Table 2.

Dissociation constants for the interaction between FluA, FluC, orBBP and fluorescein as well as related compounds

Ligand	Kd, μM
	FluA	FluC	BBP
Fluorescein	0.152  ±  0.024	0.418  ±  0.029	>50*
4-Aminofluorescein	0.201  ±  0.009	0.278  ±  0.044	>100*
4-Glutarylamidofluorescein	0.427  ±  0.010	0.062  ±  0.003	>100*
Pyrogallol red	10.07  ±  0.14		>100*
Phenolphthalein	>50*		>100*
Rhodamine B	>100*		3.75 ± 0.09

K_d values were determined by fluorescence titration of the purified protein with the ligand according to Materials and Methods. 

^*Binding effects were so weak that lower estimates for the K_d were derived by comparing the data with simulated binding isotherms.