FIGURE 4.
Simultaneous fits of SK concentration and time dependences based on numerical integration. Stopped-flow time-traces of the fractional change in fluorescence (ΔF/Fo) for reactions of 10 nm [5F]FFR-Pm with 0.025, 0.030, 0.052, 0.075, 0.1, 0.2, 0.35, 0.65, 0.9, 2, 5, 7, 10, and 14 μm SK in the absence of lysine analog (A). 0.1, 0.25, 0.4, 0.9, 2, 3, 5, 7, 10, and 15 μm SK in the presence of 50 mm 6-AHA (B), and 0.5, 1, 5 and 10 μm SK in the presence of 50 mm benzamidine (C). Data were collected during 0.5-30 s, until the reactions were >99% complete, and the fluorescence was stable. Data shown represent 92-99% completion of the reactions. Solid lines represent the least-squares fits to complete time traces using the mechanism in Equation 4, with the parameters listed in Table 1. Experiments were performed, and data were analyzed as described under “Experimental Procedures” and “Results.”