Figure 4.

Cleavage reaction of the antigenomic ribozyme variants in the presence of Co²⁺, Sr²⁺ Zn²⁺, Cd²⁺ and Co(NH₃)₆³⁺. (A) Cleavage reaction of the trans(S2) ribozyme induced by Co²⁺, Sr²⁺, Zn²⁺ and Cd²⁺ at 1 mM ion concentration. The corresponding pseudo-first order rate constants k_obs and the reaction end points were 0.016 min^–1 and 67%, 0.003 min^–1 and 25%, 0.009 min^–1 and 16% and 0.006 min^–1 and 49%, respectively. (B) Cleavage reaction of the cis(L) ribozyme in the presence of 1 mM Co²⁺ or Sr²⁺. The data were fitted to an expression describing the sum of two exponentials (see Materials and Methods) and the following rate constants k′ and k″ were obtained: 4.67 and 0.29 for Co²⁺ and 0.65 and 0.02 min^–1 for the Sr²⁺-induced reaction. The reaction end points were 76 and 66% for Co²⁺- and Sr²⁺-induced cleavage. (C) Autoradiogram of cleavage of the cis(W) ribozyme in the presence of 5 mM Co²⁺ and 5 mM Co(NH₃)₆³⁺.