Table 1.

Parameters for SC(1–246)-BODIPY and unlabeled WT SC(1–246) binding to four separate ProT^QQQ preparations

Reference titrations of SC(1–246)-BODIPY with four separate ProT^QQQ batches were obtained at two fixed probe concentrations. The competitive binding data for the ProT^QQQ preparations were obtained by titrations of fixed concentrations of SC(1–246)-BODIPY probe, and SC(1–246) as competitor, with ProT^QQQ. Data were fit simultaneously by the cubic equation to obtain the dissociation constant for ProT^QQQ and SC(1–246)-BODIPY (K_O, probe) and the competitor SC(1–246) (K_C, competitor); the stoichiometric factor for SC(1–246)-BODIPY (n) and SC(1–246) (m); and the maximum fluorescence intensity (ΔF_max/F_o). Experimental error represents ± 2 S.D. Competitive equilibrium binding studies and data analysis were performed as described under “Experimental procedures.” SF, stoichiometric factor.

SC(1–246)	SF (n or m)	KO or KC	ΔFmax/Fo
		nm
SC(1–246)-BODIPY (n)	0.90 ± 0.03	2.9 ± 0.7	0.60 ± 0.01
SC(1–246) (m)	1.10 ± 0.05	0.7 ± 0.2
SC(1–246)-BODIPY (n)	0.90 ± 0.02	5.9 ± 0.8	0.59 ± 0.01
SC(1–246) (m)	1.10 ± 0.06	1.0 ± 0.3
SC(1–246)-BODIPY (n)	1.00 ± 0.04	4.1 ± 1.1	0.57 ± 0.01
SC(1–246) (m)	1.10 ± 0.05	0.7 ± 0.2
SC(1–246)-BODIPY (n)	1.01 ± 0.06	3.0 ± 1.4	0.58 ± 0.01
SC(1–246) (m)	1.20 ± 0.08	0.6 ± 0.4