FIGURE 6.
Nucleic acid binding to Dgt measured by fluorescence anisotropy. The fluorescence anisotropy (r) of a 22-mer fluorescein-labeled DNA substrate (see “Experimental Procedures”) present at 35 nm was measured. Error bars are standard deviations of triplicate measurements. The dissociation constant (Kd) of 52 ± 5 nm for binding of Dgt to DNA was obtained after fitting the data to a quadratic equation (27). The graph also shows the lack of Dgt binding to the RNA 22-mer of identical sequence, as well as the lack of DNA binding to the Dgt S34D/G37E mutant protein.