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. Author manuscript; available in PMC: 2011 Oct 21.
Published in final edited form as: J Am Chem Soc. 2011 Sep 8;133(39):15578–15592. doi: 10.1021/ja204650q

Figure 5.

Figure 5

Kd measurements for the class I riboswitch by 2AP fluorescence. (a) The fluorescent G94(2AP) class I RNA construct showing the fluorescent 2AP base at position 94 in the P1 helix of the aptamer domain. (b) Binding constants (Kd) of ligands were determined by monitoring the decrease in fluorescence at 360 nm with increasing concentrations of ligand. Shown here is a sample titration with the c-(Sp)-Gps-GMP analog. (c) Kd values were determined by plotting the fluorescence intensity at 360 nm verses ligand concentration and fitting the data to a quadratic equation (Eqtn. 2). The c-(Sp)-Gps-GMP binding curve is shown here as a representative example.