Fig. 7.

Slow conformational changes are not required upon CYT-18 binding to native E^ΔP5abc ribozyme. A, Reaction schematic. Cleavage reactions were initiated either by adding CYT-18 to pre-folded ribozyme with bound substrate, as shown, or by adding guanosine after a 15 min preincubation with CYT-18. B, Progress curves for reactions initiated by addition of CYT-18 (triangles) or guanosine (circles). The progress curves were the same within error, with rate constants of 0.47 ± 0.07 min⁻¹ and 0.37 ± 0.06 min⁻¹ respectively, and amplitudes of 0.67.