Fig. 3.

Binding of Zn²⁺ to the redesigned RBPs (design A, circles; design B1, squares; design B2, triangles). In each case, the emission intensity of the styryl dye conjugate increases on binding of Zn²⁺. [(Inset) Emission spectra of the apoprotein (Apo) and the Zn²⁺-saturated metalloprotein complex (Sat). Spectra are shown for design A, although all three designs show similar fluorescence response.] Observed intensities are fit to a single-site binding isotherm.