Figure 4

Panel A. Fluorescence of EG (at 11.15 μM) and SG (at 11.42 μM) in response to input DNA in various media at 50°C: EG + λDNA in 100 mM Tris (open squares) or in 10 mM Tris containing 100 mM KCl (open diamonds); EG + Tbr DNA in 100 mM Tris (solid diamonds) or in 10 mM Tris containing 100 mM KCl; EG + Tbr DNA in 100 mM Tris (solid square) or in 10 mM Tris containing 100 mM KCl (solid diamond); and SG + λDNA in 100 mM Tris (solid circle). Panel B: Normalized DNA binding curves. The fluorescence of EG and SG with various DNA in 100 mM Tris pH 8.0 at 50°C was normalized to better compare the relative positions of the binding curves on the X axis. EG + λDNA (open square); EG + Tbr DNA (solid square); SG + λDNA (open triangle); and SG + Tbr DNA (solid triangle). The relative positions of the DNA binding curves show that the affinity of SG for λDNA is higher than that for Tbr DNA, and the affinities of EG for λDNA and Tbr DNA are about equal and are lower than that of SG for either type of DNA.