obtained using λex = 280 nm and λem >500 nm following rapid mixing of equal volumes of a 0.6 μm concentration of the indicated derivative and 4 μm I-2581 at 25 °C in Assay Buffer. The average of four to six traces acquired over a split time scale is illustrated in each case, and the fitted lines are drawn according to the following analyses: prothrombin (II), straight line with near-zero slope; thrombin (IIa), single exponential function with offset = 2.79 ± 0.002, A = 2.55 ± 0.004, and k = 59.3 ± 0.2 −−1; mIIaQQQ, three-exponential function with offset = 2.09 ± 0.002, A1 = 2.88 ± 0.02, k1 = 94.5 ± 1.3 s−1, A2 = 1.22 ± 0.02, k2 = 18.2 ± 0.5 s−1, A3 = 2.74 ± 0.01, k3 = 1.59 ± 0.01 s−1.