Figure 3.

Preferential binding of P5abc to the native R14C^ΔP5abc ribozyme. (A) To measure dissociation, radiolabeled P5abc (*P5abc) was allowed to bind to the ribozyme and then chased with unlabeled P5abc. (B) Dissociation kinetics of P5abc from a population of predominantly native R14C^ΔP5abc ribozyme (blue squares) or a mixture of native and misfolded R14C^ΔP5abc (blue circles). The mixture gave a major phase of dissociation with a rate constant of 0.0072 ± 0.0003 min⁻¹, whereas most of the P5abc remained bound to the native ribozyme on the observable time scale (up to 5 days, additional data points not shown). (C) Determination of the rate constant for P5abc dissociation from the native R14C^ΔP5abc ribozyme by extrapolation from measurements at higher temperatures (blue). Data for the E^ΔP5abc ribozyme obtained side-by-side are shown in black and were consistent with previous results (21). (D) Association kinetics of P5abc to predominantly native R14C^ΔP5abc ribozyme (blue squares) or a mixture of native and misfolded R14C^ΔP5abc ribozyme (blue circles).