FIGURE 6.

P-, Q-, and R-loops of Rho hexamer and TbCl₃ fluorescence. A, crystal structure of Rho hexamer (PDB ID 3ICE) highlighting the functionally important loops and the RNA at the central channel by the indicated colors. B, fluorescence emission spectra of TbCl₃ under different conditions as indicated. Two distinct peaks of the TbCl₃ at 488 and 547 nm are visible. C, modified Stern-Volmer plots to determine the quenching constant (K_SV) and the nature of quenching by a neutral quencher, acrylamide. F₀ and F are the fluorescence intensities of Tb(III)-GTP bound to the ATP-binding site of the WT and Rho* mutants, in the absence and presence of different concentrations of acrylamide, respectively. Average K_SV values are calculated from the initial slopes of the curves. Errors were calculated from two to three measurements.